JP2021175356A - Motor control device, motor system and motor control method - Google Patents

Abstract

To ensure the accuracy of the identification of a q-axis inductance.SOLUTION: A d-axis voltage command value is generated so that a difference between a d-axis electrical current command value of a motor and a d-axis electrical current detection value of the motor converges to zero, and a q-axis voltage command value is generated so that a difference between a q-axis electrical current command value of the motor and a q-axis electrical current detection value of the motor converges to zero. Based on the d-axis voltage command value, a d-axis electrical current estimation value, which is an estimated value of the d-axis electrical current detection value, is output from a d-axis electrical current estimation model, and based on the q-axis voltage command value, a q-axis electrical current estimation value, which is an estimated value of the q-axis electrical current detection value, is output from a q-axis electrical current estimation model. A q-axis inductance of the motor that minimizes the sum of squares of a difference between the q-axis electrical current detection value and the q-axis electrical current estimation value is identified. An Lq identified value, which is a value obtained by identifying the q-axis inductance, is derived by changing a frequency of the q-axis voltage command value.SELECTED DRAWING: Figure 4

Description

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

A motor vector control device is known to have a function of identifying a q-axis inductance (see, for example, Patent Document 1). In addition, the voltage command while the sine wave is being input to the current controller as the current command is used as the input, and the frequency response is obtained with the current value of the drive current of the motor as the output. From the obtained frequency response, the unknown inductance of the motor is obtained. A motor control device for calculating the current value is known (see, for example, Patent Document 2).

JP-A-2007-159212 Japanese Unexamined Patent Publication No. 2020-10433

However, in the conventional technique, the accuracy of identifying the q-axis inductance may decrease depending on the frequency of the sine wave input to the current controller.

The present disclosure provides a motor control device, a motor system, and a motor control method capable of ensuring the identification accuracy of the q-axis inductance.

The motor control device according to the embodiment of the present disclosure is
A d-axis voltage command value is generated so that the difference between the d-axis current command value of the motor and the d-axis current detection value of the motor converges to zero, and the q-axis current command value of the motor and the q-axis of the motor are generated. A current control unit that generates a q-axis voltage command value so that the difference from the current detection value converges to zero,
A d-axis current estimation model that outputs a d-axis current estimated value that is an estimated value of the d-axis current detected value from the d-axis voltage command value, and a d-axis current estimation model.
A q-axis current estimation model that outputs a q-axis current estimated value that is an estimated value of the q-axis current detected value from the q-axis voltage command value, and a q-axis current estimation model.
The d-axis inductance of the motor that minimizes the sum of squares of the error between the d-axis current detected value and the d-axis current estimated value is identified, and the q-axis current detected value and the q-axis current estimated value are identified. It is provided with an identification unit for identifying the q-axis inductance of the motor so as to minimize the sum of squares of the error with.
The identification unit derives the Ld identification value which is the value for identifying the d-axis inductance, and changes the frequency of the q-axis voltage command value for the Lq identification value which is the value for identifying the q-axis inductance. Derived.

According to the present disclosure, the identification accuracy of the q-axis inductance can be ensured.

It is a figure which shows the structural example of the motor system which concerns on Embodiment 1 of this disclosure. It is a figure which shows an example of the stator model in the current control system of a motor system. It is a functional block diagram which shows an example of the identification part which identifies the electrical parameter of a motor by the least squares method. It is a figure which illustrates the identification value of each of the q-axis inductance and the d-axis inductance with respect to the frequency of the periodic signal input as a voltage command value. Is a diagram illustrating an example of a phase change of d-axis current detection value i _d for the d axis voltage value v _d ^* of the input of the frequency A. It is a figure which shows an example of the phase change of the q-axis current detection value i _q with respect to the input of the q-axis voltage command value v _q ^{* of frequency A.} It is a diagram illustrating an example of a phase change of d-axis current detection value i _d for the d axis voltage value v _d ^* of the input frequency B. It is a figure which shows an example of the phase change of the q-axis current detection value i _q with respect to the input of the q-axis voltage command value v _q ^{* of frequency B.} It is a flowchart which shows the identification method 1. It is a flowchart which shows the identification method 2. It is a figure which shows an example of a table. It is a figure which shows an example of a table. It is a flowchart which shows the identification method 3. It is a flowchart which shows the identification method 4.

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 a 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 the real axis extending in the real angle direction (the 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 extends in the direction advanced by 90 ° in the electric angle from the d-axis. It is a real axis. 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 reference to the position of the reference coil (for example, the U-phase coil) of the motor. The dq coordinate system is advanced by θ from the reference coil. 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 is a motor having a rotor on 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 blowing air. The technique of the present disclosure can also be applied to a motor 4 to which a position sensor for detecting an angular position (pole position) of a rotor magnet is attached. The motor 4 may be a motor that does not use a position sensor that detects 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. The unit 40 is provided.

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 a plurality of switching elements, and causes a plurality of drive currents to flow through the motor 4, thereby causing the rotor of the motor 4 to flow. It is a circuit that rotates.

When the motor 4 is a three-phase brushless DC motor, the current detection unit 11 flows through 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 resistor 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 / speed detection unit 19 includes 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 commands ^{a d-axis current 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. generating values _i ^{d *} 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 torque command value τ ^* by amplifying the deviation calculated by the subtractor 16. The torque command value τ ^* represents the command value of the torque T of the motor 4.

Based on the torque command value τ ^* _{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, as the difference between the d-axis current command value i _d ^* and the d-axis current detection value i _d converges to zero, which is a command value of the d-axis voltage generated in the d-axis direction of the motor 4 d 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, and uses the d-axis voltage command value v _d ^* and the 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 / speed 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 the q-axis current detection value _iq.

The identification unit 40 identifies the electrical parameters (inductance, resistance value, etc.) of the motor 4. The current control system of the motor system 1 is configured by using the stator model including the electrical parameters identified by the identification unit 40.

FIG. 2 is a diagram showing an example of a stator model in a current control system of a motor system. The motor current unit 31 shown in FIG. 2 includes a stator model 32 of the motor 4. The stator model 32 is represented by a transfer function that inputs the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^* and outputs the d-axis current value _id and the q-axis current value i _q. L _{d and q} represent the inductance of the motor 4, R represents the resistance value of the motor 4, and s represents the Laplace operator. _{The identification unit 40 identifies the electrical parameters (inductance L d, q} and resistance value R) of the motor 4 by estimating, for example, two coefficients of the transfer function representing the stator model 32 by the least squares method. The d-axis inductance is also referred _{to as "L d} ", and the q-axis inductance _{is also referred to as "L q".}

FIG. 3 is a functional block diagram showing an example of an identification unit that identifies the electrical parameters of the motor by the least squares method. The identification unit 40 includes, for example, a periodic signal generation unit 41, an estimation model 43, an estimation unit 44, and a calculation unit 45. The actual model 42 corresponds to the stator model 32 shown in FIG. The periodic signal generation unit 41 may be inside the identification unit 40 (see FIG. 3) or outside the motor control device 100 (see FIG. 1).

In FIG. 3, the periodic signal generation unit 41 generates a periodic signal whose amplitude, frequency, and offset are variable, and uses the generated periodic signal as a command value of a q-axis voltage generated in the q-axis direction of the motor 4. It has a function to input as a voltage command value v _q ^*. The waveform of the periodic signal is not limited to the sine wave, and may be another periodic waveform such as a pseudo sine wave, a triangular wave, or a saw wave.

_{The estimation model 43 has a q-axis current value i q} from a periodic signal input from the periodic signal generator 41 as _{a q-axis voltage command value v q} ^* , which is a command value of the q-axis voltage generated in the q-axis direction of the motor 4. The q-axis current estimated value i _qm , which is an estimated value, is output. An estimation model that outputs the q-axis current estimated value i _qm from the q-axis voltage command value v _q ^{* is} called a q-axis current estimation model. The estimation model 43 is represented by the same transfer function as the real model 42. L _qm represents the q-axis inductance on the estimation model 43, and R _m represents the resistance value on the estimation model 43.

Estimation unit 44, q-axis current estimated output from the q-axis current detection value i _{q (current} coordinate converter q-axis actually obtained by 14 the current detection value i _q) with the estimation model 43 that is output from the real model 42 _{Calculate (identify) the "q-axis inductance L q} and resistance value R" that minimizes the sum of squares of the error with the value i _qm. The estimation unit 44 stores the calculated values of the q-axis inductance L _q and the resistance value R as identification values in the memory. Similar calculation (identification) is performed on the d-axis using the d-axis current value _id and the d-axis current estimated value i _dm . Estimation unit 44, d-axis current estimated output from the d-axis current detection value i _{d (current} coordinate converter d-axis actually obtained by 14 the current detection value i _d) and the estimated model 43 output from the real model 42 _{Calculate (identify) the "d-axis inductance L d} and resistance value R" that minimizes the sum of squares of the error with the value i _dm. The estimation unit 44 stores the calculated values of the d-axis inductance L _d and the resistance value R as identification values in the memory. Note that FIG. 3 shows a case where the q-axis inductance L _q and the resistance value R are calculated (identified).

_{The identification unit 40 fixes the d-axis voltage command value v d} ^* , which is the command value of the d-axis voltage generated in the d-axis direction of the motor 4, so that the motor 4 can identify the q-axis inductance L _q and the resistance value R. The rotation of the rotor can be fixed. The identification unit 40 identifies by the minimum square method by changing the frequency of the q-axis voltage command value v _q ^* while fixing the amplitude of the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^*. The accuracy of is improved. The identification unit 40 similarly identifies the d-axis inductance L _d and the resistance value R. The identification unit 40 also improves the accuracy of identification by the least squares method by superimposing the offset value on the d-axis voltage command value v _d ^* even when identifying the d-axis inductance L _{d and the resistance value R.}

_{The q-axis inductance L q} and the resistance value R derived by the estimation unit 44, _{and the identification values of the d-axis inductance L d} and the resistance value R are the control parameters such as the control gain of the current control unit 30 (FIG. 1). Used for setting. The calculation unit 45 uses the identification values of the q-axis inductance L _q and the resistance value R, and the d-axis inductance L _d and the resistance value R to calculate parameters including the control gain.

However, if the low frequency of the periodic signal generated by the periodic signal generation unit 41, the identification value of the q-axis inductance L _q is original value significantly different (the identification accuracy decreases) during operation in some cases.

FIG. 4 is a diagram illustrating each identification value of the q-axis inductance and the d-axis inductance with respect to the frequency of the periodic signal input as the voltage command value. The Ld identification value represents the identification value of the d-axis inductance, and the Lq identification value represents the identification value of the q-axis inductance. When the frequency of the q-axis voltage command value v _q ^* generated by the periodic signal generation unit 41 becomes low, the variation in the identification value of the q-axis inductance may become large as shown in FIG. FIG. 4 shows that the identification value of the q-axis inductance is non-linear with respect to frequency (frequency non-linearity).

Figure 5 is a diagram showing an example of the phase change of the d-axis current detection value i _d for the d axis voltage value v _d ^* of the input of the frequency A. FIG. 6 is a diagram showing an example of a phase change of the q-axis current detection value i _q with respect to the input of the q-axis voltage command value v _q ^{* of the frequency A.} Figure 7 is a diagram showing an example of the phase change of the d-axis current detection value i _d for the d axis voltage value v _d ^* of the input frequency B. FIG. 8 is a diagram showing an example of a phase change of the q-axis current detection value i _q with respect to the input of the q-axis voltage command value v _q ^{* of the frequency B.} Frequency B is higher than frequency A. In any of FIGS. 5, 7 and 8, the normal phenomenon that the current detection value is delayed with respect to the voltage command value is shown. However, as shown in FIG. 6, in the low frequency region where the identification value of the q-axis inductance is not stable _{, the phase of the q-axis current detection value i q} advances with respect to the phase of the q-axis voltage command value v _q ^{* (current).} Phase lead phenomenon) may occur. The phase of the q-axis current detection value i _q should be delayed with respect to the phase of the q-axis voltage command value v _q ^*.

There are various methods for identifying the electrical parameters of the motor, such as a sine wave application method using the least squares method, a sequential identification method using an M sequence, and an identification method using a step response. Among these, the method using the M sequence and the method using the step response result in the identification result affected by the frequency non-linearity, and it is difficult to reduce the influence of the frequency non-linearity.

The identification method in the present disclosure is to identify by observing the influence of frequency non-linearity by using a sine wave application method using a minimum square method that can be identified in consideration of the influence of frequency non-linearity. It makes it possible to improve the accuracy of identification. The identification unit 40 performs identification by this identification method. Even when a periodic waveform such as a triangular wave is used instead of the sine wave, the contents of the present disclosure can be applied by treating the periodic waveform such as the triangular wave as a pseudo sine wave.

Identification unit 40 is fixed to d axis voltage value v _d ^*, or the d-axis voltage command value by changing the frequency v _d ^* of the frequency to a specific one frequency to identify the d-axis inductance, Ld identified Derived the value. Further, the identification unit 40 has a function of ensuring the identification accuracy of the q-axis inductance by identifying the q-axis inductance by changing the frequency of the q-axis voltage command value v _q ^*. Hereinafter, identification methods 1 to 4 for identifying the q-axis inductance by changing the frequency of the q-axis voltage command value v _q ^{* will be described with reference to FIGS. 9 to 14.}

<Identification method 1>
Using the sine wave application method using the least squares method, identification is performed for each of Ld and Lq while changing the frequency of the applied sine wave. When the Lq identification value becomes stable, the identification unit 40 determines the Ld identification value and the Lq identification value at the frequency at the time of stabilization as the inductance. The Ld identification value is usually stable regardless of frequency (see FIG. 4). Utilizing this feature, the identification unit 40 determines that the Lq identification value converges within a certain predetermined range with respect to the Ld identification value, or that the Lq identification value becomes larger than the Ld identification value and becomes a stable value. If it becomes, it is judged that the Lq identification value is stable.

FIG. 9 is a flowchart showing the identification method 1. The identification unit 40 sets the initial values of the frequency and amplitude of the _{q-axis voltage command value v q} ^* generated by the periodic signal generation unit 41 (see FIG. 3) (step S10). First, the estimation unit 44 (FIG. 3) executes identification of Ld and Lq with the initial values (step S20).

The identification unit 40 may identify either Ld or Lq first, but when identifying Ld, the identification unit 40 sets the initial values of the frequency, amplitude, and offset value of _{the d-axis voltage command value v d} ^*. When identifying Lq, the identification unit 40 sets the initial values of the frequency, amplitude, and offset value of _{the q-axis voltage command value v q} ^*. The frequencies of the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^* have the same initial values, and the respective amplitudes and offset values do not have to be the same initial values.

The estimation unit 44 determines whether or not the Lq identification value obtained in step S20 is stable (step S30). When the estimation unit 44 determines that the Lq identification value obtained in step S20 is not stable, the estimation unit 44 changes the frequency of the _{q-axis voltage command value v q} ^{* generated by the periodic signal generation unit 41 (see FIG. 3).} (Step S60). The estimation unit 44 executes the identification of Lq at the frequency of the changed q-axis voltage command value v _q ^* , and executes the identification of Ld using the same frequency (step S20).

When the estimation unit 44 determines that the Lq identification value obtained in step S20 is stable, the estimation unit 44 determines the Lq identification value at the frequency when the value is stable as the q-axis inductance (step S40). The estimation unit 44 determines the identified value of the resistance value R identified at this frequency as the resistance value of the motor (step S40). The calculation unit 45 (FIG. 3) uses the identification value obtained by the estimation unit 44 to calculate parameters and the like including the control gain of the current control unit 30 (step S50).

According to the identification method 1, a stable Lq identification value can be obtained while avoiding the influence of the frequency non-linearity of the q-axis inductance, so that the identification accuracy of the q-axis inductance can be ensured. By calculating the control parameters based on the obtained identification values, stable motor control without abnormal operation becomes possible, and the performance of the motor can be exhibited.

<Identification method 2>
FIG. 10 is a flowchart showing the identification method 2. The identification unit 40 sets the initial values of the frequency and amplitude of the _{q-axis voltage command value v q} ^* generated by the periodic signal generation unit 41 (see FIG. 3) (step S110). First, the estimation unit 44 (FIG. 3) executes identification of Ld and Lq with the initial values (step S120).

The identification unit 40 may identify either Ld or Lq first, but when identifying Ld, the identification unit 40 sets the initial values of the frequency, amplitude, and offset value of _{the d-axis voltage command value v d} ^*. When identifying Lq, the identification unit 40 sets the initial values of the frequency, amplitude, and offset value of _{the q-axis voltage command value v q} ^*. The frequencies of the d-axis voltage command value v _d ^* and the q-axis voltage command value v _q ^* have the same initial values, and the respective amplitudes and offset values do not have to be the same initial values.

The estimation unit 44 changes the Lq identification value according to a predetermined determination condition (step S130). For example, when the Lq identification value is smaller than the Ld identification value or the Lq identification value is larger than a certain range with respect to the Ld identification value, the estimation unit 44 sets the Lq identification value to the same value as the Ld identification value.

The estimation unit 44 records the Ld identification value obtained in step S120, the identification value of the resistance value R obtained in step S120, and the Lq identification value obtained in step S120 or S130 in association with each other in a table (step). S140).

The estimation unit 44 changes the frequency of the d-axis voltage command value v _d ^{* and} the frequency of the q-axis voltage command value v _q ^* until the identification values at all the set frequencies are obtained (step S160), and steps S120 to S150. Perform the work of. The estimation unit 44 completes the table (step S170) when these operations are completed (step S150).

It should be noted that this table may include the identification value of the resistance value R identified at the time of identification of Ld and Lq for all the set frequencies (for example, f _{1 to} f _{5) (see FIG. 11).}

Further, the estimation unit 44 may create a table by a method other than the above. For example, the estimation unit 44 performs identification for each frequency, and uses the identified values to create a table in which the frequency, the Ld identification value, and the Lq identification value correspond to each other. After that, the estimation unit 44 creates a table by collectively performing a process of setting the Lq identification value of each frequency to the same value as the Ld identification value according to the above-mentioned determination conditions on the created table. May be done (see FIG. 12).

In step S180 of FIG. 10, the calculation unit 45 selects the Ld identification value and the Lq identification value at the frequency corresponding to the rotation speed from the table according to the speed detection value ω representing the rotation speed of the motor 4. The calculation unit 45 may derive the Ld identification value and the Lq identification value from the table by interpolating a plurality of identification values stored in the table according to the speed detection value ω representing the rotation speed of the motor 4. .. The calculation unit 45 uses the selected Ld identification value and Lq identification value to calculate parameters and the like including the control gain (step S190). The calculated control parameters are used to control the motor.

According to the identification method 2, a stable Lq identification value can be obtained while avoiding the influence of the frequency non-linearity of the q-axis inductance, so that the identification accuracy of the q-axis inductance can be ensured. Further, it is possible to obtain an optimum control parameter for each rotation speed, which is not affected by the frequency non-linearity of the q-axis inductance. Further, by calculating the control parameter based on the identification value created for each frequency, it is possible to set an appropriate control parameter according to the rotation speed of the motor.

<Identification method 3>
In the region where the Lq identification value shows unstable frequency non-linearity, there is a possibility that a phenomenon in which the phase of the output current advances with respect to the input voltage (see FIG. 6) occurs. In the identification method 3, the identification unit 40 observes the phase of the output current with respect to the input voltage, and identifies at a stable frequency at which the current phase advance does not occur. This makes it possible to perform identification in consideration of frequency non-linearity.

FIG. 13 is a flowchart showing the identification method 3. The identification unit 40 sets the initial values of the frequency and amplitude of the _{q-axis voltage command value v q} ^* generated by the periodic signal generation unit 41 (see FIG. 3) (step S210). The estimation unit 44 measures the phase of the q-axis current detection value i _q with respect to the q-axis voltage command value v _q ^* at that time (step S220). The estimation unit 44 determines whether or not the measured phase value satisfies the setting condition (step S230). When the estimation unit 44 determines that the measured phase value does not satisfy the setting conditions, the estimation unit 44 changes the frequency of the _{q-axis voltage command value v q} ^{* generated by the periodic signal generation unit 41 (see FIG. 3).} (Step S240), the phase of the q-axis current detection value i _q with respect to the q-axis voltage command value v _q ^* at that time is measured again (step S220). When the phase measurement value satisfies the setting condition (step S230, YES), the estimation unit 44 records the frequency when the phase measurement value satisfies the setting condition (step S250). The frequency at this time is the frequency when the phase of the q-axis current detection value i _{q with respect to the q-axis voltage command value v q} ^* is delayed.

As a case where the current phase setting condition of step S230 is satisfied, for example, when the measured value of the phase satisfies a certain set value, the current phase characteristic observed in a wide frequency range is calculated by a calculation formula or the like. In some cases, an appropriate phase value may be satisfied.

The estimation unit 44 identifies the recorded frequency by a sine wave application method using the least squares method (step S260). In step S270, the estimation unit 44 determines the Ld identification value at that frequency as the d-axis inductance, and determines the Lq identification value at that frequency as the q-axis inductance. The estimation unit 44 may also determine the resistance value R calculated at the time of identifying the inductance as the resistance value identified at the same time. The calculation unit 45 uses each of the determined identification values to calculate parameters and the like including the control gain (step S280).

According to the identification method 3, a stable Lq identification value can be obtained while avoiding the influence of the frequency non-linearity of the q-axis inductance, so that the identification accuracy of the q-axis inductance can be ensured. By calculating the control parameters based on the obtained identification values, stable motor control without abnormal operation becomes possible, and the performance of the motor can be exhibited.

<Identification method 4>
In the region where the Lq identification value shows unstable frequency non-linearity, there is a possibility that a phenomenon in which the phase of the output current advances with respect to the input voltage (see FIG. 6) occurs. In the identification method 4, the identification unit 40 observes the phase of the output current with respect to the input voltage, and performs identification in consideration of the current phase lead. This makes it possible to perform identification in consideration of frequency non-linearity.

FIG. 14 is a flowchart showing the identification method 4. The identification unit 40 sets the initial values of the frequency and amplitude of the _{q-axis voltage command value v q} ^* generated by the periodic signal generation unit 41 (see FIG. 3) (step S310). The estimation unit 44 measures the phase of the q-axis current detection value i _q with respect to the q-axis voltage command value v _q ^* at that time (step S320).

Next, the estimation unit 44 identifies Ld and Lq by a sine wave application method using the least squares method at the same set frequency as in step S320 (step S330). The estimation unit 44 determines whether or not the measured value of the phase in step S320 satisfies the setting condition (step S340). When the estimation unit 44 determines that the phase measurement value in step S320 satisfies the setting condition, the estimation unit 44 sets the Ld identification value and the Lq identification value at that frequency obtained in step S330 as the d-axis inductance and the q-axis. Determined as the inductance (step S350). The frequency at this time is the frequency when the phase of the q-axis current detection value i _{q with respect to the q-axis voltage command value v q} ^* is delayed. On the other hand, when the estimation unit 44 determines that the phase measurement value in step S320 does not satisfy the setting conditions, the estimation unit 44 records the Ld identification value obtained in step S330 as the d-axis inductance at that frequency, and Lq. The identification value is set to a value set based on the Ld identification value (step S360). The estimation unit 44 performs the same operation while sequentially changing the frequency, and records the frequency, the Ld identification value, and the Lq identification value in association with each other in the table (step S370).

The estimation unit 44 may first perform the identification (step S330) and then measure the phase (step S320), or may measure the phase at the same time as the identification (steps S330 and S320). ). The estimation unit 44 processes the identification value using the determination result of the phase measurement (step S330).

As a case where the current phase setting condition of step S340 is satisfied, for example, when the measured value of the phase satisfies a certain set value, the current phase characteristic observed in a wide frequency range is calculated by a calculation formula or the like. In some cases, an appropriate phase value may be satisfied.

The estimation unit 44 changes the frequency of the d-axis voltage command value v _d ^{* and} the frequency of the q-axis voltage command value v _q ^* until the identification values at all the set frequencies are obtained (step S390), and steps S320 to S380. Perform the work of. The estimation unit 44 completes the table (step S400) when these operations are completed (step S380).

The estimation unit 44 may measure or set the identification value of the resistance value R by another method to determine the identification value. Alternatively, the estimation unit 44 may record the resistance value identified at the time of identification of Ld and Lq in the table as the identification value at that frequency.

The estimation unit 44 may record the result of measuring the phase at all frequencies, and then sequentially perform identification while changing the frequency to create a table. Further, the estimation unit 44 may create a table by measuring the phase after performing the identification first.

For example, the calculation unit 45 extracts parameters such as an identification value corresponding to the rotation speed according to the speed detection value ω representing the rotation speed of the motor 4, and uses the extracted parameters to obtain parameters including the control gain. Is calculated and set. Thereby, the control parameter corresponding to the rotation speed can be obtained. The calculation unit 45 may record the control parameters for each frequency in the table.

According to the identification method 4, a stable Lq identification value can be obtained while avoiding the influence of the frequency non-linearity of the q-axis inductance, so that the identification accuracy of the q-axis inductance can be ensured. By calculating the control parameters based on the obtained identification values, stable motor control without abnormal operation becomes possible, and the performance of the motor can be exhibited.

Although the motor control device, the motor system, and the motor control 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.

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 controller 18 Current command calculation unit 19 Position / speed detector 20 Speed control unit 30 Current control unit 31 Current control system 32 Stator model 40 Identification unit 41 Periodic signal generation unit 42 Actual model 43 Estimated model 44 Estimating unit 45 Calculation unit 100 Motor control device

Claims (12)

A d-axis voltage command value is generated so that the difference between the d-axis current command value of the motor and the d-axis current detection value of the motor converges to zero, and the q-axis current command value of the motor and the q-axis of the motor are generated. A current control unit that generates a q-axis voltage command value so that the difference from the current detection value converges to zero,
A d-axis current estimation model that outputs a d-axis current estimated value that is an estimated value of the d-axis current detected value from the d-axis voltage command value, and a d-axis current estimation model.
A q-axis current estimation model that outputs a q-axis current estimated value that is an estimated value of the q-axis current detected value from the q-axis voltage command value, and a q-axis current estimation model.
The d-axis inductance of the motor that minimizes the sum of squares of the error between the d-axis current detected value and the d-axis current estimated value is identified, and the q-axis current detected value and the q-axis current estimated value are identified. It is provided with an identification unit for identifying the q-axis inductance of the motor so as to minimize the sum of squares of the error with.
The identification unit derives the Ld identification value which is the value for identifying the d-axis inductance, and changes the frequency of the q-axis voltage command value for the Lq identification value which is the value for identifying the q-axis inductance. Motor control device to be derived. The motor control device according to claim 1, wherein the identification unit changes the frequency and estimates the Lq identification value at the frequency when the value is stable as the q-axis inductance. According to claim 2, the identification unit changes the frequency and estimates the Lq identification value at the frequency when the difference from the Ld identification value converges within a predetermined range as the q-axis inductance. The motor control device described. The identification unit changes the frequency to create a correspondence table between the frequency and the Lq identification value, and sets the Lq identification value at the frequency corresponding to the rotation speed according to the rotation speed of the motor. The motor control device according to claim 1, which is selected from the corresponding table. The identification unit changes the frequency and records the Lq identification value at the frequency when the phase of the q-axis current detection value with respect to the q-axis voltage command value is delayed in the corresponding table. The motor control device according to claim 4. The identification unit estimates the Lq identification value at the frequency when the phase of the q-axis current detection value with respect to the q-axis voltage command value is delayed by changing the frequency as the q-axis inductance. , The motor control device according to claim 1. The motor control device according to any one of claims 1 to 6, wherein the identification unit fixes the d-axis voltage command value and the amplitude of the q-axis voltage command value to change the frequency. .. The identification unit derives the Ld identification value by changing the frequency of the d-axis voltage command value or fixing the frequency of the d-axis voltage command value to one specific frequency, claims 1 to 7. The motor control device according to any one of the above items. The identification unit identifies the q-axis inductance and the resistance value of the motor so as to minimize the sum of squares of the error between the q-axis current detected value and the q-axis current estimated value. The motor control device according to any one of the above items. The identification unit identifies the d-axis inductance and the resistance value of the motor so as to minimize the sum of squares of the error between the d-axis current detected value and the d-axis current estimated value. The motor control device according to any one of the above items. The motor control device according to any one of claims 1 to 10.
A motor system comprising the motor. It is a motor control method performed by a motor control device that controls a motor.
A d-axis voltage command value is generated so that the difference between the d-axis current command value of the motor and the d-axis current detection value of the motor converges to zero, and the q-axis current command value of the motor and q of the motor are generated. Generate a q-axis voltage command value so that the difference from the axis current detection value converges to zero,
From the d-axis voltage command value, the d-axis current estimated value, which is the estimated value of the d-axis current detected value, is output from the d-axis current estimation model.
From the q-axis voltage command value, the q-axis current estimated value, which is the estimated value of the q-axis current detected value, is output from the q-axis current estimation model.
The d-axis inductance of the motor that minimizes the sum of squares of the error between the d-axis current detected value and the d-axis current estimated value is identified, and the Ld identification value, which is the value that identifies the d-axis inductance, is derived. Lq is a value obtained by identifying the q-axis inductance of the motor that minimizes the sum of squares of the error between the q-axis current detected value and the q-axis current estimated value, and identifying the q-axis inductance. A motor control method for deriving an identification value by changing the frequency of the q-axis voltage command value.

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