The present invention relates to a control device of a refrigerant compressor including a refrigerating cycle annularly connecting with a refrigerant piping at least a refrigerant compressor, a heat-source-side heat exchanger, a decompression device, and a user-side heat exchanger, and a control device that switches ON/OFF switching elements forming an inverter circuit by a vector control using a d-axis being a magnetic flux direction that the magnetic poles of a rotor of the refrigerant compressor form and a q-axis electrically perpendicular to the d-axis, and thereby controls currents carried into stator windings, wherein the control device sequentially switches ON/OFF patterns of the switching elements according to predetermined current carrying patterns to the stator windings by the vector control to drive the refrigerant compressor, sequentially switches, at starting the refrigerant compressor, the predetermined ON/OFF patterns of the switching elements by predetermined cycles to start the refrigerant compressor, shifts to a drive of switching the ON/OFF pattern of the switching element concerned by the vector control, when a rotational frequency of the rotor reaches a set rotational frequency, and varies the ON/OFF patterns of the switching elements at starting or voltages applied to the stator windings and the set rotational frequency, on the basis of a state of the refrigerating cycle at starting the refrigerant compressor. The embodiments of the present invention will be detailed with reference to the appended drawings.
Next, the embodiment of the present invention will be detailed on the basis of the appended drawings. A motor 21 of the embodiment described hereunder is a permanent magnet built-in type synchronous motor (motor for a refrigerant compressor) that drives a refrigerant compressor 11 using carbon dioxide as a refrigerant, which is incorporated in an on-vehicle air conditioner, for example. The motor 21 is put inside a hermetic container for the above refrigerant compressor 11 together with a rotary compression element, for example, and is used for rotating to drive the compression element. Here, the refrigerant is not limited to a natural refrigerant such as carbon dioxide, hydrocarbon (HC), and so forth, but a fluorocarbon refrigerant such as R134a may be used, which is the main stream of an on-vehicle air conditioner at present.
The refrigerant flown into the radiator 12 radiates the heat therein (heat radiation into the air, for example), and maintains a supercritical state. The refrigerant experiences the heat radiation in the radiator 12 to lower the temperature thereof, and is decompressed by the expansion valve 13. The refrigerant becomes a mixed gas-liquid state in the process of the decompression, which flows into the evaporator 14 to evaporate. Owing to the heat absorbing effect by this evaporation, the evaporator 14 displays the cooling function. And the refrigerant coming out of the evaporator 14 is again absorbed into the refrigerant compressor 11, thus repeating the circulation.
The numeral 16 in
The control device 22 of the embodiment in
The motor 21 is a synchronous motor made up with a stator wherein coils are wound on each of the six teeth, for example, in three-phase connections, and a rotor having a permanent magnet that rotates inside the stator. The secondary lines 2U, 2V, and 2W of the main inverter circuit 1 are correspondingly connected to the three-phase connections of the U-phase, V-phase, and W-phase of the stator.
Further, the secondary lines 2V and 2W of the V-phase and the W-phase, respectively, are provided with current sensors 6V and 6W (current detection means, formed of C.T. or hall element, for example) that detect the currents flown into the V-phase and W-phase of the motor 21. The control circuit 23 takes in the outputs (current detection values) from each of the sensors 6V and 6W, A/D (analog/digital)-converts the outputs, and processes digital signals after A/D-converted. The control circuit 23 may use a universal microcomputer, for example.
The basic process of the control circuit 23 in starting the motor 21 will be described with
If a sufficient current is flown into (a voltage waveform obtained by chopping the battery voltage by a predetermined frequency is applied to) the U-phase through the V-phase of the stator windings at starting, it will fix the rotor at a predetermined rotational position. The current-carrying pattern at starting initiates applying the voltage waveform to the stator windings from the position t90 corresponding to the electric angle 90° in
One example of the vector control for driving the motor by the sensorless system will be described hereunder. The three-phase current-carrying system by the sensorless vector control applies the quasi sine wave voltages as shown in
To detect the magnetic pole position in the three-phase current carrying system by the sensorless system, in relation to the d-q rotational coordinate system (d-axis is the magnetic flux axis that rotates synchronously with the magnetic poles of the rotor, and q-axis is the induced voltage axis) wherein the magnetic pole position of the rotor of the motor 21 comes to the rotational position of a real angle θd (actual magnetic pole position), now conceived is a dc-qc rotational coordinate system wherein the magnetic pole position comes to an estimated angle θdc in the control circuit 23. Here, θdc is created by the control circuit 23, and if the axial error Δθ (←θ=θdc−θd) can be calculated, the magnetic pole position of the rotor can be estimated.
In practice, the magnetic pole position of the rotor is estimated by solving a motor model formula wherein voltage commands vd* and vq* for example given to the main inverter circuit 1 are expressed by the winding resistance r, d axis inductance Ld, q-axis inductance Lq, generating constant kE, d-axis current command Id*, q-axis current command Iq*, q axis current detection value Iq, speed command ω1* (inputted from a control circuit inside a vehicle and so forth on the basis of a chamber temperature and a set value of the vehicle, and a solar irradiance and so forth) and so forth, and the axial error Δθ.
The control circuit 23 executes the vector control of the motor 21 by the sensorless system, on the basis of the magnetic pole position of the rotor detected by this estimation. In this case, the control circuit 23 separates the currents flown into the motor 21 from the secondary lines 2V and 2W detected by the current sensors 6V and 6W into a q-axis current component Iq and a d-axis current component Id, and controls the q-axis current command Iq* and the d-axis current command Id* independently. Thereby, in order to execute the inputted speed command ω1*, the control circuit 23 determines the magnitude and the phase of the voltage demands vd* and vq* so that the torque becomes the maximum in relation with the magnetic flux and the current phase, and linearizes the relation between the torque and the manipulated variable.
Further, the control circuit 23 performs the phase adjustment of the currents flown into the motor 21, by using the d-axis current detection value Id, that is, it performs the adjustment of the electric angle of the current carrying pattern. And the control circuit 23 supplies the voltage commands vd* and vq* to the main inverter circuit 1, and controls each of the switching elements to control the currents carried into the stator windings. Thereby, the motor 21 is to be driven at such a rotational speed as to meet the speed command.
The varying control process by the control circuit 23 as to the starting current and connecting frequency during starting the motor 21 will be described with the flow chart in
The control circuit 23 judges at step S1 whether the high-pressure-side pressure PH detected by the pressure sensor 17 is lower than a predetermined value A; and if it is judged lower, the process advances to step S2. At step S2, the control circuit 23 judges whether the halt time ts of the refrigerant compressor 11 is longer than a predetermined value B; and if it is judged longer, the process advances to step S3. At step S3, the control circuit 23 judges whether the valve opening degree VO of the expansion valve 13 is larger than a predetermined value C; and if it is judged larger, the process advances to step S4. At step S4, the control circuit 23 judges whether the temperature TC of the refrigerant compressor 11 that the temperature sensor 16 detects is lower than a predetermined value D; and if it is judged lower, the process advances to the condition 3 of step S5, and the control circuit 23 sets the duration of the attraction interval to E, sets the starting torque generated by the starting current to F, and sets the connecting frequency to G.
That the high-pressure-side pressure PH is lower than the value A, the halt time ts of the refrigerant compressor 11 is longer than the value B, the valve opening degree VO of the expansion valve 13 is larger than the value C, and the temperature TC of the refrigerant compressor 11 is lower than the value 1) shows a condition that the load is the lightest. Therefore, at step S5, the control circuit 23 sets the duration of the attraction interval to E being the shortest time, sets the starting torque (starting current) to F being the lowest, and sets the connecting frequency to G being the lowest. When the load of the refrigerant compressor 11 is light, the attraction time of the rotor needs only a short, the starting torque also needs only a low, and the connecting frequency to the vector control by the sensorless system also needs a low; accordingly, the motor 21 can be started smoothly.
As the starting current is decreased, wasteful power consumption will be reduced, as shown in
Here, at step S1, if the high-pressure-side pressure PH is judged to be the predetermined value A or higher, the process advances from step S1 to step S6, the control circuit 23 judges whether the high-pressure-side pressure PH is higher than A and lower than the value O. And, if it is judged lower than O (A or higher and lower than O), the process advances to the condition 2 of step S10; and the control circuit 23 sets the duration of the attraction interval to I, sets the starting torque generated by the starting current to J, and sets the connecting frequency to K. The duration I is longer than E, the starting torque J is higher than F, and the connecting frequency K is higher than G, in comparison to the condition 3. In other words, when the high-pressure-side pressure PH is slightly higher and the load of the refrigerant compressor 11 is slightly increased, the control circuit 23 sets the attraction interval slightly longer, and sets the starting torque and the connecting frequency slightly higher to start the motor 21 smoothly.
And at step S2, if the halt time ts is judged to be the predetermined value B or shorter, the process advances from step S2 to step S7, the control circuit 23 judges whether the halt time ts is shorter than B and longer than P. And if it is longer than P B or shorter and longer than P), the process advances to the condition 2 of step S10. Even in case the halt time ts of the refrigerant compressor 11 becomes slightly shorter, since the load of the refrigerant compressor 11 increases slightly, the control circuit 23 follows the condition 2 of step S10 in the same manner.
And at step S4, the valve opening degree VO of the expansion valve 13 is not larger than the value C, the process advances from step S3 to step S8, and the control circuit 23 judges whether the valve opening degree VO is smaller than C and larger than Q. And if it is larger than Q (larger than Q and C or smaller), the process advances to the condition 2 of step S10 in the same manner. Even in case the valve opening degree VO of the expansion valve 13 becomes slightly smaller, since the load of the refrigerant compressor 11 increases slightly, the control circuit 23 follows the condition 2 of step S10 in the same manner.
And at step S4, the temperature TC of the refrigerant compressor 11 is judged the value D or higher, the process advances from step S4 to step S9, the control circuit 23 judges whether the temperature TC is higher than D and lower than H. And if it is lower than H (D or higher and not higher than H), the process advances to the condition 2 of step S10 in the same manner. Even in case the temperature TC of the refrigerant compressor 11 becomes slightly higher, since the load of the refrigerant compressor 11 increases slightly, the control circuit 23 follows the condition 2 of step S10 in the same manner.
Next at step S6, if the high-pressure-side pressure PH is judged to be the value O or higher, the process advances from step S6 to the condition 1 of step S11, the control circuit 23 sets the duration of the attraction interval to L, sets the starting torque generated by the starting current to M, and sets the connecting frequency to N. The duration L is longer than I, the starting torque M is higher than J, and the connecting frequency N is higher than K, in comparison to the condition 2. In other words, when the high-pressure-side pressure PH becomes still higher and the load of the refrigerant compressor 11 is further increased, the control circuit 23 sets the attraction interval still longer, and sets the starting torque and the connecting frequency still higher to start the motor 21 without hindrance.
And at step S7, if the halt time ts is judged P or shorter, the process advances from step S7 to the condition 1 of step S11. Even in case the halt time ts of the refrigerant compressor 11 becomes still shorter, the load of the refrigerant compressor 11 is further increased, and the control circuit 23 follows the condition 1 of step 11 in the same manner.
And at step S8, the valve opening degree VO of the expansion valve 13 is not larger than the value Q, the process advances from step S8 to the condition 1 of step S11. Even in case the valve opening degree VO of the expansion valve 13 is still smaller, the load of the refrigerant compressor 11 is further increased, and the control circuit 23 follows the condition 1 of step 11 in the same manner.
And at step S9, the temperature TC of the refrigerant compressor 11 is judged the value H or higher, the process advances from step S9 to the condition 1 of step S11. Even in case the temperature TC of the refrigerant compressor 11 becomes still higher, the load of the refrigerant compressor 11 increases further, the control circuit 23 follows the condition 1 of step S11 in the same manner, thereby starting the motor 21 without hindrance. When the load is increased, the current and frequency set during shifting to the sensorless vector control are also increased; accordingly, the fluctuations of the frequency during shifting become decreased as well.
Thus, as the load of the refrigerant compressor 11 is lightened, the control circuit 23 shortens the attraction interval and lowers the starting torque (starting current) and the connecting frequency; and as the load of the refrigerant compressor 11 becomes increased, the control circuit 23 extends the attraction interval and raises the starting torque (starting current) and the connecting frequency. Therefore, regardless of the load condition of the refrigerant compressor 11, a smooth shifting to the sensorless vector control can be performed continually.
In
The above embodiments apply the present invention to the control of the motor that drives the refrigerant compressor used for an on-vehicle air conditioner; the application is not limited to this, but the present invention can effectively be applied to various types of refrigerating cycle equipments using the refrigerant compressor. The values of the various variables illustrated in the embodiments are not restrictive, but they can appropriately be set according to the equipment concerned within a range not departing from the spirit of the present invention.
Number | Date | Country | Kind |
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2006-255679 | Sep 2006 | JP | national |
2007-181056 | Jul 2007 | JP | national |