Motor control device

Abstract

Provided is a motor control device capable of simultaneously estimating a gain error of a current detector and a parameter error of a three-phase motor, and capable of improving the estimation accuracy of these errors. To this end, a motor control device is provided with: a gain error estimator that estimates a gain error of a current detector on the basis of d-axis and q-axis current detection values; and a parameter error estimator that estimates a parameter error due to a three-phase imbalance of an electrical parameter of the motor from the gain error estimation value. The gain error estimator outputs, as a gain error, a first gain error estimated value estimated so as to minimize the ripple of the d-axis current and a second gain error estimated value estimated so as to minimize the ripple of the q-axis current. The parameter error estimator estimates a parameter error using the first gain error estimation value and the second gain error estimation value. The control device corrects the gain error of the current detector on the basis of the second gain error estimation value.

Description

Technical Field

[0001] The present disclosure relates to a control device for an electric motor. Background Art

[0002] In a control device for an electric motor, it is known that the control device has the following structure: a pulsating component is extracted from at least one of a d-axis current value and a q-axis current value, and based on a change in the amplitude value of the extracted pulsating component, it is determined whether a correction of an output error of a current sensor using a sensor conversion coefficient setting value is incorrect, and the sensor conversion coefficient setting value is determined according to the determination result (for example, refer to patent document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-158414 Summary of the invention

[0006] Problems to be solved by the invention

[0007] It is known that the current detector used in the control of the motor has a gain error. The gain error includes an offset error and an error caused by a deviation in the detection sensitivity. In such a control system, current pulsation caused by the error is generated by the control based on the detection value containing the error. In addition, in the control system of the motor, there is also a parameter error caused by the imbalance of the electrical parameters of the three-phase motor, namely the resistance, inductance, etc. in the three phases. When there is a parameter error in the three-phase motor, current pulsation is generated due to the parameter error.

[0008] In the control device of the motor shown in Patent Document 1, the gain error of the current detector is corrected according to the pulsating component of the current value of the d-axis and the q-axis. However, the frequency of the current pulsation caused by the gain error and the frequency of the current pulsation caused by the parameter error are both twice the electrical angular frequency of the three-phase motor, which is the same. Therefore, in a system where both the gain error of the current detector and the parameter error of the three-phase motor exist at the same time, the frequency of the pulsation generated by the two is the same. Therefore, when the gain error and the parameter error are to be estimated at the same time, the estimated values ​​of the gain error and the parameter error cannot be distinguished, resulting in a decrease in the estimation accuracy of the gain error and the parameter error. In addition, when estimating the gain error and the parameter error separately, the estimation process of each error and the adjustment operation of the three-phase motor, the control device, etc. take time, resulting in a decrease in work efficiency, etc.

[0009] The present disclosure is made to solve such a problem and aims to provide a motor control device that can simultaneously estimate a gain error of a current detector and a parameter error of a three-phase motor and improve the estimation accuracy of these errors.

[0010] Means for solving problems

[0011] The control device of the motor disclosed in the present invention comprises: a speed detector, which detects the rotation speed of the motor; a speed controller, which outputs a q-axis current command so that the speed detection value of the speed detector follows the speed command value; a current detector, which detects the current value of at least two phases among the u-phase, v-phase and w-phase input to the motor; a first coordinate converter, which performs coordinate conversion on the current detection value of the current detector and converts it into d-axis and q-axis current detection values; a d-axis current command generator, which generates a d-axis current command; a d-axis current controller, which outputs a voltage command value so that the d-axis current detection value output from the first coordinate converter follows the d-axis current command output from the d-axis current command generator; and a q-axis current controller, which outputs a voltage command value so that the q-axis current detection value output from the first coordinate converter follows the d-axis current command output from the d-axis current command generator. A value follows the q-axis current command value output from the speed controller; a gain error estimator, which estimates the gain error of the current detector based on the d-axis and q-axis current detection values ​​output from the first coordinate converter; and a parameter error estimator, which estimates the parameter error caused by the three-phase imbalance of the electrical parameters of the motor based on the gain error estimation value of the gain error estimator, the gain error estimator outputting a first gain error estimation value estimated in a manner to minimize the pulsation of the d-axis current and a second gain error estimation value estimated in a manner to minimize the pulsation of the q-axis current as the gain error, the parameter error estimator estimates the parameter error using the first gain error estimation value and the second gain error estimation value, and performs gain error correction of the current detector based on the second gain error estimation value.

[0012] Alternatively, the control device of the motor disclosed in the present invention comprises: a speed detector, which detects the rotation speed of the motor; a speed controller, which outputs a q-axis current command so that the speed detection value of the speed detector follows the speed command value; a current detector, which detects the current value of at least two phases among the u-phase, v-phase and w-phase input to the motor; a first coordinate converter, which performs coordinate conversion on the current detection value of the current detector and converts it into d-axis and q-axis current detection values; a d-axis current command generator, which generates a d-axis current command; a d-axis current controller, which outputs a voltage command value so that the d-axis current detection value output from the first coordinate converter follows the d-axis current command output from the d-axis current command generator; and a q-axis current controller, which outputs a voltage command value so that the q-axis current detection value output from the first coordinate converter follows the Based on the q-axis current command value output from the speed controller; a gain error estimator, which estimates the gain error of the current detector based on the d-axis current detection value output from the first coordinate converter and the speed detection value; and a parameter error estimator, which estimates the parameter error caused by the three-phase imbalance of the electrical parameters of the motor based on the gain error estimation value of the gain error estimator, the gain error estimator outputs a first gain error estimation value estimated in a manner to minimize the pulsation of the d-axis current and a third gain error estimation value estimated in a manner to minimize the pulsation of the speed detection value as the gain error, the parameter error estimator estimates the parameter error using the first gain error estimation value and the third gain error estimation value, and performs gain error correction of the current detector based on the third gain error estimation value.

[0013] Effects of the Invention

[0014] According to the motor control device of the present disclosure, it is possible to simultaneously estimate the gain error of the current detector and the parameter error of the three-phase motor, and to improve the estimation accuracy of these errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram showing the overall configuration of the electric motor control device according to the first embodiment.

[0016] Figure 2 1 is a diagram showing a configuration example of a gain error estimator included in the control device according to the first embodiment.

[0017] Figure 3 This is a block diagram showing a configuration equivalent to the control system of the electric motor control device according to the first embodiment, converted into dq axes.

[0018] Figure 41 is a diagram showing the frequency characteristics of the q-axis current command value related to the d-axis current detection value in the electric motor control device according to the first embodiment.

[0019] Figure 5 1 is a diagram showing the frequency characteristics of a parameter error component of a d-axis current related to a d-axis current detection value in the electric motor control device according to the first embodiment.

[0020] Figure 6 1 is a diagram showing the frequency characteristics of a parameter error component of a q-axis current related to a d-axis current detection value in the electric motor control device according to the first embodiment.

[0021] Figure 7 1 is a diagram showing the frequency characteristics of the q-axis current command value related to the q-axis current detection value in the electric motor control device according to the first embodiment.

[0022] Figure 8 1 is a diagram showing the frequency characteristics of a parameter error component of a d-axis current related to a q-axis current detection value in the electric motor control device according to the first embodiment.

[0023] Fig. 9 1 is a diagram showing the frequency characteristics of a parameter error component of the q-axis current related to the q-axis current detection value in the electric motor control device according to the first embodiment.

[0024] Fig.10 This is a block diagram showing an example of a configuration for realizing the functions of the electric motor control device according to the first embodiment.

[0025] Fig.11 This is a diagram showing the overall configuration of a control device for an electric motor according to a second embodiment.

[0026] Fig.12 This is a diagram showing a configuration example of a gain error estimator included in the control device according to the second embodiment. DETAILED DESCRIPTION

[0027] The method for implementing the control device of the electric motor disclosed in the present invention is described with reference to the accompanying drawings. In each figure, the same reference numerals are given to the same or corresponding parts, and repeated descriptions are appropriately simplified or omitted. In the following description, for the sake of convenience, the positional relationship of each structure is sometimes expressed with reference to the state shown in the figure. In addition, the present disclosure is not limited to the following embodiments, and the various embodiments can be freely combined, any structural elements of each embodiment can be deformed, or any structural elements of each embodiment can be omitted without departing from the scope of the present disclosure.

[0028] Implementation Method 1

[0029] Reference Figures 1 to 10 Embodiment 1 of the present disclosure will be described. Figure 1 It is a diagram showing the overall configuration of a control device for an electric motor. Figure 2 It is a diagram showing a configuration example of a gain error estimator included in a control device. Figure 3 This is a block diagram showing a structure equivalent to a control system of a motor control device converted into dq axes. Figure 4 : is a diagram showing the frequency characteristics of the q-axis current command value related to the d-axis current detection value in the control device of the electric motor. Figure 5 : is a diagram showing the frequency characteristics of the parameter error component of the d-axis current related to the d-axis current detection value in the control device of the electric motor. Figure 6 1 is a diagram showing frequency characteristics of a parameter error component of a q-axis current related to a d-axis current detection value in a control device for an electric motor. Figure 7 : is a diagram showing the frequency characteristics of the q-axis current command value related to the q-axis current detection value in the control device of the electric motor. Figure 8 1 is a diagram showing frequency characteristics of a parameter error component of a d-axis current related to a q-axis current detection value in a control device for an electric motor. Fig. 9 1 is a diagram showing frequency characteristics of a parameter error component of a q-axis current related to a q-axis current detection value in a control device for an electric motor. Fig.10 This is a block diagram showing an example of a configuration for realizing the functions of a motor control device.

[0030] The motor control device 100 of this embodiment controls the three-phase motor 10. Figure 1 As shown, a speed detector 20 is installed on the three-phase motor 10. The speed detector 20 detects the rotation speed of the three-phase motor 10. The speed detector 20 outputs the value of the detected rotation speed as a speed detection value. The speed detection value output from the speed detector 20 is input to the control device 100. A speed command value provided from the outside of the control device 100 is input to the control device 100. The speed command value is a command value of the rotation speed of the three-phase motor 10. The control device 100 controls the power supply to the three-phase motor 10 so that the speed detection value of the speed detector 20 follows the speed command value.

[0031] like Figure 1As shown, the control system of the motor in this embodiment is provided with a current detector 200. The current detector 200 detects the current values ​​of the u phase, the v phase and the w phase supplied from the control device 100 to the three-phase motor 10. The current detector 200 outputs the detected current value as the current detection value. In addition, the current detector 200 only needs to detect the current value of at least two of the three phases, namely the u phase, the v phase and the w phase, which are input to the three-phase motor 10. In the case where the current detector 200 detects the current value of two of the three phases, the current detector 200 estimates the current value of the remaining one phase based on the relationship of the three-phase balance, and outputs the estimated current value as the current detection value for the remaining one phase. In the present disclosure, in order to simplify the description, it is not distinguished whether the estimated current value is included, and the current detection value is referred to in any case.

[0032] like Figure 1 As shown, the motor control device 100 of this embodiment includes a speed controller 101 , a d-axis current command generator 102 , a d-axis current controller 103 , a q-axis current controller 104 , a first coordinate converter 111 , and a second coordinate converter 112 .

[0033] The speed controller 101 receives the difference between the speed command value input to the control device 100 and the speed detection value of the speed detector 20. The speed controller 101 outputs a q-axis current command value based on the difference between the speed command value and the speed detection value so that the speed detection value follows the speed detection value. The q-axis current command value is a torque current command value.

[0034] The d-axis current command generator 102 generates and outputs a d-axis current command value. The d-axis current command value generated by the d-axis current command generator 102 is an arbitrary value set in advance. The d-axis current command value may also be zero. In addition, in order to perform weak excitation control, the d-axis current command value may also be an arbitrary negative value. In order to perform strong excitation control, the d-axis current command value may also be an arbitrary positive value.

[0035] The first coordinate converter 111 performs coordinate conversion on the current detection value of the current detector 200 and converts it into the current detection value of the d-axis and q-axis. The current detection values ​​of the three phases, namely the u-phase, the v-phase and the w-phase, outputted from the current detector 200 are inputted to the first coordinate converter 111. Then, the first coordinate converter 111 converts the inputted three-phase current detection values ​​into current values ​​in the coordinate system of the d-axis and the q-axis, and outputs them as the d-axis current detection value and the q-axis current detection value.

[0036] Here, the coordinate conversion in the first coordinate converter 111 requires the magnetic pole position information of the three-phase motor 10. Figure 1, the input of the magnetic pole position information to the control device 100 is omitted. For example, the speed detector 20 may also output the magnetic pole position information based on the rotation speed of the three-phase motor 10. In this case, more specifically, the speed detector 20 includes, for example, an encoder or a rotary transformer for detecting the magnetic pole position of the three-phase motor 10. Then, the speed detector 20 performs time differentiation on the detected magnetic pole position, converts it into a rotation speed and outputs it. Alternatively, the speed detector 20 may also detect the rotation speed using the principle of a generator whose output voltage changes according to the rotation speed (rotation speed). In this case, the speed detector 20 performs time integration on the detected rotation speed and outputs the magnetic pole position information. The first coordinate converter 111 may also use the magnetic pole position information output by the speed detector 20 to perform coordinate conversion.

[0037] The d-axis current controller 103 receives the difference between the d-axis current command value output from the d-axis current command generator 102 and the d-axis current detection value output from the first coordinate converter 111. The d-axis current controller 103 outputs a d-axis voltage command value based on the difference between the d-axis current command value and the d-axis current detection value so that the d-axis current detection value follows the d-axis current detection value.

[0038] The q-axis current controller 104 receives the difference between the q-axis current command value output from the speed controller 101 and the q-axis current detection value output from the first coordinate converter 111. The q-axis current controller 104 outputs a q-axis voltage command value based on the difference between the q-axis current command value and the q-axis current detection value so that the q-axis current detection value follows the q-axis current detection value.

[0039] The second coordinate converter 112 performs coordinate conversion on the voltage command values ​​of the d-axis and q-axis and converts them into voltage command values ​​of the three phases, namely, the u-phase, the v-phase, and the w-phase. The d-axis voltage command value output from the d-axis current controller 103 and the q-axis voltage command value output from the q-axis current controller 104 are input to the second coordinate converter 112. Then, the second coordinate converter 112 converts the input d-axis and q-axis voltage command values ​​into voltage command values ​​of the three phases and outputs them as voltage command values ​​of the three phases, namely, the u-phase, the v-phase, and the w-phase.

[0040] Here, similarly to the coordinate conversion in the first coordinate converter 111, the coordinate conversion in the second coordinate converter 112 requires the magnetic pole position information of the three-phase motor 10. Figure 1 , the input of the magnetic pole position information to the control device 100 is omitted. As described above, the speed detector 20 may also output the magnetic pole position information based on the rotation speed of the three-phase motor 10. In this case, the second coordinate converter 112 may also use the magnetic pole position information output from the speed detector 20 for coordinate conversion.

[0041] The control device 100 supplies three-phase power to the three-phase motor 10 based on the three-phase voltage command values ​​output from the second coordinate converter 112. The three-phase motor 10 is driven by the three-phase power supplied from the control device 100 to generate rotation torque and rotation speed.

[0042] like Figure 1 As shown, the motor control device 100 of this embodiment further includes a gain error estimator 120 and a parameter error estimator 130 . The gain error estimator 120 estimates the gain error of the current detector 200 .

[0043] Here, the current detection gain of the u-phase in the current detector 200 is Gu, the current detection gain of the v-phase is Gv, and the current detection gain of the w-phase is Gw. In the gains of these three phases, offset errors and errors caused by deviations in detection sensitivity may occur. These offset errors and errors caused by deviations in detection sensitivity are collectively referred to as gain errors.

[0044] When there is no gain error in the current detector 200, the current detection gains of the three phases are equal (Gu=Gv=Gw). On the other hand, when there is a gain error in the current detector 200, the current detection gains of the three phases are inconsistent. Moreover, when there is a gain error in the current detector 200, current pulsation occurs due to the gain error. The frequency of the current pulsation caused by the gain error becomes a value twice the electrical angular frequency (power-on frequency) of the three-phase motor 10. In addition, when the gains of the three phases are consistent with a value other than 1, no imbalance in the three-phase current occurs, which is consistent with the situation where the efficiency of the three-phase motor 10 changes equivalently.

[0045] The gain error estimator 120 estimates the gain error of the current detector 200 based on the current detection values ​​of the d-axis and the q-axis output from the first coordinate converter 111. Then, the gain error estimator 120 outputs the gain error estimation value to the current detector 200 and the parameter error estimator 130. The current detector 200 corrects the current detection gain Gu of the u-phase, the current detection gain Gv of the v-phase, and the current detection gain Gw of the w-phase using the gain error estimation value output from the gain error estimator 120. The method of estimating the gain error by the gain error estimator 120 will be described later.

[0046] The parameter error estimator 130 estimates the parameter error based on the gain error estimation value output from the gain error estimator. The parameter error is an error caused by the electrical parameters of the three-phase motor 10, i.e., resistance, inductance, etc., being unbalanced in the three phases. When there is a parameter error in the three-phase motor 10, current pulsation is generated due to the parameter error. The frequency of the current pulsation generated by the parameter error is the same as the frequency of the current pulsation caused by the gain error, and becomes a value twice the electrical angular frequency (power-on frequency) of the three-phase motor 10.

[0047] The parameter error estimator 130 converts the parameter error estimation value into a three-phase voltage and outputs it. In the present disclosure, the value obtained by converting the parameter error estimation value into a three-phase voltage is called an electrical parameter error voltage. The parameter error estimation method of the parameter error estimator 130 will be described later.

[0048] The control device 100 uses the electrical parameter error voltage output from the parameter error estimator 130 to correct the voltage command value of the three phases output from the second coordinate converter 112. More specifically, the control device 100 takes the difference between the voltage command value and the electrical parameter error voltage so that the electrical parameter error voltage is removed from the voltage command value of the three phases. Then, the control device 100 performs correction so that the difference between the voltage command value and the electrical parameter error voltage becomes the input voltage of the three-phase motor 10.

[0049] In this embodiment, an error caused when the phase impedance is unbalanced is assumed as a parameter error of the three-phase motor 10. Therefore, it is assumed that the three-phase current and the three-phase voltage in the three-phase motor 10 are unbalanced due to the parameter error.

[0050] Next, the method for estimating the gain error by the gain error estimator 120 is described. The gain error estimator 120 estimates the gain error in a manner that minimizes the current pulsation of each of the d-axis and the q-axis. The gain error estimator 120 can estimate the gain error offline or online. The offline estimation is a gain error estimation based on the prior drive data of the three-phase motor 10. The online estimation is an estimation in which the gain error at which the current pulsation is reduced is determined while changing the estimated value of the gain error during the drive of the three-phase motor 10.

[0051] like Figure 2As shown, the gain error estimator 120 may also include a frequency analyzer 121 and a gain error estimation operator 122. The frequency analyzer 121 takes the current of the d-axis and q-axis, and any one of the time and the rotation angle of the three-phase motor 10 as input, and outputs the amplitude information A of the cosine (cos) component and the amplitude information B of the sine (sin) component of the desired frequency. Here, the "desired frequency" is the frequency of the current pulsation component caused by the gain error and the parameter error. Therefore, as described above, the "desired frequency" is a value twice the electrical angular frequency (power-on frequency) of the three-phase motor 10. Thus, the frequency analyzer 121 outputs the amplitude information A and the amplitude information B of the pulsation component of the d-axis and q-axis current. The amplitude information A and the amplitude information B output from the frequency analyzer 121 are input to the gain error estimation operator 122. The gain error estimation operator 122 calculates the gain error estimation value using the amplitude information A and the amplitude information B of the pulsation component of the input current and outputs it.

[0052] When time is input to the frequency analyzer 121, the frequency analyzer 121 outputs amplitude information A and amplitude information B at the temporal frequency of the current pulsation caused by the gain error. When the rotation angle of the three-phase motor 10 is input to the frequency analyzer 121, the frequency analyzer 121 outputs amplitude information A and amplitude information B at the spatial frequency of the current pulsation caused by the gain error.

[0053] The temporal frequency mentioned here refers to the number of waves per second expressed as the inverse of the period. In addition, the spatial frequency refers to the number of waves per cycle of the mechanical rotation of the three-phase motor 10 or per cycle of the electrical angle of the three-phase motor 10 in a determined interval. For example, when the frequency of the electrical angle is 50 Hz, the frequency of the current pulsation caused by the gain error is 100 Hz in the temporal frequency and is the second harmonic of the electrical angle in the spatial frequency.

[0054] When the gain error is estimated offline using the previous driving data, the estimation is performed according to the following steps.

[0055] Step 1. Drive the three-phase motor 10 with an arbitrarily set gain error setting value and obtain the frequency component of the current ripple value at this time. Repeat this process with at least three modes of gain error setting values, and obtain the gain error setting value and the frequency component information of the current ripple value for each mode.

[0056] Step 2. Using the obtained gain error setting values ​​of at least three patterns and the frequency component information of the current ripple value, an initial value of the gain error when the gain error is not set is used as a gain error estimation value.

[0057] In step 1, driving the three-phase motor 10 using the arbitrarily set gain error setting value means that the control device 100 drives the three-phase motor 10 by multiplying the current detection value including the unknown gain error by the gain error setting value. The gain error setting value is an arbitrarily set constant magnification.

[0058] When the gain error setting value of phase V is set to α n The gain error setting value of phase W is β n When the gain error of the V phase is α0 and the gain error of the W phase is β0, the actual gain including the error can be expressed by the following equations (1) and (2).

[0059]

Mathematical formula 1

[0060] (1+α0)(1+α n )=1+α n +α0+α n α0…(1)

[0061]

Mathematical formula 2

[0062] (1+β0)(1+β n )=1+β n +β0+β n β0…(2)

[0063] When the error components of equations (1) and (2) are independent of each other in the V phase and the W phase and are proportional to the amplitude of the pulsating component of the current, the following equations (3) to (6) are established. d0 represents the gain error estimate of the V phase based on the d-axis current, with the capped α q0 represents the estimated gain error of the V phase based on the q-axis current, with the capped β d0 represents the estimated gain error of the W phase based on the d-axis current, with the capped β q0 Indicates the estimated value of the gain error of the W phase based on the q-axis current.

[0064]

Mathematical formula 3

[0065]

[0066]

Mathematical formula 4

[0067]

[0068]

Mathematical formula 5

[0069]

[0070]

Mathematical formula 6

[0071]

[0072] When θ is the energized phase, A is as shown in equations (7) and (8). dn , B dn , A qn , B qn Indicates the amplitude component of the frequency twice the electrical angle of the d-axis current and the q-axis current.

[0073]

Mathematical formula 7

[0074] id n =A dn cos2θ+B dn sin2θ…(7)

[0075]

Mathematical formula 8

[0076] iq n =A qn cos2θ+B qn sin2θ…(8)

[0077] Here, the subscript n represents the setting value of the gain error (α n , β n ) mode. Equations (3) to (8) are generalized for mode n. A of the pulsation amplitude component dn , B dn , A qn , B qn Indicates the amplitude component of the gain error setting value in mode n. For example, when the gain error setting value (α n , β n ), n is 1 to 3, and Formula (3) to Formula (8) include three formulas of n=1, 2, and 3, respectively.

[0078] In formula (3), the capped α d0 , K dAα , K dBα These three variables are unknown. n is a set value and is therefore known. In addition, A in formula (3) dn , B dn is obtained as a result of frequency analysis and is therefore known. In addition, in equation (4), the capped β d0 , K dAβ , K dBβ These three variables are unknown. n is a set value, so it is known. Moreover, A in formula (4) dn , B dnis obtained as a result of frequency analysis, so it is known. Similarly, equations (5) and (6) also contain 3 unknowns respectively. Therefore, these equations (3) to (6) are respectively combined into 3 equations, and by solving the combined equations, the unknowns can be obtained. That is, when obtaining the unknowns, the setting value of the gain error requires at least 3 modes. In this way, the gain error setting value of at least 3 modes set in advance and the current pulsation component A at this time are used. dn , B dn , A qn , B qn , solve the simultaneous equations related to equations (3) to (6), thereby obtaining the estimated value of the gain error of the current detector 200, i.e., the capped α d0 , α with cap q0 , capped beta d0 , capped beta q0 .

[0079] When the gain error is estimated online while driving the three-phase motor 10, the estimation can be performed according to the following steps. That is, in the driving of the three-phase motor 10, the gain correction value of the current detector 200 is changed. Moreover, if the current ripple value becomes larger, the gain correction value is changed in the opposite direction to the current. On the other hand, if the current ripple value becomes smaller, the gain correction value is changed in the same direction as the current. In this way, the gain correction value when the current ripple value is the smallest is set as the gain error estimation value. In addition, the offline estimation and the online estimation can be performed separately, or the offline estimation and the online estimation can be combined.

[0080] Next, refer to Figure 3 to Figure 9 The current ripples that appear in the current detection values ​​of the dq axes are described. Next, the effect that the main cause of the current ripple value and its frequency characteristics are clarified and the control device 100 of this embodiment can estimate the gain error and the parameter error at the same time is described. Figure 3 The control block in the case where the current detector 200 has a gain error is equivalently represented by the dq axis. In this figure, the internal model of the three-phase motor 10 is represented by the dq axis. Figure 1 The equivalent block of the current detector 200 and the first coordinate converter 111 detects the current converted into the dq axes.

[0081] The d-axis current controller 103 provides a voltage command to the three-phase motor 10 so that the d-axis current command ID generated by the d-axis current command generator 102 is ref The voltage supplied to the three-phase motor 10 is equal to the d-axis current detection value ids. md (s) is converted into current. At this time, the d-axis current id is affected by the parameter errorp e The current affected by the current detector 200 becomes the actual d-axis current ida. The value obtained by detecting the actual d-axis current ida by the current detector 200 becomes the d-axis current detection value ids.

[0082] In addition, the speed controller 101 provides a q-axis current command so that Figure 3 The speed detection value of the three-phase motor 10 detected by the speed detector 20 not shown in the figure is consistent with the speed command. The d-axis current controller 103 provides a voltage command to the three-phase motor 10 so that the axis current command iq outputted from the speed controller 101 is equal to the speed command. ref The voltage supplied to the three-phase motor 10 is equal to the q-axis magnetic circuit P in the three-phase motor 10. mq (s) is converted into current. At this time, the influence of parameter error on the q-axis current iq p e The current affected by the current detector 200 becomes the actual q-axis current iqa. The value obtained by detecting the actual q-axis current iqa by the current detector 200 becomes the q-axis current detection value iqs.

[0083] like Figure 3 As shown, let the d-axis current actually flowing through the three-phase motor be ida, the q-axis current actually flowing through be iqa, let the d-axis detection current converted into the dq-axis be ids, and the q-axis detection current be iqs. As shown in the figure, when the current value actually flowing through the three-phase motor 10 and the detection current value of the current detector 200 differ due to the gain error of the current detector 200, the currents of the dq axes affect each other. At this time, the detection current values ​​ids, iqs and the actual dq-axis current values ​​ida, iqa are in the relationship of the following formula (9).

[0084]

Mathematical formula 9

[0085]

[0086] Here, G dd (s), G dq (s), G qd (s) and G qq (s) as described below.

[0087] G dd (s): Coefficient that simulates the effect of the actual d-axis current on the detected d-axis current

[0088] G dq (s): Coefficient that simulates the effect of the actual d-axis current on the detected q-axis current

[0089] Gqd (s): Coefficient that simulates the effect of the actual q-axis current on the detected d-axis current

[0090] G qq (s): Coefficient that simulates the effect of the actual q-axis current on the detected q-axis current

[0091] Moreover, G dd (s), G dq (s), G qd (s) and G qq (s) is expressed using the following equations (10) to (13).

[0092]

Mathematical formula 10

[0093]

[0094]

Mathematical formula 11

[0095]

[0096]

Mathematical formula 12

[0097]

[0098]

Mathematical formula 13

[0099]

[0100] In addition, α, β, and θ are as follows.

[0101] α: Gain error of phase v based on phase u

[0102] β: Gain error of phase w based on phase u

[0103] θ: Phase during coordinate transformation

[0104] In addition, the current detection gain Gu of the u-phase, the current detection gain Gv of the v-phase, and the current detection gain Gw of the w-phase are expressed by the following formula (14).

[0105]

Mathematical formula 14

[0106]

[0107] At this time, the current detection value of the current detector 200 can be referred to Figure 3 It can be expressed using the following equations (15) and (16).

[0108]

Mathematical formula 15

[0109]

[0110]

Mathematical formula 16

[0111]

[0112] In addition, each variable is as follows.

[0113] ids: d-axis current detection value

[0114] iqs: q-axis current detection value

[0115] id ref : d-axis current command value

[0116] iq ref : q-axis current command value

[0117] id p e : D-axis current ripple value based on parameter error

[0118] iq p e : Q-axis current ripple value based on parameter error

[0119] ida: actual d-axis current

[0120] iqa: actual q-axis current

[0121] Here, for simplicity, the three-phase motor 10 is assumed to be a SPM motor (Surface Permanent Magnet Motor). In this case, the magnetic paths of the d-axis and the q-axis are equal. In addition, the gains of the current control of the d-axis and the q-axis are assumed to be the same, that is, C id (s) = C iq (s), and control is performed as shown in the following equation (17): Wherein, ωc is the response angular frequency of the current control.

[0122]

Mathematical formula 17

[0123]

[0124] Usually, in d-axis control, the current command value is often a fixed value. In particular, in an SPM motor without weak field control, it is usually controlled to id = 0. In this way, when it is controlled to a fixed value, the d-axis current command value does not have a pulsating component. r e f When the control is 0, equations (15) and (16) can be rewritten as the following equations (18) and (19), respectively.

[0125]

Mathematical formula 18

[0126]

[0127]

Mathematical formula 19

[0128]

[0129] Equations (18) and (19) include actual current values ​​ida and iqa that cannot be detected. Therefore, when they are eliminated and the current command values ​​of the d-axis and q-axis and the influence of parameter errors idpe and iqpe are taken as input, equations (18) and (19) can be rewritten as equations (20) and (21), respectively.

[0130]

Mathematical formula 20

[0131] ids=H d (s)iq ref +J d (s)id pe +K d (s)iq pe …(20)

[0132]

Mathematical formula 21

[0133] iqs=H q (s)iq ref +J q (s)id pe +K q (s)iq pe …(twenty one)

[0134] In addition, H d (s), J d (s), K d (s), H q (s), J q (s), K q (s) are respectively shown in the following equations (22) to (27).

[0135]

Mathematical formula 22

[0136]

[0137]

Mathematical formula 23

[0138]

[0139]

Mathematical formula 24

[0140]

[0141]

Mathematical formula 25

[0142]

[0143]

Mathematical formula 26

[0144]

[0145]

Mathematical formula 27

[0146]

[0147] Here, the formula becomes complicated, so we use G dd =G qq ≒1. G dq ≒G qd ≒0.05, G dq *G qd The results obtained by investigating the frequency characteristics of the dq-axis detection current of equations (20) and (21) using the approximation of ≒0 are as follows: Figures 4 to 9 .in addition, Figure 4 Show H d (s) frequency characteristics, Figure 5 Show J d (s) frequency characteristics, Figure 6 Show K d (s) frequency characteristics, Figure 7 Show H q (s) frequency characteristics, Figure 8 Show J q (s) frequency characteristics, Fig. 9 Show K q (s) frequency characteristics.

[0148] like Figure 4 As shown, H d The frequency characteristics of (s) are similar to those of BPF (Band Pass Filter). Figure 5 As shown, J d The frequency characteristics of (s) are the characteristics of a first-order HPF (High Pass Filter) whose cutoff frequency is the current control response frequency ωc. Figure 6 As shown, K d The frequency characteristics of (s) are the characteristics of the first-order HPF whose cutoff frequency is the current control response frequency ωc. Figure 7 As shown, H q The frequency characteristics of (s) are the characteristics of the LPF (Low Pass Filter) whose cutoff frequency is the current control response frequency ωc. Figure 8 As shown, J q The frequency characteristics of (s) are the characteristics of a second-order HPF whose cutoff frequency is the current control response frequency ωc. Fig. 9 As shown, Kq The frequency characteristics of (s) are the characteristics of the first-order HPF whose cutoff frequency is the current control response frequency ωc. These frequency characteristics are characteristics caused by the gain error and the current control system, and can be considered to be the influence of the gain error.

[0149] In the case of having the characteristics of the HPF, when the frequency of the current pulsation component is sufficiently low compared to the response of the current control, the gain becomes small, and the pulsation component of the detection current becomes small. Figure 7 H q (s) is the LPF characteristic. It can be seen that the pulsating component of the q-axis current command and the influence of the gain error appear strongly in the pulsating value of the q-axis current, and the influence of the pulsating component caused by the parameter error on the q-axis current detection value becomes relatively small.

[0150] On the other hand, in the d-axis current detection value, H d , J d , K d Both represent the characteristics of HPF. The current ripple value itself becomes smaller. However, when the H d , J d , K d When comparing the current pulsation components relatively, H d Relatively small, J d , K d Therefore, it can be seen that the influence of the pulsating component caused by the parameter error remains in the pulsating component of the d-axis current, and the pulsating component of the d-axis current is affected by both the parameter error and the gain error.

[0151] Therefore, it can be seen that the influence of the parameter error appears to a small extent in the detection value of the current pulsation of the q-axis, and the influence of the gain error appears to a large extent, and the influence of both the gain error and the parameter error appears in the detection value of the current pulsation of the d-axis. Therefore, when estimating the gain error based on the q-axis current pulsation value, the estimation can be performed without including the influence of the parameter error. On the other hand, when estimating the gain error based on the d-axis current pulsation value, the influence of the parameter error is also included in the estimated value.

[0152] Therefore, in the control device 100 of the present disclosure, the gain error estimator 120 outputs the first gain error estimation value estimated in a manner to minimize the ripple of the d-axis current and the second gain error estimation value estimated in a manner to minimize the ripple of the q-axis current as the gain error of the current detector 200. Figure 1 As shown, the control device 100 does not use the first gain error estimation value in the gain error correction of the current detector 200 , and performs the gain error correction of the current detector 200 based only on the second gain error estimation value.

[0153] Furthermore, parameter error estimator 130 estimates parameter error using both the first gain error estimate value and the second gain error estimate value output from gain error estimator 120. Specifically, parameter error estimator 130 calculates an estimate of parameter error by taking a difference between the first gain error estimate value and the second gain error estimate value.

[0154] In this way, in the control device 100 of this embodiment, the d-axis current pulsation includes the influence of both the gain error and the parameter error, and in the q-axis current pulsation, the influence of the parameter error is relatively small, and the influence of the gain error is relatively large. Using this characteristic, the parameter error estimator 130 can estimate the parameter error based on the difference between the gain errors of the d-axis and the q-axis.

[0155] For example, consider a case where the v-phase gain error based on the q-axis is +5% and the v-phase gain error based on the d-axis is +3%. In addition, the v-phase gain error of +5% means that the current detection value of the v-phase when the u-phase is used as the reference phase and the same current as the u-phase is detected is 105%. In this case, the gain error correction of the current detector 200 is performed using the q-axis gain error of +5%. In addition, the parameter error estimator 130 estimates the parameter error to be -2% based on the difference between the d-axis gain error of +3% and the q-axis gain error of +5%. In addition, the parameter error of -2% means that the impedance of the v-phase is 2% greater than the reference phase.

[0156] According to the motor control device 100 configured as described above, the gain error and the parameter error can be estimated simultaneously with high accuracy. Therefore, the time required for adjusting the gain error and the parameter error can be shortened, and the influence of the estimation error caused by using the detection data containing the error can be reduced.

[0157] use Figures 4 to 9 The frequency characteristics of the dq-axis current pulsation values ​​output by the current detector 200 and the first coordinate converter 111 are affected by the d-axis current controller 103 and the q-axis current controller 104. In addition, the magnitude of the current pulsation changes due to the influence of both the parameter error and the gain error appearing in the current detection value according to the HPF characteristics of the dq-axis current pulsation values.

[0158] When the gain error is estimated by the gain error estimator 120, the magnitude of the current pulsation can be changed by changing the current control gain. By utilizing this characteristic, the estimation error can also be improved. As described above, the d-axis current shows a tendency for the current pulsation value to become smaller due to the HPF characteristic. Therefore, in a case where the detection resolution of the current detector 200 is low and it is difficult to detect the current pulsation value, by reducing the current control gain of the d-axis, the gain on the low-frequency side increases compared to before the change, and the current pulsation value becomes larger. Therefore, the d-axis current pulsation value can be increased, and detection can be performed even when the resolution is low.

[0159] On the other hand, the main component of the q-axis current pulsation value is the q-axis current command value, which has LPF characteristics. Therefore, by increasing the q-axis current control gain as much as possible, the pulsation component caused by the parameter error can be reduced, and the estimation error of the gain error estimation can be reduced. In this way, the gain error estimator 120 can also estimate the gain error of the current detector 200 in the current control response different from the normal operation of the three-phase motor 10.

[0160] In addition, it is preferable to make the rotation speed of the three-phase motor 10 constant to perform gain error estimation. That is, the gain error estimator 120 can estimate the gain error of the current detector 200 when the three-phase motor 10 rotates at a constant speed. When the rotation speed of the three-phase motor 10 changes, the frequency of the current pulsation caused by the gain error changes. Therefore, Figures 4 to 9 The frequency characteristic shown in the figure changes, and the amplitude of the pulsation component changes. Therefore, when the rotation speed of the three-phase motor 10 changes during online estimation, it is impossible to distinguish whether the change in the detected current pulsation is caused by a change in the gain error correction value or a change in the frequency characteristic, which may result in a decrease in the estimation accuracy of the gain error.

[0161] Furthermore, when performing offline estimation, when the rotation speed of the three-phase motor 10 changes, the amplitude of the current pulsation changes according to the rotation speed even with the same gain error, so the premise that the gain error and the current pulsation are proportional is destroyed, which may lead to a decrease in the estimation accuracy of the gain error. However, when it is known in advance that the amplitude component of the current pulsation value accompanying the rotation speed change of the three-phase motor 10 changes, the amplitude of the current pulsation value is corrected in combination with the rotation speed, thereby making it possible to estimate the gain error.

[0162] in addition, Fig.10301 is a diagram showing an example of a structure for realizing the functions of the control device 100 in this embodiment. The functions of the control device 100 are realized, for example, by a processing circuit. The processing circuit may also include a processor 301 and a memory 302. The processing circuit may also be dedicated hardware 303. Alternatively, a portion of the processing circuit may be formed as dedicated hardware 303, and the processing circuit may also include a processor 301 and a memory 302. In the example shown in the figure, a portion of the processing circuit is formed as dedicated hardware 303. In addition, in the example shown in the figure, the processing circuit also includes a processor 301 and a memory 302.

[0163] The processing circuit whose part is at least one dedicated hardware 303 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. When the processing circuit has at least one processor 301 and at least one memory 302, the functions of the control device 100 are implemented by software, firmware, or a combination of software and firmware.

[0164] Software and firmware are described as programs and stored in the memory 302. The processor 301 reads out and executes the program stored in the memory 302, thereby realizing the functions of each part. The processor 301 is also called a CPU (Central Processing Unit), a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP. The memory 302 is, for example, a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, and an EEPROM, or a magnetic disk, a floppy disk, an optical disk, a high-density disk, a mini disk, and a DVD.

[0165] In this way, the processing circuit of the control device 100 can realize each function of the control device 100 through hardware, software, firmware or a combination thereof. In addition, when the processing circuit of the control device 100 has at least a processor 301 and a memory 302, in the control device 100, the processor 301 executes the program stored in the memory 302, and the hardware and software of the control device 100 cooperate to realize the functions of each part of the control device 100.

[0166] Implementation Method 2

[0167] Reference Fig.11 and Fig.12 Embodiment 2 of the present disclosure will be described. Fig.11 It is a diagram showing the overall configuration of a control device for an electric motor. Fig.12 It is a diagram showing a configuration example of a gain error estimator included in a control device.

[0168] Next, the control device for the electric motor of this embodiment 2 will be described with a focus on the differences from embodiment 1. The structure whose description is omitted is basically the same as that of embodiment 1. In the following description, the structure that is the same as or corresponds to that of embodiment 1 is, in principle, marked with the same reference numerals as those used in the description of embodiment 1.

[0169] like Fig.11 As shown, the control device of the motor of this embodiment includes a speed controller 101, a d-axis current command generator 102, a d-axis current controller 103, a q-axis current controller 104, a first coordinate converter 111, a second coordinate converter 112, a gain error estimator 120, and a parameter error estimator 130. The speed controller 101, the d-axis current command generator 102, the d-axis current controller 103, the q-axis current controller 104, the first coordinate converter 111, and the second coordinate converter 112 are basically the same as those in the first embodiment.

[0170] In this embodiment, the gain error estimator 120 estimates the gain error of the current detector 200 based on the current detection value of the d-axis output from the first coordinate converter 111 and the speed detection value output from the speed detector 20. More specifically, the gain error estimator 120 outputs a first gain error estimation value estimated in a manner that minimizes the pulsation of the d-axis current and a third gain error estimation value estimated in a manner that minimizes the pulsation of the speed detection value as the gain error. Then, the control device performs gain error correction of the current detector 200 based on the third gain error estimation value. In addition, the parameter error estimator 130 estimates the parameter error using the first gain error estimation value and the third gain error estimation value.

[0171] The equations (20) and (21) described in the first embodiment are obtained by using the q-axis current command value iq ref Here, when the control device 100 is performing speed control of the three-phase motor 10, the speed controller 101 calculates the q-axis current command value based on the difference between the speed detection value of the three-phase motor 10 detected by the speed detector 20 and the speed command value. The q-axis current command value iq ref The speed control gain Cω(s), speed detection value ω, speed command value ω can be used. ref It is expressed using the following formula (28).

[0172]

Mathematical formula 28

[0173] iq ref =C ω (s)(ω ref -ω)…(28)

[0174] According to formula (28), especially when the speed command value ω ref When the speed is constant, the speed command value ω ref It only contains the DC component, so it can be known that the q-axis current command value iq ref The pulsation component of is caused by the speed detection value ω. Therefore, when the speed command value ω ref When the speed is constant, the gain error can be estimated using the pulsating component of the speed detection value ω instead of estimating the gain error using the pulsating component of the q-axis detection current.

[0175] Therefore, in this embodiment, as described above, the gain error estimator 120 estimates the gain error of the current detector 200 based on the d-axis current detection value output from the first coordinate converter 111 and the speed detection value output from the speed detector 20. This motor control device can also achieve the same effects as in the first embodiment.

[0176] In addition, if Fig.12 As shown, the gain error estimator 120 of this embodiment may also include a frequency analyzer 121 and a gain error estimation operator 122. The frequency analyzer 121 receives the current detection value and speed detection value of the d-axis and either time or the rotation angle of the three-phase motor 10 as input, and outputs the amplitude information A and the amplitude information B of the frequency of the current pulsation component caused by the gain error and the parameter error, and the amplitude information A and the amplitude information B of the frequency of the speed pulsation component caused by the gain error and the parameter error. Here, the amplitude information A is the amplitude information of the cosine (cos) component, and the amplitude information B is the amplitude information of the sine (sin) component.

[0177] The amplitude information A and the amplitude information B output from the frequency analyzer 121 are input to the gain error estimation calculator 122. The gain error estimation calculator 122 calculates and outputs a first gain error estimation value estimated so as to minimize the pulsation of the d-axis current and a third gain error estimation value estimated so as to minimize the pulsation of the speed detection value, using the input amplitude information A and the amplitude information B of the pulsation component of the current and the speed. Therefore, the gain error estimator 120 of this embodiment can estimate the gain error in accordance with both the input of the pulsation component of the current and the pulsation component of the speed detection value.

[0178] Industrial Applicability

[0179] The control device disclosed in the present disclosure can be applied to control of a three-phase motor.

[0180] Description of symbols

[0181] 10 Three-phase motor

[0182] 20 Speed ​​detector

[0183] 100 Control device

[0184] 101 Speed ​​Controller

[0185] 102 d-axis current command generator

[0186] 103 d-axis current controller

[0187] 104 q-axis current controller

[0188] 111 First coordinate converter

[0189] 112 Second coordinate converter

[0190] 120 Gain Error Estimator

[0191] 121 Frequency Analyzer

[0192] 122 Gain error estimation operator

[0193] 130 Parameter Error Estimator

[0194] 200 Current detector

[0195] 301 Processor

[0196] 302 Memory

[0197] 303 Specialized Hardware

Claims

1. A control device for an electric motor, the control device for an electric motor comprising: a speed detector that detects the rotation speed of the motor; a speed controller that outputs a q-axis current command so that a speed detection value of the speed detector follows a speed command value; a current detector for detecting current values ​​input to at least two phases of a u-phase, a v-phase, and a w-phase of the motor; a first coordinate converter for converting the current detection value of the current detector into a d-axis and a q-axis current detection value by performing coordinate conversion; a d-axis current command generator, which generates a d-axis current command; a d-axis current controller that outputs a voltage command value so that the d-axis current detection value output from the first coordinate converter follows the d-axis current command output from the d-axis current command generator; a q-axis current controller that outputs a voltage command value so that the q-axis current detection value output from the first coordinate converter follows the q-axis current command value output from the speed controller; a gain error estimator for estimating a gain error of the current detector based on the d-axis and q-axis current detection values ​​output from the first coordinate converter; and a parameter error estimator that estimates a parameter error caused by three-phase imbalance of an electrical parameter of the motor based on a gain error estimation value of the gain error estimator, The gain error estimator outputs, as the gain error, a first gain error estimation value estimated in a manner to minimize the ripple of the d-axis current and a second gain error estimation value estimated in a manner to minimize the ripple of the q-axis current. The parameter error estimator estimates a parameter error using the first gain error estimate value and the second gain error estimate value, The motor control device performs gain error correction of the current detector based on the second gain error estimated value.

2. A control device for an electric motor, the control device for an electric motor comprising: a speed detector that detects the rotation speed of the motor; a speed controller that outputs a q-axis current command so that a speed detection value of the speed detector follows a speed command value; a current detector for detecting current values ​​input to at least two phases of a u-phase, a v-phase, and a w-phase of the motor; a first coordinate converter for converting the current detection value of the current detector into a d-axis and a q-axis current detection value by performing coordinate conversion; a d-axis current command generator, which generates a d-axis current command; a d-axis current controller that outputs a voltage command value so that the d-axis current detection value output from the first coordinate converter follows the d-axis current command output from the d-axis current command generator; a q-axis current controller that outputs a voltage command value so that the q-axis current detection value output from the first coordinate converter follows the q-axis current command value output from the speed controller; a gain error estimator for estimating a gain error of the current detector based on the current detection value of the d-axis output from the first coordinate converter and the speed detection value; and a parameter error estimator that estimates a parameter error caused by three-phase imbalance of an electrical parameter of the motor based on a gain error estimation value of the gain error estimator, The gain error estimator outputs, as the gain error, a first gain error estimation value estimated so as to minimize the pulsation of the d-axis current and a third gain error estimation value estimated so as to minimize the pulsation of the speed detection value. The parameter error estimator estimates the parameter error using the first gain error estimate value and the third gain error estimate value, The motor control device performs gain error correction of the current detector based on the third gain error estimated value.

3. The control device for the electric motor according to claim 1 or 2, wherein: The gain error estimator estimates a gain error of the current detector during constant speed rotation of the motor.

4. The control device for the electric motor according to claim 1 or 2, wherein: The gain error estimator estimates a gain error of the current detector in a current control response different from that in a normal operation of the motor.

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