JP7023409B2 - Motor control device - Google Patents

Description

The present application relates to a control device for an electric motor that drives a rotary machine, and relates to a device that suppresses torque pulsation or speed pulsation of the electric motor.

Pulsation occurs in the output torque of the motor due to the motor itself and the inverter that drives the motor. The factors of the motor itself are that the permanent magnet of the rotor superimposes the spatial harmonic component on the magnetic flux of the armature winding of each phase, and that the harmonic is superimposed on the inductance of the armature winding of each phase. It is conceivable that a cogging torque consisting of the minimum common multiple of the number of poles of the rotor of the motor and the number of slots of the stator is generated, and that it is due to the structural imbalance of the motor.

Possible causes of pulsation caused by the inverter are an error of the current sensor that detects the output current of the inverter and a dead time that prevents a short circuit between the upper arm and lower arm switches of the inverter. Torque pulsation can be reduced by devising the structure of the motor, but there are also adverse effects due to design limitations and high cost. Therefore, it is cost-effective to suppress the pulsation of the motor by control.

As a conventional control technology for suppressing the pulsation of a motor, the rotation angular velocity of the motor is detected using a detection device such as an encoder or a resolver, the pulsating component of the angular velocity is extracted, and the extracted angular velocity pulsating component is suppressed. There was a technique for suppressing torque pulsation generated in the shaft (see Patent Document 1).

In addition, as a conventional pulsation suppression technology for motors, the angular velocity is acquired from the output voltage and current of the inverter that drives the motor, the angular velocity is differentiated to obtain the angular acceleration, and the fundamental wave component of the angular acceleration is extracted. There was a technique for suppressing the torque pulsation of the motor by superimposing the opposite phase on the average current command (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2008-79477 Japanese Unexamined Patent Publication No. 2004-153866

In Patent Document 1, the technique of detecting the rotational angular velocity of a motor using a detection device such as an encoder and suppressing the pulsation of the motor by extracting the pulsating component of the angular velocity is an encoder or a resolver having high decomposition performance. By using the detection device of, the pulsation superimposed on the angular velocity of the motor can be detected. However, there is a problem that a detection device having high performance increases the cost of the system. Further, there is a problem that the double redundancy function cannot be guaranteed when the detection device fails.
This double redundancy function will be described in detail later.

In Patent Document 2, the rotational angular velocity of the motor is obtained using the output voltage and current of the inverter, the angular acceleration is obtained by differentiating the rotational angular velocity, and the pulsation of the motor is further extracted by extracting the fundamental wave component of the angular acceleration. In the suppression, there is a problem that the pulsation suppression effect is reduced when the characteristics of the motor fluctuate.

The present application discloses a technique for solving the above-mentioned problems, and solves the problems that the cost of the system increases, the functional problem of double redundancy, and the pulsation suppressing effect decrease. It was done for the sake of. That is, the rotational angular velocity of the motor is detected by combining the detection of the rotational angular velocity of the motor using the detection device and the estimation of the rotational angular velocity using the output voltage and current of the inverter, and the pulsating component superimposed on the angular velocity of the motor is suppressed. The purpose is to suppress the pulsation of the motor.

The motor control device disclosed in the present application includes a current command conversion unit that converts a motor rotation command value into a d-axis current command value and a q-axis current command value in a rotating coordinate system in vector control.
An inverter that controls the motor based on the d-axis current command value and the q-axis current command value, and
An angular velocity detection unit that detects the rotational angular velocity of the motor,
It is equipped with a correction command generation unit that generates a command correction value for suppressing the pulsation superimposed on the detected rotational angular velocity.
The angular velocity detection unit uses a rotation speed calculation unit that detects the rotation angular velocity of the electric motor based on the output of the detection unit that detects the rotation of the electric motor, and the output voltage and current of the inverter to determine the rotation angular velocity of the electric motor. It has a rotation speed estimation unit for estimation and a synthesis unit for summing the average value of rotation angular velocities detected by the rotation speed calculation unit and the pulsating angular velocity.
The pulsating angular velocity is generated by using the difference between the rotational angular velocity generated by the angular velocity detection unit and the rotational angular velocity estimated by the rotational speed estimation unit.

According to the motor control device disclosed in the present application, even when the characteristics of the motor fluctuate, it is possible to suppress the periodic pulsation generated in the shaft of the motor due to the motor itself, the inverter, and the load.

It is a block block diagram which shows the control apparatus provided with the pulsation suppression means of the electric motor according to Embodiment 1. FIG. It is a diagram which shows the example of the torque pulsation of an electric motor. It is a figure which shows an example of the pulsation component of the torque of a motor. It is a diagram which shows the detection example of the rotation speed of an electric motor. It is a block block diagram which shows the control device which provided the pulsation suppressing means of the electric motor by Embodiment 2. FIG. It is a block block diagram which shows the control apparatus provided with the pulsation suppression means of the electric motor according to Embodiment 3. FIG. It is a block block diagram which shows the pulsation suppression device of the electric motor in the comparative example of this application. It is a block block diagram which shows the control device which provided the pulsation suppressing means of the electric motor by Embodiment 4. FIG. It is a hardware block diagram for realizing the operation of the control device of the electric motor according to Embodiment 1. FIG.

Embodiment 1.
FIG. 1 is a block configuration diagram showing a control device including the pulsation suppressing means of the electric motor according to the first embodiment. The motor control system according to the present embodiment includes a current command conversion unit 1, a controller 2, a controller 3, an abc / dq coordinate conversion unit 4, an inverter 5, an electric motor 6, a load 7, and dq /. It includes an abc coordinate conversion unit 11, an angular velocity detection unit 9, and a correction command generation unit 10. Then, the current command conversion unit 1 converts the torque command value T ^* (or speed command value), which is the rotation command value, into the d-axis current component I _d ^* and the q-axis current component I _q ^* of the rotating coordinate system in the vector control. The output is taken as a d-axis current command value and a q-axis current command value. The controller 2 causes the q-axis current I _q obtained from the current detection values Ia and Ib of the inverter to follow the I _q ^** on which the current correction value described later is superimposed. The controller 3 causes the d-axis current command value I _d ^* to follow the d-axis current I _d obtained from the current detection values Ia and Ib of the inverter. The abc / dq coordinate conversion unit 4 converts the output signal u _d of the controller 3 and the output signal u _q of the controller 2 into the static coordinate system signals u _a , _ub , and _uc . The inverter 5 is controlled by signals u _a , _ub , and _uc . The motor 6 and the load 7 are driven by the output voltage and current of the inverter 5. The dq / abc coordinate conversion unit 11 converts the output currents Ia and Ib of the inverter 5 into the currents I _d and I _q of the rotating coordinate system. The angular velocity detection unit 9 detects the rotational angular velocity of the motor 6. The correction command generation unit 10 generates a command correction value for suppressing the velocity pulsation superimposed on the detected angular velocity.

Further, the current control unit 8 is configured by the controllers 2, 3 and the like. Further, although only the output currents Ia and Ib are shown in FIG. 1, the current output by the inverter 5 is three-phase, and Ic also exists. However, since the relationship between Ia, Ib, and Ic has a relationship of Ic = -Ia-Ib, only two-phase detection is sufficient. Further, ed is an input value for the controller 3, and ed = _Id ^* _−Id . Similarly, eq is an input value for the controller 2. Further, the controllers 2 and 3 correspond to PI (PROPORTIONAL INTERGRAL) controllers and the like.
FIG. 9 is a hardware configuration diagram for realizing the operation of the motor control device according to the first embodiment. In FIG. 9, the control device includes a microcontroller (MCU (MICRO CONTROL UNIT)) 34 having a processor and a memory. The microcontroller 34 receives the current detection values Ia and Ib detected by the current sensor 40, the rotation speed ω4 detected by the angular velocity detection unit 9, and the torque command value T ^* input from the upper controller, and receives the voltage of the voltage. The signals ua, ub, and uc are output to the inverter 5. The processor that executes the program stored in the memory operates the current control unit 8, the angular velocity detection unit 9, and the correction command generation unit 10 shown in FIG.

Next, the cause of the torque pulsation of the motor 6 will be described. Pulsation occurs in the output torque of the motor 6 due to the motor 6 itself and the inverter 5. One of the factors caused by the motor 6 itself will be described below. The magnetic flux generated by the permanent magnets of the rotor of the motor 6 does not interlink in a distortion-free sinusoidal shape with respect to the armature windings (stator windings) of each phase in the stator of the motor 6, but the spatial harmonic component It is superimposed. Further, when magnetic saturation occurs in the inductance of the armature winding of the motor 6, the magnetic characteristics become non-linear, so that the harmonic component is superimposed on the magnetic flux of the armature winding. The degree of influence of this harmonic component differs depending on the winding method (concentrated winding and distributed winding), and the concentrated winding tends to have a greater effect.

Next, the second factor due to the motor 6 itself will be described. In a permanent magnet type synchronous motor, magnetic flux passes through the motor even when it is not energized by the permanent magnet, so positive or negative torque is applied to the rotation direction depending on the relative positional relationship between the armature slot and teeth of the motor 6 and the rotor. Occur. This torque is called cogging torque and becomes torque pulsation during rotation. The embedded permanent magnet type synchronous motor has a large effect because the rotor structure has a protruding polarity. Due to its generation principle, cogging torque is generated based on the number of rotor poles and the least common multiple of the number of slots.
The third factor caused by the motor 6 itself is that when the motor 6 has a structural imbalance, torque pulsation of the order due to a multiple of the number of poles and the number of slots is generated.

Next, the pulsation generated in the output torque caused by the inverter 5 will be described below. It is considered that the error of the current sensor 40 for detecting the output current of the inverter 5 and the dead time for preventing the short circuit between the upper arm and the lower arm switch of the inverter 5 are factors. The error of the current sensor 40 of the inverter 5 includes an offset error and a gain error. When these errors are present, a spatial harmonic current having the same frequency as the electric angular frequency of the motor 6 is generated in the d-axis current and the q-axis current of the rotational coordinate system due to the offset error, and the frequency is doubled from the gain error. Generates the harmonic current that it has. The harmonic current causes a higher-order torque pulsation in the output torque of the motor 6 which is 1 times or 2 times the synchronous frequency. To briefly explain the electric angular frequency, the rotational speed of the shaft of the motor is generally the mechanical angular frequency, and the frequency of the current flowing from the inverter to the motor due to the structure of the motor is a multiple of the mechanical angular frequency, and this frequency is used as electricity. It is called angular frequency.

Torque pulsation with a frequency of 6 times is mainly generated due to the dead time of the inverter 5. When the above factors occur at the same time, a complex waveform in which a plurality of frequency components are overlapped appears. Further, when the load 7 of the motor 6 is an air conditioner, an elevator, or the like, the rotor pulsates due to periodic fluctuations in the load torque synchronized with the shaft rotation of the motor 6.
FIG. 2 shows the torque at a low load by taking as an example a permanent magnet type synchronous motor with 4 poles and 6 slots used in the present embodiment. FIG. 3 is a diagram showing an example of the pulsating component of the torque of the electric motor by Fourier transforming the torque shown in FIG. As shown in FIG. 3, the ratio of the sixth-order and the twelfth-order torque pulsations is large. In order to suppress the pulsation of torque, it is necessary to suppress the pulsation component as shown in FIG.

When the torque pulsation of the motor 6 as shown above occurs, the pulsation also occurs at the rotation speed of the motor 6. Since the torque pulsation or speed pulsation of the motor 6 contributes to vibration, noise, and deterioration of system operating characteristics, it is necessary to suppress the torque pulsation or speed pulsation of the motor 6. FIG. 7 is a block configuration diagram showing a pulsation suppressing device of an electric motor, which is a comparative example of the present application. The pulsation suppression principle shown in FIG. 7 is described below. The rotation angular velocity of the electric motor is detected by using a speed detection means 28 such as an encoder, the position is detected by the absolute position detection unit 29, and the pulsating component of the angular velocity is extracted by the Fourier conversion unit 30 or a filter, and the extracted angular velocity is obtained. The positive and negative reverses of the pulsating component of the above are generated by the current compensation unit 31 and the compensation calculation element 32, and the positive and negative reverses of the angular velocity are superimposed on the speed command to suppress the pulsation of the electric motor. To suppress the pulsation of such a motor, it is necessary to use a detection means such as an encoder or a resolver having high decomposition performance.

In another reference example, the rotation angular velocity and rotation position of the motor are detected using the output voltage and current of the inverter, the angular acceleration is differentiated to obtain the angular acceleration, and the fundamental wave component of the angular acceleration is extracted and the amplitude. After adjusting, the pulsation of the motor is suppressed by superimposing it on the average current command. In such a pulsation suppression technology for a motor, when the characteristics of the motor fluctuate, for example, when the internal temperature of the motor fluctuates, it becomes impossible to cope with the fluctuation of the magnetic flux of the permanent magnet of the rotor of the motor, and the pulsation suppression effect of the motor. There was a problem that it decreased.

Next, the pulsation suppression technique of the electric motor 6 according to the present embodiment will be described. First, the principle of the angular velocity detection unit 9 of the motor 6 will be described. As the detection unit 17 for detecting the rotation of the motor 6 in FIG. 1, an encoder or a hall sensor having low decomposition performance is used, and the rotation speed calculation unit 18 detects the rotation angular velocity of the motor 6 based on the output pulse of the detection unit 17. do.

Next, the principle of estimating the rotational angular velocity of the motor 6 using the output voltage and current of the inverter 5 will be described. As shown in the following equation (1), the rotation speed estimation unit 20 estimates the estimated angular velocity ω1 of the motor 6 using the output voltage and the current of the inverter 5.

ω1 = {v _q- (R _a + sL _q ) I _q } / P (L _d I _d + Φ _f ) ... (1)

Here, the reference numeral s is a derivative, and P is the pole logarithm of the rotor. R _a is the resistance of the armature winding of each phase of the motor 6, L _d and L _q are the values obtained by converting the inductance of the armature winding of each phase of the motor 6 into a rotational coordinate system, and Φ _f is. It is the interlinkage magnetic flux to the armature winding of each phase by the permanent magnet of the rotor of the motor 6. The voltage v _q is the output of the inverter 5, but since it is difficult to detect the output voltage of the inverter 5, the bus voltage V _d input to the inverter 5 is used to obtain the voltage v q by the following equation (2).

v _q = V _d × u _q ... (2)

Here, u _q is the output of the controller 2.
The bus voltage V _d is the voltage of the DC power supply connected to the inverter 5, and is the same as the voltage between the DC buses on the input side of the inverter 5.

FIG. 4 shows the rotation speed of the motor used in the present embodiment at low rotation speed when an encoder having a slightly high decomposition performance that outputs 3600 pulses in a single phase in one rotation is used. When an encoder or Hall sensor or resolver having low decomposition performance is used in the detection unit 17, the number of output pulses of the detection unit 17 is smaller than that shown in FIG. For example, when the Hall sensor is used as the detection unit 17, the pulse is output from the Hall sensor only at the points A, B, and C in FIG. 4, and only the rotational angular velocity at the points A, B, and C can be calculated. It becomes. Therefore, when only the detection unit having low decomposition performance is used, the operating performance of the motor 6 deteriorates. However, the rotational angular velocity calculated from the rotational positions of points A, B, and C in FIG. 4 is the actual rotational velocity of the motor 6, and this rotational angular velocity or its average value may be used as a reference value.

On the other hand, as shown in the equation (1), in the rotation speed estimation unit 20, the interlinkage magnetic flux Φ _f to the armature winding of each phase by the rotor of the motor 6 and the resistance R _a of each armature winding are used. calculate. Since the internal temperature of the motor 6 has a particularly large influence on the interlinkage magnetic flux Φ _f , the rotational angular velocity estimated by the equation (1) fluctuates when the internal temperature of the motor 6 fluctuates.
In order to correct this estimated rotational angular velocity, the pulsating angular velocity ω3 is added to the average value ω2 of the rotational angular velocity ω10 for each rotation cycle detected by the above-mentioned detection unit 17, and the rotational angular velocity ω4 generated by the synthesis unit 23 is used. ..

The correction of the estimated rotation angular velocity by the rotation speed estimation unit 20 will be described below.
The difference ω5 between the rotation angular velocity ω4 generated by the synthesis unit 23 and the estimated angular velocity ω1 by the rotation speed estimation unit 20 is obtained, and the average value ω6 for each rotation cycle is obtained by the average calculation unit 21, and this average value ω6 is the target value 0. The pulsating angular velocity ω3 is generated by being controlled by the controller 22 so as to be.
As a general example of the controller 22, there is a PI (PROFORMIONAL INTERGRAL) controller that performs PI control as shown in the following equation (3).

Here, k _P and k _I are the coefficients of the controller, n is the time, and eω is the input value.
The pulsating angular velocity ω3 is added up with the average value ω2 obtained by the average calculation unit 19 in the synthesis unit 23 to generate the rotation angular velocity ω4.
The electric angular velocity ω7 is obtained from the rotational angular velocity ω4 by the electric angular velocity conversion unit 12, and the rotation position θr of the electric motor 6 is acquired by the integrator 13. As described above, the rotational angular velocity ω4 is the mechanical rotational angular velocity, and has the following relationship with the electric rotational angular velocity ω7.
ω7 = P × ω4
Here, P is the logarithm of the rotor, and the units of ω7 and ω4 are the same, which is rad / s.
This rotation position θr is used for the dq / abc coordinate conversion unit 11 and the abc / dq coordinate conversion unit 4.

Next, the operation of the correction command generation unit 10 for suppressing the speed pulsation of the electric motor 6 will be described. The rotation angular velocity ω4 acquired by the angular velocity detection unit 9 is input to the velocity pulsation extraction unit 14, and the velocity pulsation extraction unit 14 extracts the pulsation component of the order to be suppressed. In the velocity pulsation extraction unit 14, only the order component to be suppressed can be extracted by using the Fourier transform. Since it is necessary to use a certain amount of velocity data to perform the Fourier transform, the calculation time of the Fourier transform becomes long, which is disadvantageous for real-time pulsation suppression.

Therefore, instead of the Fourier transform, a bandpass filter may be used in the velocity pulsation extraction unit 14. However, when the rotation speed of the motor 6 changes, it is necessary to use a bandpass filter having a variable pass band.
The difference (input value) eh between the extracted velocity pulsation amplitude ah and the target value 0 is corrected so that the amplitude ah of the extracted velocity pulsation (pulsation component) is reduced and the amplitude ah becomes 0. Is input to, and the current correction value I _qc is generated under the control of the correction value generation unit 15. Then, the current correction value I _qc , which is the output of the correction value generation unit 15, is superimposed on the q-axis current command value I _q ^* by the current superimposition unit 16 to generate the q-axis current command value I _q ^** of the current I _q . ..
As a general example of the correction value generation unit 15, there is a PI controller that performs PI control as shown in the following equation (4).

Here, k _P and k _I are the coefficients of the controller, n is the time, and eh is the input value.
The correction value generation unit 15 obtains Iqc_amp, and the current correction value Iqc is generated by the following equation (5).

Iqc = Iqc_amp × sin (ω _c + δc) ... (5)

Here, ω _c is the angular velocity of the q-axis current with respect to the angular velocity ω _h of the torque pulsation to be suppressed. However, the formula for converting ω _h to ω _c differs depending on the motor. δc is the initial phase angle and is a fixed value.

By the above principle, the pulsation superimposed on the speed of the motor 6 is suppressed to reduce the speed pulsation and also to reduce the torque pulsation of the motor 6.
Using the velocity pulsation suppression principle of the electric motor 6, the velocity pulsation extraction unit 14 can extract a plurality of pulsation components and suppress a plurality of pulsations at the same time.
Further, the correction value generation unit 15 may generate a current correction value I _dc and superimpose it on the d-axis current command value I _d ^* . Alternatively, the correction value generation unit 15 may generate both the current correction values I _qc and I _dc and superimpose them on the q-axis current command value I _q ^* and the d-axis current command value I _d ^* , respectively.

In addition to generating the current correction value by the correction value generation unit 15, it is also possible to suppress the pulsation of the electric motor 6 by generating the torque correction value and superimposing the torque correction value on the torque command. Alternatively, the pulsation of the motor 6 can be suppressed by generating a speed correction value by the correction value generation unit 15 and superimposing the speed correction value on the speed command.
Combining the detection of the rotational speed of the motor 6 using an encoder or Hall sensor with such low decomposition performance and the estimation of the rotational speed of the motor 6 using the output voltage and current of the inverter 5. , The speed pulsation of the motor 6 can be suppressed. As a result, the cost of the system can be reduced, and the torque pulsation of the motor 6 can be further reduced.

Embodiment 2.
FIG. 5 is a block configuration diagram showing a control device including the pulsation suppressing means of the electric motor according to the second embodiment. In FIG. 5, the structure other than the correction command generation unit 10 is the same as the structure shown in FIG. Further, the operation of this embodiment is the same as the operation principle of the current control of the motor 6 and the angular velocity detection unit 9 described in the first embodiment, except for the operation of the correction command generation unit 10.
When the load 7 coupled to the motor 6 is an air conditioner, an elevator, or the like, a periodic load torque fluctuation occurs in synchronization with the shaft rotation of the motor 6, which causes the rotor to pulsate and the rotor rotation speed to fluctuate. Therefore, it is necessary to suppress the angular acceleration of the motor 6.

The correction command generation unit 10 shown in FIG. 5 differentiates the angular velocity ω4 acquired by the angular velocity detection unit 9 by the angular acceleration extraction unit 24 to obtain the angular acceleration αT. Then, the pulsating component of the angular acceleration αT is extracted by the Fourier transform or the bandpass filter, and the correction value generation unit 25 controls the pulsating component so that the amplitude ah1 becomes 0 to generate the current correction value _Iqc . The extraction of the pulsation of the angular acceleration αT is the same as the principle of the correction command generation unit 10 described in the first embodiment. The pulsating component of arbitrary order is extracted from the angular acceleration αT by Fourier transform or bandpass filter, and the amplitude ah1 of the extracted pulsating component is obtained. By reducing the amplitude ah1 of the extracted pulsating component and controlling the amplitude ah1 to be 0, a current correction value, a torque correction value, or a speed correction value is generated, and this correction command is superimposed on the command to be corrected. .. In FIG. 5, eh is the difference between the target value 0 and ah1, and is an input value of the PI controller which is the correction value generation unit 25.

Combining the detection of the rotational speed of the motor 6 using an encoder or Hall sensor with such low decomposition performance and the estimation of the rotational speed of the motor 6 using the output voltage and current of the inverter 5. Therefore, the angular acceleration pulsation of the motor 6 can be suppressed. In particular, the pulsation that affects the shaft of the motor 6 from the load 7 can be reduced.

Embodiment 3.
FIG. 6 is a block configuration diagram showing a control device including the pulsation suppressing means of the synchronous motor according to the third embodiment. In FIG. 6, the configuration other than the angular velocity detection unit 9 is the same as the configuration shown in FIG.
The angular velocity detection unit 9 shown in FIG. 6 performs the same operation as the angular velocity detection unit 9 shown in FIG. 1 except that it outputs both the rotation angular velocity ω4 and the estimated angular velocity ω1.
As the correction command generation unit 10 shown in FIG. 6, the correction command generation unit 10 shown in FIG. 1 or the correction command generation unit 10 shown in FIG. 5 is used. In the present embodiment, the angular velocity switching unit 26 is added.
Regarding the operation of the present embodiment, the operating principle of the current control unit 8 is the same as the principle described in the first embodiment. When the correction command generation unit 10 shown in FIG. 1 is used as the correction command generation unit 10, the operation principle of the correction command generation unit 10 of FIG. 1 is the same. When the correction command generation unit 10 shown in FIG. 5 is used as the correction command generation unit 10, the operation principle of the correction command generation unit 10 of FIG. 5 is the same.

Next, the operation of the angular velocity switching unit 26 will be described. The state of the detection unit 17 of the angular velocity detection unit 9 is monitored, and for example, when a pulse does not normally come out from the detection unit 17, the angular velocity switching unit 26 determines the rotation speed used for the current control unit 8 and the correction command generation unit 10. The rotation angular velocity ω4 is quickly switched to the estimated angular velocity ω1. By this switching of the angular velocity, when the detection unit 17 of the angular velocity detection unit 9 fails, the operation of the entire system shown in FIG. 6 can be maintained, and the double redundant function of the entire system can be guaranteed.
That is, even if one of the detection units 17 fails, the output of the other rotation speed estimation unit 20 may be used. Combining the detection of the rotational speed of the motor 6 using an encoder or Hall sensor with such low decomposition performance and the estimation of the rotational speed of the motor 6 using the output voltage and current of the inverter 5. Furthermore, even if the detection unit 17 fails, the pulsation of the electric motor 6 can be suppressed. Furthermore, the double redundancy function of the entire system can be guaranteed.

Two detection means such as an encoder are attached to the motor rotation to constantly monitor the state of the encoder, and normally one encoder is used to measure the rotation of the motor, but when one fails, the other is normal. The industry has adopted a dual redundancy function that guarantees the maintenance of operation by switching and issuing a warning at the same time. On the other hand, one detection means such as an encoder is attached, and a sensorless rotation speed detection means by calculation is also provided to constantly monitor the status of the two detection means, and when the encoder fails, the sensorless type There is also a method such as switching to the rotation speed detection of. The present application is somewhat similar to a method using a detection means such as one encoder described later and a sensorless rotation speed detection. This application usually uses a combination of a rotation speed detection means such as an encoder or a hall sensor having low decomposition performance and a sensorless rotation speed detection means, but when the encoder or the like fails, the sensorless rotation speed is used. It switches to the use of detection means only.

Embodiment 4.
FIG. 8 is a block configuration diagram showing a control device including the pulsation suppressing means of the electric motor according to the fourth embodiment. In FIG. 8, the configuration is the same as that shown in FIG. 1 except that the correction value table 33 is provided and the correction command generation unit 10 is deleted. Regarding the operation of the present embodiment, the operating principle of the current control unit 8 and the angular velocity detection unit 9 is the same as the principle described in the first embodiment.
The correction value table 33 shown in FIG. 8 is prepared in advance, and instead of the correction command generation unit 10, the d-axis current correction value or the q-axis current correction value is read from the correction value table 33, and the d-axis current command is given. It is superimposed on the value or the q-axis current command value.

Next, a method of creating the correction value table 33 will be described. The correction value table 33 is created according to the following procedure.
The electric motor 6 is rotated by the control configuration of FIG. 1 or 5, and the d-axis current correction value or the q-axis current correction value is recorded and stored in, for example, a disk memory of a personal computer together with the rotation conditions.
Next, for example, the correction value table 33 in Table 1 is created by using the saved current correction value and the rotation condition. Table 1 is an example of reading the current correction value from the correction value table 33 with the torque command value as the rotation condition, and the correction value table 33 can be created by recording the rotation angular velocity ω1 or the rotation angular velocity ω2 and the current correction value. .. Further, the correction value table 33 shown in Table 1 below shows a correction value table in the case of suppressing one of the pulsation component of the rotational speed of the motor 6 or the pulsation component of the torque ripple (for example, the sixth-order pulsation component). .. When suppressing a plurality of pulsating components, it is necessary to record the rotation conditions and the current correction values for suppressing the plurality of pulsating components to create a correction value table 33.

The correction value table 33 is prepared in advance, and the d-axis current correction value or the q-axis current correction value is read from the correction value table 33 when the motor 6 is rotated in the control configuration of FIG. 8, and the d-axis current command value is read. It is superimposed on I _d ^* or the q-axis current command value I _q ^* to suppress the pulsation of the rotational speed or torque of the motor 6.

In addition, the number, dimensions, materials, etc. of the above-mentioned components can be changed as appropriate.
Further, the present application describes various exemplary embodiments and examples, although the various features, embodiments, and functions described in one or more embodiments are those of a particular embodiment. It is not limited to application, but can be applied to embodiments alone or in various combinations.
Therefore, innumerable variations not exemplified are envisioned within the scope of the techniques disclosed in the present application. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 Current command conversion unit, 5 Inverter, 6 Electric motor, 9 Angular velocity detection unit, 10 Correction command generation unit, 12 Electrical angular velocity conversion unit, 14 Speed pulsation extraction unit, 15 Correction value generation unit, 17 Detection unit, 18 Rotation speed calculation unit , 20 Rotation speed estimation unit, 24-angular acceleration extraction unit, 33 correction value table.

Claims (10)

A current command converter that converts the rotation command value of the motor into the d-axis current command value and the q-axis current command value of the rotating coordinate system in vector control.
An inverter that controls the motor based on the d-axis current command value and the q-axis current command value, and
An angular velocity detection unit that detects the rotational angular velocity of the motor,
It is a control device of an electric motor equipped with a correction command generation unit that generates a command correction value for suppressing pulsation superimposed on the detected rotational angular velocity.
The angular velocity detection unit uses a rotation speed calculation unit that detects the rotation angular velocity of the electric motor based on the output of the detection unit that detects the rotation of the electric motor, and the output voltage and current of the inverter to determine the rotation angular velocity of the electric motor. It has a rotation speed estimation unit for estimation and a synthesis unit for summing the average value of rotation angular velocities detected by the rotation speed calculation unit and the pulsating angular velocity.
The pulsating angular velocity is a control device for an electric motor generated by using the difference between the rotational angular velocity generated by the angular velocity detection unit and the rotational angular velocity estimated by the rotational speed estimation unit . The pulsating angular velocity is generated by controlling the average value of the difference between the rotational angular velocity generated by the angular velocity detection unit and the rotational angular velocity estimated by the rotational speed estimation unit to be zero. 1. The motor control device according to 1. The correction command generation unit reduces the amplitudes of the velocity pulsation extraction unit that extracts the pulsating component of the order to be suppressed from the rotational angular velocity obtained by the angular velocity detection unit and the pulsation component extracted by the velocity pulsation extraction unit. The control device for an electric motor according to claim 1 or 2 , further comprising a correction value generation unit that generates a correction value that causes the current to be corrected. The correction command generation unit extracts the angular acceleration extraction unit for obtaining the angular acceleration by differentiating the angular velocity obtained by the angular velocity detection unit and the pulsating component of the angular acceleration, and reduces the amplitude of the pulsating component. The control device for an electric motor according to claim 1 or 2 , further comprising a correction value generation unit that generates such a current correction value. It has an electric angular velocity converter that obtains the electric angular velocity from the detected rotational angular velocity.
When the detection unit of the angular velocity detection unit fails, the correction command generation unit and the electric angular velocity conversion unit use the rotation angular velocity estimated by the rotation speed estimation unit as the rotation angular velocity according to claims 1 to 4 . The control device for the electric motor according to any one of the above items. The control device for a motor according to claim 3 or 4 , wherein a correction value table in which the current correction value generated by the correction command generation unit is recorded together with rotation conditions is provided, and the current correction value is read from the correction value table. .. The control device for a motor according to claim 3 or 4 , wherein the current correction value is superimposed on at least one of the d-axis current command value and the q-axis current command value. The motor control device according to any one of claims 1 to 7 , wherein the rotation command value is a torque command value. The control device for an electric motor according to any one of claims 1 to 7 , wherein the rotation command value is a speed command value. The control device for a motor according to any one of claims 1 to 9 , wherein the detection unit is an encoder or a hall sensor having low decomposition performance.

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