This invention relates to a control device for an AC rotating machine having a current limiting function for protecting the AC rotating machine and its drive circuit from over-current.
The conventional control device for the AC rotating machine of this kind was disclosed in JP5-68398A (patent document 1). The control device for the AC rotating machine as disclosed in this patent document 1 comprises a current arithmetic circuit for computing a detected current value from each phase current flowing through the AC rotating machine, a correction frequency arithmetic circuit for computing a frequency correction value from the current set value and the detected current value in accordance with a predetermined arithmetic operation, a subtracter for subtracting the frequency correction value from a frequency command value, a voltage command arithmetic circuit for computing a voltage command value in accordance with the subtraction output of the subtracter, and voltage application means for applying a drive voltage to the AC rotating machine based on the voltage command value.
In the control device for the AC rotating machine as disclosed in the patent document 1, the detected current value is outputted by the current arithmetic circuit. If the detected current value exceeds a preset current set value, the correction frequency arithmetic circuit computes and outputs the frequency correction value by integrating at least a deviation between the detected current value and the current set value.
The frequency correction value is subtracted from a frequency command value inputted from the outside by the subtracter, and inputted as an inverter frequency into the voltage command circuit. The voltage command circuit computes a voltage command value in accordance with a preset functional relation, in which the voltage command value is outputted to the voltage application means. In the voltage application means, a drive voltage applied to the AC rotating machine is controlled to follow the voltage command value.
Herein, the correction frequency arithmetic circuit outputs the frequency correction value for correcting the frequency command value in accordance with a predetermined functional operation so that the detected current value may not exceed the current set value, irrespective of the power or regenerative state of the AC rotating machine. With such a configuration, the control device for the induction motor can protect an inverter circuit from over-current by conducting the current limiting operation which is stable not only during the normal operation but also during the hard acceleration or deceleration or the regeneration.
Patent document 1: JP5-68398A
In the control device for the AC rotating machine, the current limiting performance greatly depends on the rating or kind of the AC rotating machine and the gain of the frequency correction value arithmetic means. For example, if the gain is too low for the AC rotating machine to be driven, a transient response of the current limiting performance is worse and an over-current occurs. Conversely, if the gain is too high for the AC rotating machine to be driven, the control system becomes unstable due to influence of the control period or the carrier frequency of a power inverter. For these reasons, it is required to appropriately set the gain for the AC rotating machine to be driven to obtain the desired current limiting performance. However, a method of setting the gain was not disclosed in the patent document 1.
Because of a difference in the operation area of the AC rotating machine, especially when the AC rotating machine operates in the constant output area, there is a problem that the desired current limiting performance can not be obtained even by using a method as described in the patent document 1.
This invention has been achieved to solve the above-mentioned problem, and it is an object of the invention to obtain the reliable current limiting performance in driving the AC rotating machine with a known or unknown electrical constant, and provide the control device for the AC rotating machine in which the amplification gain in the frequency correction value arithmetic means is appropriately computed from the electrical constant of the AC rotating machine.
According to this invention, there is provided a control device for an AC rotating machine comprising current detection means for detecting a current supplied to the AC rotating machine as a detected current value, frequency correction value arithmetic means for outputting a frequency correction value, inverter frequency arithmetic means for outputting an inverter frequency based on a frequency command value and the frequency correction value, voltage command arithmetic means for computing a voltage command value in accordance with the inverter frequency, and voltage application means for applying a voltage to the AC rotating machine based on the voltage command value, wherein the frequency correction value arithmetic means comprises a current deviation computing element for outputting a current deviation based on the detected current value and a current limiting command value, a constant storage memory for storing an electrical constant of the AC rotating machine, an amplification gain computing element for computing an amplification gain by using the electrical constant of the AC rotating machine outputted from the constant storage memory, an amplifier for amplifying the current deviation outputted by the current deviation computing element based on the amplification gain computed by the amplification gain computing element to compute a frequency correction arithmetic value, and an output selector for outputting the frequency correction arithmetic value as the frequency correction value in a predetermined running state of the AC rotating machine.
With the control device for the AC rotating machine according to this invention, the amplitude of current of the AC rotating machine can be limited to the current limiting command value or less by correcting the inverter frequency if the detected current value exceeds the current limiting command value. Also, in driving the AC rotating machine with the electrical constant stored in the constant storage memory, the amplification gain can be appropriately designed, whereby the reliable current limiting performance can be obtained.
The preferred embodiments of a control device for an AC rotating machine according to the present invention will be described below in detail with reference to the drawings.
The AC rotating machine 10 is an induction motor 10I in this embodiment 1. The voltage application means 11 is a drive circuit for the AC rotating machine 10, and specifically is composed of a three-phase inverter of VVVF type, which generates a three-phase AC drive voltage Vuvw, based on a three-phase voltage command V* inputted from the voltage command means 15, and applies this three-phase AC drive voltage Vuvw to the AC rotating machine 10. The three-phase inverter of VVVF type making up the voltage application means 11, which is variable in the drive voltage V of the three-phase AC drive voltage Vuvw for output and its drive frequency f, generates the three-phase AC drive voltage Vuvw having the drive voltage V designated by the three-phase voltage command V* and the drive frequency f, and supplies this three-phase AC drive voltage Vuvw to the induction motor 10I.
The current detection means 13 comprises a current detector 131 and the three-phase/dq-axis coordinate transformer 132. The current detector 131, which is made by using a current transformer, for example, detects each phase current iu, iv, iw of three phases flowing through the induction motor 10I, based on the three-phase AC drive voltage Vuvw, and supplies each phase current to the iu, iv, iw to the three-phase/dq-axis coordinate transformer 132. The three-phase/dq-axis coordinate transformer 132, which is a coordinate transformation unit for transforming the three phase coordinates into the rotation biaxial coordinates including the orthogonal d axis and q axis, inputs a phase signal θ and generates the corresponding d-axis current value id and q-axis current value iq from each phase current iu, iv, iw, by using this phase signal θ. The three-phase/dq-axis coordinate transformer 132 generates a detected current value I, along with the d-axis current value id and the q-axis current value iq. The d-axis current value id and the q-axis current value iq are supplied to the voltage command means 15. The detected current value I is supplied to the frequency correction value arithmetic means 20. The detected current value I is made equal to the q-axis current value iq in this embodiment 1, and given in the following Numerical Expression 1.
I=iq [Numerical expression 1]
The voltage command means 15 is configured as a well-known induced voltage/drive frequency constant control system (hereinafter referred to as the (E/f) constant control system) or a well-known drive voltage/drive frequency constant control system (hereinafter referred to as the (V/f) constant control system). The (E/f) constant control system involves controlling a ratio (E/f) of the induced voltage E induced inside the AC rotating machine 10 based on the three-phase AC drive voltage Vuvw to the drive frequency f to be constant. The (V/f) constant control system involves controlling a ratio (V/f) of the drive voltage V of the three-phase AC drive voltage Vuvw to the drive frequency f to be constant. In this embodiment 1, the voltage command means 15 is configured as the (E/f) constant control system. The voltage command means 15 of this (E/f) constant control system has voltage command arithmetic means 153 of the (E/f) constant control method and a dq-axis/three-phase coordinate transformer 157.
The inverter frequency arithmetic means 17 comprises a subtracter 171. This subtracter 171 is supplied with a frequency command value ω* from the outside, and also supplied with a frequency correction value Δω from the frequency correction value arithmetic means 20. The inverter frequency arithmetic means 17 subtracts the frequency correction value Δω from the frequency command value ω* in accordance with the following Numerical Expression 2, and outputs an inverter frequency ωi.
ωi=ω*−Δω [Numerical Expression 2]
The voltage command arithmetic means 153 of the (E/f) constant control system is supplied with a d-axis current value id and a q-axis current value iq from the three-phase/dq-axis coordinate transformer 132 of the current detection means 13, and also supplied with the inverter frequency ωi from the inverter frequency arithmetic means 17. This voltage command arithmetic means 153 computes a d-axis voltage command vd* and a q-axis voltage command vq* based on the d-axis current value id, the q-axis current value iq and the inverter frequency ωi in accordance with the following Numerical Expressions 3 and 4, and supplies the d-axis voltage command vd* and the q-axis voltage command vq* to the dq-axis/three-phase coordinate transformer 157. The dq-axis/three-phase coordinate transformer 157, into which a phase signal θ is inputted, transforms the d-axis voltage command vd* and the q-axis voltage command vq* into a three-phase voltage command V*, by using this phase signal θ, and supplies this three-phase voltage command V* to the voltage application means 11.
vd*=R
1
×id [Numerical Expression 3]
vq*=(R1×iq)+(ωi×L1×id*) [Numerical Expression 4]
In the Numerical Expressions 3 and 4, R1 is a stator resistance of the induction motor 10I, and L1 is a stator inductance of it.
The frequency correction value arithmetic means 20 has six input ports 20-I1 to 20-I6, and one output port 20-O, and internally comprises a current deviation computing element 201, a constant storage memory 203, an amplification gain computing element 210, an amplifier 230, a zero value output part 231, a state signal generator 233, and an output selector 235. The input port 20-I1 is supplied with the detected current value I from the three-phase/dq-axis coordinate transformer 132 of the current detection means 13. The input port 20-I2 is supplied with a current limiting value Ilimit from the outside. The input port 20-I3 is supplied with the inverter frequency ωi. The input port 20-I4 is supplied with the frequency command value ω*. The input port 20-I5 is supplied with at least one of the inverter frequency ωi, the frequency command value ω* and the three-phase voltage command V. The input port 20-I6 is supplied with a d-axis current command id* for the AC rotating machine 10, or the induction motor 10I in this embodiment 1. This d-axis current command id*, which is an exciting current for the induction motor 10I, is used in the voltage command arithmetic means 153, and supplied from this voltage command arithmetic means 153. The output port 20-O outputs the frequency correction value Δω to the subtracter 171 of the inverter frequency arithmetic means 17.
The current deviation computing element 201 comprises a subtracter 202, and this subtracter 202 is connected to the input ports 20-I1 and 20-I2. The current deviation computing element 201 subtracts the current limiting value Ilimit from the detected current value I in accordance with the following Numerical Expression 5, and outputs a current deviation ΔI.
ΔI=I−Ilimit [Numerical Expression 5]
The constant storage memory 203 stores various kinds of electrical constants regarding the AC rotating machine 10, or the induction motor 10I in this embodiment 1. The electrical constants stored in this constant storage memory 203 include at least a leakage constant σ of the induction motor 10I, its rotor resistance R2, its rotor inductance L2 and a set value ωx of the current limiting response speed for the induction motor 10I.
The amplification gain computing element 210 comprises an amplification gain arithmetic part 213, a zero value output part 221, a switch signal generating part 223, and a switching part 225. The electrical constants σ, R2, L2 and ωx stored in the constant storage memory 203 are supplied to the amplification gain arithmetic part 213. The amplification gain arithmetic part 213 is connected to the constant storage memory 203 and the input port 20-I6. This amplification gain arithmetic part 213 computes the amplification gains G1 and G2 by using the electrical constants σ, R2, L2 and ωx supplied from the constant storage memory 203 and the d-axis current command id* supplied to the input port 20-I6 in accordance with the following Numerical Expressions 6 and 7, and supplies these amplification gains G1 and G2 to an input a of the switching part 225.
The d-axis current command id* is given by the following Numerical Expression 8.
In this expression (8), V0 is the rated voltage of the AC rotating machine 10, or the induction motor 10I in the embodiment 1, f0 is the base frequency, and Kvf is what is called a V/F transformation gain. This V/f transformation gain Kvf is given by the following Numerical Expression 9.
The zero value output part 221 supplies a zero value output to an input b of the switching part 225. The switch signal generating part 223 is connected to the input port 20-I5. The switch signal generating part 223 determines whether or not an operating range of the AC rotating machine 10, or the induction motor 10I, is in the constant torque area, based on at least one of the inverter frequency ωi, the frequency command value ω* and the three-phase voltage command V* supplied to the input port 20-I5, and generates a switch signal SS, based on this determination. The switching part 225 has the input a-connected to the amplification gain arithmetic part 213, the input b connected to the zero value output part 221 and the output c. In the state where the AC rotating machine 10, or the induction motor 10I in the embodiment 1, is run in the constant torque area, the switch signal SS enables the switching part 225 to select the input a to be output to the output c and supply the amplification gains G1 and G2 as represented in the Numerical Expressions 6 and 7 from the output c to the amplifier 230. In the state where the AC rotating machine 10, or the induction motor 10I, shifts from the constant torque area to the constant output area, the switch signal SS enables the switching part 225 to select the input b to be output to the output c and supply the zero value output from the zero value output part 221 from the output c to the amplifier 230.
In the state where the AC rotating machine 10, or the induction motor 10I, is run in the constant torque area, the amplifier 230 computes the frequency correction arithmetic value Δωa by using the amplification gains G1 and G2 supplied from the amplification gain arithmetic part 213 in accordance with the following Numerical Expression 10, and outputs this frequency correction arithmetic value Δωa to an input a of the output selector 235.
In this expression (10), s is the Laplace operator.
The zero value output part 231 outputs the zero value output to an input b of the output selector 235. The output selector 235 selects any one of the inputs a and b to be output to the output c. The output c of this output selector 235 is the frequency correction value Δω, and supplied from the output port 20-O of the frequency correction value arithmetic means 20 to the subtracter 171 of the inverter frequency arithmetic means 17. The frequency correction value Δω outputted from the output c of the output selector 235 is the frequency correction arithmetic value Δωa outputted from the amplifier 230 or the zero value output outputted from the zero value output part 231.
The state signal generator 233 is connected to the input ports 20-I1 to 20-I4, in which the detected current value I is supplied from the input port 20-I1, the current limiting value Ilimit is supplied from the input port 20-I2, the inverter frequency ωi is supplied from the input port 20-I3, and the frequency command value ω* is supplied from the input port 20-I4. This state signal generator 233 firstly compares the detected current value I with the current limiting value Ilimit, in which as a result of comparison, if the detected current value I is greater than the current limiting value Ilimit, or there is the relationship of I>Ilimit, a switch signal CS enables the output selector 235 to select the input a to output the frequency correction arithmetic value Δωa supplied to the input a as the frequency correction value Δω to the output c. Also, if the detected current value I is smaller than the current limiting value Ilimit and if the inverter frequency ωi is greater than the frequency command value w, or the relationship of ωi<ω* is negated, in the state where the output selector 235 selects the input a, the state signal CS generated by the state signal generator 233 enables the output selector 235 to select the input b to output the zero value output supplied to the input b as the frequency correction value Δω.
Herein, the phase signal θ for use in the coordinate transformation can be obtained by integrating the inverter frequency ωi as represented in the following Numerical Expression 11.
θ=∫ωidt [Numerical Expression 11]
For the three phase/dq-axis coordinate transformer 132, among the d-axis current value id and the q-axis current value iq on the rotational biaxial coordinates including the d-axis and the q-axis that are orthogonal, the d-axis current value id is a current component in phase with the phase signal θ and the q-axis current value iq is a current component in phase orthogonal to the phase signal θ. Also, for the dq-axis/three phase coordinate transformer 157, among the d-axis voltage command vd* and the q-axis voltage command vq* on the rotational biaxial coordinates including the d-axis and the q-axis that are orthogonal, the d-axis voltage command vd* is a voltage command component in phase with the phase signal θ and the q-axis voltage command vq* is a voltage command component in phase orthogonal to the phase signal θ.
Referring to
In the state where the induction motor 10I is run in the constant torque area, the running state where the current flowing through the induction motor 10I exceeds the current limiting command Ilimit may possibly occur when a hard acceleration command value or a hard deceleration command value in which the frequency command value ω* suddenly changes temporarily is given, or there is a sudden load variation such as an impact load in the induction motor 10I, for example. In such running state, the current flowing through the induction motor 10I is suppressed by adjusting the inverter frequency ωi to increase or decrease with the frequency correction value Δω.
Herein, if the current flowing through the AC rotating machine 10 exceeds the current limiting command Ilimit, the operation of adjusting the inverter frequency ωi is called a stall operation SA, and if the current flowing through the AC rotating machine 10 is not more than the current limiting command Ilimit, the operation of adjusting the inverter frequency ωi to be coincident with the frequency command value ω* is called a recovery operation RA. The frequency correction value arithmetic means 20 in the embodiment 1 has an action of automatically performing the operation of adjusting the inverter frequency ωi in the state where the induction motor 10I is run in the constant torque area, if the induction motor 10I becomes in the running state where the current flowing through the induction motor 10I exceeds the current limiting command Ilimit.
Specifically, first of all, the current deviation computing element 201 computes the current deviation ΔI in accordance with the Numerical Expression 5. The amplifier 230 computes the frequency correction arithmetic value Δωa corresponding to a current excess amount of the induction motor 10I in accordance with the Numerical Expression 10 in the state where the AC rotating machine 10, or the induction motor 10I, is run in the constant torque area, because the switching part 225 outputs the amplification gains G1 and G2 computed in the amplification gain arithmetic part 213. The state signal generator 233 firstly compares the detected current value with the current limiting value Ilimit, then compares the inverter frequency ωi with the frequency command value ω*, and generates the state signal CS. Based on the state signal CS, the output selector 235 outputs the zero value output from the zero value output part 231 in the normal running state, or outputs the frequency correction arithmetic value Δωa in the running state where the current flowing through the induction motor 10I exceeds the current limiting command Ilimit.
In this way, the state signal generator 233 controls the switching of the output of the output selector 235 between the zero value output and the frequency correction arithmetic value Δωa, whereby the current limiting operation as shown in
Proceeding from step S12 to step S13, the state signal generator 233 makes a determination again at step S13 whether or not the detected current value I is greater than the current limiting command Ilimit. If the determination result is yes, the operation goes to step S14, where the stall operation SA is executed. If the stall operation SA is ended at this step S14, the operation returns to step S13 again. If the determination result at step S13 is no, the operation goes to step S15, where the recovery operation RA is executed. If the recovery operation RA at this step S15 is ended, the operation advances to step S16.
At step S16, the state signal generator 233 makes a determination whether or not the inverter frequency ωi is smaller than the frequency command value ω*. If the inverter frequency ωi is greater than the frequency command value ω*, and so the determination result at step S16 is no, the operation goes to step S17, where the output selector 235 selects the zero value output of the input b, and the operation returns to step S11. If the determination result at step S16 is yes, the operation returns to step S13.
With this flowchart of
In this way, if the detected current value I exceeds the current limiting command value Ilimit, the inverter frequency ωi is corrected with the frequency correction arithmetic value Δωa, whereby the current amplitude of the induction motor 10I can be limited to the current limiting command value Ilimit or less, or otherwise, the frequency correction value Δω of the frequency correction value arithmetic means 20 is made the zero value, whereby the induction motor 10I can be controlled at the frequency coincident with the frequency command value ω*.
The operation of correcting the inverter frequency ωi with the frequency correction value Δω and suppressing the current of the induction motor 10I to the current limiting command value Ilimit or less is persistently limited to the case where the amplification gains G1 and G2 of the amplifier 230 are appropriately set. For example, if the amplification gains G1 and G2 of the amplifier 230 are set to be extremely low, a sudden increase in the current amplitude can not be suppressed, so that an excess current flows through the induction motor I. Also, if the amplification gains G1 and G2 of the amplifier 230 are set to be extremely large, for example, the entire control system becomes unstable. In such a case, there is a problem that the inverter making up the voltage application means 11 may trip.
Next, the amplification gain computing element 210 will be described below. The amplification gain computing element 210 computes the amplification gains G1 and G2 for use in the amplifier 230 based on the electrical constants inputted from the constant storage memory 203 storing the electrical constants of the induction motor 10I and sets these amplification gains G1 and G2 to the amplifier 230 in the state where the induction motor 10I is run in the constant torque area. It is an important feature of the embodiment 1 that the amplification gains G1 and G2 are appropriately set by using the electrical constants of the induction motor 10I inputted from the constant storage memory 203.
In the embodiment 1, the amplification gains G1 and G2 of the amplifier 230 used to compute the frequency correction arithmetic value Δωa corresponding to the current excess amount of the induction motor 10I are computed as the appropriate gains for limiting the current flowing through the induction motor 10I, based on the electrical constants of the induction motor 10I, in the state where the induction motor 10I is run in the constant torque area, and the amplification gains of the amplifier 230 are automatically set by the computed amplification gains G1 and G2. This amplifier 230 computes the frequency correction arithmetic value Δωa by using the amplification gains G1 and G2 set at the appropriate values in accordance with the Numerical Expression 10, whereby the problem that the excess current may flow through the induction motor 10I or the problem that the entire control system becomes unstable is solved. If the current flowing through the induction motor 10I exceeds the current limiting command value the current flowing through the induction motor 10I is suppressed with the speed corresponding to the set value ωx of the current limiting response speed included in the Numerical Expressions 6 and 7.
As described above, in the embodiment 1, by using the frequency correction value arithmetic means 20, the amplification gains G1 and G2 of the amplifier 210 can be appropriately designed and automatically set for the induction motor 10I to be driven, when the induction motor 10I with the known electrical constants is driven in the state where the induction motor 10I is run in the constant torque area, and the current flowing through the induction motor 10I can be securely suppressed with the arbitrary set value ωx of current limiting response speed, whereby the problem that the excess current may flow through the induction motor 10I or the problem that the entire control system becomes unstable is solved.
Next, the principle of deriving the Numerical Expressions 6 and 7 that are operation expressions for computing the amplification gains G1 and G2 of the amplifier 230 will be described below.
The detected current value I is outputted from block 31 representing the transfer characteristic GIM, and this detected current value I is supplied to the subtracter 202. This detected current value I is I=iq, in which this detected current value I means the output current from the voltage application means 11. This current is also supplied to block 33 indicating the mechanical system of the AC rotating machine 10, and the rotational frequency ωr of the AC rotating machine 10 is outputted from the block 33. The current deviation ΔI is inputted from the subtracter 202 into block 32 representing the transfer characteristic GPI, and the frequency correction value Δω is outputted from block 32 to the subtracter 171. The subtracter 171 outputs the inverter frequency ωi to the subtracter 34. This subtracter 34, which is equivalently inserted on the input side of block 31, subtracts the rotational frequency ωr of the AC rotating machine 10 from the inverter frequency ωi and inputs its subtraction output into block 31.
The current limiting performance of the control system in the embodiment 1 is decided by the amplification gains G1 and G2 of the amplifier 230, and the appropriate values of the amplification gains G1 and G2 can be obtained from the characteristic of the transfer function GIMSYS from the frequency correction value Δω to the output current I=iq as shown in
The output phase characteristic of
In
Thus, as the transfer characteristic GIMSYS≈GIM, the transfer characteristic GIM is derived by linearizing a voltage equation of the induction motor 10I in the following way. First of all, the q-axis current value iq, represented from the voltage equation of the induction motor 10I, is given in the following Numerical Expression 12.
In the Numerical Expression 12, id is the d-axis current value of the induction motor 10I, R1 is the stator resistance of the induction motor 10I, iq is the q-axis current value of the induction motor 10I, R2 is the rotor resistance of the induction motor 10I, φd2 is the d-axis component of the rotor magnetic flux of the induction motor 10I, L1 is the stator inductance of the induction motor 10I, vq is the q-axis voltage of the stator voltage of the induction motor 10I, L2 is the rotor inductance of the induction motor 10I, σ is the leakage constant of the induction motor 10I, M is the mutual inductance of the induction motor 10I, ωr is the rotational frequency (electrical angle) of the induction motor 10I, and ωi is the inverter frequency (electrical angle) of the induction motor 10I.
Herein, a steep characteristic change near the inverter frequency ωi in the transfer characteristic of the induction motor 10I is caused by an interference characteristic between d-axis and q-axis. In the Numerical Expression 12 representing the q-axis current value iq, the second term contains the d-axis current value id, and the second term is the interference component between d-axis and q-axis. Accordingly, the transfer characteristic without consideration for the steep characteristic change near the inverter frequency ωi can be derived by making the second term of the Numerical Expression 12 zero. Herein, if by making the second term of the Numerical Expression 12 zero, and vq=vq* in additionally assuming an ideal power source, the following Numerical Expression 13 can be obtained.
Also, the voltage operation expression of the q-axis voltage command vq* is the Numerical Expression 4, and substituting the Numerical Expression 4 into the Numerical Expression 13 yields the following Numerical Expression 14.
From this Numerical Expression 14, the following Numerical Expression 15 is obtained.
Accordingly, based on the Numerical Expression 15, the DC gain K of the transfer characteristic G from the inverter frequency ωi to the q-axis current value iq and the frequency 1/T at bended point are given in the following Numerical Expressions 16 and 17, respectively.
The DC gain K of the transfer characteristic GIM is illustrated by the dotted line parallel to the horizontal axis of
The relational expression between the frequency correction value Δω and the inverter frequency ωi as shown in
Next, the amplification gains G1 and G2 of the amplifier 230 are set so that the current limiting response speed at the time of limiting the current may be ωx, by using the above transfer characteristic GIM. From the Numerical Expression 10, the transfer characteristic GPI of the amplifier 230 is given by the following Numerical Expression 18. Herein, the current limiting response speed at the time of limiting the current becomes ωx by setting the amplification gains G1 and G2 so that the open loop transfer characteristic of GIM×GPI may be ωx/s.
From the relational expression of the following Numerical Expression 19, the amplification gains G1 and G2 of the amplifier 230 can be obtained in the following Numerical Expressions 20 and 21. The Numerical Expression 6 is obtained from the Numerical Expression 20, and the Numerical Expression 7 is obtained from the Numerical Expression 21.
As described above, in the Numerical Expression 10 that is the operation expression of the frequency correction arithmetic value Δωa in the amplifier 230, the current limiting response speed at the time of limiting the current can be made the set value ωx by using the amplification gains G1 and G2 as shown in the Numerical Expressions 6 and 7.
Also, when the frequency 1/T at bended point in the transfer characteristic GIM of the induction motor 10I is sufficiently small, that is equal to or less than one-fifth of the current limiting response speed set value ωx, the operation expression of the amplification gain G2 uses the following Numerical Expression 22, instead of the Numerical Expressions 7 and 21, whereby the amplification gain in the low frequency area can be increased to improve the characteristic.
As described above, in the state where the AC rotating machine 10, or the induction motor 10I in the embodiment 1, is run in the constant torque area, the running state where the current flowing through the induction motor 10I exceeds the current limiting command Ilimit may possibly occur when a hard acceleration command value or a hard deceleration command value in which the frequency command value ω* suddenly changes temporarily is given, or there is a sudden load change such as an impact load in the induction motor 10I, for example. Accordingly, as an indicator of setting the set value ωx of the current limiting response speed at the time of limiting the current, it is desirable that the design value ωx of the current limiting response speed at the time of limiting the current is set to be above or at the inverter frequency ωi, or as high as possible, in order to securely limit the current flowing through the induction motor 10I within the current limiting command Ilimit against this sudden current change.
In
On the other hand, if the inverter frequency ωi is increased with the ratio of (E/f) or (V/f) kept constant until the inverter frequency ωi reaches a base frequency, the drive voltage V can not be increased because of the constraints of the power source, so that the operation is out of the constant torque area CTA, and if the drive frequency f is raised with this drive voltage V kept constant, the input of the AC rotating machine 10 is constant and the torque is inversely proportional to the inverter frequency ωi, whereby the constant output operation in which the output is almost constant is enabled. The area where such constant output operation is performed is the constant output area COA.
Though in the embodiment 1, the AC rotating machine 10 is the induction motor 10I, the transfer characteristic GIM as described in this embodiment 1 is the characteristic for the constant torque area CTA, and the amplification gains G1 and G2 in the Numerical Expressions 6 and 7 and the Numerical Expressions 20 and 21 are also appropriate in the constant torque area CTA, but inappropriate values in the constant output area COA. Therefore, in the embodiment 1, the switching part 225 selects the zero value output from the zero value output part 221 in the state where the induction motor 10I is run in the constant output area COA by the switch signal SS of the switch signal generating part 223, thereby making the amplification gains G1 and G2 of the amplifier 230•zero and making the frequency correction arithmetic value Δωa of the amplifier 230 zero. Consequently, it is effective that the current flowing through the induction motor 10I is limited to the set value ωx of the current limiting response speed in the state where the induction motor 10I is run in the constant torque area CTA in the embodiment 1.
Though in the embodiment 1, the AC rotating machine 10 is the induction motor 10I, the AC rotating machine 10 is not limited to it, but may be any other AC rotating machine, for example, the synchronous motor 10S, to achieve the same effects.
In the modification 1A as shown in
ωi=ω*−Δω−ωhigh [Numerical Expression 23]
The voltage command means 15A in the modification 1A, like the embodiment 1, relies on an (E/f) constant control system, and has voltage command arithmetic means 154 of the (E/f) constant control system and the dq-axis/three phase coordinate transformer 157. The voltage command arithmetic means 154 computes the d-axis voltage command vd* and the q-axis voltage command vq* based on the inverter frequency ωi from the inverter frequency arithmetic means 17A and the d-axis current value id and the q-axis current value iq from the three phase/dq-axis coordinate transformer 132 of the current detection means 13 in accordance with the following Numerical Expressions 24 and 25, and outputs them.
vd*=R×id [Numerical Expression 24]
vq*=R×iq+ω
i×φf [Numerical Expression 25]
In the Numerical Expressions 24 and 25, R is the armature resistance [Ω] of the synchronous motor 10S, and φf is the magnetic flux of magnet [Wb] of the synchronous motor 10S.
In the modification 1A, the amplification gain arithmetic part 213 of the frequency correction value arithmetic means 20 computes the amplification gains G1 and G2 in accordance with the following Numerical Expressions 26 and 27.
In these Numerical Expressions 26 and 27, Lq is the q-axis inductance [H] of the synchronous motor 10S, Kh is the gain of the stabilization high pass filter 40, and ωx is the set value of the current limiting response speed. The electrical constants regarding the synchronous motor 10S, specifically, the q-axis inductance Lq of the synchronous motor 10S, the magnetic flux of magnet φf, the gain Kh of the stabilization high pass filter 40 and the set value ωx of the current limiting response speed, are stored in the constant storage memory 203, and supplied to the amplification gain arithmetic part 213.
The principle of deriving the Numerical Expressions 26 and 27 in the modification 1A will be described below. In this modification 1A, the following Numerical Expressions 28 to 32 are substituted for the Numerical Expressions 13 to 17. First of all, in the modification 1A, the q-axis current value iq of the synchronous motor 10S is given by the following Numerical Expression 28. This Numerical Expression 28 is the substitute for the Numerical Expression 13 in the embodiment 1.
Substituting the Numerical Expression 25 into the q-axis voltage command vq* of the Numerical Expression 28 yields the following Numerical Expression 29. This Numerical Expression 29 is the substitute for the Numerical Expression 14 in the embodiment 1.
From this Numerical Expression 29, the following Numerical Expression 30 is obtained. This Numerical Expression 30 is the substitute for the Numerical Expression 15 in the embodiment 1.
From this Numerical Expression 30, the DC gain K of the transfer characteristic and the frequency 1/T at bended point are represented as in the following Numerical Expressions 31 and 32, respectively. These Numerical Expressions 31 and 32 are the substitute for the Numerical Expressions 16 and 17 in the embodiment 1.
Based on the Numerical Expressions 31 and 32, in the modification 1A, the amplification gains G1 and G2 are given by the following Numerical Expressions 33 and 34. These Numerical Expressions 33 and 34 are the numerical expressions corresponding to the Numerical Expressions 20 and 21 in the embodiment 1, and the Numerical Expressions 26 and 27 are obtained from these Numerical Expressions 33 and 34.
In this modification 1A, like the embodiment 1, using the frequency correction value arithmetic means 20, the amplification gains G1 and G2 of the amplifier 230 can be appropriately designed and automatically set for the synchronous motor 10S to be driven, when the synchronous motor 10S with the known electrical constants is driven in the state where the synchronous motor 10S is run in the constant torque area CTA, and the current flowing through the synchronous motor 10S can be securely suppressed with the arbitrary set value ωx of current limiting response speed, whereby the problem that the excess current may flow through the synchronous motor 10S or the problem that the entire control system becomes unstable is solved.
In the embodiment 2, the voltage command arithmetic means 155 outputs the d-axis voltage command vd*=0 based on the following Numerical Expression 35, computes the q-axis voltage command vq*, based on the q-axis current value iq from the current detection means 13 and the inverter frequency ωi from the inverter frequency arithmetic means 17 in accordance with the following Numerical Expression 36, and supplies the d-axis voltage command vd* and the q-axis voltage command vq* to the dq-axis/three phase coordinate transformer 157.
vd*=0 [Numerical Expression 35]
vq*=ω
j
×L
i
×id* [Numerical Expression 36]
In the Numerical Expression 36, id* is the d-axis current command, or the command value of exciting current for the induction motor 10I. This d-axis current command id* is changed corresponding to the specifications of the induction motor 10I if they are different, but if the specifications of the induction motor 10I are fixed, it is the constant value. In this embodiment 2, the d-axis voltage command vd* is 0 as shown in the Numerical Expression 35, and additionally if the specifications of the induction motor 10I are decided, the d-axis current command id* is also the constant value. As will be clear from the Numerical Expression 36, the q-axis voltage command vq* is changed in proportion to the inverter frequency ωi, and consequently controlled so that the ratio of the drive voltage V to the drive frequency f from the voltage application means 11 may be kept constant, whereby the control is made by the (V/f) constant control system.
In this embodiment 2, the amplification gain arithmetic part 213 of the amplification gain computing element 210 in the frequency correction value arithmetic means 20 computes the amplification gains G1 and G2 in accordance with the following Numerical Expressions 37 and 38, and supplies these amplification gains G1 and G2 to the amplifier 230 as the gains for amplifier in the state where the induction motor 10I is run in the constant torque area.
In this embodiment 2, the leakage constant σ of the induction motor 10I, the stator resistance R1, the stator inductance L1, and the set value ωx of the current limiting response speed are supplied from the constant storage memory 203 to the amplification gain arithmetic part 213, and the d-axis current command id* is supplied via the input port 20-I6 from the voltage command arithmetic means 155 to the amplification gain arithmetic part 213. The amplification gain arithmetic part 213 computes the amplification gains G1 and G2 based on these σ, R1, L1, ωx and id* in accordance with the Numerical Expressions 37 and 38, and supplies them to the amplifier 230.
In the embodiment 2, the amplifier 230 computes the frequency correction arithmetic value Δωa by using the amplification gains G1 and G2 in accordance with the Numerical Expression 10 in the state where the induction motor 10I is run in the constant torque area, thereby achieving the same effects as the embodiment 1.
The ground of deriving the operation expressions 37 and 38 of the amplification gains G1 and G2 in the embodiment 2 includes substituting the q-axis voltage command vq* given by the Numerical Expression 36 into the Numerical Expression 13, and expanding the expressions similar to the Numerical Expressions 14 to 23, whereby the Numerical Expressions 37 and 38 are obtained.
That is, in the embodiment 2, first of all, substituting the Numerical Expression 36 into the Numerical Expression 13 yields the following Numerical Expression 39.
From this Numerical Expression 39, the following Numerical Expression 40 is obtained.
Accordingly, the DC gain K of the transfer characteristic GIM from the inverter frequency ωi to the q-axis current value iq and the frequency at bended point are obtained from the Numerical Expression 40 as in the following Numerical Expressions 41 and 42.
Substituting the Numerical Expressions 41 and 42 into the Numerical Expression 20 yields the following Numerical Expression 43, and substituting the Numerical Expression 42 into the Numerical Expression 21 yields the following Numerical Expression 44.
In the Numerical Expression 44, because R1×L2(1−σ)×R2×L1, (1−σ)×R2×L1 is regarded as 0. The Numerical Expression 37 is obtained from the Numerical Expression 43, and the Numerical Expression 38 is obtained from the Numerical Expression 44. In the embodiment 2, the amplification gains G1 and G2 are computed in accordance with the Numerical Expressions 37 and 38, thereby achieving the same effects as the embodiment 1.
As described above, in the embodiment 2, the current limiting response speed at the time of limiting the current can be made the set value ωx, by using the amplification gains G1 and G2 as shown in the Numerical Expressions 37 and 38 in the Numerical Expression 10 that is the operation expression of the amplifier 230 in the state where the induction motor 10I is run in the constant torque area.
Though in the embodiment 2, the AC rotating machine 10 is the induction motor 10I, the AC rotating machine 10 is not limited to it, but may be any other AC rotating machine, for example, the synchronous motor 10S, to achieve the same effects.
In the modification 2A of the embodiment 2 as shown in
The voltage command means 15C in the modification 2A is configured as the voltage command means of the (V/f) constant control system, and has voltage command arithmetic means 156 of the (V/f) constant control system and the dq-axis/three phase coordinate transformer 157 as shown in
vd*=0 [Numerical Expression 45]
vq=ω
i×φf [Numerical Expression 46]
In the Numerical Expression 46, φf is the magnetic flux of magnet [Wb] of the synchronous motor 10S.
In the modification 2A of the embodiment 2, the amplification gain arithmetic part 213 of the frequency correction value arithmetic means 20 computes the amplification gains G1 and G2 in accordance with the following Numerical Expressions 47 and 48.
In these Numerical Expressions 47 and 48, Lq is the q-axis inductance [H] of the synchronous motor 10S, R is the armature resistance [Ω], Kh is the gain of the stabilization high pass filter 40, and ωx is the same set value of the current limiting response speed as used in the embodiment 2. The electrical constants regarding the synchronous motor 10S, specifically, the q-axis inductance Lq of the synchronous motor 10S, the magnetic flux of magnet φf, the armature resistance R, the gain Kh of the stabilization high pass filter 40 and the set value ωx of the current limiting response speed, are stored in the constant storage memory 203, and supplied to the amplification gain arithmetic part 213.
The Numerical Expressions 47 and 48 in the modification 2A are derived in the same way as the Numerical Expressions 33 and 38 in the modification 1A of the embodiment 1, though the explanation for the principle of deriving them is omitted. In this modification 2A, by using the frequency correction value arithmetic means 20, the amplification gains G1 and G2 of the amplifier 210 can be appropriately designed and automatically set for the synchronous motor 10S to be driven, when the synchronous motor 10S with the known electrical constants is driven in the state where the synchronous motor 10S is run in the constant torque area, and the current flowing through the synchronous motor 10S can be securely suppressed with the arbitrary set value ωx of current limiting response speed, whereby the problem that the excess current may flow through the synchronous motor 10S or the problem that the entire control system becomes unstable is solved.
Though in the embodiment 1 and its modification 1A, as well as the embodiment 2 and its modification 2A, the current detection means 13 detects all the three phase currents iu, iv and iw flowing through the AC rotating machine 10, two phase currents of these three phase currents may be detected, for example, or bus currents of the voltage application means 11 may be detected, and the three phase currents flowing through the AC rotating machine 10 may be detected based on the detected value of the bus currents. Furthermore, for the detected current value I that is outputted to the frequency correction value arithmetic means 20, I=iq, but the effective values of the three phase currents flowing through the AC rotating machine 10 may be outputted by computing the detected current value I in accordance with the following Numerical Expression 49, or the bus currents of the voltage application mean 11 may be detected and outputted.
I=√{square root over (id2+iq2)} [Numerical Expression 49]
The frequency correction value arithmetic means 20A in the embodiment 3 has five input ports 20-I1 to 20-I5, and one output port 20-O. In this frequency correction value arithmetic means 20A, the input port 20-I6 in the frequency correction value arithmetic means 20 of the embodiment 1 is deleted. In the same way as the embodiment 1, the input port 20-I1 is supplied with the detected current value I from the three-phase/dq-axis coordinate transformer 132 of the current detection means 13, the input port 20-I2 is supplied with the current limiting value Ilimit from the outside, the input port 20-I3 is supplied with the inverter frequency ωi, the input port 20-I4 is supplied with the frequency command value ω*, and the input port 20-I5 is supplied with at least one of the inverter frequency ωi, the frequency command value ω* and the three-phase voltage command V. Also, the output port 20-O supplies the frequency correction value Δω to the subtracter 171 of the inverter frequency arithmetic means 17.
The frequency correction value arithmetic means 20A in the embodiment 3 internally comprises the current deviation computing element 201, the constant storage memory 203, an amplification gain computing element 210A, the amplifier 230, the zero value output part 231, the state signal generator 233, and the output selector 235. The current deviation computing element 201, the constant storage memory 203, the amplifier 230, the zero value output part 231, the state signal generator 233, and the output selector 235 in the embodiment 3 are configured in the same way as the embodiment 1. The amplification gain computing element 210A is substituted for the amplification gain computing element 210 of the embodiment 1. The amplification gain computing element 210A in the embodiment 3 has an amplification gain arithmetic part 214, the zero value output part 221, the switch signal generating part 223, and the switching part 225. The amplification gain arithmetic part 214 is connected to the input b of the switching part 225, and the zero value output part 221 is connected to the input port a of the switching part 225.
The amplification gain arithmetic part 214 in the embodiment 3 is supplied with the inverter frequency ωi from the input port 20-I3, and the electrical constants of the induction motor 10I from the constant storage memory 203. This amplification gain arithmetic part 214 computes the amplification gains G1 and G2 of the amplifier 230 based on the inverter frequency ωi and the electrical constants of the induction motor 10I in accordance with the following Numerical Expressions 50 and 51, and supplies the amplification gains G1 and G2 to the amplifier 230.
In the Numerical Expressions 50 and 51, a is the leakage constant of the induction motor 10I, R1 is the stator resistance, R2 is the rotor resistance, L1 is the stator inductance, V0 is the rated voltage of the induction motor 10I, and ωi is the inverter frequency. The leakage constant σ of the induction motor 10I, the stator resistance R1, the rotor resistance R2, stator inductance L1, and the rated voltage V0 are stored in the constant storage memory 203, and supplied to the amplification gain arithmetic part 214. The inverter frequency ωi is supplied from the input port 20-I3 to the amplification gain arithmetic part 214.
When the AC rotating machine 10 is driven by the voltage application means 11 made up using the inverter, the operating area of the AC rotating machine 10 includes the constant torque area CTA and the constant output area COA, as shown in
In the state where the induction motor 10I is run in the constant output area COA, the amplification gain computing element 210A computes the gains G1 and G2 of the amplifier 230 in accordance with the Numerical Expressions 50 and 51.
With the frequency correction value arithmetic means 20A configured in this way, when the induction motor 10I with the known electrical constants is driven, the amplification gains G1 and G2 of the amplifier 230 can be appropriately designed and set online for the induction motor 10I to be driven in the constant output area COA, whereby the current flowing through the induction motor 10I can be suppressed to the set value ωx of the current limiting response speed. Thereby, the desired current limiting performance can be attained in the state where the induction motor 10I is run in the constant output area COA. In the embodiment 3, the switching part 225 of the amplification gain arithmetic means 210A outputs the zero value from the zero value output part 221 to the amplifier 230 in the state where the AC rotating machine, or the induction motor 10I, is run in the constant torque area CTA.
In this embodiment 3, the set value ωx of the current limiting response speed is given by the following Numerical Expression 52.
The set value ωx of this current limiting response speed may be stored as the set value of ωx in the constant storage memory 203, or computed by the amplification gain arithmetic part 214 from the stator resistance R1, the stator inductance L1 and the leakage constant σ which are stored in the constant storage memory 203.
Next, the principle of deriving the Numerical Expressions 50 and 51 that are design expressions of the amplification gains G1 and G2 of the amplifier 230 in the constant output area COA will be described below. The processes of deriving the Numerical Expressions 50 and 51 are to design the amplification gains G1 and G2 of the amplifier 230 in the constant output area COA from the transfer characteristic GIM of the induction motor 10I driven in the constant output area COA as in the embodiment 1.
The output phase characteristic of
In
From
The transfer characteristic GIM in the constant output area COA can be described as in the following Numerical Expression 53 by linearizing a voltage equation of the induction motor 10I as vq*=V0.
In the Numerical Expression 53, all the constants are values decided from the electrical constants of the induction motor 10I.
Though in the embodiment 1, the high response current limiting can be realized by setting the current limiting response speed ωx at the time of limiting the current in a frequency range higher than the inverter frequency ωi, the transfer characteristic GIM in the constant output area COA is not the first-order lag characteristic because the output magnitude suddenly falls at an inclination of −20 dB/decade or less as shown in
In the embodiment 3, the gains of the amplifier 230 are designed in a frequency band below the inverter frequency ωi indicating the first-order lag characteristic in
The Numerical Expression 53, like the Numerical Expression 15, is approximated by K/(1+T×s). In this case, first of all, the Laplace operator s in the Numerical Expression 53 is made zero, whereby the following Numerical Expression 54 is obtained to give the DC gain K.
Also, if the first-order lag characteristic contained in the Numerical Expression 53 is extracted, this first-order lag characteristic is represented in the following Numerical Expression 55.
The transfer characteristic GIM approximated by the first-order lag characteristic is a combination of the Numerical Expressions 54 and 55, and the reciprocal of σ×L1/R1 included in the denominator of the Numerical Expression 55 becomes the frequency 1/T at bended point. That is, the frequency 1/T at bended point is given by the following Numerical Expression 56.
From the Numerical Expressions 55 and 56, the amplification gains G1 and G2 in the embodiment 3 are given by the following Numerical Expressions 57 and 58 in the same way as the Numerical Expressions 20 and 21.
Herein, considering the characteristic of the transfer function GIM in the constant output area COA, the set value ωx of the current limiting response speed at the time of limiting the current is set to a smaller frequency than the inverter frequency ωi in the Numerical Expressions 57 and 58, whereby the stability can be secured. A rough estimate of setting the set value ωx of the current limiting response speed may be about one-fifth of the inverter frequency ωi. Further, in the characteristic of the transfer characteristic GIM in the constant output area COA as shown in
Accordingly, if the gains G1 and G2 of the amplifier 230 are designed in consideration of the transfer characteristic GIM in the constant output area COA, substituting the Numerical Expression 52 into the Numerical Expressions 57 and 58 yields the Numerical Expressions 50 and 51.
If the frequency (1/T)=R1/(σ×L1) at bended point in first-order lag characteristic does not remote from the inverter frequency ωi with a distance which is equal to or more than one-fifth of the inverter frequency ωi, the set value ωx of the current limiting response speed is designed as ωx=ωi/5, whereby the stabilization can be made. At this time, substituting ωx=ωi/5 into the Numerical Expressions 50 and 51 for designing the gains G1 and G2 of the amplifier 230 yields the following Numerical Expressions 59 and 60.
In this way, if the current of the induction motor 10I driven in the constant output area COA is limited to the current limiting command value Ilimit, the reliable current limiting performance can be attained by using the above-mentioned amplifier gains according to the inverter frequency ωi to drive the induction motor 10I. Though in the embodiment 3, the inverter frequency ωi is used to compute the gains G1 and G2, the frequency command value ω* may be used, instead of the inverter frequency ωi, to achieve the same effects.
Though in the embodiment 3, the AC rotating machine 10 is the induction motor 10I, in this modification 3A, the AC rotating machine 10 in the embodiment 3 is replaced with any other AC rotating machine, for example, the synchronous motor 10S.
In the modification 3A of the embodiment 3, the Numerical Expressions 50 and 51 as well as the Numerical Expressions 59 and 60 in the embodiment 3 are changed corresponding to the synchronous motor 10S, to compute the amplification gains G1 and G2, and the amplification gains G1 and G2 are supplied to the amplifier 230 in the state where the synchronous motor 10S is run in the constant output area COA. In the modification 3A of the embodiment 3, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2, thereby achieving the same effects.
The voltage command means 15B in the embodiment 4 is the same as the embodiment 2 as shown in
In the embodiment 4, like the embodiment 3, the amplification gain arithmetic part 214 of the frequency correction value arithmetic means 20A computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 50 and 51 or the Numerical Expressions 59 and 60, and supplies these amplification gains G1 and G2 to the amplifier 230 in the state where the induction motor 10I is run in the constant output area COA, thereby achieving the same effects as the embodiment 3. In the embodiment 4, in computing the gains G1 and G2, the frequency command value ω* may be used, instead of the inverter frequency ωi, thereby achieving the same effects.
Though in the embodiment 4, the AC rotating machine 10 is the induction motor 10I, in this modification 4A the AC rotating machine 10 in the embodiment 4 is any other AC rotating machine, for example, the synchronous motor 10S.
The stabilization high pass filter 40 in this modification 4A is the same as the stabilization high pass filter 40 in the modification 2A as shown in
In the modification 4A of this embodiment 4, the Numerical Expressions 50 and 51 as well as the Numerical Expressions 59 and 60 in the embodiment 3 are changed corresponding to the synchronous motor 10S, to compute the amplification gains G1 and G2, whereby the amplification gains G1 and G2 are supplied to the amplifier 230 in the state where the synchronous motor 10S is run in the constant output area COA. In the modification 4A of the embodiment 4, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2, thereby achieving the same effects.
The frequency correction value arithmetic means 20B for use in the embodiment 5 has amplification gain computing element 210B which is substituted for the amplification gain computing element 210 in the frequency correction value arithmetic means 20 in the embodiment 1 as shown in
The amplification gain computing element 210B for use in the embodiment 5 has a first amplification gain arithmetic part 211, a second amplification gain arithmetic part 212, the switch signal generating part 223, and the switching part 225. The switch signal generating part 223 and the switching part 225 are the same as used in the embodiment 1 as shown in
The second amplification gain arithmetic part 212 is configured by using the same amplification gain arithmetic part 214 as used in the frequency correction value arithmetic means 20A as shown in
In the embodiment 5 as shown in
In the embodiment 5 as shown in
Consequently, the frequency correction value arithmetic means 203 in the embodiment 5 performs the same operation as the amplifier 230 in the embodiment 1 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 213 in the state where the induction motor 10I is run in the constant torque area, and performs the same operation as the amplifier 230 in the embodiment 3 amplifies the current deviation ΔI using the amplification gains G1 and G2 with the amplification gain arithmetic part 214 in the state where the induction motor 10I is run in the constant output area COA. Accordingly, the current flowing through the induction motor 10I can be limited to the current limiting value Ilimit or less, irrespective of whether the induction motor 10I is run in the constant torque area CTA or the constant output area COA.
In this way, with the embodiment 5, when the induction motor 10I is driven at variable speed in a wide speed range from the constant torque area CTA to the constant output area COA, the current limiting can be securely performed. Also, the gains G1 and G2 of the amplifier 230 are switched while the components of the control system are unchanged, whereby the program for installing the control system can be simplified. In the embodiment 5, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2 with the amplification gain arithmetic part 214, thereby achieving the same effects.
The voltage command means 15A in the modification 5A is configured as the voltage command means of the (E/f) constant control system as in the modification 1A of the embodiment 1 as shown in
In this modification 5A, the same frequency correction value arithmetic means 20B as shown in
Consequently, the frequency correction value arithmetic means 20B in the modification 5A of the embodiment 5 performs the same operation as the amplifier 230 in the modification 1A of the embodiment 1 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 213 in the state where the synchronous motor 10S is run in the constant torque area CTA, and performs the same operation as the amplifier 230 in the modification 3A of the embodiment 3 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 214 in the state where the synchronous motor 10S is run in the constant output area COA. Accordingly, the current flowing through the synchronous motor 10S can be limited to the current limiting value Ilimit or less, irrespective of whether the synchronous motor 10S is run in the constant torque area CTA or the constant output area COA.
In this way, with the modification 5A of the embodiment 5, when the synchronous motor 10S is driven at variable speed in a wide speed range from the constant torque area CTA to the constant output area COA, the current limiting can be securely performed. Also, the gains G1 and G2 of the amplifier 230 are switched with the components of the control system unchanged, whereby the program for installing the control system can be simplified. In the modification 5A of the embodiment 5, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2 with the amplification gain arithmetic part 214, thereby achieving the same effects.
In this embodiment 6, the same frequency correction value arithmetic means 20B as shown in
Consequently, the frequency correction value arithmetic means 20B in the embodiment 6 performs the same operation as the amplifier 230 in the embodiment 2 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 213 in the state where the induction motor 10I is run in the constant torque area CTA, and performs the same operation as the amplifier 230 in the embodiment 4 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 214 in the state where the induction motor 10I is run in the constant output area COA. Accordingly, the current flowing through the induction motor 10I can be limited to the current limiting value Ilimit or less, irrespective of whether the induction motor 10I is run in the constant torque area CTA or the constant output area COA.
In this way, with the embodiment 6, when the induction motor 10I is driven at variable speed in a wide speed range from the constant torque area CTA to the constant output area COA, the current limiting can be securely performed. Also, the gains G1 and G2 of the amplifier 230 are switched with the components of the control system unchanged, whereby the program for installing the control system can be simplified. In the embodiment 6, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2 with the amplification gain arithmetic part 214, thereby achieving the same effects.
The voltage command means 15C in the modification 6A is configured as the voltage command means of the (V/f) constant control system as in the modification 2A of the embodiment 2 as shown in
In this modification 6A, the same frequency correction value arithmetic means 20B as shown in
Consequently, the frequency correction value arithmetic means 20B in the modification 6A of the embodiment 6 performs the same operation as the amplifier 230 in the modification 2A of the embodiment 2 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 213 in the state where the synchronous motor 10S is run in the constant torque area CTA, and performs the same operation as the amplifier 230 in the modification 4A of the embodiment 4 amplifies the current deviation ΔI by using the amplification gains G1 and G2 with the amplification gain arithmetic part 214 in the state where the synchronous motor 105 is run in the constant output area COA. Accordingly, the current flowing through the synchronous motor 10S can be limited to the current limiting value Ilimit or less, irrespective of whether the synchronous motor 10S is run in the constant torque area CTA or the constant output area COA.
In this way, with the modification 6A of the embodiment 6, when the synchronous motor 10S is driven at variable speed in a wide speed range from the constant torque area CTA to the constant output area COA, the current limiting can be securely performed. Also, the gains G1 and G2 of the amplifier 230 are switched with the components of the control system unchanged, whereby the program for installing the control system can be simplified. In the modification 6A of the embodiment 6, the frequency command value ω* may be used, instead of the inverter frequency ωi, in computing the gains G1 and G2 with the amplification gain arithmetic part 214, thereby achieving the same effects.
The frequency correction value arithmetic means 20C for use in the embodiment 7 has the amplification gain computing element 210C which is substituted for the amplification gain computing element 210B in the frequency correction value arithmetic means 20B in the embodiment 5 as shown in
The first amplification gain adjustment part 215 receives the amplification gain G1, G2 computed by the amplification gain arithmetic part 213, adjusts its magnitude, and supplies the amplification gain G1, G2 with the magnitude adjusted to the input a of the switching part 225. The second amplification gain adjustment part 216 receives the amplification gain G1, G2 computed by the amplification gain arithmetic part 214, adjusts its magnitude, and supplies the amplification gain G1, G2 with the magnitude adjusted to the input b of the switching part 225.
The first and second amplification gain adjustment parts 215 and 216 adjust the magnitude of the amplification gains G1 and G2 computed by the amplification gain arithmetic parts 213 and 214 to adjust the natural vibration in a mechanical system into which the AC rotating machine 10 is built. Specifically, when the mechanical system into which the AC rotating machine 10 is built has the natural vibration based on an unknown large moment of inertia, if the current limiting operation is performed for the AC rotating machine 10 built into this mechanical system, the natural vibration of the mechanical system appears in the current limiting response. The first and second amplification gain adjustment parts 215 and 216 adjust the natural vibration appearing in the current limiting response, by adjusting the magnitude of the amplification gains G1 and G2 computed by the amplification gain arithmetic parts 213 and 214, whereby it is possible to attain the reliable current limiting performance, and to adjust the natural vibration of the mechanical system based on this current limiting performance.
In this modification 7A, the same frequency correction value arithmetic means 20C as in the embodiment 7 as shown in
In this embodiment 8, the same frequency correction value arithmetic means 20C as in the embodiment 7 as shown in
The voltage command means 15C in this modification 8A is configured as the voltage command means of the (V/f) constant control system as in the modification 2A of the embodiment 2 as shown in
In this modification 8A, the same frequency correction value arithmetic means 20C as in the embodiment 7 as shown in
The voltage command means 15a used in this embodiment 9 has first voltage command arithmetic means 151, second voltage command arithmetic means 152, the dq-axis/three phase coordinate transformer 157, and voltage command selection means 159. The first voltage command arithmetic means 151 used in this embodiment 9 has two of first and second functions. The first function is to supply a measurement voltage command vm* for measuring the electrical constants of the induction motor 10I to the voltage application means 11 and supply a measurement single phase AC voltage vm for measuring the electrical constants of the induction motor 10I from the voltage application means 11 to the induction motor 10. The second function is to compute the electrical constants of the induction motor 10I by receiving a measurement current im of single phase AC outputted from the current detection means 13 based on the current flowing from the voltage application means 11 to the induction motor 10I at the measurement single phase AC voltage vm.
The second voltage command arithmetic means 152 is the voltage command means of the (E/f) constant control system, and is configured by using the same voltage command arithmetic means 153 as shown in
The frequency correction value arithmetic means 20Ba for use in the embodiment 9 has an input port 20-I7 added to the frequency correction value arithmetic means 20B in the embodiment 5 as shown in
A constant measuring device for measuring the electrical constants of the AC rotating machine 10 such as the induction motor was described in the international publication official gazette WO2006/008846 by the same applicant as for this application, and the detailed description is omitted. When the voltage command selection means 159 in the embodiment 9 selects the measurement voltage command vm* with the first voltage command arithmetic means 151, the measurement single phase AC voltage vm for measuring the electrical constants is supplied from the voltage application means 11 to the induction motor 10I, and the current detection means 13 detects the measurement current im of single phase AC flowing through the induction motor 10I at this measurement single phase AC voltage vm. The first voltage command arithmetic means 151 computes the electrical constants of the induction motor 10I based on and the measurement current im and anyone of the measurement voltage command vm* and the measurement single phase AC voltage vm, and supplies them to the constant storage memory 203.
In the embodiment 9, the AC rotating machine 10 is the induction motor 10I, and the amplification gain arithmetic part 213 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 6 and 7 or the Numerical Expressions 6 and 22, and the amplification gain arithmetic part 214 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 50 and 51 or the Numerical Expressions 59 and 60, whereby the electrical constants of the induction motor 10I required for these arithmetic operations are computed by the first voltage command arithmetic means 151 and stored in the constant storage memory 203. The set value ωx of the current limiting response speed is not measured by the first voltage command arithmetic means 151 but stored in the constant storage memory 203. In the embodiment 9, in computing the gains G1 and G2 with the amplification gain arithmetic part 214, the frequency command value ω* may be used, instead of the inverter frequency ωi, thereby achieving the same effects.
With this embodiment 9, even when the electrical constants of the induction motor 10I is unknown, the electrical constants of the induction motor 10I can be firstly measured by using the first voltage command arithmetic means 151, and stored in the constant storage memory 203. Thereafter, when the voltage command selection means 159 selects again the three phase voltage command V* with the d-axis voltage command vd* and the q-axis voltage command vq* outputted by the second voltage command arithmetic means 152 to drive the induction motor 10, the frequency correction value arithmetic value Δωa can be computed with the amplification gains G1 and G2 of the amplifier 230 appropriately designed, whereby the current can be securely limited to the current limiting command value Ilimit with the desired current limiting performance.
In the embodiment 9, the frequency correction value arithmetic means 20Ba may be replaced with the frequency correction value arithmetic means 20a in which the input port 20-I7 is added to the frequency correction value arithmetic means 20 as shown in
The voltage command means 15Aa used in this modification 9A has the first voltage command arithmetic means 151, the second voltage command arithmetic means 152, the dq-axis/three phase coordinate transformer 157, and the voltage command selection means 159 in the same way as in the embodiment 9. The first voltage command arithmetic means 151 used in the modification 9A is configured in the same way as the first voltage command means 151 as shown in
The second voltage command arithmetic means 152 is the voltage command means of the (E/f) constant control system, and is configured by using the same voltage command arithmetic means 154 as the modification 5A of the embodiment 5 as shown in
The frequency correction value arithmetic means 20Ba for use in the modification 9A is configured in the same way as the embodiment 9. In this frequency correction value arithmetic means 20Ba, the newly added input port 20-I7 is connected to the first voltage command arithmetic means 151, and also connected to the constant storage memory 203 inside the frequency correction value arithmetic means 20Ba.
In this modification 9A, the AC rotating machine 10 is the synchronous motor 10S, and the amplification gain arithmetic part 213 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 26 and 27, and the amplification gain arithmetic part 214 computes the amplification gains G1 and G2 in accordance with the expressions changed corresponding to the synchronous motor 10S from the Numerical Expressions 50 and 51 or the Numerical Expressions 59 and 60, whereby the electrical constants of the synchronous motor 10S required for these arithmetic operations are computed by the first voltage command arithmetic means 151 and stored in the constant storage memory 203. The set value ωx of the current limiting response speed is not measured by the first voltage command arithmetic means 151 but stored in the constant storage memory 203. In the modification 9A of the embodiment 9, in computing the gains G1 and G2 by the amplification gain arithmetic part 214, the frequency command value ω* may be used, instead of the inverter frequency ωi, thereby achieving the same effects.
With this modification 9A, even when the electrical constants of the synchronous motor 10S are unknown, the electrical constants of the synchronous motor 10S can be firstly measured by using the first voltage command arithmetic means 151, and stored in the constant storage memory 203. Thereafter, when the voltage command selection means 159 selects again the three phase voltage command V* with the d-axis voltage command vd* and the q-axis voltage command vq* outputted by the second voltage command arithmetic means 152 to drive the synchronous motor 10S, the frequency correction value arithmetic value Δωa can be computed with the amplification gains G1 and G2 of the amplifier 230 appropriately designed, whereby the current can be securely limited to the current limiting command value Ilimit with the desired current limiting performance.
In the modification 9A, the frequency correction value arithmetic means 20Ba may be replaced with the frequency correction value arithmetic means 20a in which the input port 20-I7 is added to the frequency correction value arithmetic means 20 as shown in
The voltage command means 15Ba for use in this embodiment 10 has the first voltage command arithmetic means 151, the second voltage command arithmetic means 152, the dq-axis/three phase coordinate transformer 157, and the voltage command selection means 159. The first voltage command arithmetic means 151 for use in this embodiment 10 is configured in the same way as shown in
The second voltage command arithmetic means 152 is the voltage command means of the (V/f) constant control system, and is configured using the same voltage command arithmetic means 155 as shown in
The frequency correction value arithmetic means 20Ba for use in the embodiment 10 is configured in the same way as the embodiment 9. In this frequency correction value arithmetic means 20Ba, the newly added input port 20-I7 is connected to the first voltage command arithmetic means 151, and also connected to the constant storage memory 203 inside the frequency correction value arithmetic means 20Ba.
In this embodiment 10, the AC rotating machine 10 is the induction motor 10S, and the amplification gain arithmetic part 213 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 37 and 38, and the amplification gain arithmetic part 214 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 50 and 51 or the Numerical Expressions 59 and 60, whereby the electrical constants of the induction motor 10I required for these arithmetic operations are computed by the first voltage command arithmetic means 151 and stored in the constant storage memory 203. The set value ωx of the current limiting response speed is not measured by the first voltage command arithmetic means 151 but stored in the constant storage memory 203. In the embodiment 10, in computing the gains G1 and G2 by the amplification gain arithmetic part 214, the frequency command value ω* may be used, instead of the inverter frequency ωi, thereby achieving the same effects.
With this embodiment 10, even when the electrical constants of the induction motor 10I is unknown, the electrical constants of the induction motor 10I can be firstly measured using the first voltage command arithmetic means 151, and stored in the constant storage memory 203. Thereafter, when the voltage command selection means 159 selects again the three phase voltage command V* with the d-axis voltage command vd* and the q-axis voltage command vq* outputted by the second voltage command arithmetic means 152 to drive the induction motor 10I, the frequency correction value arithmetic value Δωa can be computed with the amplification gains G1 and G2 of the amplifier 230 appropriately designed, whereby the current can be securely limited to the current limiting command value Ilimit with the desired current limiting performance.
In the embodiment 10, the frequency correction value arithmetic means 20Ba may be replaced with the frequency correction value arithmetic means 20a in which the input port 20-I7 is added to the frequency correction value arithmetic means 20 as shown in
The voltage command means 15Ca for use in this modification 10A has the first voltage command arithmetic means 151, the second voltage command arithmetic means 152, the dq-axis/three phase coordinate transformer 157, and the dq-axis/three phase coordinate transformer 157. The first voltage command arithmetic means 151 for use in this modification 10A is configured in the same way as shown in
The second voltage command arithmetic means 152 is the voltage command means of the (V/f) constant control system, and is configured by using the same voltage command arithmetic means 156 as shown in
The frequency correction value arithmetic means 20Ba for use in the modification 10A is configured in the same way as the embodiment 9. In this frequency correction value arithmetic means 20Ba, the newly added input port 20-I7 is connected to the first voltage command arithmetic means 151, and also connected to the constant storage memory 203 inside the frequency correction value arithmetic means 20Ba.
In this modification 10A, the AC rotating machine 10 is the synchronous motor 10S, and the amplification gain arithmetic part 213 computes the amplification gains G1 and G2 in accordance with the Numerical Expressions 47 and 48, and the amplification gain arithmetic part 214 computes the amplification gains G1 and G2 in accordance with the expressions changed corresponding to the synchronous motor 10S from the Numerical Expressions 50 and 51 or the Numerical Expressions 59 and 60, whereby the electrical constants of the synchronous motor 10S required for these arithmetic operations are computed by the first voltage command arithmetic means 151 and stored in the constant storage memory 203. The set value ωx of the current limiting response speed is not measured by the first voltage command arithmetic means 151 but stored in the constant storage memory 203. In the modification 10A of the embodiment 10, in computing the gains G1 and G2 by the amplification gain arithmetic part 214, the frequency command value ω* may be used, instead of the inverter frequency ωi, thereby achieving the same effects.
With this modification 10A, even when the electrical constants of the synchronous motor 10S are unknown, the electrical constants of the synchronous motor 10S can be firstly measured by using the first voltage command arithmetic means 151, and stored in the constant storage memory 203. Thereafter, when the voltage command selection means 157 selects again the three phase voltage command V* with the d-axis voltage command vd* and the q-axis voltage command vq* outputted by the second voltage command arithmetic means 152 to drive the synchronous motor 10S, the frequency correction value arithmetic value Δωa can be computed with the amplification gains G1 and G2 of the amplifier 230 appropriately designed, whereby the current can be securely limited to the current limiting command value Ilimit with the desired current limiting performance.
In the modification 10A, the frequency correction value arithmetic means 20Ba may be replaced with the frequency correction value arithmetic means 20a in which the input port 20-I7 is added to the frequency correction value arithmetic means 20 as shown in
The control device for the AC rotating machine according to this invention is used to control the AC rotating machine, for example, the induction motor and the synchronous motor.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2009/054640 | 3/11/2009 | WO | 00 | 8/22/2011 |