阅读说明：本技术 马达控制装置 (Motor control device ) 是由 田中政仁 大野悌 于 2019-03-13 设计创作，主要内容包括：本发明提供一种具有推断电感及电阻不详的马达的电感及电阻的功能的马达控制装置。马达控制装置包括：电力转换器,将与所输入的电压指令相应的电压施加至马达；电流控制器,利用马达的驱动电流的电流值的检测结果算出输入至电力转换器的电压指令；电流指令生成部,基于马达的电时间常数确定马达常数计算用频率,生成马达常数计算用频率的正弦波并作为电流指令输入至电流控制器；以及马达常数计算部,求出频率响应,根据所求出的频率响应算出马达的电阻及电感,所述频率响应是将在电流指令生成部将正弦波作为电流指令而输入至电流控制器的期间内的电压指令、马达的驱动电流的电流值分别作为输入、输出。(The invention provides a motor control device having a function of estimating inductance and resistance of a motor with unknown inductance and resistance. The motor control device includes: a power converter that applies a voltage corresponding to the input voltage command to the motor; a current controller for calculating a voltage command to be input to the power converter using a detection result of a current value of a drive current of the motor; a current command generation unit that determines a motor constant calculation frequency based on an electrical time constant of the motor, generates a sine wave of the motor constant calculation frequency, and inputs the sine wave to the current controller as a current command; and a motor constant calculation unit that calculates a frequency response, which is input and output by a voltage command and a current value of a drive current of the motor during a period in which the current command generation unit inputs the sine wave as the current command to the current controller, and calculates a resistance and an inductance of the motor based on the calculated frequency response.)

1. A motor control device for controlling a motor, the motor control device comprising:

a power converter that applies a voltage corresponding to the input voltage command to the motor;

a current controller that calculates the voltage command input to the power converter so that a current value specified by the input current command matches the current value of the drive current of the motor, using a detection result of the current value of the drive current of the motor;

a current command generation unit that determines a motor constant calculation frequency based on an electrical time constant of the motor, generates a sine wave of the motor constant calculation frequency, and inputs the sine wave to the current controller as the current command; and

and a motor constant calculation unit that calculates a frequency response that inputs and outputs the voltage command and the current value of the drive current of the motor during a period in which the current command generation unit inputs the sine wave as the current command to the current controller, and calculates a resistance and an inductance of the motor from the calculated frequency response.

2. The motor control device according to claim 1, wherein the current command generating unit determines an inverse of the electrical time constant of the motor as the motor constant calculation frequency.

3. The motor control device according to claim 1 or 2, wherein the current command generating unit generates the sine wave of the motor constant calculation frequency after a frequency band of a current control loop including the power converter and the current controller is made lower than the motor constant calculation frequency, and inputs the sine wave as the current command to the current controller.

4. The motor control device according to claim 1 or 2,

the current command generation unit inputs a plurality of sine waves having different amplitudes of the motor constant calculation frequency as the current command one by one to the current controller, and

the motor constant calculation unit calculates the resistance and the inductance of the motor for each of the plurality of sine waves.

5. The motor control device according to claim 1 or 2, characterized by further comprising:

an estimation unit configured to obtain frequency responses in which the voltage command and the current value of the drive current of the motor are input and output in a predetermined frequency range by inputting a current command for applying a voltage equal to or lower than a predetermined voltage to the motor, the predetermined voltage being a voltage at which an excessive current does not flow into the motor regardless of a specification of the motor, to the current controller, and to estimate the electric time constant of the motor from the obtained frequency responses;

wherein the current command generation unit determines the motor constant calculation frequency based on the electric time constant of the motor estimated by the estimation unit.

Technical Field

The present invention relates to a motor control device.

Background

In order to control a motor well by a motor control device, a motor constant (inductance, resistance, etc.) of the motor is required. Also, a motor constant of the motor may vary according to a temperature of the motor or a current flowing through the motor. Accordingly, various techniques have been developed for inferring the motor constant. For example, the following techniques have been developed: motor resistances are known, and d-axis and q-axis inductances corresponding to currents flowing through the motor are estimated from various voltages and currents when pulse voltages are applied to the d-axis and q-axis (see, for example, patent document 1). Further, the following techniques have been developed: the d-axis and q-axis inductances corresponding to the current flowing through the motor and the temperature of the motor are estimated from various voltages and currents when high-frequency components are superimposed on the d-axis and q-axis current commands (see, for example, patent document 2).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2001-69782

[ patent document 2] Japanese patent laid-open No. Hei 9-28198

When the motor constant of the motor in the predetermined state is known, the motor can be controlled more favorably by correcting the motor constant by the above-described technique after setting the motor control device in accordance with the motor constant. However, motor constants (inductance and resistance) of the motor controlled by the motor control device may not be known at all. Moreover, if the motor constant of the motor is unknown, a complicated operation for inferring the motor constant of the motor must be performed.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor control device having a function of estimating inductance and resistance of a motor, which are unknown in inductance and resistance.

A motor control device that controls a motor according to an embodiment of the present invention includes: a power converter that applies a voltage corresponding to the input voltage command to the motor; a current controller that calculates the voltage command input to the power converter so that a current value specified by the input current command matches the current value of the drive current of the motor, using a detection result of the current value of the drive current of the motor; a current command generation unit that determines a motor constant calculation frequency based on an electrical time constant of the motor, generates a sine wave of the motor constant calculation frequency, and inputs the sine wave to the current controller as the current command; and a motor constant calculation unit that calculates a frequency response that inputs and outputs the voltage command and the current value of the drive current of the motor during a period in which the current command generation unit inputs the sine wave as the current command to the current controller, and calculates a resistance and an inductance of the motor from the calculated frequency response.

That is, basically, the resistance and inductance of the motor can be obtained from a frequency response obtained by inputting and outputting a voltage command and a current value of a drive current of the motor during a period in which a sine wave as a current command is inputted to a current controller, respectively, but if the frequency of the sine wave inputted to the current controller as the current command is too low, the calculation accuracy (estimation accuracy) of the inductance is deteriorated. If the frequency of the sine wave is too high, the calculation accuracy (estimation accuracy) of the resistance is deteriorated, but when the frequency response for calculating the resistance and the inductance of the motor is obtained, the motor control device inputs the sine wave of the motor constant calculation frequency determined based on the electrical time constant of the motor as a current command to the current controller. Therefore, according to the motor control device, the inductance and the resistance of the motor, whose inductance and resistance are unknown, can be accurately estimated (calculated).

The current command generating unit of the motor control device may determine an inverse of an electric time constant of the motor as the motor constant calculation frequency. The current command generation unit may determine a frequency in the vicinity of the reciprocal of the electric time constant of the motor (for example, a value in a predetermined frequency range including the reciprocal of the electric time constant) as the motor constant calculation frequency.

In order to prevent deterioration of the accuracy of determination of the inductance and resistance of the motor due to the influence of feedback (feedback) control of the current control loop, the motor control device may be configured such that the "current command generating unit generates a sine wave of the motor constant calculation frequency after the frequency band of the current control loop including the power converter and the current controller is made lower than the motor constant calculation frequency, and inputs the sine wave as the current command to the current controller".

In order to obtain the resistance and the inductance of the motor under various driving currents, the motor control device may be configured such that the "current command generating unit inputs a plurality of sine waves having different amplitudes of the motor constant calculation frequency as the current command to the current controller one by one", and the motor constant calculating unit calculates the resistance and the inductance of the motor for the plurality of sine waves, respectively ".

Further, the motor control device may be configured as follows: "further includes an estimation unit that obtains frequency responses in which the voltage command and a current value of a drive current of the motor are input and output in a predetermined frequency range by inputting a current command for applying a voltage equal to or lower than a predetermined voltage to the motor, the predetermined voltage being predetermined as a voltage at which an excessive current does not flow into the motor regardless of a specification of the motor, to the current controller, and estimates an electric time constant of the motor from the obtained frequency responses, and the current command generation unit determines the motor constant calculation frequency based on the electric time constant of the motor estimated by the estimation unit". If the above-described structure is adopted in advance, the inductance and resistance of the motor, whose electrical time constant, inductance, and resistance are unknown, can be estimated.

According to the present invention, the inductance and resistance of the motor, whose inductance and resistance are unknown, can be estimated.

Drawings

Fig. 1 is an explanatory diagram of a motor control function of a motor control device according to an embodiment of the present invention.

Fig. 2 is an explanatory diagram of a motor constant calculation function of the motor control device of the embodiment.

Fig. 3 is a diagram of gain lines (gain lines) when the voltage command and the detected current are input and output, respectively.

Fig. 4 is a Bode plot (Bode plot) of the current control loop.

Fig. 5 is an explanatory diagram of the current dependence of the inductor.

[ description of symbols ]

10: motor control device

11: position controller

12: speed controller

13: current controller

14: power converter

15: current detector

16: speed arithmetic unit

20: motor constant estimating unit

21: current command generating unit

22: RL calculating section

30: AC servomotor

31: machine with a movable working part

32: position detecting unit

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 and 2 are explanatory diagrams of a motor control function and a motor constant calculation function of a motor control device 10 according to an embodiment of the present invention.

The motor control device 10 of the present embodiment is a device (fig. 1) for controlling an Alternating Current (AC) servo motor (hereinafter, simply referred to as a motor) 30 connected to a machine 31, and is additionally provided with a function (fig. 2) of calculating an inductance and a resistance of the motor 30.

First, a motor control function of the motor control device 10 will be described. As shown in fig. 1, when controlling the motor 30, the motor control device 10 operates as a device including a position controller 11, a speed controller 12, a current controller 13, a power converter 14, a current detector 15, and a speed calculator 16. Each section shown in fig. 1 is a unit that operates in the following manner.

The position controller 11 calculates a speed command by multiplying a position proportional gain by a deviation between a position command input from a higher-level device (not shown) such as a Programmable Logic Controller (PLC) and a position of the motor 30 detected by a position detector 32 attached to the motor 30 (hereinafter referred to as a detection position). The speed calculator 16 calculates a speed (hereinafter referred to as a detection speed) by time-differentiating the detected position.

The speed controller 12 multiplies the integral of the deviation between the speed command and the detected speed calculated by the position controller 11 by a speed integral gain, and multiplies the sum of the calculation result and the speed deviation by a speed proportional gain, thereby calculating a current command.

The current controller 13 generates a voltage command corresponding to a difference between the current command calculated by the speed controller 12 and the magnitude of the current actually flowing through the motor 30 (hereinafter referred to as a detected current) detected by the current detector 15. As the current controller 13, a Proportional Integral (PI) controller is generally used. The power converter 14 amplifies a voltage command from the current controller 13 and applies the amplified voltage command to the motor 30.

The motor constant calculation function of the motor control device 10 will be described below.

As described above, the motor control device 10 is a device that performs current control when controlling the motor 30. Accurate values of the resistance and the inductance of the motor 30 are required for high-precision current control, but the resistance and the inductance of the motor 30 may not be known at all. In this case, the function for determining the resistance and the inductance of the motor 30 is the motor constant calculation function.

As shown in fig. 2, the motor constant calculation function of the motor control device 10 is realized by a motor constant estimation unit 20 including a current command generation unit 21 and a resistance inductance (RL) calculation unit 22, a current controller 13, a power converter 14, and a current detector 15.

The motor constant estimation unit 20 has the first to third operation modes as the operation modes. The operation of the motor constant estimation unit 20 in each mode will be described below.

[ first operation mode ]

The first mode of operation is a mode that can be used by a user knowing the electrical time constant of the motor 30.

When the motor constant estimation unit 20 is operated in the first operation mode, the user performs a predetermined operation (hereinafter referred to as a first operation) including an input operation of the electric time constant of the motor 30 to a higher-level device connected to the motor control device 10. When the first operation is performed, the host device notifies the motor constant estimation unit 20 of the electric time constant input by the user, and the motor constant estimation unit 20 starts the operation in the first operation mode.

When the motor constant estimation unit 20 starts the operation in the first operation mode, the current command generation unit 21 calculates the inverse of the electric time constant input by the user as the frequency for calculating the motor constant. Next, the current command generating unit 21 determines whether or not the current band frequency (band frequency) of the current control loop including the current controller 13 and the like is equal to or higher than the motor constant calculation frequency.

When the current band frequency of the current control loop is equal to or higher than the motor constant calculation frequency, the current command generation unit 21 changes the control parameter (PI gain) of the current controller 13 so that the band frequency of the current control loop is lower than the motor constant calculation frequency. Then, the current command generating unit 21 performs a current command input process of inputting a sine wave having a predetermined amplitude and a frequency for calculating the motor constant to the current control loop as a current command for a predetermined time period. The sine wave input to the current control loop means that the sine wave is input to a differentiator at a previous stage of the current controller 13.

On the other hand, when the current band frequency of the current control loop is lower than the motor constant calculation frequency, the current command generating unit 21 performs the current command input process without changing the control parameter of the current controller 13.

While the current command generating unit 21 performs the current command input process, the RL calculating unit 22 collects the voltage command and the detected current. After the current command input processing is completed, the RL calculation unit 22 obtains frequency responses in which the voltage command and the detected current are input and output, respectively, based on the collected information. Next, the RL calculation unit 22 calculates the resistance R and the inductance L of the motor 30 from the obtained frequency response by the following expressions (1) and (2).

[ numerical formula 1]

Here, ω is a frequency for calculating a motor constant, and P (ω) and G (ω) are a gain and a phase obtained as the frequency response, respectively. The expressions (1) and (2) are obtained by assuming the following motor model.

[ numerical formula 2]

After the RL calculation unit 22 finishes calculating the resistance and the inductance of the motor 30, the motor constant estimation unit 20 transmits the calculated resistance and inductance to the host device as the processing result, and then ends the operation in the first operation mode.

[ second operation mode ]

The second mode of operation is also a mode that can be used by the user knowing the electrical time constant of the motor 30.

When the motor constant estimation unit 20 is operated in the second operation mode, the user performs a predetermined operation (hereinafter referred to as a second operation) on the host device, including an input operation of the electric time constant of the motor 30 and one or more specified values of the drive current. When the second operation is performed, the host device notifies the motor constant estimation unit 20 of the values input by the user, and the motor constant estimation unit 20 starts the operation in the second operation mode.

When the motor constant estimation unit 20 starts the operation in the second operation mode, the current command generation unit 21 calculates the inverse of the electric time constant input by the user as the frequency for calculating the motor constant. Next, the current command generating unit 21 determines whether or not the current band frequency of the current control loop including the current controller 13 and the like is equal to or higher than the motor constant calculation frequency. Then, the current command generating unit 21 changes the control parameter of the current controller 13 so that the current band frequency of the current control loop becomes lower than the motor constant calculation frequency only when the current band frequency of the current control loop becomes equal to or higher than the motor constant calculation frequency.

Then, the current command generating unit 21 performs a current command input process for each drive current designated value input by the user, inputs a sine wave of a motor constant calculation frequency as a current command to the current control loop for a predetermined time period, and determines the amplitude of the current flowing through the motor so that the time average value of the current coincides with the drive current designated value.

When the motor constant estimating unit 20 operates in the second operation mode, the RL calculating unit 22 collects a voltage command and a detected current for each current command input process performed by the current command generating unit 21, obtains frequency responses in which the voltage command and the detected current are input and output, respectively, based on the collected information, and calculates the resistance and inductance of the motor 30 from the obtained frequency responses. When the RL calculation unit 22 completes the processing for all the current command input processes, the motor constant estimation unit 20 transmits the (all) pair (pair) resistances and inductances calculated by the RL calculation unit 22 to the host device as the processing results, and then ends the operation in the second operation mode.

[ third operation mode ]

The third operating mode is a mode that is typically used when the electrical time constant of the motor 30 is unknown.

When the motor constant estimation unit 20 is operated in the third operation mode, the user performs a predetermined operation (hereinafter referred to as a third operation) for instructing the host device to start the operation in the third operation mode. When the third operation is performed, the host device instructs the motor constant estimation unit 20 to start the operation in the third operation mode, and the motor constant estimation unit 20 starts the operation in the third operation mode.

When the motor constant estimation unit 20 starts operating in the third operation mode, the following processing is performed by the current command generation unit 21 and the RL calculation unit 22: in a state where only a voltage equal to or lower than a predetermined voltage predetermined such that an excessive current does not flow into the motor 30 regardless of the specification of the motor 30 is applied to the motor 30, a frequency response in a predetermined frequency range (for example, several hertz (Hz) to several kilohertz (kHz)) in which a voltage command and a detection current are input and output, respectively, is measured. The predetermined voltage may be a predetermined voltage of about several volts (V) or a value (for example, power supply voltage × 5%) obtained from the power supply voltage of the motor control device 10.

The RL calculation unit 22, which has finished measuring the frequency response, calculates the inductance and resistance of the motor 30 from the gain and phase at several frequencies of the measured frequency response. Next, the RL calculation unit 22 calculates a set of inductance and resistance by a predetermined process (for example, a process of removing an abnormal value and then averaging) based on the calculation results of the plurality of sets of inductance and resistance. Then, the RL calculation unit 22 calculates an electric time constant of the motor 30 from the calculation result of the set of inductance and resistance.

When the calculation of the electric time constant of the motor 30 in the above-described order is completed, the current command generating unit 21 and the RL calculating unit 22 perform the following processes, which are different from those of the current command generating unit 21 and the RL calculating unit 22 in the first operation mode: the electric time constant used for calculating the frequency for motor constant calculation is not a value input by the user. Then, the motor constant estimation unit 20 transmits the calculated resistance and inductance as the processing result to the host device, and then ends the operation in the third operation mode.

As described above, the motor control device 10 of the present embodiment basically determines the resistance and inductance of the motor 30 based on the frequency response in which the voltage command and the detected current are input and output, respectively, during the period in which the sine wave is input to the current controller 13 as the current command. Fig. 3 shows frequency responses (gain line graphs) in which a voltage command and a detected current are input and output, respectively. Therefore, if the frequency of the sine wave input to the current controller 13 as the current command is too low, the calculation accuracy (estimation accuracy) of the inductance is deteriorated. If the frequency of the sine wave is too high, the calculation accuracy (estimation accuracy) of the resistance is deteriorated, but the motor control device 10 is configured such that the frequency of the sine wave input to the current controller 13 as a current command is the reciprocal of the electrical time constant (T in fig. 3) of the motor 30. Therefore, the calculation result of the resistance and the inductance of the motor 30 calculated by the motor control device 10 is accurate. Further, the motor 30 can be controlled favorably by setting the proportional gain Kp and the integral gain Ki of the current controller 13 to the following values, for example, based on the calculated resistance R and inductance L of the motor 30.

Kp ═ Wc × L (3) formula

Ki ═ R/L (4) formula

In the formula (3), Wc is a predetermined proportionality coefficient.

Fig. 4 shows a frequency response (bode diagram) of a current control loop of the motor control device 10. Therefore, when "the motor constant measurement frequency < the band frequency of the current control loop" is satisfied, the deviation input to the current controller 13 approaches "0", and the accuracy of determination of the resistance and the inductance of the motor 30 deteriorates, but the motor control device 10 has a function of changing the band frequency of the current control loop to be equal to or lower than the motor constant measurement frequency. Therefore, according to the motor control device 10, it is possible to suppress a decrease in the determination accuracy caused by the deviation close to "0" input to the current controller 13.

As shown in fig. 5, the inductance of the motor 30 changes according to the current flowing through the motor 30. By operating the motor constant estimating unit 20 in the second operation mode, the inductance and the resistance of the motor 30 at each current value can be calculated (estimated). Therefore, according to the motor control device 10, the parameter of the current controller 13 may be changed according to the drive current of the motor 30.

Further, by operating the motor constant estimation unit 20 of the motor control device 10 in the third operation mode, it is possible to estimate the resistance and inductance of the motor 30 whose power-off time constant is unknown. In the third operation mode, only a low voltage is applied to the motor 30. Therefore, it is possible to prevent the occurrence of a phenomenon in which the current excessively flows into the motor 30 having a low resistance.

Manner of modification

The motor control device 10 is a device capable of various modifications. For example, the motor control device 10 may be modified to automatically change the control parameter of the current controller 13 based on the calculation result of the resistance and inductance of the motor 30. When the control parameters of the current controller 13 are automatically changed to the calculation results of the resistance and inductance in the second operation mode, it is sufficient to add a table storing the resistance and inductance calculated for each current value to the motor control device 10 and then change the values of the resistance and inductance in advance according to the current value (see expressions (3) and (4)).

The motor constant calculation frequency may be a value near the reciprocal of the electric time constant of the motor 30. The motor constant calculation frequency may be determined in advance for each range (section) including the reciprocal of the electrical time constant, and the motor constant calculation frequency corresponding to the range including the reciprocal of the electrical time constant may be used.

Please note

1. A motor control device (10) for controlling a motor (30), said motor control device (10) comprising:

a power converter 14 that applies a voltage corresponding to the input voltage command to the motor;

a current controller 13 that calculates the voltage command to be input to the power converter 14 so that a current value specified by the input current command matches the current value of the drive current of the motor, using a detection result of the current value of the drive current of the motor;

a current command generating unit 21 that determines a motor constant calculation frequency based on an electrical time constant of the motor 30, generates a sine wave of the motor constant calculation frequency, and inputs the sine wave as the current command to the current controller 13; and

the motor constant calculation unit 22 calculates a frequency response that receives and outputs the voltage command and the current value of the drive current of the motor 30 during a period in which the current command generation unit 21 inputs the sine wave as the current command to the current controller 13, and calculates the resistance and the inductance of the motor 30 from the calculated frequency response.