Patent Grant
6914404
The present invention relates to a motor controller for an electric motor such as a direct-current motor, an induction motor, a synchronous motor, a linear motor or the like for driving a load mechanism such as a table or an arm of a robot in a machine tool.
As a controller for controlling a machine system comprised of a load mechanism such as a table or an arm of a robot in a machine tool, a driving device such as a direct-current motor, an induction motor, a synchronous motor, a linear motor or the like, and a transmission mechanism for connecting the load mechanism with the driving device, a controller having two degrees of freedom is often used, which has a feedback control unit which relies on a command value and an output value of a machine system to perform the control, and a feed forward control unit which relies only on the command value to perform the control. For example, Japanese Patent Application Laid Open No. 06-030578 discloses an exemplary controller having two degrees of freedom.
Power converting circuit 4 drives electric motor 3 in response to torque command T applied thereto, and a rotating force of electric motor 3 is transmitted to load mechanism 1 through transmission mechanism 2, thereby operating load mechanism 1. Actual observing unit 5 is rotation detector 4 for detecting a rotational speed ω and a rotation angle θ of electric motor 3.
Feed forward signal processing circuit 25 comprises two-inertia-system simulation circuit 24 in which a system is built through approximation and modeling of machine system 6, and A control circuit 22 which is intended to control this two-inertia-system simulation circuit 24. Two-inertia-system simulation circuit 24 receives torque signal TMr applied from the A control circuit, and performs predetermined functional operations including at least two integrations to provide simulation rotation angle signal θMr and simulation speed signal ωMr. A control circuit 22 generates simulation torque signal TMr applied to two-inertia-system simulation circuit 24 based on commanded rotation angle signal ωref provided from command generator 7 as well as simulation rotation angle signal θMr and simulation speed signal ωMr provided from two-inertia-system simulation circuit 24.
B control circuit 23 comprises a position control circuit (not shown) and a speed control circuit (not shown). The position control circuit calculates and provides a speed command based on a deviation of simulation rotation angle signal θMr from actual rotation angle signal θ detected by actual observing unit 5, while the speed control circuit calculates torque command T based on a deviation of the speed command provided from the position control circuit from actual speed signal ω, and provides torque command T to power converting circuit 4. B control circuit 23 can achieve high speed position control performance with the provision of the position control circuit and speed control circuit as mentioned.
Generally, in a motor controller as described above, the control response varies in high-speed property and stability depending on control parameters set in A control circuit 22, two-inertia-system simulation circuit 24 and the like. Generally, in such a motor controller, the parameters are relatively readily set for its control system when the high-speed property is solely required for the control response, or when the stability is solely required for the control response. Typically, however, such a motor controller is often required to provide both the high-speed property and high stability of the control response. In this event, the control parameters of A control circuit 22 and two-inertia-system simulation circuit 24 must be set to meet the requirements for both the high-speed property and high stability of the control response.
However, such a motor controller implies a problem in that adjustments of the control parameters to meet the requirements for both the high-speed property and high stability for the control response are very difficult and time-consuming work for an operator.
Particularly, in failure of establishment of conditions under which a machine system such as machine system 6 is regarded as an ideal rigid body, for example, when machine system 6 appears to include spring characteristics, two-inertia-system simulation circuit 24, which models machine system 6, is subjected to a fourth or higher order control, so that the motor control must find roots of a quartic equation in order to adjust control parameters of A control circuit 22 and two-inertia-system circuit 24 that meet the requirements for both the high-speed property and high stability of the control response, causing a problem in that the adjustments of these control parameters are made difficult and time-consuming.
As described above, in the motor controller, the control response varies in the high-speed property and stability depending on the control parameters set in control circuits. Generally, in such a motor controller, the control parameters are relatively readily set for its control system when the high-speed property is solely required for the control response, or when the stability is solely required for the control response. Typically, however, such a motor controller is often required to provide both the high-speed property and high stability of the control response. In this event, the control parameters of control circuits must be set to meet the requirements for both the high-speed property and high stability of the control response. However, the conventional motor controller implies a problem in that adjustments of the control parameters to meet the requirements for both the high-speed property and high stability of the control response are very difficult and time-consuming works for the operator.
It is an object of the present invention to provide a motor controller which is capable of readily realizing both of the high-speed property and high stability of a control response.
To achieve the above object, a motor controller according to the present invention includes two components: first simulation control means and second simulation control means as feed forward control means for applying a command to an actual control unit for performing a feedback control. By doing so, the overall feed forward control means can be designed to meet the requirements for the high-speed property and high stability of a control response by setting a control parameter of the first simulation control means to increase the high-speed property of the control response and setting a control parameter of the second simulation control means to increase the stability of the control response. While it is easy to set the control parameter of each simulation control means to meet the requirement for either the high-speed property or high stability of the control response, the motor controller according to the present invention can readily realize both the high-speed property and high stability of the control response.
First Embodiment
First, description will be made on a motor controller according to a first embodiment of the present invention.
As illustrated in
First simulation control unit 8 receives commanded rotation angle signal θref provided from command generator 7, calculates first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1 based on commanded rotation angle signal θref and a first control parameter, and provides the calculated signals. First simulation control unit 9 calculates first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1 as expressed by the following equations (1)-(3):
θm1=1/(T1×s+1)2×θref (1)
ωm1=s/(T1×s+1)2×θref (2)
αm1=s2/(T1×s+1)2×θref (3)
where T1 is a time constant which is the first control parameter, and s is a differential operator.
Second simulation control unit 9 calculates second simulation position signal θm2, second simulation speed signal ωm2, second simulation acceleration signal a αm2, and simulation torque signal Tm2 based on first simulation position signal θm1, first simulation speed signal ωm1, first simulation acceleration signal αm1, and a second control parameter, and provides the calculated signals.
Second simulation control unit 9 calculates second simulation position signal θm2, second simulation speed signal ωm2, second simulation acceleration signal αm2, and simulation torque signal Tm2 as expressed by the following equations (4)-(6):
θm2=θm1/(T2×s+1) (4)
ωm2=ωm1/(T2×s+1) (5)
αm2=αm1/(T2×s+1) (6)
Tm2=αm2×J (7)
where T2 is a time constant which is the second control parameter, s is a differential operator, and J is the inertia of machine system 6.
Actual control unit 10 receives second simulation position signal θm2, second simulation speed signal ωm2, second simulation acceleration signal αm2 and simulation torque signal Tm2 for performing a feedback control to calculate and provide torque command T.
The motor controller according to this embodiment comprises a pair of first simulation control unit 8 and second simulation control unit 9 as feed forward control means which applies a command to actual control unit 10 for performing the feedback control. By doing so, the control parameter of first simulation control unit 8 is set to improve the high-speed property of the control response, while the control parameter of second simulation control unit 9 is set to increase the stability of the control response, thereby making it possible to allow the design of the overall feed forward control means to meet the requirements for the high-speed property and high stability of the control response. Since it is easy to set the control parameters of respective simulation control units 8, 9 to meet the requirement for either the high-speed property or high stability of the control response, the motor controller according to this embodiment can readily realize both the high-speed property and high responsibility of the control response.
In addition, the motor controller according to this embodiment can generate smooth second simulation position signal θm2, second simulation speed signal ωm2 and second simulation acceleration signal αm2, which are applied to actual control unit 10, even if command generator 7 provides a discontinuous commanded rotation angle signal.
Second Embodiment
Next, description will be made on a motor controller according to a second embodiment of the present invention. This embodiment and third through fourteenth embodiments illustrate embodiments of first simulation control means in the motor controller according to the present invention, and in the motor controller according to this embodiment, those illustrated in fifteenth through twenty seventh embodiments are applied to second simulation control means, actual control means, and the like.
The motor controller according to this embodiment differs from the motor controller in
First simulation controller 8a receives commanded rotation angle signal θref, first simulation position signal θm1 and first simulation speed signal ωm1, and provides first simulation torque signal Tm1. First numerical model 8b receives first simulation torque signal Tm1 provided from first simulation controller 8a, and provides first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1.
First simulation controller 8a calculates first simulation torque signal Tm1 as expressed by the following equation (8):
Tm1=Jm1×{K1×(θref−θm1)−K2×ωm1} (8)
where Jm1 represents the inertia of first numerical model 8b, and K1, K2 represent control gains.
First numerical model 8b in turn calculates first simulation acceleration signal αm1 by dividing inertia Jm1 by first simulation torque signal Tm1, first simulation speed signal ωm1 by integrating first simulation acceleration signal αm1, and first simulation position signal θm1 by integrating first simulation speed signal ωm1. In other words, first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1 are calculated as expressed by the following equations (9)-(11):
αm1=Tm1/Jm1 (9)
ωm1=αm1/s (10)
θm1=ωm1/s (11)
The motor controller according to this embodiment provides smooth first simulation acceleration signal αm1 by forming first simulation control unit 28 of first simulation controller 8a and first numerical model 8b, and simultaneously can speed up the response characteristic of first simulation position signal θm1 to commanded rotation angle signal θref because first simulation controller 8a performs the feedback control to reduce an error of first simulation position signal θm1 with respect to commanded rotation angle signal θref.
Third Embodiment
Next, detailed description will be made on a motor controller according to a third embodiment of the present invention. The motor controller according to this embodiment differs from the motor controller of
First command processor 8c receives commanded rotation angle signal θref and calculates first simulation speed signal ωm1 through the calculation of the aforementioned equation (2), and provides first simulation speed signal ωm1. First simulation signal processor 8d integrates the value of first simulation speed signal ωm1, and provides the integrated value signal as first simulation position signal θm1. Second simulation signal processor 8e differentiates the value of first simulation speed signal ωm1, and provides the differentiated value signal as first simulation acceleration signal αm1.
The motor controller according to this embodiment can calculate first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1 with a less amount of processing, as compared with the motor controller according to the second embodiment.
Fourth Embodiment
Next, detailed description will be made on a motor controller according to a fourth embodiment of the present invention. The motor controller according to this embodiment differs from the motor controller of
Second command processor 8f receives commanded rotation angle signal θref, calculates first simulation position signal θm1 through the aforementioned equation (1), and provides the calculated signal. Third simulation signal processor 8g differentiates first simulation position signal θm1 to provide first simulation speed signal ωm1. Fourth simulation signal processor 8h differentiates first simulation speed signal ωm1 to provide first simulation acceleration signal αm1.
The motor controller according to this embodiment can generate first simulation position signal θm1, first simulation speed signal ωm1 and first simulation acceleration signal αm1 with a less amount of processing, as compared with the motor controller according to the second embodiment, and can reduce the error of first simulation position signal θm1 with respect to commanded rotation angle signal θref in a steady state from the motor controller according to the second embodiment because first simulation control unit 48 does not include a feedback element.
Fifth Embodiment
As illustrated in
First numerical model 8i receives first simulation torque signal Tm1, divides first simulation torque signal Tm1 by inertia Jm1, integrates the result, as shown in the following equation (12), which is provided as first simulation speed signal ωm1, and integrates first simulation speed signal ωm1 as shown in the following equation (13) and provides the integrated signal as first simulation position signal θm1.
ωm1=Tm1/(s×Jm1) (12)
θm1=ωm1/s (13)
Fifth simulation signal processor 8j differentiates an output value of a first-order filter, which receives first simulation speed signal ωm1, as shown in the following equation (14), and provides the differentiated value as first simulation acceleration signal αm1.
αm1=s×ωm1/(T3×s+1) (14)
where T3 is the time constant of the first-order filter.
The motor controller according to the present invention can adjust the amplitude and phase of first simulation acceleration signal αm1 with the provision of fifth simulation signal processor 8j.
Sixth Embodiment
Next, detailed description will be made on a motor controller according to a sixth embodiment of the present invention. While the motor controller according to this embodiment is substantially similar to first simulation control unit 28 of FIG. 3 and first simulation control unit 58 of
First simulation position control unit 8a1 receives commanded rotation angle signal θref and first simulation position signal θm1, and solves the following equation (15) to calculate and provide first simulation speed command signal ωref:
ωref=KP1×(θref−θm1) (15)
where KP1 is a position proportional control gain.
First simulation speed control unit 8a2 receives first simulation speed command signal ωref and first simulation speed signal ωm1, and solves the following equation (16) to calculate and output first simulation torque signal Tm1:
Tm1=KV1×(ωref−ωm1) (16)
where KV1is a speed proportional control gain.
With the first simulation controller comprised of the first simulation position control unit and first simulation speed control unit, the motor controller according to this embodiment can achieve similar response characteristics to the motor controllers according to the second and fifth embodiments even if the first simulation position control unit has a gain smaller than control gains K1, K2 of the second and fifth motor controllers.
Seventh Embodiment
Next, detailed description will be made on a motor controller according to a seventh embodiment of the present invention.
The motor controller according to this embodiment differs from the motor controller according to the sixth embodiment in that first simulation controller 78a is provided instead of first simulation controller 68a.
First simulation position control unit 8a3 receives commanded rotation angle signal θref and first simulation position signal θm1, and solves the following equation (17) to provide first simulation torque command signal Txm1:
Txm1=KP1×(θref−θm1) (17)
where KP1 is a position proportional control gain.
First simulation speed control unit 8a4 receives commanded rotation angle signal θref and first simulation speed signal ωm1, and solves-the following equation (18) to provide second simulation torque command signal Tvm1:
Tvm1=KV1×(θref/s−ωm1) (18)
where KV1 is a speed proportional control gain.
Adder 8a5 adds first simulation torque command signal Txm1 and second simulation torque command signal Tvm1, and provides the sum signal as first simulation torque signal Tm1.
The motor controller according to this embodiment can switch a position control mode and a speed control mode because first simulation position control unit 8a3, which is a position controller, is arranged in parallel with first simulation speed control unit 8a4 which is a speed controller.
Eighth Embodiment
Next, detailed description will be made on a motor controller according to an eighth embodiment of the present invention. The motor controller according to this embodiment is substantially similar in the configuration to the motor controllers according to the sixth and seventh embodiments, and differs from the sixth and seventh embodiments in that first simulation controllers 88a, 98a illustrated in FIGS. 9(a) and 9(b) are provided instead of first simulation controllers 68a, 78a in
FIG. 9(a) is a block diagram illustrating the configuration of first simulation controller 88a, and FIG. 9(b) is a block diagram illustrating the configuration of first simulation controller 98a.
As illustrated in FIGS. 9(a) and 9(b), first simulation controllers 88a, 98a differ from first simulation controllers 68a, 78a in
First simulation limiter 8a6 and first simulation limiter 8a7 limit the value of first simulation torque signal Tm1 such that first simulation torque signal Tm1 falls within a predetermined torque range of electric motor 3. With the addition of such simulation limiters 8a6, 8a7, the motor controller according to this embodiment can previously generate first simulation torque signal Tm1 in consideration of a maximum driving torque of the electric motor.
Ninth Embodiment
Next, detailed description will be made on a motor controller according to a ninth embodiment of the present invention.
The motor controller according to this embodiment comprises first simulation position control unit 8a12 instead of first simulation position control unit 8a1 of first simulation controllers 68a, 88a in
Subtractor 8a1a subtracts first simulation position signal θm1 from commanded rotation angle signal θref to provide first simulation position error signal Exm1.
Coefficient multiplier 8a1b multiplies first simulation position error signal Exm1 by KP1, and provides the product signal as tenth simulation signal SI10. Coefficient multiplier 8a1c multiplies first simulation position error signal Exm1 by KI1, and provides the product signal as eleventh simulation signal SI11. Integrator 8a1d integrates the eleventh simulation signal, and provides the integrated value as twelfth simulation signal SI12.
Adder 8a1e adds tenth simulation signal SI10 and twelfth simulation signal SI12, and provides the sum signal as first simulation speed command signal ωref.
Since integrator 8a1d is added to first simulation position control unit 8a12 to perform a proportional and integral control, the motor controller according to this embodiment can eliminate an error between first simulation position signal θm1 and commanded rotation angle signal θref even if a processing error exists.
Tenth Embodiment
Next, a motor controller according to a tenth embodiment of the present invention will be described in detail with reference to FIG. 11. The motor controller according to this embodiment comprises first simulation speed control unit 8a22 instead of first simulation speed control unit 8a1 in first simulation controllers 68a, 88a of
Subtractor 8a2a subtracts first simulation speed signal ωm1 from first simulation speed command signal ωref, and provides the difference value as first simulation position error signal Evm1.
Coefficient multiplier 8a2b multiplies first simulation speed error signal Evm1 by KV1, and provides the product value as thirteenth simulation signal SI13, while coefficient multiplier 8a2c multiplies first simulation speed error signal Evm1 by KI1, and provides the product value as fourteenth simulation signal SI14.
Integrator 8a2d integrates fourteenth simulation signal SI14, and provides the integrated value as fifteenth simulation signal SI15.
Adder 8a2e adds thirteenth simulation signal SI13 and fifteenth simulation signal SI15, and provides the sum signal as first simulation torque command signal Tm1a.
With the addition of integrator 8a2d to first simulation speed control unit 8a22, a proportional and integral control is performed even when a position control mode is switched to a speed control mode and vice versa, so that the motor controller according to this embodiment can eliminate an error between first simulation position signal θm1 and commanded rotation angle signal θref in a steady state.
Eleventh Embodiment
Next, detailed description will be made on a motor controller according to an eleventh embodiment of the present invention. The motor controller according to this embodiment comprises first simulation speed control unit 8a32 instead of first simulation speed control unit 8a3 of first simulation controllers 78a, 98a in
Subtractor 8a3a subtracts first simulation position signal θm1 from commanded rotation angle signal θref, and provides the difference value as first simulation position error signal Exm1. Coefficient multiplier 8a3b multiplies first simulation position error signal Exm1 by KP1, and provides the product signal as sixteenth simulation signal SI16. Coefficient multiplier 8a3c multiplies first simulation position error signal Exm1 by KI1, and provides the product signal as seventeenth simulation signal SI17. Integrator 8a3d integrates seventeenth simulation signal SI17, and provides the integrated signal as eighteenth simulation signal SI18.
Adder 8a3e adds sixteenth simulation signal SI16 and eighteenth simulation signal SI18, and provides the sum signal as first simulation torque command signal Txm1.
Since integrator 8a3d is added to first simulation position control unit 8a32 to perform a proportional and integral control, the motor controller according to this embodiment can eliminate an error between first simulation position signal θm1 and commanded rotation angle signal θref even if a calculation error exists.
Twelfth Embodiment
Next, detailed description will be made on a motor controller according to a twelfth embodiment of the present invention. The motor controller according to this embodiment comprises first simulation speed control unit 8a42 instead of first simulation speed control unit 8a4 of first simulation controllers 78a, 98a in
Differentiator 8a4a differentiates commanded rotation angle signal θref to provide nineteenth simulation signal SI19. Subtractor 8a4b subtracts nineteenth simulation signal SI19 from first simulation speed signal ωm1 to provide first simulation speed error signal Evm1. Coefficient multiplier 8a4c multiplies first simulation speed error signal Evm1 by KI1, and provides the product signal as twentieth simulation signal SI20. Coefficient multiplier 8a4f multiplies the value of first simulation speed error signal Evm1 by Kv1, and provides the product signal as twenty first simulation signal SI21. Integrator 8a4d integrates twentieth simulation signal SI20 to provide twenty second simulation signal SI22. Adder 8a4e adds twenty first simulation signal SI21 and twenty second simulation signal SI22 to provide second simulation torque command signal Tvm1.
Since first simulation speed control unit 8a42 comprises integrator 8a4d to perform a proportional and integral control, the motor controller according to this embodiment can eliminate an error between first simulation position signal θm1 and commanded rotation angle signal θref in a steady state even if the position control mode is switched to the speed control mode and vice versa.
Thirteenth Embodiment
Next, detailed description will be made on a motor controller according to a thirteenth embodiment of the present invention.
The motor controller according to this embodiment comprises first numerical model 138b instead of first model 8b in first simulation control unit 28 of FIG. 3.
Coefficient multiplier 8b1 receives first simulation torque signal Tm1, calculates first simulation acceleration signal αm1 as expressed by the following equation (19), and provides first simulation acceleration signal αm1. Integrator 8b2 integrates first simulation acceleration signal αm1 as expressed by the following equation (20), and provides the integrated signal as first simulation speed signal ωm1. Integrator 8b3 integrates first simulation speed signal ωm1 as expressed by the following equation (21), and provides the integrated value as first simulation position signal θm1.
αm1=Tm1/J (19)
ωm1=αm1/s (20)
θm1=θm1/s (21)
Like the motor controller according to the second embodiment, by fixing first numerical model 138b to a rigid body model, the motor controller according to this embodiment can readily set control parameters such as control gains K1, K2, and the like of first simulation controllers 8a, 68a, 78a, 88a, 98a in accordance with required response characteristics.
Fourteenth Embodiment
Next, detailed description will be made on a motor controller according to a fourteenth embodiment of the present invention.
The motor controller according to this embodiment comprises first numerical model 148i instead of first numerical model 8i in first simulation control unit 58 of FIG. 6.
Coefficient multiplier 8i1 receives first simulation torque signal Tm1, and provides sixteenth simulation signal SI16 as expressed by the aforementioned equation (19). Integrator 8i2 integrates sixteenth simulation signal SI16 to provide first simulation speed signal ωm1. Integrator 8i3 integrates first simulation speed signal ωm1 to provide first simulation position signal θm1.
By fixing first numerical model 148i to a rigid body model in a manner similar to first numerical model 8i, the motor controller according to this embodiment can readily set control parameters such as control gains K1, K2, and the like of the first simulation controllers in accordance with required response characteristics.
Fifteenth Embodiment
Next, detailed description will be made on a motor controller according to a fifteenth embodiment of the present invention. This embodiment and sixteenth through twenty fourth embodiments illustrate embodiments of second simulation control means in the motor controller according to the present invention, and in the motor controller according to this embodiment, those illustrated in the first through fourteenth and twenty fifth through twenty seventh embodiments are applied to the first simulation control means, actual control means, and the like.
Second simulation controller 9a receives first simulation position signal θm1, first simulation speed signal ωm1, first simulation acceleration signal αm1, second simulation position signal θm2, and second simulation speed signal ωm2, calculates second simulation torque signal Tm2 in accordance with the following equation (22), and provides the calculated signal:
Tm2=Jm2×αm1×Jm3×{K3(θm1−θm2)−K4(ωm1−ωm2)} (22)
where Jm2, Jm3 represent the inertia of the second numerical model, and K3, K4 represent control gains.
Second numerical model 9b receives second simulation torque signal Tm2, calculates second simulation position signal θm2, second simulation speed signal ωm2, and second simulation acceleration signal αm2 in accordance with following equations (23)-(25), and provides the calculated signals:
αm2=Tm2/Jm3 (23)
ωm2=Tm2/(s×Jm3) (24)
θm2=Tm2/(s2×Jm3) (25)
Since second simulation controller 9a performs the control using first simulation acceleration signal αm1, first simulation position signal θm1, first simulation speed signal ωm1, second simulation position signal θm2 and second simulation speed signal ωm2, the motor controller according to this embodiment can bring the response characteristics of second simulation position signal θm2 and second simulation speed signal ωm2 close to the response characteristics of first simulation position signal θm1 and first simulation speed signal ωm1 without increasing the values of gains K3, K4 to such an extent that the motor controller would lose the stability in the control.
Also, the motor controller according to this embodiment can provide smoother response characteristics of second simulation position signal θm2, second simulation speed signal ωm2 and second simulation acceleration signal αm2, as compared with the response characteristics of first simulation acceleration signal αm1, first simulation position signal θm1 and first simulation speed signal ωm1.
Further, when machine system 6 is a rigid body system, the motor controller according to this embodiment can operate machine system 6 in accordance with commanded rotation angle signal θref by building second numerical model 9b with a rigid body model.
As described above, the motor controller according to this embodiment can readily provide appropriate second simulation position signal θm2, second simulation speed signal ωm2, second simulation acceleration signal αm2, and simulation torque signal T in accordance with the speed and smoothness of required response characteristics by forming second simulation control unit 19 of second simulation controller 9a and second numerical model 9b.
Sixteenth Embodiment
Next, detailed description will be made on a motor controller according to a sixteenth embodiment of the present invention.
The motor controller according to this embodiment differs from the motor controller according to the fifteenth embodiment in that second simulation control unit 29 is provided instead of second simulation control unit 19 of FIG. 16.
Second simulation controller 9c receives first simulation position signal θm1, first simulation speed signal ωm1, first simulation acceleration signal αm1, second simulation position signal θm2, second simulation speed signal ωm2, and second simulation acceleration signal αm2, and calculates second simulation torque signal Tm2 in accordance with following equation (26), and provides the calculated signal:
Tm2=Jm2×αm1−Jm4×αm2+Jm3×{K3(θm1−θm2)−K4(ωm1−ωm2)} (26)
The motor controller according to this embodiment can reduce the amount of overshoot of second simulation speed signal ωm2, as compared with second simulation controller 9a of
Seventeenth Embodiment
Next, detailed description will be made on a motor controller according to a seventeenth embodiment of the present invention.
The motor controller according to this embodiment employs second numerical model 179b which is another embodiment of second numerical model 9b in the motor controllers according to the fifteenth and sixteenth embodiments.
Coefficient multiplier 9b1 multiplies second simulation torque signal Tm2 by a coefficient to provide second simulation acceleration signal αm2. Integrator 9b2 integrates second simulation acceleration signal αm2 to provide second simulation speed signal ωm2. Integrator 9b3 integrates second simulation speed signal ωm2 to provide second simulation position signal θm2.
By fixing second numerical model 179b to a rigid body mode, the motor controller according to this embodiment can further reduce an error between actual position signal θ and commanded rotation angle signal θref of machine system 6, and simultaneously reduce high frequency components included in actual torque command T when machine system 6 is a rigid body system.
Eighteenth Embodiment
Next, detailed description will made on a motor controller according to an eighteenth embodiment of the present invention.
The motor controller according to this embodiment employs second simulation controller 19a which is another embodiment of second simulation controller 9a in the motor controller according to the fifteenth embodiment.
Subtractor 9a1 subtracts second simulation position signal θm2 from first simulation position signal θm1 to provide seventeenth simulation signal SI17. Second simulation position control unit 9a2 multiplies seventeenth simulation signal SI17 by KP2 as expressed by the following equation (27), and provides the product as eighteenth simulation signal SI18:
SI18=KP2×SI17 (27)
where KP2 is a position proportional control gain of second simulation position control unit 9a2.
Adder/subtractor 9a3 subtracts second simulation speed signal ωm2 from the sum of eighteenth simulation signal SI18 and first simulation speed signal ωm1, and provides the difference signal as nineteenth simulation signal SI19.
Second simulation speed control unit 9a6 multiplies nineteenth simulation signal SI19 by KV2 as expressed by the following equation (28) to provide twentieth simulation signal SI20:
SI20=KV2×SI19 (28)
where KV2 is a speed proportional control gain of second simulation speed control unit 9a6.
Coefficient multiplier 9a5 receives first simulation acceleration signal αm1, calculates twenty first simulation signal SI21 in accordance with the following equation (29), and provides the calculated signal:
SI21=Jm2×αm1 (29)
Adder 9a4 adds twentieth simulation signal SI20 and twenty first simulation signal SI21 to provide second simulation torque signal Tm2.
In the motor controller according to this embodiment, second simulation controller 19a can be readily implemented by an electric circuit or the like by separating the control operations expressed by the aforementioned equations (22) or (26) and the like into second simulation position control unit 9a2, second simulation speed control unit 9a6 and coefficient multiplier 9a5.
The motor controller according to this embodiment can set each gain of second simulation position control unit 9a2 to a small value to readily maintain the stability of the motor controller by separating the operation for generating twentieth simulation signal SI20 into second simulation position control unit 9a2 and second simulation speed control unit 9a6.
Nineteenth Embodiment
Next, detailed description will be made on a motor controller according to a nineteenth embodiment of the present invention.
The motor controller according to this embodiment employs second simulation controller 29awhich is another embodiment of second simulation controller 9a in the motor controller according to the fifteenth embodiment.
Differentiator 9a7 differentiates second simulation speed signal ωm2 to provide twenty second simulation signal SI22. Subtractor 9a8 subtracts twenty second simulation signal SI22 from first simulation acceleration signal αm1 to provide twenty third simulation signal SI23. Second simulation acceleration control unit 9a9 receives twenty third simulation signal SI23, calculates twenty fourth simulation signal SI24 in accordance with the following equation (30), and provides the calculated signal:
SI24=Ka2×SI23 (30)
where Ka2 is an acceleration proportional control gain.
Twenty fourth simulation signal SI24 is added to the sum of twentieth simulation signal SI20 and twenty first simulation signal SI21 by adder 9a4 to generate second simulation torque signal Tm2.
With the introduction of second simulation acceleration control unit 9a9, the motor controller according to this embodiment can bring the response characteristic of second simulation acceleration signal αm2 closer to the response characteristic of first simulation acceleration signal αm1, and more rapidly ascend second simulation position signal θm2 and second simulation speed signal ωm2.
Twentieth Embodiment
Next, detailed description will be made on a motor controller according to a twentieth embodiment of the present invention.
The motor controller according to this embodiment employs second simulation controller 19c as another embodiment of second simulation controller 9c in the motor controller according to the sixteenth embodiment.
Subtractor 9c7 subtracts first simulation acceleration signal αm1 from second simulation acceleration signal αm2 to provide twenty fifth simulation signal SI25. Second simulation acceleration control unit 9c8 multiplies twenty fifth simulation signal SI25 by a coefficient to provide twenty sixth simulation signal SI26. Twenty first simulation signal SI21 is applied to adder 9a4 which adds it to twenty sixth simulation signal SI26 and twentieth simulation signal SI20 to provide second simulation torque signal Tm2.
The motor controller according to this embodiment can set a smaller value to control gain KP2 of second simulation position control unit 9a2 than in an exclusive position control by separating the operation for generating the twentieth simulation signal SI20 into second simulation position control unit 9a2 and second simulation speed control unit 9a6.
Twenty First Embodiment
Next, detailed description will be made on the configuration of a motor controller according to a twenty first embodiment of the present invention. The motor controller according to this embodiment differs from the motor controller according to the fifteenth embodiment in that second simulation control unit 39 is provided instead of providing second simulation control unit 19 of FIG. 16.
Second simulation controller 9d receives first simulation position signal θm1, first simulation speed signal ωm1, first simulation acceleration signal αm1, second simulation position signal θm2, second simulation speed signal ωm2, second simulation acceleration signal αm2, third simulation position signal θL2, and third simulation speed signal ωL2, and calculates second simulation torque signal Tm2 in accordance with following equation (31), and provides second simulation torque signal Tm2:
Tm2=Jm2×αm1−Jm4×αm2+Jm3×{K3(θm1−θm2)−K4(ωm1−ωm2)}−K5×θL2−K6×ωL2 (31)
Second numerical model 9e receives second simulation torque signal Tm2, and solves the following equations (32)-(37) to provide second simulation acceleration signal αm2, second simulation speed signal ωm2, second simulation position signal θm2, third simulation position signal θL2, and third simulation speed signal ωL2:
αm2=(Tm2−Tk)/(Jm5) (32)
ωm2=(Tm2−Tk)/(Jm5×s) (33)
θm2=(Tm2−Tk)/(Jm5×s2) (34)
θL2=Tk/(Jm6×s2) (35)
θL2=Tk/(Jm6×s) (36)
Tk=Kc×(θm2−θL2) (37)
where Jm5, Jm6 are inertia, Kc is a control gain, and Tk is a simulation torsional torque signal.
Second simulation controller 9d performs a feedback control using third simulation position signal θL2 and third simulation speed signal ωL2 fed back from second numerical model 9e which models a two-inertia system, so that the motor controller according to this embodiment can generate appropriate second simulation torque signal Tm2, second simulation acceleration signal αm2, second simulation speed signal ωm2, and second simulation angle signal θm2 even when machine system 6 is a two-inertia system.
Twenty Second Embodiment
Next, detailed description will be made on a motor controller according to a twenty second embodiment of the present invention. The motor controller according to this embodiment employs second simulation controller 19d instead of second simulation controller 9d used in the motor controller according to the twenty first embodiment.
Subtractor 9d1 subtracts third simulation speed signal ωL2 from first simulation position signal θm1 to provide twenty seventh simulation signal SI27. Second simulation position control unit 9d2 provides twenty eighth simulation signal SI28 based on twenty seventh simulation signal SI27.
Adder/subtractor 9d3 subtracts third simulation speed signal ωL2 from the sum of twenty eighth simulation signal SI28 and first simulation speed signal ωm1 to provide twenty ninth simulation signal SI29. Second simulation speed control unit 9d6 provides thirtieth simulation signal SI30 based on twenty ninth simulation signal SI29.
Subtractor 9d9 subtracts the aforementioned third simulation position signal θL2 from second simulation position signal θm2 to provide thirty first simulation signal SI31.
Second simulation torsional position compensator 9d10 provides thirty second simulation signal SI32 based on thirty first simulation signal SI31.
SI32=KP3×SI31 (38)
where KP3 is a position proportional control gain.
Subtractor 9d7 subtracts the aforementioned third simulation speed signal ωL2 from second simulation speed signal ωm2 to provide thirty third simulation signal SI33.
Second simulation torsional speed compensator 9d8 receives thirty third simulation signal SI33 to provide thirty fourth simulation signal SI34.
SI34=Kv3×SI33 (39)
where KV3 is speed proportional control gain.
Coefficient multiplier 9d5 multiplies first simulation acceleration signal αm1 by a coefficient to provide thirty fifth simulation signal SI35. Adder 9d4 adds thirtieth simulation signal SI30, thirty second simulation signal SI32, thirty fourth simulation signal SI34 and thirty fifth simulation signal SI35 to provide second simulation torque signal Tm2.
With the addition of second simulation torsional position compensator 9d10 and second simulation torsional speed compensator 9d8, the motor controller according to this embodiment can generate appropriate second simulation torque signal Tm2 even when machine system 6 is a two-inertia system.
Also, the motor controller according to this embodiment can set a smaller value to control gain KP2 of second simulation position control unit 9d2 than in an exclusive position control by separating the operation for generating the twentieth simulation signal SI30 into second simulation position control unit 9d2 and second simulation speed control unit 9d6.
Twenty Third Embodiment
Next, detailed description will be made on a motor controller according to twenty third embodiment of the present invention.
The motor controller according to this embodiment employs second simulation controller 29d which is another embodiment of second simulation controller 9d in the motor controller according to the twenty second embodiment.
Differentiator 9d11 differentiates third simulation speed signal ωL2 to provide thirty sixth simulation signal SI36. Subtractor 9d12 subtracts thirty sixth simulation signal SI36 from first simulation acceleration signal αm1 to provide thirty seventh simulation signal SI37.
Second simulation acceleration control unit 9d13 receives thirty seventh simulation signal SI37, calculates thirty eighth simulation signal SI38 in accordance with the following equation (40), and provides the calculated signal:
SI38=Ka3×SI37 (40)
where Ka3 is an acceleration proportional control gain.
Adder 9d4 adds thirtieth simulation signal SI30, thirty second simulation signal SI30, thirty fourth simulation signal SI34, thirty fifth simulation signal SI35 and thirty eighth simulation signal SI38 to provide second simulation torque signal Tm2.
With the addition of second simulation acceleration control unit 9d13, the motor controller according to this embodiment can generate appropriate second simulation torque signal Tm2 such that third simulation speed signal ωL2 can have the response characteristic close to that of first simulation speed signal ωm1 to readily speed up the control response of machine system 6, even when machine system 6 is a two-inertia system.
Twenty Fourth Embodiment
Next, detailed description will be made on a motor controller according to a twenty fourth embodiment of the present invention.
The motor controller according to this embodiment employs second numerical model 19e instead of second numerical model 9e used in the motor controller according to the twenty first embodiment.
First inertia system numerical model 9e1 receives second simulation torque signal Tm2, calculates second simulation position signal θm2, second simulation speed signal ωm2, and second simulation acceleration signal αm2 in accordance with the following equations (41)-(43), and provides the calculated signals:
αm2=(Tm2−Tk)/(Jm5) (41)
ωm2=αm2/s (42)
θm2=ωm2/s (43)
Spring numerical model 9e2, which has the configuration as in
Tk=Kc×(θm2−θL2) (44)
Second inertia system numerical model 9e3 calculates third simulation position signal θL2 and third simulation speed signal ωL2 in accordance with the following equations (45), (46) based on simulation torsional torque signal Tk, and provides the calculated signals:
ωL2=Tk/(Jm6×s) (45)
θL2=ωL2/s (46)
In addition, first inertia system numerical model 9e1 may impose limitations to second simulation torque signal Tm2 as following equation (47):
Tm2=Tmax (Tm2≧Tmax)
Tm2=−Tmax (Tm2−<Tmax) (47)
where Tmax is a maximum torque of the electric motor.
By doing so, the motor controller according to this embodiment an generate more appropriate second simulation torque signal Tm2.
As described above, the motor controller according to this embodiment can achieve a response of the second numerical model similar to the response of machine system 6 by forming the second numerical model of the two inertia system models and spring numerical model, and can reduce high frequency components included in torque command T, when machine system 6 can be approximated by a two-inertia spring vibration system.
Twenty Fifth Embodiment
Next, detailed description will be made on a motor controller according to a twenty fifth embodiment of the present invention.
This embodiment illustrates an embodiment of actual control means in the motor controller according to the present invention, and in the motor controllers according to this embodiment and twenty sixth and twenty seventh embodiments, those illustrated in the first through twenty fourth embodiments are applied to the first simulation control means, second simulation control means, and the like.
Subtractor 10a subtracts actual rotation angle signal θ from second simulation position signal θm2, and provides the difference value as thirty ninth simulation signal SI39. Actual position control unit 10b receives thirty ninth simulation signal SI39, performs a position control, and provides fortieth simulation signal SI40.
Differentiator 10d provides forty third simulation signal SI43 based on actual rotation angle signal θ. Adder/subtractor 10c subtracts forty third simulation signal SI43 from the sum of second simulation speed signal ωm2 and fortieth simulation signal SI40 to generate and provide forty first simulation signal SI41. Actual speed control unit 10f differentiates forty first simulation signal SI41, and provides the differentiated signal as forty second simulation signal SI42.
Differentiator 10e differentiates forty third simulation signal SI43, and provides the differentiated signal as forty fourth simulation signal SI44. Subtractor 10g subtracts forty fourth simulation signal SI44 from second simulation acceleration signal αm2, and provides the difference value as forty fifth simulation signal SI45.
First actual acceleration control unit 10h receives forty fifth simulation signal SI45, and solves the following equation (48) to provide forty sixth simulation signal SI46:
SI46=Ka×SI45 (48)
where Ka is an acceleration proportional control gain.
Adder 10i adds forty second simulation signal SI42, forty sixth simulation signal SI46 and second simulation torque signal Tm2 to provide the sum value as torque command T.
In the motor controller according to this embodiment, actual rotation angle signal can also have the characteristic close to second simulation position signal θm2 with the addition of first actual acceleration control unit 10h, even if a slight model error exists between second numerical model and machine system 6.
The motor controller according to this embodiment can further reduce an error in response between machine system 6 and second numerical model with the addition of first actual acceleration controller to actual control unit 10.
Twenty Sixth Embodiment
Next, detailed description will be made on a twenty sixth embodiment of the present invention.
SI47=θ/(T4×s+1) (49)
where T4 is a time constant.
With the inclusion of filter 10j, the motor controller according to this embodiment can reduce a deleterious effect on the response characteristic of actual torque signal T resulting from noise and quantizing error included in actual rotation angle signal θ.
Twenty Seventh Embodiment
Next, detailed description will be made on a motor controller according to a twenty seventh embodiment of the present invention.
SI43=θ/(T5×s+1) (50)
where T5 is a time constant.
Generally, the level of noise included in actual rotation angle signal θ is smaller than the level of noise included in a differentiated actual rotation angle signal θ, so that the noise included in actual rotation angle signal θ merely exerts an inappreciable deleterious effect on actual torque signal T. Rather, actual rotation angle signal θ often suffers from a delay in phase by filtering actual rotation angle signal θ, resulting in a serious exacerbation of the response characteristic of actual torque signal T.
Thus, in the motor controller according to this embodiment, actual rotation angle signal θ is applied to actual position control unit 10b without filtering, while differentiated actual rotation angle signal θ alone is filtered, thereby making it possible to reduce a deleterious effect on the response characteristic of actual torque signal T due to the noise and quantizing error included in differentiated actual rotation angle signal θ and to prevent a phase delay of actual rotation angle signal θ caused by the filtering.
Consequently, the motor controller according to this embodiment can improve the phase characteristic of position control without applying manipulations to the actual position signal.
In the motor controllers according to the first through twenty seventh embodiments, the actual control unit, first simulation control unit and second simulation control unit may be comprised of a plurality of processors, wherein respective operations thereof may be implemented by software which runs on these processors. The motor controller according to each embodiment, when comprising a plurality of processors, can largely reduce a control processing time.
Twenty Eighth Embodiment
As described above, the motor controllers according to the first through twenty seventh embodiments each comprise two components: the first simulation control unit and second simulation control unit as feed forward control means for applying a command to the actual control unit which performs a feedback control. By doing so, the overall feed forward control means can be designed to meet the requirements for the high-speed property and high stability of a control response by setting a control parameter of the first simulation control unit to improve the high-speed property of the control response and setting a control parameter of the second simulation control unit to increase the stability of the control response.
However, the motor controllers according to the first through twenty seventh embodiments each imply a problem of a long actual settlement time required for electric motor 3 due to a delay of second simulation position signal θm2 with respect to commanded rotation angle signal θref. In this regard, the following description will be made on motor controllers according to a twenty eighth through a thirtieth embodiment of the present invention for solving the problem.
Described first will be a motor controller according to the twenty eighth embodiment of the present invention in detail.
First simulation control unit 68 calculates first simulation speed signal ωm1 and first simulation torque signal Tm1 based on commanded rotation angle signal θref provided from command generator 7 and a first control parameter, and provides the calculated signals. First simulation control unit 68 calculates first simulation speed signal ωm1 and second simulation torque signal Tm1 as expressed by the following equations (51), (52):
ωm1=s(T1×s+1)2×θref (51)
Tm1=J×s2/(T1s+1)2×θref (52)
where T1 is a time constant which is the first control parameter, s is a differential operator, and J is the inertia of machine system 6.
Second simulation control unit 49 performs a proportional control based on a deviation of second simulation position signal θm2 from commanded rotation angle signal θref to derive a value, performs an integral control based on a deviation of second simulation position signal θm2 from commanded rotation angle signal θref to derive a value, performs a proportional control based on a deviation of first simulation speed signal ωm1 from second simulation speed signal ωm2, adds these values and first simulation torque signal Tm1, and provides the sum as second simulation torque signal Tm2. In addition, second simulation control unit 49 integrates second simulation torque signal Tm2 once and provides the integrated value as second simulation speed signal ωm2, and integrates second simulation speed signal ωm2 once and provides the integrated value as second simulation position signal θm2, Specifically, second simulation control unit 49 calculates second simulation position signal θm2, second simulation speed signal ωm2 and second simulation torque signal Tm2 as expressed by the following equations (53)-(55):
θm2=ωm2/s (53)
θm2=Tm2/s (54)
Tm2=KP×(θref−θm2)+KV×(ωm1−ωm2)+Tm1+KI×(θref−θm2/s (55)
where KP is a first proportional gain, KV is a second proportional gain, KI is an integral gain, and s is a differential operator.
As shown in
As described above, since second simulation control unit 49 performs the position control based on commanded rotation angle signal θref and second simulation position signal θm2 the motor controller according to this embodiment can reduce an actual settlement time of electric motor 3 because a delay in second simulation position signal θm2 can be reduced with respect to commanded rotation angle signal θref.
Twenty Ninth Embodiment
Next, description will be made on a motor controller according to a twenty ninth embodiment of the present invention.
Signal switch 31 applies second simulation control unit 59 with first simulation speed signal ωm1 and first simulation torque signal Tm1, provided from first simulation control unit 68, as they are when command completion signal S takes the first value (for example, S=−1), while sets zero to the value of first simulation speed signal ωm1 and the value of first simulation torque signal Tm1 applied to second simulation control unit 59 when command completion signal S takes the second value (S=0) or third value (for example, S=1).
Second simulation control unit 59 receives command completion signal S, and calculates second simulation position signal θm2, second simulation speed signal ωm2 and second simulation torque signal Tm2 using the aforementioned equations (53)-(55) to provide the calculated values when command completion signal S takes the first value (S<0) or second value (S>0). However, when command completion signal S takes the second value, i.e., zero, second simulation control unit 59 substitutes zero into the term “KI×(θref−θm2)/s” in equation (55) and calculates second simulation torque signal Tm2.
Since second simulation control unit 49 performs the position control based on a deviation of second simulation position signal θm2 from commanded rotation angle signal θref, the motor controller according to this embodiment can reduce an actual settlement time of electric motor 3 because a delay in second simulation position signal θm2 can be reduced with respect to commanded rotation angle signal θref.
Further, the motor controller according to this embodiment clears the output of the integrator in the position control, which would cause oscillations and overshooting of second simulation position signal θm2 when commanded rotation angle signal θref stops fluctuating, and clears the output of the speed control and first simulation torque signal Tm1 when commanded rotation angle signal θref is not fluctuating. Consequently, the motor controller according to this embodiment can limit overshooting and oscillations of second simulation position signal θm2 which could occur when commanded rotation angle signal θref stops fluctuating.
As shown in
Thirtieth Embodiment
Next, description will be made on a motor controller according to a thirtieth embodiment of the present invention.
Command completion detector 32 receives commanded rotation angle signal θref provided from command generator 7, and provides command completion signal S. Command completion detector 32 sets command completion signal S to a first value (S<0, for example, −1) when a differentiated value of commanded rotation angle signal θref is non-zero, i.e., when commanded rotation angle signal θref is fluctuating. Also, command completion detector 32 sets command completion signal S provided therefrom to a second value (S=0) when a differentiated value of commanded rotation angle signal θref is zero and a twice differentiated value of the same is non-zero, i.e., when the commanded rotation angle signal stops fluctuating. Further, command completion detector 32 sets command completion signal S to a third value (S>0, for example, one) when the differentiated value and twice differentiated value of commanded rotation angle signal θref are both zero, i.e., when the commanded rotation angle signal is not fluctuating. Signal switch 31 and second simulation control unit 59 receive command completion signal S provided from command completion detector 31 to perform similar operations to those described in the twenty ninth embodiment.
As described above, the motor controller according to this embodiment, with command completion detector 32 provided therein, can automatically create command completion signal S for limiting overshooting and oscillations occurring in second simulation position signal θm2.
In the motor controllers according to the twenty eighth through thirtieth embodiments, the actual control unit, first simulation control unit, and second simulation control unit may be comprised of a plurality of processors, wherein their respective operations may be implemented by software which runs on these processors. The motor controller according to each embodiment, when comprising a plurality of processors, can largely reduce a control processing time. The reduced control processing time results in a shorter delay of second simulation position signal θm2 with respect to commanded rotation angle signal θref and in reduced overshooting and oscillations occurring in second simulation position signal θm2.
Description will be made on reference numerals shown in FIGS. 1 through 38.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP01/08280 | 9/25/2001 | WO | 00 | 3/12/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO02/27911 | 4/4/2002 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20030169004 A1 | Sep 2003 | US |
