JP7311759B2 - Rotating machine control device - Google Patents

Description

The present invention relates to a control device that controls driving of a rotating machine.

In recent years, with the electrification of automobiles, aircraft, and the like, there is a demand for motors with large capacity and high output. Generally, in a motor such as a permanent magnet motor, a torque ripple occurs in which the torque fluctuates depending on the rotational position of the rotor.

On the other hand, a method has been proposed in which table data or the like is generated based on data of an actual motor and the table data or the like is used to suppress the torque ripple. As a device for suppressing torque ripple in this way, for example, in Patent Document 1, a torque ripple compensation current for suppressing torque ripple is learned based on a shaft torque detection value, and a table is prepared. A torque pulsation suppression system that performs pulsation compensation control is disclosed.

Specifically, the torque ripple suppression system has a controller that extracts a torque ripple frequency component from the shaft torque detection value, learns a torque ripple compensation current based on this, and creates a table.

Japanese Patent Application Laid-Open No. 2011-50118

By the way, when the controller learns the torque ripple compensation current in order to suppress the torque ripple of the rotating machine as in the configuration disclosed in the above-mentioned Patent Document 1, a high-performance hardware having a learning function is used as the controller. you need clothing. In addition, since it is necessary to measure the torque ripple in an actual rotating machine, it is necessary to manufacture the actual rotating machine and to construct a system for measuring and learning the torque ripple.

Generally, PI control is used as current control for rotating machines. In PI control, a voltage command is calculated from the difference between the current current value and the command value, and proportional integral control is performed so that the difference becomes zero. In such PI control, a control response delay occurs due to a delay in calculation of the voltage command, a delay in detection timing of the current value with respect to the voltage command, and the like.

Therefore, when the value obtained by the PI control is used for control to suppress the torque ripple of the rotating machine, the torque ripple may not be suppressed so much.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device capable of suppressing torque ripple of a rotating machine with high accuracy by a simple configuration.

A power conversion device according to an embodiment of the present invention is a control device that controls driving of a rotating machine. This control device includes, for each control cycle, a current prediction unit that obtains a predicted value of the current flowing through the rotating machine in the next control cycle, and a predicted electrical angle value of the rotating machine in the next control cycle for each control cycle. and a current command generation unit that generates a current command that reduces torque ripple of the rotating machine using the input torque command, the current prediction value, and the electrical angle prediction value. (first configuration).

Thus, for each control cycle, the predicted current value and the predicted electrical angle value in the next control cycle are obtained, and the torque command, the predicted current value, and the predicted electrical angle value are used to reduce the torque ripple of the rotating machine. By generating the command, the torque ripple can be effectively suppressed. That is, since the predicted current value and the predicted electrical angle value do not have a delay like the current value and the electrical angle obtained by PI control, they do not deviate from the timing at which the torque fluctuates due to the torque ripple. can be generated to reduce the current command.

Moreover, the above configuration eliminates the need for learning for suppressing torque ripple, thus eliminating the need for high-performance hardware such as a control device having a learning function. Therefore, torque ripple of the rotating machine can be suppressed with a simpler configuration than when learning control is performed.

Therefore, with the simple configuration described above, it is possible to obtain a control device capable of suppressing the torque ripple of the rotating machine with high precision.

In the first configuration, the current command generation unit generates the current command by considering, in the torque command, a current command correction value generated using the current predicted value and the electrical angle predicted value. (second configuration).

As a result, a current command that suppresses the torque ripple of the rotating machine is generated by the current command correction value generated using the current predicted value and the electrical angle predicted value, and the rotating machine is driven based on the current command. can do. Therefore, current control without delay can be performed on the rotating machine.

In the second configuration, the current command generator generates a current correction signal using the predicted electrical angle value based on the relationship between the electrical angle and the torque obtained by simulation using the model of the rotating machine. a correction signal generation unit; a command correction value generation unit that generates the current command correction value for correcting the torque command from the current correction signal in consideration of the current prediction value; and a current command correction value that is applied to the torque command. and a command signal generator that generates the current command by taking into account (third configuration).

As a result, the relationship between the electrical angle and the torque can be obtained in advance by simulation using a model of the rotating machine, and the predicted electrical angle value can be obtained from the relationship. That is, since the relationship can be obtained by a device other than the control device, the control device does not need to be configured with high-performance hardware. Therefore, the torque ripple of the rotating machine can be suppressed with a simple configuration of the control device.

In any one of the first to third configurations, the current prediction unit may generate a current value detected by the rotating machine, a voltage command for the rotating machine, a voltage command for the rotating machine, and the rotation The predicted current value is obtained based on the electrical angle of the machine (fourth configuration). As a result, the predicted current value for the next control cycle can be obtained with high accuracy.

According to the control device for a rotating machine according to an embodiment of the present invention, torque is calculated using a torque command, a predicted value of current flowing through the rotating machine in the next control cycle, and a predicted value of electrical angle in the next control cycle. Generates a current command that reduces ripple. As a result, it is possible to obtain a control device capable of suppressing the torque ripple of the rotating machine with high accuracy with a simple configuration.

FIG. 1 is a block diagram showing a schematic configuration of a control device according to an embodiment. FIG. 2 is a block diagram showing a schematic configuration of the current control section. FIG. 3 is a diagram showing an example of torque ripple. FIG. 4 is a diagram showing an example of q-axis current that cancels torque ripple. FIG. 5 is a diagram showing an example of torque ripple. FIG. 6 is a diagram showing an example of the torque of the motor driven by the control device of this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

(overall structure)
FIG. 1 is a diagram showing a schematic configuration of a control device 1 according to an embodiment of the invention. This control device 1 is a device that controls driving of a motor 2 (rotating machine). The control device 1 of the present embodiment controls driving of the motor 2 so as to suppress torque ripple generated in the motor 2 . The control device 1 generates a voltage command based on the torque command, the electrical angle θ _E calculated from the mechanical angle θ _M of the motor 2 , and the three-phase currents Iu, Iv, and Iw. Output to the main circuit 3 to be driven.

Motor 2 is, for example, a permanent magnet motor. Although not shown, the motor 2 has a rotor having permanent magnets and a stator having three-phase coils wound on teeth of a stator core. Since the configuration of the motor 2 is the same as that of a general motor, detailed description thereof will be omitted. Note that the control target of the control device 1 may be a rotating machine other than a motor as long as the rotating machine generates torque ripple.

A mechanical angle _θM of the motor 2 is detected by a rotation angle detector 2a such as an encoder. The mechanical angle _θM detected by the rotation angle detector 2a is input to a current control section 11 of the control device 1, which will be described later.

The main circuit 3 has a plurality of switching elements, and controls the three-phase currents Iu, Iv, and Iw input to the three-phase coils of the motor 2 by driving the plurality of switching elements. The main circuit 3 includes, for example, an inverter circuit. Since the configuration of the main circuit 3 is also the same as that of a general main circuit, detailed description thereof will be omitted.

Three-phase currents Iu, Iv, and Iw flowing from the main circuit 3 to the motor 2 are detected by a current sensor 2b. The three-phase currents Iu, Iv, and Iw detected by the current sensor 2b are input to a current control section 11 of the control device 1, which will be described later. Note that the current sensor 2b may detect only two-phase currents among the three-phase currents Iu, Iv, and Iw. In this case, the remaining one-phase current is obtained from the detected two-phase currents.

The control device 1 controls the torque ripple of the motor 2 based on the input torque command, the electrical angle _θE calculated from the mechanical angle _θM of the motor 2, and the three-phase currents Iu, Iv, and Iw. A voltage command is generated and output to the main circuit 3 .

Specifically, the control device 1 has a current control section 11 , a current command generation section 15 and an angle calculation section 16 .

The angle calculator 16 calculates an electrical angle θ _E from the mechanical angle θ _M detected by the rotation angle detector 2a. The electrical angle θ _E obtained by the angle calculator 15 is input to the current controller 11 .

The current control unit 11 calculates a predicted current value Ia based on the electrical angle θE of the motor 2 and the three-phase currents _Iu , Iv, and Iw, and issues a current command in consideration of the predicted current value Ia and the predicted electrical angle value θa. is used to generate the voltage command. The current control unit 11 uses the control period Tc and the angular velocity ω of the electrical angle _θE to generate the electrical angle predicted value θa.

FIG. 2 shows a schematic configuration of the current control section 11 in a block diagram. The current control unit 11 has a current prediction unit 21 , an electrical angle prediction unit 22 , a voltage command generation unit 23 , a three-phase two-phase conversion unit 24 and a two-phase three-phase conversion unit 25 .

The three-phase to two-phase converter 24 converts the three-phase currents Iu, Iv, and Iw into a d-axis current Id and a q-axis current Iq. The configuration of the three-to-two phase conversion section 24 is the same as that of a conventional three-to-two phase conversion section. Therefore, the detailed configuration of the three-phase to two-phase converter 24 is omitted.

The current prediction unit 21 calculates a current prediction value Ia based on a voltage command generated by a voltage command generation unit 23, which will be described later, the electrical angle θ _E of the motor 2, and the three-phase currents Iu, Iv, and Iw. Specifically, the current prediction unit 21 predicts current voltage commands Vd, Vq, current values Id, Iq obtained from the three-phase currents Iu, Iv, Iw by the three-phase to two-phase conversion unit 24, Based on the electrical angle θ _E , predicted values of the current flowing in the next control cycle (hereinafter referred to as current predicted values) Ide(n+1) and Iqe(n+1) are predicted. Vd means a d-axis voltage command, and Vq means a q-axis voltage command.

The current prediction unit 21 uses the current values Id and Iq, the current voltage commands Vd and Vq, and the electrical angle θ _E of the motor 2 to calculate the predicted current value Ide from the following equations (1) and (2). (n+1) and Iqe(n+1) are obtained. Equations (1) and (2) are derived from a general voltage equation of a permanent magnet motor and the forward finite difference method.

In equations (1) and (2), Vd and Vq are the d-axis voltage command and the q-axis voltage command in the current control cycle. Id(n) and Iq(n) are the d-axis current and q-axis current in the current control cycle. Ide(n+1) and Iqe(n+1) are the d-axis current prediction value and the q-axis current prediction value predicted by the current prediction unit 21 to flow in the next control cycle. Tc is the control period, Ld is the d-axis inductance, Lq is the q-axis inductance, R is the armature resistance, ω is the electrical angular velocity, and φ is the armature flux linkage.

Thus, by using the current values Id and Iq, the current voltage commands Vd and Vq, and the electrical angle _θE of the motor 2, it is possible to accurately obtain the predicted current value in the next control cycle.

The predicted d-axis current value Ide(n+1) and the predicted q-axis current value Iqe(n+1) obtained by the current prediction unit 21 are input to the current command generation unit 15, which will be described later, and used to generate a current command.

The electrical angle prediction unit 22 predicts the electrical angle (hereinafter referred to as electrical angle prediction value) θa of the motor 2 in the next control cycle. Specifically, the electrical angle prediction unit 22 of the present embodiment has the advantage that the angular velocity ω of the electrical angle _θE of the motor 2 does not change greatly, and that the voltage command generated from the current command is output to the main circuit 3. Taking into consideration the fact that the control period is one cycle ahead, or 1.5 cycles ahead on average, the electrical angle θa in the next control cycle is predicted by the following equation (3).
θa= _θE + _ΔθE = _θE +ω×1.5Tc (3)

In equation (3), Δθ _E is the advance angle of the electrical angle of the motor 2 .

The electrical angle prediction value θa obtained by the electrical angle prediction section 22 is input to a current command generation section 15, which will be described later, and used to generate a current command.

The voltage command generator 23 generates a voltage command using the current command generated by the current command generator 15, which will be described later. Since the method of generating the voltage command from this current command is the same as the conventional method, detailed description thereof will be omitted. The voltage command output from the voltage command generation unit 23 is converted into a three-phase voltage command by the two-phase three-phase conversion unit 25, and then output to the main circuit 3. The current prediction unit 21 predicts the next control cycle. is used to obtain the predicted current value of Since the configuration of the two-to-three-phase conversion section 25 is also the same as that of the conventional configuration, the detailed description of the configuration of the two-to-three-phase conversion section 25 is omitted.

The current command generator 15 generates a current command using the torque command, the predicted current value Ia output from the current controller 11, and the predicted electrical angle value θa. Specifically, the current command generator 15 includes a correction signal generator 12, a compensator 13 (command correction value generator), a command converter 14, and an adder 15a (command signal generator).

The correction signal generator 12 uses the electrical angle prediction value θa output from the current controller 11 to generate a current correction signal. Specifically, the correction signal generator 12 has a correction table that defines the relationship between the electrical angle and the current. The correction signal generator 12 uses the correction table to generate a current correction signal for correcting the current command so as to suppress the torque ripple of the motor 2 with respect to the input electrical angle prediction value θa.

The correction table is table data previously generated off-line by a computer other than the control device 1 . The computer calculates the torque including the torque ripple of the motor 2 by simulation using the model of the motor 2, and the relationship between the current obtained from the torque and the electrical angle of the motor 2 at that time is used as the correction table. demand.

When generating the correction table, for example, a model for simulation obtained by inputting conditions such as physical properties to mesh data created from an FEM model is used as a model of the motor 2 . The torque of the motor 2 can be calculated by simulating inverter control using this simulation model using analysis software.

FIG. 3 is a diagram showing an example of torque calculation results including torque ripple of the motor 2 obtained by simulation. FIG. 4 is a diagram showing an example of a current correction value of the q-axis current that suppresses torque ripple of the motor 2. In FIG. A current correction value for the q-axis current shown in FIG. 4 is set to a current value that generates a torque that cancels out the torque ripple shown in FIG. Therefore, the current correction value of the q-axis current changes in phase opposite to the torque ripple of the motor 2 in electrical angle. The correction table is, for example, data as shown in FIG.

Note that the correction signal generator 12 may generate the current correction signal using a formula instead of the correction table as described above. From the viewpoint of shortening the calculation time, it is preferable that the correction signal generator 12 uses the correction table described above.

In this embodiment, the correction table is generated off-line by a computer other than the control device 1 . However, the correction table may be generated when the control device 1 is off-line, or may be generated by the control device 1 on-line.

The compensator 13 generates and outputs a current command correction value by correcting the current correction signal using the current prediction value Ia output from the current control section 11 . The relationship between the electrical angle and torque changes depending on the current flowing through the motor 2 . Therefore, the compensator 13 corrects the relationship between the predicted electrical angle value and the corrected current value obtained from the correction table by the predicted current value Ia of the motor 2 .

The command conversion unit 14 converts the torque command input to the control device 1 into current. The adder 15a generates a current command by considering the current command correction value output from the compensator 13 in the torque command converted into the current. The generated current command is input to the current control section 11 . As described above, in the current controller 11 , the voltage command generator 23 generates a voltage command based on the input current command and outputs the voltage command to the main circuit 3 .

FIG. 5 shows an example of the torque ripple of the motor 2. As shown in FIG. FIG. 6 shows an example of the torque of the motor 2 when the motor 2 is driven and controlled by the control device 1 having the above configuration.

As shown in FIGS. 5 and 6, by driving and controlling the motor 2 by the control device 1 of the present embodiment, for example, the value of torque ripple generated in the motor 2 can be halved or less. Therefore, the torque ripple of the motor 2 can be effectively reduced by the configuration of the control device 1 of the present embodiment.

In this embodiment, the control device 1 includes, for each control cycle, a current prediction unit 21 that obtains a predicted value of the current flowing through the motor 2 in the next control cycle, and a An electrical angle prediction unit 22 for obtaining an electrical angle prediction value, and a current command generation unit for generating a current command for reducing torque ripple of the motor 2 using the input torque command, the current prediction value, and the electrical angle prediction value. 15 and.

Thus, for each control cycle, the predicted current value and the predicted electrical angle value in the next control cycle are obtained, and the torque command, the predicted current value, and the predicted electrical angle value are used to reduce the torque ripple of the motor 2. By generating the command, the torque ripple can be effectively suppressed. That is, since the predicted current value and the predicted electrical angle value do not have a delay like the current value and the electrical angle obtained by PI control, they do not deviate from the timing at which the torque fluctuates due to the torque ripple. can be generated to reduce the current command.

Moreover, the above configuration eliminates the need for learning for suppressing torque ripple, thus eliminating the need for high-performance hardware such as a control device having a learning function. Therefore, torque ripple of the motor 2 can be suppressed with a simpler configuration than when learning control is performed.

Therefore, a control device capable of suppressing the torque ripple of the motor 2 with high accuracy can be obtained with a simple configuration.

Further, the control device 1 uses the electrical angle predicted value θa and the current predicted value Ia in the next control cycle of the motor 2 to generate a current command capable of suppressing the torque ripple of the motor 2. A correction table obtained in advance in 12 is used.

Accordingly, in order to obtain a current command capable of suppressing the torque ripple of the motor 2, there is no need to calculate a correction value of the current command in real time, unlike conventional learning control. Therefore, the control device 1 that obtains a current command capable of suppressing the torque ripple of the motor 2 does not need to be configured with high-performance hardware unlike the conventional one.

Moreover, as described above, by obtaining a current command capable of suppressing the torque ripple of the motor 2 using the predicted electrical angle value θa and the predicted current value Ia, current control with little delay in control of the motor 2 is realized. can.

(Other embodiments)
Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, without being limited to the above-described embodiment, it is possible to modify the above-described embodiment as appropriate without departing from the spirit thereof.

In the above-described embodiment, the current prediction unit 21 of the current control unit 11 obtains the current prediction values Ide(n+1) and Iqe(n+1) in the next control cycle using equations (1) and (2). However, the current control section may have any configuration as long as it can obtain the predicted current value in the next control cycle.

In the above embodiment, the correction table of the correction signal generator 12 is table data including the relationship between the electrical angle and the current. However, the correction table may include table data in which the relationship between the electrical angle and current changes depending on at least one of the motor rotation speed and motor temperature.

In the above embodiment, the current command correction value is obtained from the current correction signal by the compensator 13 using the current prediction value Ia output from the current control section 11 . However, the correction signal generation unit may obtain the current command correction value using the electrical angle prediction value and the current prediction value. That is, the correction table of the correction signal generation unit may be table data containing a three-dimensional relationship between the electrical angle, torque, and current, considering that the relationship between the electrical angle and the torque changes depending on the current. . In this case, the compensator of the current command generator is unnecessary.

In the above-described embodiment, the electrical angle prediction unit 22 does not greatly change the angular velocity ω of the electrical angle θ _E of the motor 2, and the output of the voltage command obtained from the current command to the main circuit 3 is one control cycle. The electrical angle θa in the next control cycle is predicted by the above-described equation (3), taking into account the fact that the control cycle is 1.5 cycles ahead on average.

However, the electrical angle prediction unit calculates the torque T using the current prediction value, and the acceleration α (=T/J) obtained from this torque and the inertia amount J of the entire shaft system including the motor 2 which is the test piece. , the electrical angle may be predicted.

In this case, the electrical angle prediction unit outputs the voltage command obtained from the current command to the main circuit 3 after one control cycle, and on average after 1.5 cycles. Using the angular velocity ω2 (=α×1.5Tc) 1.5 cycles ahead and the current angular velocity ω1, the average angular velocity ωave (=(ω2−ω1)/2) is obtained. As a result, the electrical angle predicted value θa in the next control cycle is obtained by the following equation (4).
θa= _θE + _ΔθE = _θE +(ωave×1.5Tc) (4)

Also, the electrical angle prediction unit may predict the electrical angle from the difference in torque of the motor and the change in acceleration. Specifically, the electrical angle prediction unit predicts the torque Tn in the current control cycle, the torque Tn-1 in the previous control cycle, the acceleration αn in the current control cycle and the acceleration αn- in the previous control cycle. 1, the change in acceleration αn+1 in the next control cycle for αn is predicted with respect to the change in torque Tn in the next control cycle for Tn.

θａ＝θ_Ｅ＋αａｖｅ×（１．５Ｔｃ）^２ （６） In this case, the electrical angle prediction unit estimates αn+1 using the following equation (5), and obtains the average acceleration αave from the estimated αn+1 and the current acceleration αn. The electrical angle prediction unit can obtain the electrical angle prediction value θa from the obtained αave and the equation (6).

θa= _θE +αave×(1.5Tc) ² (6)

Although the configuration of the control device 1 that controls the driving of the three-phase motor 2 has been described in the above embodiment, the present invention is not limited to this, and may be applied to a control device that drives a multi-phase motor other than the three-phase motor.

INDUSTRIAL APPLICABILITY The present invention can be used for a control device that controls driving of a motor.

1 control device 2 motor 2a rotation angle detector 2b current sensor 3 main circuit 11 current control unit 12 correction signal generation unit 13 compensator (command correction value generation unit)
14 command conversion unit 15 current command generation unit 15a addition unit (command signal generation unit)
16 angle calculator 21 current predictor 22 electrical angle predictor 23 voltage command generator 24 three-phase two-phase converter 25 two-phase three-phase converter Ia current predicted value θa electrical angle predicted value θ _E electrical angle θ _M mechanical angle I current

Claims (4)

A control device for controlling the drive of a rotating machine,
a current prediction unit that obtains, for each control cycle, a predicted value of the current flowing through the rotating machine in the next control cycle;
an electrical angle prediction unit that calculates, for each control cycle, a predicted electrical angle value of the rotating machine in the next control cycle;
a current command generation unit that generates a current command that reduces torque ripple of the rotating machine using the input torque command, the current predicted value, and the electrical angle predicted value;
A control device for a rotating machine. In the control device for a rotating machine according to claim 1,
The current command generation unit generates the current command by considering the torque command with a current command correction value generated using the current predicted value and the electrical angle predicted value. . In the control device for a rotating machine according to claim 2,
The current command generation unit
a correction signal generation unit that generates a current correction signal using the electrical angle prediction value from the relationship between the electrical angle and the torque obtained by a simulation using the model of the rotating machine;
a command correction value generation unit that generates the current command correction value for correcting the torque command from the current correction signal in consideration of the current prediction value;
a command signal generator that generates the current command by considering the current command correction value in the torque command;
A control device for a rotating machine. In the control device for a rotating machine according to any one of claims 1 to 3,
The current prediction unit obtains the predicted current value based on a current value detected in the rotating machine, a voltage command to the rotating machine, and an electrical angle of the rotating machine for each control cycle. machine controller.

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