JP4123333B2 - Electric motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric motor control device for applying an appropriate driving voltage to an electric motor that drives a load machine.
[0002]
[Prior art]
Conventional devices include a two-degree-of-freedom motor position control device disclosed in Japanese Patent Laid-Open No. 06-030578 and a motor digital current control device disclosed in Japanese Patent Laid-Open No. 11-18469. In the case of Japanese Patent Laid-Open No. 06-030578, the response frequency of the feedback loop requires high-speed response in the order of position control loop <speed control loop <current control loop. Normally, the response frequency of the speed control loop is the position control loop. The gain of the control system is set so as to be several times greater than. Therefore, in order to increase the response of the position control loop (using the proportional constant Kp), it is necessary to increase the response of the speed control loop. However, if the response frequency of the speed control loop is increased, this time mechanical vibration is generated. .
Because it is difficult to increase the gain of the position control loop due to this speed control system's responsiveness limitation, the feedforward that controls the machine system simulation circuit that ignores the machine resonance is controlled regardless of the position / speed feedback loop. A separate position / velocity control loop is provided, the response frequency is increased by feedforward control, and at the same time a two-degree-of-freedom control system that suppresses mechanical vibration is formed by one feedback loop. On the other hand, a predetermined torque command is generated to enable high-speed response. In the case of Japanese Patent Laid-Open No. 11-18469, in order to obtain a current control performance with a high-speed response, a device that attempts to solve the problem of an increase in overshoot when the response frequency of the current control loop is increased, and current control feedback Separately from the loop, a feedforward control unit is provided to output a model current obtained by delaying the primary current command by one sampling cycle, so that the model current follows the change of the primary current command value with a delay of one sampling cycle. generates a voltage command for a given current command or torque command, to suppress the overshoot by deadbeat response, is to achieve high-speed response. In this way, JP 06-30578 A raises the response frequency of the position / velocity control loop by constructing a mechanical feed forward. In JP 11-18469 A, the current feed forward is performed in the current control loop. If a high-speed response system of a position control loop, a speed control loop, and a current control loop is configured by combining these to achieve a high-speed response, an electric motor control device as shown in FIG. It becomes. This apparatus includes a mechanical system 5, an actual measurement unit 6, a position command generator 7, a mechanical feedforward control unit 21, a mechanical feedback control unit 22, an adder 23, a current feedforward control unit 24, and a current feedback. A control unit 25 and an adder 26 are included. First, in response to the position command, the machine feedforward control unit 21 increases the response frequency of the position control and speed control loop, and the machine feedback control unit 22 suppresses the machine vibration and outputs the torque command Tref. In response to the torque command Tref, the current feedforward control unit 24 applies the voltage command Vref capable of reducing the vibration by deadbeat response control and enabling the high-speed response of the current control loop to the power unit 4. By introducing the unit 21, high-speed position response control is obtained, and by introducing the current feedforward control unit 24, high-speed current response control is obtained.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, as shown in FIG. 5, the mechanical feedforward control unit 21 includes the input / output characteristics of the current feedforward control unit 24, the input / output characteristics of the current feedback control unit 25, and the input / output characteristics of the adder 26. And the input / output characteristics of the power unit 4 and the electromagnetic characteristics of the electric motor 4 are not considered, the modeling error is present in the mechanical feedforward control unit 21, and the actual position command is compared with the actual position command. There was a problem that overshoot and vibration occurred in the response.
Furthermore, suppose that the mechanical feedforward control unit 21 is connected to the input / output characteristics of the current feedforward control unit 24, the input / output characteristics of the current feedback control unit 25, the input / output characteristics of the adder 26, and the input / output characteristics of the power unit 4. In consideration of the characteristics and the electromagnetic characteristics of the motor 3, both the mechanical feedforward control section 21 and the current feedforward 24 are used to simulate at least the input / output characteristics of the power section 4 and the electromagnetic characteristics of the motor 3. Since this simulation calculation is performed, the configuration of the control device becomes complicated, and there is a problem that the calculation time becomes longer than necessary and adversely affects the control performance.
Furthermore, since the output Vff of the current feedforward control unit 24 is generated based on the torque signal Tref including the output Tfb of the mechanical feedback control unit 22, the output Vff of the current feedforward control unit 24 is Influenced by 22K output Tfb.
The output Tfb of the mechanical feedback control unit 22 is affected by position / velocity observation noise, mechanical disturbance, and the like. . Therefore, the output Vff of the current feedforward control unit 24 is affected by position / velocity observation noise, mechanical disturbance, and the like, and the design of the current feedback control unit 24 is based on the characteristics (position of the output signal Tfb of the mechanical feedback control unit 22).・ It was limited by speed observation noise, mechanical disturbance, etc.) and could not be done freely. That is, there has been a problem that the response characteristic to the position command and the response characteristic to noise and disturbance cannot be designed independently.
Therefore, the present invention provides a response characteristic to the position command that does not cause overshoot or vibration in the actual position response to the actual position command and does not adversely affect the shortening of the sampling time for realizing a high-speed response. An object of the present invention is to provide an electric motor control device that can independently design response characteristics against noise and disturbance.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 includes a transmission mechanism for transmitting power,
An electric motor that drives a load machine via the transmission mechanism;
A mechanical system having a power section for supplying power for driving the electric motor;
An actual measurement unit that observes the state quantity of the mechanical system and provides at least an actual position signal θ and an actual current I;
A position command generator for providing a position command θref;
An electric motor control device that gives an appropriate voltage command to the power unit so that the mechanical system performs a desired operation,
Based on the position command θref, a simulated position command θff, a simulated speed command ωff, a simulated current command Iff, and a simulated voltage command Vff are obtained.
θff = θref / (Tf * s + 1) ^ 4 (1)
ωff = θref * s / (Tf * s + 1) ^ 4 (2)
If = Kf1 * θref * s ^ 2 / (Tf * s + 1) ^ 4 (3)
Vff = Kf2 * θref * s ^ 3 / (Tf * s + 1) ^ 4 (4)
(Where s is a differential operator, Tf is a time constant, Kf1 is a proportional coefficient, and Kf2 is a proportional coefficient)
A feed forward control unit be provided by the simulation position instruction [theta] ff, the simulated speed command Omegaff, the simulated current command Iff, a feedback voltage command Vfb based the on the actual position signal θ and the actual current signal I
Vfb = {Kfbv [Kfbp * (θff−θ) + ωff−θ * s]
+ Iff-I} * Kfbi (5)
(However, Kfbv, Kfbp, and Kfbi are control gains.)
And a feedback control unit provided by the above and an adder that adds the feedback voltage command Vfb and the simulated voltage command Vff to provide the voltage command Vref.
According to a second aspect of the present invention, in the electric motor control device according to the first aspect, the feedforward control unit simulates the mechanical system by at least third-order integration calculation and at least a simulated position based on the simulated voltage command Vff. A simulation model that provides a simulated state quantity Xθi having a command θff, a simulated speed command ωff, and a simulated current command Iff, and a feedforward controller that provides a simulated voltage command Vff based on the simulated state quantity Xθi and the position command θref It is characterized by having.
According to a third aspect of the present invention, in the electric motor control apparatus according to the second aspect, the simulation model is configured such that the electromagnetic characteristic of the electric motor and the characteristic of the power unit are at least a first-order integral operation and one proportional operation. And a simulated electromagnetic model that provides a simulated current command Iff and a simulated torque command Tff based on the simulated voltage command Vff, mechanical characteristics of the motor, mechanical characteristics of the load machine, and mechanical characteristics of the transmission mechanism. A simulated machine model that simulates at least a second-order integral calculation and one proportional calculation and provides a simulated machine state quantity Xθ having at least a simulated position command θff and a simulated speed command ωff based on the simulated torque command Tff; It is characterized by having.
According to a fourth aspect of the present invention, in the electric motor control apparatus according to any one of the first to third aspects, the control of the electric motor is configured by software that operates on a plurality of processors. .
According to the motor control unit of the first aspect, the motor control device capable of fast operation with a simple configuration, there is no modeling error, and is not limited to feed-forward control unit designs Tfb feedback controller As described above, the flexibility to independently design the response characteristics for the position command, speed command, and current command and the response characteristics for noise and disturbance is ensured, the vibration of the mechanical system is suppressed, and the delay of the current control loop is improved. , Enabling high-speed response of the system.
[0005]
In addition, according to the motor control device of the second aspect, the feedforward control unit is configured by the simulation model 8b in which the feedforward controller and the mechanical system are simulated by integration calculation, and the simulated state quantity Xθi is generated by the simulation model 8b. Therefore, control in consideration of the characteristics of the mechanical system becomes easy, and vibration suppression and high-speed response are possible. Further, the simulation model is configured using the simulation electromagnetic model and the simulation machine model 8b2 in which the mechanical system is simulated by an approximate model such as a two-inertia model, and the simulation machine state quantity Xθ is generated. Therefore, the simulation model 8b is constructed. In this case, it becomes easy to simulate the characteristics of the mechanical system, and high-speed response control becomes possible.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of an electric motor control device according to a first embodiment of the present invention. In FIG. 1, an electric motor control device includes a load machine 1, a transmission mechanism 2 that transmits power, an electric motor 3 that drives the load machine 1 through the transmission mechanism 2, and a power unit that supplies electric power that drives the electric motor 3. 4, an actual measurement unit 6 that observes a state quantity of the mechanical system 5 and provides at least an actual position signal θ and an actual current signal I by a current detector, an encoder, and the like, and a position command θref. Based on the position command generator 7 to be output, the simulated position command θff, the simulated speed command ωff, the simulated current command Iff, and the simulated voltage command Vff based on the position command θref, the simulated position command θff, A feedback control unit 9 that provides a feedback voltage command Vfb based on the simulated speed command ωff, the simulated current command Iff, the actual position signal θ, and the actual position signal I. And an adder 10 that adds the feedback voltage command Vfb and the simulated voltage command Vff and outputs the voltage command Vref. The mechanical system 5, the actual measuring device 6, and the position command generator 7 may be those of a conventional device. Next, the operation will be described. The feedforward control unit 8 generates a simulated position command θff, a simulated speed command ωff, a simulated current command Iff, and a simulated voltage command Vff based on the position command θref from the following equation.
θff = θref / (Tf * s + 1) ^ 4 (1)
ωff = θref * s / (Tf * s + 1) ^ 4 (2)
If = KfI * θref * s ^ 2 / (Tf * s + 1) ^ 4 (3)
Vff = Kf2 * θref * s ^ 3 / (Tf * s + 1) ^ 4 (4)
Here, s is a differential operator, Tf is a time constant, and Kf1 and Kf2 are proportional coefficients. The θff, ωff, and Iff created by the feedforward control unit 8 are provided to the feedback control unit 9, and the feedback control unit 9 feedbacks from the following equation using the actual position signal θ and the actual position current I from the actual measurement unit 6. A voltage command Vfb is generated.
Vfb = {Kfbv [Kfbp * (θff−θ) + ωff−θ * s]
+ If -I} * Kfbi (5)
However, Kfbv, Kfbp, and Kfbi are control gains. The control gains Kfbv, Kfbp, and Kfbi are set theoretically by, for example, a transfer function equation as in a conventional feedback controller, and are set to optimum values by actually entering numerical values by self-tuning or the like. . Next, the adder 10 inputs and adds the simulated voltage command Vff from the feedforward control unit 8 and the feedback voltage command Vfb from the feedback control unit 9 to generate a voltage command Vref and apply it to the power unit 4. Thus, the delay of the current control loop is eliminated by the feedforward control unit 8, and the simulated voltage command Vff that has been made to respond at high speed is added to the feedback voltage command Vfb from the feedback control unit 9 that suppresses the vibration component of the mechanical system 5. Thus, the voltage command Vref that suppresses the vibration component and realizes the high-speed response without the modeling error by the quick calculation process is obtained. The feedback control unit 9 may be configured as in conventional PID control. Since the control configuration and gain setting in that case are obvious to those skilled in the art, the evaluation is omitted. Although details are omitted in FIG. 1, in an actual circuit, the simulated current command Iff, the simulated voltage command Vff and the like of the feedforward control unit 8 are passed through a coordinate converter, as shown in FIG. It is assumed that the d-axis components Iffq, Iffd, Vffq, and Vffd are separated and calculation is performed with Ifd = 0.
[0007]
Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a block diagram of a feedforward control unit according to the second embodiment of the present invention. In FIG. 2, the feedforward control unit 8 simulates the feedforward controller 8 a that provides a simulated voltage command Vff based on the simulated state quantity and the position command θref, and the mechanical system 5 by at least third-order integration calculation, and simulates the simulated voltage command. Based on Vff, it is composed of a simulation model 8b that provides a simulated state quantity Xθi having at least a simulated position command θff, a simulated speed command ωff, and a simulated current command Iff. The simulation model 8b generates a simulation state quantity Xθi from the following equation.
If = Kf3 * Vff / s (6)
ωff = Kf4 * Iff / s (7)
θff = ωff / s (8)
Xθi = [θff , ωff , Iff] (9)
However, Kf3 is an equivalent inductance and Kf4 is a torque coefficient. The feedforward controller 8a feeds back the simulated state quantity Xθi from the simulated model 8b and generates a simulated voltage command Vff from the following equation.
Vff = Kff1 * (θref−θff) −Kff2 * ωff
-Kff3 * Iff (10)
However, Kff1, Kff2, and Kff3 are control gains. In this case, the control gains Kff1 to Kff3 may be set by a so-called pole arrangement method. By the way, the pole placement method is usually used and is obtained by converting the state equation and transfer function coefficient (pole) into a determinant. If the eigenvalue (pole) in the closed loop is set by the pole placement method, the system Can be stabilized.
[0008]
As described above, in the second embodiment, separately from the first embodiment, the feedforward control unit 8 is used by using the simulation model 8b simulating the mechanical system 5 by the third order integration. (9) The calculation of the equation is performed.
It should be noted that Iff, ωff, θff, Vff and the like obtained by the equations (6) to (10) are provided to the feedback control unit 9 and similarly, the adder 10 adds Vff and Vfb to be applied to the power unit 4. The The simulated state quantity Xθi can also be used for a vibration suppression loop.
[0009]
Next, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a block diagram of a simulation model according to the third embodiment of the present invention.
In FIG. 3, a simulation model 8b simulates the electromagnetic characteristics of the electric motor 3 and the characteristics of the power unit 4 by at least a first-order integral calculation and a single proportional calculation, and generates a simulated current command based on the simulated voltage command Vff. A simulated electromagnetic model 8b1 that provides an Iff and a simulated torque command Tff, a mechanical characteristic of the electric motor 3, a mechanical characteristic of the load machine 1, and a mechanical characteristic of the transmission mechanism 2, and at least a second-order integral operation and one proportional operation And a simulated machine model 8b2 that provides a simulated machine state quantity Xθ having at least a simulated position command θff and a simulated speed command ωff based on the simulated torque command Tff.
The simulated electromagnetic model 8b1 generates a simulated current command Iff and a simulated torque command Tff from the following equations.
Iff = (Vff−ωff * φ * L) / (L * s + R) (11)
Tff = K * Iff (12)
Where L is the equivalent inductance of the motor, R is the equivalent resistance of the motor, φ
Is a magnetic flux coefficient, and K is a torque coefficient.
The simulated machine model 8b2 represents the characteristics obtained by simulating the mechanical characteristics of the electric motor 3, the mechanical characteristics of the load machine 1, and the mechanical characteristics of the transmission mechanism 2 with an approximate model such as a rigid model and a two-inertia model.
When approximated by a two-inertia model, the simulated machine model 8b2 generates a simulated machine state quantity Xθ from the following equation.
θff = ωff / s (13)
ωff = (Tff−Tk) / (Jm * s) (14)
Tk = Ka * (θff−θffL) (15)
θffL = ωffL / s (16)
ωffL = Tk / (JL * s) (17)
Xθ = [θff, ωff, θffL, ωffL] (18)
Where Ka is the spring coefficient, Jm is the inertia on the drive side of the 2-inertia model,
JL is the inertia on the load side of the 2-inertia model.
As described above, the third embodiment simulates the mechanical system 5 from the two-inertia model, and is effective for suppressing vibrations by correcting the torsion angle.
[0010]
Next, a fourth embodiment of the present invention will be described.
The fourth embodiment relates to claim 4, and is an example in which the feedforward control unit 8 and the feedback control unit 9 are configured by separate processors. With such a configuration, the processing time of each process is shortened, so that a high-speed response can be realized.
Further, if distributed processing is performed by using a plurality of limited types of processors instead of a high-speed CPU processor, the sampling cycle for reducing overshoot can be shortened, and high-speed response processing can be realized.
[0011]
【The invention's effect】
As described above, according to the present invention, an electric motor control device that gives an appropriate voltage command to the power unit so that the mechanical system performs a desired operation, and the simulated position command θff and simulated speed command ωff based on the position command θref. Based on the feedforward control unit that provides the simulated current command Iff and the simulated voltage command Vff, the simulated position command θff, the simulated speed command ωff, the simulated current command Iff, the actual position signal θ, and the actual current signal I A feedback control unit that provides the feedback voltage command Vfb and an adder that adds the feedback voltage command Vfb and the simulated voltage command Vff to provide the voltage command Vref. Does not cause overshoot or vibration, and does not adversely affect the sampling time. There is an effect that it provides a motor control device can be designed and response independently to the response characteristics and noise and disturbances that.
In addition, the feedforward control unit may be configured by a feedforward controller that provides a simulated voltage command Vff and a simulated model that simulates a mechanical system by at least a third-order integral operation and provides a simulated state quantity Xθi, or a simulation thereof The model is a simulated electromagnetic model in which the electromagnetic characteristics of the motor and the characteristics of the power section are simulated by at least a first-order integral calculation and a single proportional calculation, the mechanical characteristics of the motor, the mechanical characteristics of the load machine, and the machine of the transmission mechanism An electric motor that can easily simulate the characteristics of a mechanical system by simulating the characteristics by at least a second-order integral calculation and a single proportional calculation and comprising a simulated machine model that provides a simulated machine state quantity Xθ There is an effect that a control device can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electric motor control device according to a first embodiment of the present invention.
FIG. 2 is a block diagram of a feedforward control unit according to a second embodiment of the present invention.
FIG. 3 is a block diagram of a simulation model according to a third embodiment of the present invention.
4 is a detailed view of a simulation command of the feedforward control unit shown in FIG.
FIG. 5 is a block diagram of a conventional motor control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric motor 2 Transmission mechanism 3 Electric motor 4 Power part 5 Mechanical system 6 Actual measurement part 7 Position command generator 8 Feedforward control part 9 Feedback control part 10 Adder 8a Feedforward controller 8b Simulation model 8a1 Simulation electromagnetic model 8b2 Simulation machine model

Claims (4)

A transmission mechanism for transmitting power;
An electric motor that drives a load machine via the transmission mechanism;
A mechanical system having a power section for supplying power for driving the electric motor;
An actual measurement unit that observes the state quantity of the mechanical system and provides at least an actual position signal θ and an actual current I;
A position command generator for providing a position command θref;
An electric motor control device that gives an appropriate voltage command to the power unit so that the mechanical system performs a desired operation,
Based on the position command θref, a simulated position command θff, a simulated speed command ωff, a simulated current command Iff, and a simulated voltage command Vff are obtained.
θff = θref / (Tf * s + 1) ^ 4 (1)
ωff = θref * s / (Tf * s + 1) ^ 4 (2)
If = Kf1 * θref * s ^ 2 / (Tf * s + 1) ^ 4 (3)
Vff = Kf2 * θref * s ^ 3 / (Tf * s + 1) ^ 4 (4)
(Where s is a differential operator, Tf is a time constant, Kf1 is a proportional coefficient, and Kf2 is a proportional coefficient)
A feed forward control unit be provided by,
Based on the simulated position command θff, the simulated speed command ωff, the simulated current command Iff, the actual position signal θ, and the actual current signal I, a feedback voltage command Vfb is obtained.
Vfb = {Kfbv * [Kfbp * (θff−θ) + ωff−θ * s]
+ Iff-I} * Kfbi (5)
(However, Kfbv, Kfbp, and Kfbi are control gains.)
A feedback control unit for providing a result,
An electric motor control device comprising: an adder that adds the feedback voltage command Vfb and the simulated voltage command Vff to provide a voltage command Vref. The feedforward control unit
A simulation model for simulating the mechanical system by at least a third integral calculation and providing a simulated state quantity Xθi having at least a simulated position command θff, a simulated speed command ωff, and a simulated current command Iff based on the simulated voltage command Vff;
The motor control apparatus according to claim 1, further comprising a feedforward controller that provides a simulated voltage command Vff based on the simulated state quantity Xθi and the position command θref. The simulated model is
The electromagnetic characteristics of the motor and the characteristics of the power section are simulated by at least a first-order integral calculation and a single proportional calculation, and a simulated current command Iff and a simulated torque command Tff are provided based on the simulated voltage command Vff. A simulated electromagnetic model,
The mechanical characteristics of the electric motor, the mechanical characteristics of the load machine, and the mechanical characteristics of the transmission mechanism are simulated by at least a quadratic integral calculation and a single proportional calculation, and at least a simulated position command θff is calculated based on the simulated torque command Tff. The motor control device according to claim 2, further comprising a simulated machine model that provides a simulated machine state quantity Xθ having a simulated speed command ωff. The motor control apparatus according to claim 1, wherein the control of the electric motor is configured by software that operates on a plurality of processors.

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