JP2022101783A - Control device, motor system, and identification method - Google Patents

Abstract

To provide a control device, a motor system, and an identification method that can reduce a calculation process for estimating the inertia and viscosity coefficient of a motor.SOLUTION: In an identification method, a rise time of the speed of a motor is measured by changing a q-axis current of the motor in a stepwise manner, the inertia of the motor is estimated according to the measured value of the rise time, the q-axis current of the motor is measured at each of first rotation speed and second rotation speed, the viscous resistance of the motor is estimated on the basis of a speed difference between the first rotation speed and the second rotation speed, and a current difference between the measured value of the q-axis current at the first rotation speed and the measured value of the q-axis current at the second rotation speed, and the estimated value of the inertia is corrected by using the estimated value of the viscous resistance.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to control devices, motor systems and identification methods.

An identification device that identifies the inertia and viscosity coefficient of a motor by estimating the coefficient of the transfer function from the generated torque of the motor to the motor speed by the least squares method is known (see, for example, Patent Document 1). Further, there is known a technique of performing a minimum square estimation process based on a torque command and motor position information and outputting an inertia estimated value and a viscous friction coefficient estimated value (see, for example, Patent Document 2). Furthermore, the technology to calculate the total moment of inertia of the motor by calculating the angular acceleration from the rising curve of the estimated angular velocity value that rises by changing the current command value of the q-axis in steps and using the calculated value of the angular acceleration is known. (See, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 8-201097 International Publication No. 2014/156164 Japanese Unexamined Patent Publication No. 2004-242430

However, if the identification method by the least squares method is used to estimate the inertia and the viscosity coefficient of the motor, the calculation process may increase.

The present disclosure provides a control device, a motor system, and an identification method capable of reducing the calculation process for estimating the inertia and viscosity coefficient of a motor.

In one aspect of the disclosure,
A measuring unit that measures the rise time of the speed of the motor by changing the q-axis current of the motor in steps.
An inertia estimation unit that estimates the inertia of the motor according to the measured value of the rise time, and an inertia estimation unit.
A measuring unit that measures the q-axis current of the motor at each of the first rotation speed and the second rotation speed,
The speed difference between the first rotation speed and the second rotation speed, and the current difference between the measured value of the q-axis current at the first rotation speed and the measured value of the q-axis current at the second rotation speed. Based on the viscous resistance estimation unit that estimates the viscous resistance of the motor,
A control device is provided that includes a correction unit that corrects the estimated value of the inertia by using the estimated value of the viscous resistance.

According to the present disclosure, it is possible to reduce the calculation process for estimating the inertia and the viscosity coefficient of the motor.

It is a figure which shows the structural example of the motor system which concerns on Embodiment 1 of this disclosure. It is a functional block diagram which shows an example of the identification part which identifies the mechanical parameter of a motor. It is a flowchart which shows the identification method 1. It is a figure for demonstrating the method of estimating viscous resistance.

Hereinafter, the motor control device, the motor system, and the motor control method according to the embodiment of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration example of a motor system 1 according to the first embodiment of the present disclosure. The motor system 1 shown in FIG. 1 realizes high-performance torque control and speed control by controlling the motor 4 on the dq axis, which is an orthogonal rotation coordinate axis that rotates in synchronization with the rotor of the motor 4.

The d-axis is an axis extending in the real angle direction (direction of the magnetic flux generated by the magnet of the rotor) representing the actual magnetic pole position of the rotor, and the q-axis is an axis extending in a direction advanced by 90 ° in electrical angle from the d-axis. Is. The d-axis and q-axis may be collectively referred to as dq-axis or d, q-axis. The dq axis is the axis on the model in vector control. The magnetic pole position θ of the rotor is represented by an angle at which the d-axis advances with respect to the position of the reference coil (for example, the U-phase coil) of the motor. The d-axis and the q-axis are axes on the model in vector control, and the d-axis and the q-axis can be used regardless of the presence or absence of various sensors.

The equipment on which the motor system 1 is mounted is, for example, a copier, a personal computer, a refrigerator, a pump, and the like, but the equipment is not limited thereto. The motor system 1 includes at least a motor 4 and a motor control device 100.

The motor 4 is a motor having a plurality of coils. The motor 4 has, for example, a three-phase coil including a U-phase coil, a V-phase coil, and a W-phase coil. Specific examples of the motor 4 include a three-phase brushless DC motor, a stepping motor, and the like. The motor 4 has a rotor in which at least one permanent magnet is arranged and a stator. The motor 4 is, for example, a fan motor that rotates a fan for ventilation. The motor 4 may be a motor that does not use a position sensor for detecting the angular position (pole position) of the magnet of the rotor (sensorless type motor) or a motor that uses a position sensor (motor with a sensor).

When the motor 4 is a three-phase brushless DC motor, the motor control device 100 controls a plurality of switching elements connected by a three-phase bridge on / off (ON / OFF) according to an energization pattern including a three-phase PWM signal. The motor 4 is driven via the inverter 12. When the motor 4 is a stepping motor, the motor control device 100 drives the motor 4 via the inverter 12, for example, by controlling on / off of a plurality of switching elements connected in two phases according to an energization pattern including a two-phase PWM signal. do.

The motor control device 100 includes, for example, an inverter 12, a PWM circuit 13, a current detection unit 11, a position / speed detection unit 19, a speed control unit 20, a current control unit 30, a current coordinate converter 14, a voltage coordinate converter 15, and identification. A unit 40 is provided. The functions of each part such as the identification unit 40 are realized by operating a processor such as a CPU (Central Processing Unit) according to a program stored in the memory.

When the motor 4 is a three-phase brushless DC motor, the inverter 12 converts the DC supplied from the DC power supply into a three-phase alternating current by switching a plurality of switching elements, and causes the drive current of the three-phase alternating current to flow to the motor 4. This is a circuit for rotating the rotor of the motor 4. The inverter 12 drives the motor 4 based on a plurality of energization patterns (more specifically, three-phase PWM signals) generated by the PWM circuit 13. PWM means Pulse Width Modulation. When the motor 4 is a stepping motor, the inverter 12 converts the direct current supplied from the direct current power supply into a plurality of alternating currents by switching of a plurality of switching elements, and causes a plurality of drive currents to flow through the motor 4 to cause the rotor of the motor 4 to flow. It is a circuit to rotate.

When the motor 4 is a three-phase brushless DC motor, the current detection unit 11 flows to the motor 4 based on a plurality of energization patterns (more specifically, a three-phase PWM signal) generated by the PWM circuit 13. The phase currents Iu, Iv, and Iw of each of the U, V, and W phases are detected. For example, the current detection unit 11 detects the phase currents Iu, Iv, and Iw of each phase based on the voltage generated in one shunt resistance provided on the DC side of the inverter 12. The current detection unit 11 may detect the phase currents Iu, Iv, Iw by the current sensor that detects the current flowing between the inverter 12 and the motor 4. When the motor 4 is a stepping motor, the current detection unit 11 detects the phase current of each phase flowing through the motor 4 based on a plurality of energization patterns generated by the PWM circuit 13.

The position / velocity detection unit 19 has a d-axis current detection value _id and a q-axis current detection value i _q generated by the current coordinate converter 14, and a d-axis voltage command value v _d ^* generated by the current control unit 30. And the magnetic pole position θ and the rotation speed ω of the rotor are detected based on the q-axis voltage command value v _q ^* . When the position sensor is attached to the motor 4, the position / speed detection unit 19 may detect the magnetic pole position θ and the rotation speed ω based on the output signal of the position sensor. The magnetic pole position θ represents the magnetic pole position (electrical angle) of the rotor of the motor 4, and the rotational speed ω represents the electric angular velocity of the rotor of the motor 4. The detection value of the rotation speed ω detected by the position / speed detection unit 19 is also referred to as a speed detection value ω.

The speed control unit 20 gives a d-axis current command in the dq coordinate system so that the difference between the speed command value ω ^* from the outside and the speed detection value ω detected by the position / speed detection unit 19 converges to zero. Generates the values _id ^* and the q-axis current command value i _q ^* . The speed command value ω ^* represents the command value of the rotation speed represented by the electric angular velocity of the rotor of the motor 4. The speed control unit 20 includes, for example, a subtractor 16, a speed controller 17, and a current command calculation unit 18.

The subtractor 16 calculates the deviation between the speed command value ω ^* and the speed detection value ω. The speed controller 17 calculates the current command value i ^* by amplifying the deviation calculated by the subtractor 16. The torque command value τ ^* is obtained by multiplying the current command value i ^* by a coefficient, is equivalent to a value proportional to the current value, and represents the command value of the torque T of the motor 4.

Based on the current command value i ^* and the speed detection value ω, the current command calculation unit 18 has a _d -axis current command value id ^* , which is a command value of the d-axis current flowing in the d-axis direction of the motor 4, and the q-axis of the motor 4. The q-axis current command value i _q ^* , which is the command value of the q-axis current flowing in the direction, is calculated. The torque T generated in the motor 4 increases in proportion to the q-axis current command value i _q ^* .

The current control unit 30 is a command value of the d-axis voltage generated in the d-axis direction of the motor 4 so that the difference between the _d -axis current command value id ^* and the _d -axis current detection value id converges to zero. Generates the shaft voltage command value v _d ^* . The current control unit 30 is a command value of the q-axis voltage generated in the q-axis direction of the motor 4 so that the difference between the q-axis current command value i _q ^* and the q-axis current detection value i _q converges to zero. Generates the shaft voltage command value v _q ^* .

When the motor 4 is a brushless motor DC motor, the voltage coordinate converter 15 uses the magnetic pole position θ detected by the position / speed detection unit 19 to obtain a d-axis voltage command value v _d ^* and a q-axis voltage command value v _q . ^* Is converted into the phase voltage commands v _u *, v _v *, v _w * for each of the U, V, and W phases. The current coordinate converter 14 uses the magnetic pole position θ detected by the position / velocity detection unit 19 to convert the three-phase phase currents Iu, Iv, and Iw detected by the current detection unit 11 into two-phase d-axis currents. It is converted into the detected value _id and the q-axis current detected value i _q .

When the motor 4 is a stepping motor, the voltage coordinate converter 15 uses the magnetic pole position θ detected by the position / velocity detection unit 19 to generate a d-axis voltage command value v _d ^* and a q-axis voltage command value v _q ^* . , Convert to the phase voltage command value of each phase. The current coordinate converter 14 uses the magnetic pole position θ detected by the position / velocity detection unit 19 to convert the phase current of each phase detected by the current detection unit 11 into the two-phase _d -axis current detection value id and. Convert to q-axis current detection value i _q .

The identification unit 40 identifies the mechanical parameters (inertia, viscous resistance, etc.) of the motor 4. When a mechanical load is connected to the motor 4, the identification unit 40 identifies the mechanical parameters (inertia J and viscosity coefficient D) in the state where the mechanical load and the motor 4 are combined. The identification unit 40 is inside or outside the motor control device 100.

FIG. 2 is a functional block diagram showing an example of an identification unit that identifies mechanical parameters of a motor. The identification unit 40 shown in FIG. 2 includes a measurement unit 55, an inertia estimation unit 56, a measurement unit 58, a viscosity resistance estimation unit 59, and a correction unit 50.

The measuring unit 55 measures the rise time tr of the rotational speed ω of the motor 4 by changing the q-axis current of the motor 4 in steps. The inertia estimation unit 56 estimates the inertia J of the motor 4 according to the measured value of the rise time tr obtained by the measurement unit 55. The measuring unit 58 measures the q-axis current of the motor 4 at each of the first rotation speed ω1 and the second rotation speed ω2. The viscous resistance estimation unit 59 is the speed difference between the first rotation speed ω1 and the second rotation speed ω2, and the measured value of the q-axis current at the first rotation speed ω1 Iq1 and the measured value of the q-axis current at the second rotation speed ω2. The viscous resistance D is estimated based on the current difference from Iq2. The correction unit 50 corrects the estimated value of the inertia J obtained by the inertia estimation unit 56 by using the estimated value of the viscous resistance D obtained by the viscous resistance estimation unit 59.

The correction unit 50 stores the corrected estimated value of the inertia J and the estimated value of the viscous resistance D as identification values in the memory. The identification values of the inertia J and the viscous resistance D are used to set the control gain of the speed control unit 20 (FIG. 1). In setting the control gain, it is not always necessary to use the identification values of the inertia J and the viscous resistance D in the speed control unit 20. For example, the identification unit 40 may present the identification values of the inertia J and the viscous resistance D to the user, and set the control gain according to the information input from the user.

<Identification method 1>
FIG. 3 is a flowchart showing the identification method 1. First, the identification unit 40 sets the motor control device 100 to the current control by vector control, and sets the _d -axis current command value id ^* to the current control for controlling the q-axis current while being fixed to zero (step). S10).

Next, the identification unit 40 sets the current value of the step-shaped q-axis current (I _q current), and applies the step-shaped q-axis current in which the I _q current changes from zero to a predetermined current value (step). S11). The identification unit 40 observes the rotation speed ω of the motor 4 and measures the rise time tr until the rotation speed ω rises to a predetermined speed (step S12). For example, the measuring unit 55 of the identification unit 40 measures the rise time tr by changing the q-axis current command value i _q ^* in steps.

Since the inertia estimation unit 56 of the identification unit 40 has a correlation between the rise time tr and the inertia (the larger the actual inertia, the longer the rise time tr), the inertia J corresponding to the measured value of the rise time tr is estimated. (Step S13). The inertia estimation unit 56 of the identification unit 40 estimates the inertia J corresponding to the measured value of the rise time tr, for example, based on the relational rule between the rise time tr and the inertia (for example, a corresponding table or an arithmetic expression). The relational rules such as the correspondence table or the data for deriving the relational rules are stored in the memory or the like in advance.

Next, the identification unit 40 sets the motor control device 100 to speed control by vector control (step S14). At this time, the measurement unit 58 of the identification unit 40 calculates and sets the control gain of the speed control unit 20 using the estimated value of the inertia J obtained in step S13 (step S15).

The measuring unit 58 has a plurality of rotation speeds (for example, the first rotation speed ω1 and the second rotation speed) different from each other with the control gain set in step S15 in a state where the _d -axis current command value id ^* is fixed to zero. The motor 4 is rotated at a constant speed by ω2). The measuring unit 58 measures the q-axis current of the motor 4 at each of the plurality of rotation speeds. For example, the measuring unit 58 measures the q-axis current detection value i _q at the first rotation speed ω 1 (step S16), and measures the q-axis current detection value i _q at the second rotation speed ω 2 (step S17).

The viscous resistance estimation unit 59 has a speed difference between the first rotation speed ω1 and the second rotation speed ω2, and the measured value Iq1 of the _q -axis current detection value iq at the first rotation speed ω1 and the q-axis at the second rotation speed ω2. The viscous resistance D is estimated based on the current difference between the current detection value i _q and the measured value I q 2 (step S18).

The estimation of the viscous resistance D will be described in more detail. Assuming that the torque of the motor 4 is T, the rotation speed of the motor 4 is ω, the acceleration of the motor 4 is α, and the viscous resistance of the motor 4 is D.
T = J × α + D × ω ・ ・ ・ Equation 1
The relational expression is established. If the rotation speed ω is a constant velocity, the acceleration α is zero, so the component of inertia J can be ignored.
T = D × ω ・ ・ ・ Equation 2
The relational expression is established. Since the torque T is proportional to the q-axis current Iq, assuming that the torque constant of the motor 4 is Kt,
T = Kt × IQ ・ ・ ・ Equation 3
Therefore, from Equation 2 and Equation 3, the viscous resistance D is
D = Kt × Iq / ω ・ ・ ・ Equation 4
It is expressed by the relational expression. Therefore, according to FIGS. 4 and 4, the viscous resistance D can be accurately obtained from the slope of the straight line passing through the measurement points (ω1, Iq1) and the measurement points (ω2, Iq2). Therefore, the viscosity resistance estimation unit 59 is
D = Kt × (Iq2-Iq1) / (ω2-ω1) ・ ・ ・ Equation 5
The viscous resistance D can be calculated accordingly. That is, according to the equation 5, the viscous resistance estimation unit 59 has the speed difference between the first rotation speed ω1 and the second rotation speed ω2, and the measured values Iq1 and the second rotation speed of the q-axis current at the first rotation speed ω1. The viscous resistance D can be estimated based on the current difference between the measured value of the q-axis current in ω2 and the measured value Iq2 (step S18).

The correction unit 50 derives a correction amount C corresponding to the estimated value of the viscous resistance D obtained in step S18, and adds the correction amount C to the estimated value of the inertia J obtained in step S13 in step S13. The obtained inertia J is corrected (step S19). As a result, it is possible to suppress the deviation of the estimated value of the inertia J due to the difference in the viscous resistance D. The correction unit 50 derives a correction amount C corresponding to an estimated value of the viscous resistance D, for example, based on a relational rule between the viscous resistance D and the correction amount C (for example, a corresponding table or an arithmetic expression). The relational rules such as the correspondence table or the data for deriving the relational rules are stored in the memory or the like in advance.

The correction unit 50 determines the corrected estimated value of the inertia J obtained in step S19 and the estimated value of the viscous resistance D obtained in step S18 as identification values, and stores them in the memory (step S20).

As described above, in the identification method 1, the identification unit 40 can estimate the viscous resistance by rotating the motor 4 at a constant speed at a plurality of rotation speeds, and the rise time of the rotation speed ω with respect to the input of the stepped q-axis current. Inertia can be estimated by measurement. Therefore, it is possible to reduce the calculation process for estimating the inertia and the viscous resistance as compared with the identification method by the least squares method.

In the identification method 1, the inertia is estimated by the step response of the rotation speed, and then the viscous resistance is estimated by rotating the motor at a constant speed. However, the order may be reversed, the viscous resistance may be estimated by rotating the motor at a constant speed, and then the inertia may be estimated by the step response of the rotation speed. For example, the measuring unit 58 rotates the motor 4 at a constant speed at a plurality of rotation speeds different from each other with the default control gain of the speed control unit 20 in a state where the _d -axis current command value id ^* is fixed to zero. Then, the viscous resistance D is estimated. After that, the measuring unit 55 sets the current control to control the q-axis current with the _d -axis current command value id ^* fixed to zero, and sets the rise time of the rotation speed ω with respect to the input of the step-shaped q-axis current. The inertia J is estimated by the measurement of. The correction unit 50 corrects the inertia J using the estimated value of the viscous resistance D.

Although the control device, the motor system, and the identification method have been described above by the embodiment, the present invention is not limited to the above embodiment. Various modifications and improvements, such as combinations and substitutions with some or all of the other embodiments, are possible within the scope of the present invention.

For example, the current value of the step-shaped q-axis current may be a predetermined fixed value, a value adjusted by a user or the like, or a value set according to the rated value of the motor 4. The rated value is an example of a value (characteristic value) representing the characteristics of the motor. Rated values include, for example, motor capacity, voltage or current.

The identification unit 40 calculates the average value or the median value of the time Tr for a plurality of rises obtained by applying a plurality of step-shaped q-axis currents having different current values (step heights) a plurality of times, and the average value thereof. The inertia corresponding to the value or median may be estimated.

1 Motor system 4 Motor 11 Current detector 12 Inverter 13 PWM circuit 14 Current coordinate converter 15 Voltage coordinate converter 16 Subtractor 17 Speed regulator 18 Current command calculation unit 19 Position / speed detection unit 20 Speed control unit 30 Current control unit 33 Motor speed system 34 Mechanical system model 40 Identification unit 50 Correction unit 55 Measurement unit 56 Inertia estimation unit 58 Measurement unit 59 Viscous resistance estimation unit 100 Motor control device

Claims (6)

A measuring unit that measures the rise time of the speed of the motor by changing the q-axis current of the motor in steps.
An inertia estimation unit that estimates the inertia of the motor according to the measured value of the rise time, and an inertia estimation unit.
A measuring unit that measures the q-axis current of the motor at each of the first rotation speed and the second rotation speed,
The speed difference between the first rotation speed and the second rotation speed, and the current difference between the measured value of the q-axis current at the first rotation speed and the measured value of the q-axis current at the second rotation speed. Based on the viscous resistance estimation unit that estimates the viscous resistance of the motor,
A control device including a correction unit for correcting an estimated value of inertia using the estimated value of viscous resistance. The measuring unit sets a control gain for speed control of the motor using the estimated value of the inertia, rotates the motor at the first rotation speed and the second rotation speed with the control gain, and causes the first rotation speed. The control device according to claim 1, wherein the q-axis current of the motor at each of the rotation speed and the second rotation speed is measured. A q-axis current command value is generated so that the difference between the speed command value of the motor and the speed detection value of the motor converges to zero, and the difference between the q-axis current command value and the q-axis current detection value of the motor. A control unit that controls the motor so that the current converges to zero is provided.
The control device according to claim 1 or 2, wherein the measuring unit measures the rise time by changing the q-axis current command value in steps. The correction unit derives a correction amount corresponding to the estimated value of the viscous resistance, and corrects the inertia by adding the correction amount to the estimated value of the inertia, according to any one of claims 1 to 3. The control device described in. A motor system comprising the control device according to any one of claims 1 to 4 and the motor. By changing the q-axis current of the motor in steps, the rise time of the speed of the motor is measured.
The inertia of the motor is estimated according to the measured value of the rise time.
The q-axis current of the motor at each of the first rotation speed and the second rotation speed was measured, and
Based on the speed difference between the first rotation speed and the second rotation speed, and the current difference between the measured value of the q-axis current at the first rotation speed and the measured value of the q-axis current at the second rotation speed. To estimate the viscous resistance of the motor,
An identification method in which the estimated value of inertia is corrected by using the estimated value of viscous resistance.

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