Electric motor control device

Abstract

Provided is an electric motor control device capable of simultaneously estimating the gain error of a current detector and the parameter error of a three-phase electric motor and improving the estimation accuracies of these errors. The electric motor control device comprises: a gain error estimator that estimates the gain error of a current detector on the basis of the current detection values of a d-axis and a q-axis; and a parameter error estimator that estimates, on the basis of the estimated value of the gain error, a parameter error due to the three-phase unbalance of the electric parameters of an electric motor. The gain error estimator outputs, as gain errors, a first gain error estimated value that is estimated so as to minimize d-axis current ripple and a second gain error estimated value that is estimated so as to minimize q-axis current ripple. The parameter error estimator estimates a parameter error using the first gain error estimated value and the second gain error estimated value. The control device corrects the gain error of the current detector on the basis of the second gain error estimated value.

Description

[Technical Field]

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

[0002] Known motor control devices have a configuration in which a pulsating component is extracted from at least one of the d-axis current value and the q-axis current value, and based on the change in the amplitude value of the extracted pulsating component, a sensor conversion coefficient setting value is used to determine whether or not the correction made to the output error of the current sensor is incorrect, and the sensor conversion coefficient setting value is determined in accordance with the determination result (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-158414 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that current detectors used in controlling electric motors have gain errors. Gain errors include offset errors and errors due to variations in detection sensitivity. In such control systems, control based on detected values ​​containing errors can result in current pulsations caused by the errors. Furthermore, in electric motor control systems, parameter errors can occur due to imbalances in the electrical parameters of three-phase motors, such as resistance and inductance, among the three phases. If a three-phase motor has parameter errors, current pulsations can occur due to these parameter errors.

[0005] In a motor control device such as that disclosed in Patent Document 1, the gain error of a current detector is corrected based on the pulsation components of the d-axis and q-axis current values. 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, and are therefore the same. Therefore, in a system in which both the gain error of the current detector and the parameter error of the three-phase motor coexist, the pulsation frequencies caused by both are the same. Therefore, when attempting to simultaneously estimate the gain error and the parameter error, it is not possible to distinguish between the estimated values ​​of the gain error and the parameter error, resulting in a decrease in the estimation accuracy of the gain error and the parameter error. Furthermore, if the gain error and the parameter error are estimated separately, the estimation process for each error and the adjustment of the three-phase motor, the control device, etc., take time, resulting in a decrease in work efficiency, etc.

[0006] The present disclosure has been made to solve such problems, and its purpose is to provide a motor control device that can simultaneously estimate the gain error of a current detector and the parameter error of a three-phase motor, and that can improve the accuracy of estimating these errors. [Means for solving the problem]

[0007] A control device for an electric motor according to the present disclosure includes a speed detector that detects the rotational speed of the electric motor, a speed controller that outputs a q-axis current command so that the speed detection value of the speed detector follows a speed command value, a current detector that detects current values ​​of at least two phases out of a u-phase, a v-phase, and a w-phase input to the electric motor, a first coordinate converter that coordinate-converts the current detection value of the current detector into d-axis and q-axis current detection values, a d-axis current command generator that 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, and 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 q-axis current controller for controlling a current detector based on the detected d-axis and q-axis current values ​​output from the first coordinate converter; a gain error estimator for estimating a gain error of the current detector based on the detected d-axis and q-axis current values ​​output from the first coordinate converter; and a parameter error estimator for estimating a parameter error due to a three-phase imbalance in the electrical parameters of the motor based on the gain error estimated by the gain error estimator, wherein the gain error estimator outputs, as the gain error, a first gain error estimate estimated to minimize pulsation in the d-axis current and a second gain error estimate estimated to minimize pulsation in the q-axis current, and the parameter error estimator estimates a parameter error using the first gain error estimate and the second gain error estimate, and performs gain error correction of the current detector based on the second gain error estimate.

[0008] Alternatively, a control device for an electric motor according to the present disclosure includes a speed detector that detects the rotation speed of an electric motor, a speed controller that outputs a q-axis current command so that the speed detection value of the speed detector follows a speed command value, a current detector that detects current values ​​of at least two phases out of a u phase, a v phase, and a w phase input to the electric motor, a first coordinate converter that coordinate-converts the current detection value of the current detector into d-axis and q-axis current detection values, a d-axis current command generator that 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, and 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. The inverter includes a q-axis current controller, a gain error estimator that estimates a gain error of the current detector based on the d-axis current detection value and the speed detection value output from the first coordinate converter, and a parameter error estimator that estimates a parameter error due to a three-phase imbalance in the electrical parameters of the motor based on the gain error estimated by the gain error estimator, wherein the gain error estimator outputs, as the gain error, a first gain error estimate that is estimated so as to minimize pulsation in the d-axis current and a third gain error estimate that is estimated so as to minimize pulsation in the speed detection value, and the parameter error estimator estimates a parameter error using the first gain error estimate and the third gain error estimate, and performs gain error correction of the current detector based on the third gain error estimate. [Effects of the Invention]

[0009] The motor control device according to the present disclosure has the advantage that 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 accuracy of estimating these errors. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing the overall configuration of a control device for an electric motor according to a first embodiment. [Figure 2]3 is a diagram illustrating an example of the configuration of a gain error estimator included in the control device according to the first embodiment. FIG. [Figure 3] 1 is a block diagram showing a configuration equivalent to the control system of the control device for an electric motor according to the first embodiment, converted into dq axes. [Figure 4] 5 is a diagram showing the frequency characteristics of a q-axis current command value related to a d-axis current detection value in the control device for the electric motor according to the first embodiment. FIG. [Figure 5] 5 is a diagram showing frequency characteristics of a parameter error component of a d-axis current related to a d-axis current detection value in the control device for an electric motor according to the first embodiment. FIG. [Figure 6] 5 is a diagram showing frequency characteristics of a parameter error component of a q-axis current related to a detected d-axis current value in the control device for an electric motor according to the first embodiment. FIG. [Figure 7] 5 is a diagram showing the frequency characteristics of a q-axis current command value related to a q-axis current detection value in the control device for the electric motor according to the first embodiment. FIG. [Figure 8] 5 is a diagram showing frequency characteristics of a parameter error component of a d-axis current related to a detected q-axis current value in the control device for an electric motor according to the first embodiment. FIG. [Figure 9] 5 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 the control device for an electric motor according to the first embodiment. FIG. [Figure 10] 1 is a block diagram showing an example of a configuration that realizes the functions of a control device for an electric motor according to a first embodiment. [Figure 11] FIG. 10 is a diagram showing the overall configuration of a control device for an electric motor according to a second embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of the configuration of a gain error estimator included in the control device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of an electric motor control device according to the present disclosure will be described with reference to the accompanying drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals, and redundant explanations are appropriately simplified or omitted. For convenience, the following description may express the positional relationship of each structure based on the illustrated state. Note that the present disclosure is not limited to the following embodiments, and any combination of the embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment are possible within the scope of the present disclosure.

[0012] Embodiment 1 A first embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. FIG. 1 is a diagram illustrating the overall configuration of a motor control device. FIG. 2 is a diagram illustrating an example configuration of a gain error estimator included in the control device. FIG. 3 is a block diagram illustrating a configuration equivalent to a control system of the motor control device converted into dq axes. FIG. 4 is a diagram illustrating the frequency characteristics of a q-axis current command value related to a d-axis current detection value in the motor control device. FIG. 5 is a diagram illustrating the frequency characteristics of a parameter error component of a d-axis current related to a d-axis current detection value in the motor control device. FIG. 6 is a diagram illustrating the frequency characteristics of a parameter error component of a q-axis current related to a d-axis current detection value in the motor control device. FIG. 7 is a diagram illustrating the frequency characteristics of a q-axis current command value related to a q-axis current detection value in the motor control device. FIG. 8 is a diagram illustrating the frequency characteristics of a parameter error component of a d-axis current related to a q-axis current detection value in the motor control device. FIG. 9 is a diagram illustrating the frequency characteristics of a parameter error component of a q-axis current related to a q-axis current detection value in the motor control device. FIG. 10 is a block diagram illustrating an example configuration for implementing the functions of the motor control device.

[0013] An electric motor control device 100 according to this embodiment controls a three-phase electric motor 10. As shown in FIG. 1, a speed detector 20 is attached to the three-phase electric motor 10. The speed detector 20 detects the rotational speed of the three-phase electric motor 10. The speed detector 20 outputs the detected rotational speed value 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 given from outside the control device 100 is input to the control device 100. The speed command value is a command value for the rotational speed of the three-phase electric motor 10. The control device 100 controls the power supply to the three-phase electric motor 10 so that the speed detection value by the speed detector 20 follows the speed command value.

[0014] As shown in FIG. 1 , the control system for the electric motor according to this embodiment includes a current detector 200. The current detector 200 detects current values ​​of u-phase, v-phase, and w-phase supplied from the control device 100 to the three-phase electric motor 10. The current detector 200 outputs the detected current values ​​as current detection values. Note that the current detector 200 only needs to detect current values ​​of at least two of the three phases, i.e., the u-phase, v-phase, and w-phase, input to the three-phase electric motor 10. When the current detector 200 detects current values ​​of two of the three phases, the current detector 200 estimates the current value of the remaining phase based on the three-phase balance relationship and outputs the estimated current value for that phase as the current detection value. In this disclosure, for the sake of simplicity, it is not distinguished whether the estimated current value is included or not, and both cases are referred to as the current detection value.

[0015] As shown in FIG. 1, the motor control device 100 according to 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.

[0016] The speed controller 101 receives the difference between the speed command value input to the control device 100 and the speed detection value detected by the speed detector 20. Based on the difference between the speed command value and the speed detection value, the speed controller 101 outputs a q-axis current command value so that the speed detection value follows the speed detection value. The q-axis current command value is a command value for the torque current.

[0017] 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 be zero. The d-axis current command value may also be an arbitrary negative value for field-weakening control. The d-axis current command value may also be an arbitrary positive value for field-strengthening control.

[0018] The first coordinate converter 111 performs coordinate conversion of the current detection values ​​of the current detector 200 into d-axis and q-axis current detection values. The three-phase current detection values ​​of u-phase, v-phase, and w-phase output from the current detector 200 are input to the first coordinate converter 111. The first coordinate converter 111 then converts the input three-phase current detection values ​​into current values ​​in the d-axis and q-axis coordinate system, and outputs them as d-axis current detection values ​​and q-axis current detection values.

[0019] Here, the coordinate conversion in the first coordinate converter 111 requires magnetic pole position information of the three-phase electric motor 10. Input of the magnetic pole position information to the control device 100 is omitted in FIG. 1 . For example, the speed detector 20 may output magnetic pole position information in addition to the rotational speed of the three-phase electric motor 10. In this case, more specifically, the speed detector 20 includes, for example, an encoder or resolver that detects the magnetic pole position of the three-phase electric motor 10. The speed detector 20 then performs time differentiation on the detected magnetic pole position, converts it into a rotational speed, and outputs it. Alternatively, the speed detector 20 may detect the rotational speed using the principle of a generator, in which the output voltage changes depending on the number of rotations (rotational speed). In this case, the speed detector 20 time-integrates the detected rotational speed and outputs the magnetic pole position information. The first coordinate converter 111 may perform coordinate conversion using the magnetic pole position information output by the speed detector 20 in this manner.

[0020] 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. Based on the difference between the d-axis current command value and the d-axis current detection value, the d-axis current controller 103 outputs a d-axis voltage command value so that the d-axis current detection value follows the d-axis current detection value.

[0021] 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. Based on the difference between the q-axis current command value and the q-axis current detection value, the q-axis current controller 104 outputs a q-axis voltage command value so that the q-axis current detection value follows the q-axis current detection value.

[0022] The second coordinate converter 112 performs coordinate conversion of the d-axis and q-axis voltage command values ​​into three-phase voltage command values ​​of the u-phase, v-phase, and w-phase. The second coordinate converter 112 receives 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. The second coordinate converter 112 then converts the input d-axis and q-axis voltage command values ​​into three-phase voltage command values ​​and outputs them as three-phase voltage command values ​​of the u-phase, v-phase, and w-phase.

[0023] Here, similar to the coordinate conversion in the first coordinate converter 111, the coordinate conversion in the second coordinate converter 112 requires magnetic pole position information of the three-phase electric motor 10. In FIG. 1, input of the magnetic pole position information to the control device 100 is omitted. As described above, the speed detector 20 may output magnetic pole position information in addition to the rotational speed of the three-phase electric motor 10. In this case, the second coordinate converter 112 may perform coordinate conversion using the magnetic pole position information output from the speed detector 20.

[0024] 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, and generates rotational torque and rotational speed.

[0025] 1, the motor control device 100 according to 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.

[0026] Here, in current detector 200, the current detection gain of the u phase is Gu, the current detection gain of the v phase is Gv, and the current detection gain of the w phase is Gw. These three-phase gains may contain offset errors and errors due to variations in detection sensitivity. These offset errors and errors due to variations in detection sensitivity are collectively referred to as gain errors.

[0027] 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 do not match. When there is a gain error in the current detector 200, current pulsation occurs due to this gain error. The frequency of the current pulsation caused by the gain error is twice the electrical angular frequency (energization frequency) of the three-phase electric motor 10. Note that when the gains of the three phases match at a value other than 1, no imbalance in the three-phase currents occurs, which corresponds to a situation in which the efficiency of the three-phase electric motor 10 has changed equivalently.

[0028] The gain error estimator 120 estimates the gain error of the current detector 200 based on the d-axis and q-axis current detection values ​​output from the first coordinate converter 111. Then, the gain error estimator 120 outputs the gain error estimate to the current detector 200 and the parameter error estimator 130. The current detector 200 corrects the u-phase current detection gain Gu, the v-phase current detection gain Gv, and the w-phase current detection gain Gw using the gain error estimate output from the gain error estimator 120. The method of estimating the gain error by the gain error estimator 120 will be described later.

[0029] The parameter error estimator 130 estimates the parameter error based on the gain error estimate output from the gain error estimator. The parameter error is an error that occurs due to an imbalance in the electrical parameters of the three-phase motor 10, i.e., the resistance, inductance, etc., among the three phases. If there is a parameter error in the three-phase motor 10, current pulsation occurs due to this parameter error. The frequency of the current pulsation caused by the parameter error is twice the electrical angular frequency (energization frequency) of the three-phase motor 10, just like the frequency of the current pulsation caused by the gain error.

[0030] The parameter error estimator 130 converts the parameter error estimates into three-phase voltages and outputs them. In this disclosure, the parameter error estimates converted into three-phase voltages are also referred to as electrical parameter error voltages. The method for estimating the parameter errors by the parameter error estimator 130 will be described later.

[0031] The control device 100 corrects the three-phase voltage command values ​​output from the second coordinate converter 112 using the electrical parameter error voltages output from the parameter error estimator 130. More specifically, the control device 100 calculates the differences between the voltage command values ​​and the electrical parameter error voltages so as to remove the electrical parameter error voltages from the three-phase voltage command values. The control device 100 then performs correction so that the differences between the voltage command values ​​and the electrical parameter error voltages become the input voltages of the three-phase electric motor 10.

[0032] In this embodiment, it is assumed that the error occurs when the phase impedance is unbalanced as the parameter error of the three-phase motor 10. Therefore, it is assumed that the parameter error causes an imbalance in the three-phase current and three-phase voltage of the three-phase motor 10.

[0033] Next, a method for estimating a gain error by the gain error estimator 120 will be described. The gain error estimator 120 estimates a gain error so as to minimize the current pulsation of each of the d-axis and q-axis. The gain error estimator 120 may estimate the gain error offline or online. Offline estimation is estimation of the gain error based on prior drive data of the three-phase motor 10. Online estimation is estimation of a gain error that reduces the current pulsation while changing the estimated value of the gain error while the three-phase motor 10 is being driven.

[0034] As shown in FIG. 2, the gain error estimator 120 may include a frequency analyzer 121 and a gain error estimation calculator 122. The frequency analyzer 121 receives d-axis and q-axis currents and either time or the rotation angle of the three-phase electric motor 10 as inputs, and outputs amplitude information A of the cosine (cos) component and amplitude information B of the sine (sin) component of a desired frequency. Here, the "desired frequency" is the frequency of a current pulsation component caused by a gain error and a parameter error. Therefore, as described above, the "desired frequency" is twice the electrical angular frequency (energization frequency) of the three-phase electric motor 10. As a result, the frequency analyzer 121 outputs amplitude information A and amplitude information B of the d-axis and q-axis current pulsation components. The amplitude information A and 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 gain error estimation value using the amplitude information A and amplitude information B of the pulsating component of the input current.

[0035] When time is input to the frequency analyzer 121, the frequency analyzer 121 outputs amplitude information A and amplitude information B at the time 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.

[0036] The time frequency here refers to the number of waves per second, expressed as the reciprocal of the period. The spatial frequency refers to the number of waves in a predetermined interval, such as one mechanical rotation period of the three-phase motor 10, or one electrical angle rotation of the three-phase motor 10. For example, when the frequency of the electrical angle is 50 Hz, the frequency of the current ripple caused by the gain error is 100 Hz in terms of time frequency, and is the second harmonic of the electrical angle in terms of spatial frequency.

[0037] When the gain error is estimated offline using the prior driving data, the estimation is performed according to the following procedure. 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 that time. This process is repeated with at least three patterns of gain error setting values, and obtain the gain error setting value and frequency component information of the current ripple value for each pattern. Step 2: Using the obtained gain error setting values ​​of at least three patterns and frequency component information of the current ripple value, the initial value of the gain error when no gain error is set is set as the gain error estimated value.

[0038] In step 1, driving the three-phase motor 10 with an arbitrarily set gain error setting value means that the control device 100 multiplies the current detection value including an unknown gain error by the gain error setting value to drive the three-phase motor 10. The gain error setting value is an arbitrarily set constant multiplication factor.

[0039] The V phase gain error setting value is α n , the gain error setting value of W phase 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).

[0040]

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[0041]

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[0042] If the error components of equations (1) and (2) are assumed to be proportional to the amplitude of the current pulsation component independently and without correlation in the V phase and the W phase, the following equations (3) to (6) hold. Note that in these equations, α with a hat (^) d0 is the V-phase gain error estimate based on the d-axis current, and α q0 is the V-phase gain error estimate based on the q-axis current, and β d0 is the estimated gain error of the W phase based on the d-axis current, and β q0 and represent the estimated gain error of the W phase based on the q-axis current.

[0043]

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[0044]

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[0045]

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[0046]

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[0047] However, A dn , B dn , A qn , B qn When θ is the conduction phase, these represent the amplitude components of the frequency twice the electrical angle of the d-axis current and q-axis current as shown in equations (7) and (8), respectively.

[0048]

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[0049]

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[0050] Here, the subscript n is the gain error setting (α n , β n ) pattern. Equations (3) to (8) are generalized for pattern n. A of the pulsation amplitude component dn , B dn , A qn , B qn represents the amplitude component of the gain error setting value of pattern n. For example, the gain error setting value (α n , β n ) are set in three patterns, n is 1 to 3, and equations (3) to (8) include three equations with n=1, 2, and 3, respectively.

[0051] In equation (3), α d0 , K. dAα , K. dBα The three variables are unknowns. n is a set value and is therefore known. dn , B dn is known because it is obtained as a result of frequency analysis. In addition, in equation (4), β d0 , K. dAβ , K. dBβ The three variables are unknowns. n is a set value and is therefore known. dn , B dn is known because it is obtained as a result of frequency analysis. Similarly, equations (5) and (6) each contain three unknowns. Therefore, equations (3) to (6) are each set up as three simultaneous equations, and the unknowns can be found by solving these simultaneous equations. In other words, at least three patterns of gain error setting values ​​are required to find the unknowns. In this way, at least three patterns of gain error setting values ​​set in advance and the current ripple component A at that time are obtained. dn , B dn , A qn , Bqn By solving the simultaneous equations for each of the equations (3) to (6) using d0 , α with hat q0 , hatched β d0 , hatched β q0 can be obtained.

[0052] When estimating the gain error online while driving the three-phase motor 10, the estimation can be performed using the following procedure. That is, the gain correction value of the current detector 200 is changed while the three-phase motor 10 is being driven. Then, if the current pulsation value is likely to increase, the gain correction value is changed in the opposite direction. On the other hand, if the current pulsation value is likely to decrease, the gain correction value is changed in the same direction as the current value. In this way, the gain correction value when the current pulsation value is minimized is used as the gain error estimate. Note that offline estimation and online estimation may be performed independently, or offline estimation and online estimation may be performed in combination.

[0053] Next, with reference to Figures 3 to 9, we will explain the current pulsation that appears in the detected current values ​​on the dq axes. We will then clarify the main causes of the current pulsation values ​​and their frequency characteristics, and explain the effect of the control device 100 according to this embodiment, which allows simultaneous estimation of gain error and parameter error. Figure 3 shows a control block equivalently represented on the dq axes when the current detector 200 has a gain error. In this figure, the internal model of the three-phase motor 10 is represented on the dq axes. In addition, in this figure, the current converted to the dq axes is detected by an equivalent block of the current detector 200 and the first coordinate converter 111 in Figure 1.

[0054] The d-axis current controller 103 uses the d-axis current command id generated by the d-axis current command generator 102. ref A voltage command is given to the three-phase motor 10 so that the d-axis current detection value ids coincides with the d-axis magnetic circuit P md(s) is converted to current. At this time, the influence of parameter error on the d-axis current is pe The actual d-axis current ida is the current affected by the above. The actual d-axis current ida detected by the current detector 200 is the d-axis current detection value ids.

[0055] The speed controller 101 provides a q-axis current command so that the speed detection value of the three-phase motor 10 detected by the speed detector 20 (not shown in Fig. 3) coincides with the speed command. The d-axis current controller 103 controls the d-axis current command iq output from the speed controller 101. ref A voltage command is given to the three-phase motor 10 so that the detected value iqs of the q-axis current coincides with the voltage given to the three-phase motor 10. The voltage given to the three-phase motor 10 is mq (s) is converted to current. At this time, the effect of parameter error on the q-axis current iq pe The actual q-axis current iqa is the current affected by the above. The actual q-axis current iqa detected by the current detector 200 is the q-axis current detection value iqs.

[0056] As shown in Figure 3, the d-axis current that actually flows through the three-phase motor is ida, the q-axis current that actually flows is iqa, the detected d-axis current converted to the dq axes is ids, and the detected q-axis current is iqs. As shown in the figure, if a difference occurs between the current value that actually flows through the three-phase motor 10 and the current value detected by the current detector 200 due to a gain error in the current detector 200, the dq-axis currents will affect each other. In this case, the detected current values ​​ids, iqs and the actual dq-axis current values ​​ida, iqa have the relationship shown in the following equation (9).

[0057]

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[0058] where G dd (s), G dq (s), G qd (s) and G qq (s) are as follows: G dd (s): Coefficient simulating the effect of the actual d-axis current on the detected d-axis current G dq (s): A coefficient that simulates the effect that the actual d-axis current has on the detected q-axis current. G qd (s): A coefficient that simulates the effect that the actual q-axis current has on the detected d-axis current. G qq (s): A coefficient that simulates the effect of the actual q-axis current on the detected q-axis current.

[0059] And G dd (s), G dq (s), G qd (s) and G qq (s) is expressed by the following equations (10) to (13).

[0060]

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[0061]

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[0062]

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[0063]

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[0064] Note that α, β, and θ are as follows: α: Gain error of v phase based on u phase β: Gain error of w phase based on u phase θ: Phase during coordinate transformation

[0065] Further, 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 equation (14).

[0066]

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[0067] At this time, the current detection value by the current detector 200 can be expressed by the following equations (15) and (16) with reference to FIG.

[0068]

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[0069]

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[0070] The variables are as follows: ids: d-axis current detection value iqs: q-axis current detection value id ref : d-axis current command value iq ref : q-axis current command value id pe : d-axis current pulsation due to parameter error iq pe : q-axis current pulsation due to parameter error ida: Actual d-axis current iqa: Actual q-axis current

[0071] For simplicity, the three-phase motor 10 is assumed to be an SPM motor (Surface Permanent Magnet Motor). In this case, the magnetic circuits of the d-axis and q-axis are the same. Also, the gains of the current control of the d-axis and 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): where ωc is the response angular frequency of the current control.

[0072]

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[0073] Normally, in d-axis control, the current command value is often a fixed value. In particular, in an SPM motor without field-weakening control, it is usually controlled to id=0. In this way, when controlled to a fixed value, the d-axis current command value does not have a pulsating component. The d-axis current command id ref If control is performed to set the value to 0, then equations (15) and (16) can be rewritten as the following equations (18) and (19), respectively.

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[0075]

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[0076] Since equations (18) and (19) contain the actual current values ​​ida and iqa that cannot be detected, by eliminating these and inputting the d-axis and q-axis current command values ​​and the influence of parameter errors idpe and iqpe, equations (18) and (19) can be rewritten as equations (20) and (21), respectively.

[0077]

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[0078]

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[0079] In addition, H d (s), J d (s), K d (s), H q (s), J q (s), K q (s) are as shown in the following equations (22) to (27), respectively.

[0080]

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[0081]

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[0082]

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[0083]

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[0084]

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[0085]

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[0086] Now, since the formula has become complicated, G dd =G qq ≒ 1, G dq ≒G qd ≒0.05, G dq *G qd Figures 4 to 9 show the frequency characteristics of the detected currents on the dq axes in equations (20) and (21) using the approximation that H d (s), Figure 5 shows J d (s), Figure 6 shows K d (s), and Fig. 7 shows the frequency characteristics of H q (s), Figure 8 shows J q (s), Figure 9 shows K q (s) show the frequency characteristics of

[0087] As shown in Figure 4, H d The frequency characteristics of (s) are similar to those of a BPF (Band Pass Filter). dThe frequency characteristics of (s) are those of a first-order HPF (High Pass Filter) whose cutoff frequency is the current control response frequency ωc. As shown in Figure 6, d The frequency characteristics of (s) are those of a first-order HPF whose cutoff frequency is the current control response frequency ωc. As shown in Figure 7, q The frequency characteristics of (s) are those of a low pass filter (LPF) whose cutoff frequency is the current control response frequency ωc. As shown in Figure 8, q The frequency characteristic of (s) is that of a second-order HPF whose cutoff frequency is the current control response frequency ωc. As shown in Figure 9, K q The frequency characteristics of (s) are those of a first-order HPF whose cutoff frequency is the current control response frequency ωc. These frequency characteristics are caused by the gain error and the current control system, and can be considered to be the influence of the gain error.

[0088] When the HPF characteristic is used, if the frequency of the current ripple component is sufficiently low compared to the response of the current control, the gain becomes small and the ripple component of the detected current becomes small. q (s) is the LPF characteristic, and it can be seen that the pulsation value of the q-axis current is strongly affected by the pulsation component of the q-axis current command and the gain error, while the effect of the pulsation component due to parameter error on the detected q-axis current value is relatively small.

[0089] On the other hand, the d-axis current detection value is H d , J d , K. d Both of these show the characteristics of an HPF, and the current ripple value itself becomes small, but the current ripple component is d , J d , K. d When compared relatively, H d becomes relatively small, and J d , K. d Therefore, the influence of the pulsating component due to the parameter error remains in the pulsating component of the d-axis current, and it can be seen that the pulsating component of the d-axis current is affected by both the parameter error and the gain error.

[0090] Therefore, it can be seen that the detected value of the q-axis current pulsation is less affected by parameter error and more affected by gain error, while the detected value of the d-axis current pulsation is affected by both gain error and parameter error. Therefore, if the gain error is estimated based on the q-axis current pulsation value, it can be estimated without including the influence of parameter error. On the other hand, if the gain error is estimated based on the d-axis current pulsation value, the estimated value will also include the influence of parameter error.

[0091] Therefore, in the control device 100 according to the present disclosure, the gain error estimator 120 outputs a first gain error estimate estimated so as to minimize the pulsation of the d-axis current and a second gain error estimate estimated so as to minimize the pulsation of the q-axis current, as the gain error of the current detector 200. Then, as shown in Fig. 1 , the control device 100 performs the gain error correction of the current detector 200 based only on the second gain error estimate without using the first gain error estimate.

[0092] Furthermore, parameter error estimator 130 estimates the parameter error using both the first gain error estimate and the second gain error estimate output from gain error estimator 120. Specifically, parameter error estimator 130 calculates the estimate of the parameter error by taking the difference between the first gain error estimate and the second gain error estimate.

[0093] In this way, in control device 100 according to this embodiment, the d-axis current pulsation is affected by both gain error and parameter error, while the q-axis current pulsation is relatively less affected by parameter error and relatively more affected by gain error. By utilizing this characteristic, parameter error estimator 130 can estimate the parameter error from the difference between the d-axis and q-axis gain errors.

[0094] For example, consider a case where the v-phase gain error due to the q-axis is +5% and the v-phase gain error due to the d-axis is +3%. A v-phase gain error of +5% means that when the u-phase is used as the reference phase and the same current as the u-phase is detected, the detected v-phase current value is 105%. In this case, the gain error correction of current detector 200 is performed using the q-axis gain error of +5%. Furthermore, 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%. A parameter error of -2% means that the impedance of the v-phase is 2% higher than the reference phase.

[0095] The electric motor control device 100 configured as described above can accurately estimate the gain error and parameter error simultaneously. This makes it possible to shorten the time required for adjustment work that was previously performed separately for the gain error and parameter error, and also to reduce the influence of estimation errors caused by using detection data that includes errors.

[0096] The frequency characteristics of the d-axis and q-axis current pulsation values ​​output using the current detector 200 and first coordinate converter 111 shown in Figures 4 to 9 are affected by the d-axis current controller 103 and the q-axis current controller 104. The magnitude of the current pulsation due to the influence of both parameter errors and gain errors appearing in the current detection value changes depending on the HPF characteristics of the d-axis and q-axis current pulsation values.

[0097] 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. This characteristic can be used to improve the estimation error. As described above, the d-axis current tends to have a small current pulsation value due to the HPF characteristic. Therefore, if the detection resolution of the current detector 200 is low and it is difficult to detect the current pulsation value, lowering the d-axis current control gain increases the gain on the low-frequency side compared to before the change, and the current pulsation value increases. Therefore, the d-axis current pulsation value can be increased, making it possible to detect it even when the resolution is low.

[0098] On the other hand, the q-axis current pulsation value has an LPF characteristic, with its main component being the q-axis current command value. Therefore, by increasing the q-axis current control gain as much as possible, the pulsation component due to the parameter error can be reduced, and the estimation error in the gain error estimation can be reduced. In this way, the gain error estimator 120 may estimate the gain error of the current detector 200 in a current control response different from that during normal operation of the three-phase motor 10.

[0099] It is desirable to perform the gain error estimation while maintaining a constant rotational speed of the three-phase motor 10. That is, the gain error estimator 120 should estimate the gain error of the current detector 200 while the three-phase motor 10 is rotating at a constant speed. When the rotational speed of the three-phase motor 10 changes, the frequency of the current pulsation caused by the gain error changes. This causes the frequency characteristics shown in Figures 4 to 9 to fluctuate, resulting in fluctuations in the amplitude of the pulsation component. Therefore, when performing online estimation, if the rotational speed of the three-phase motor 10 changes, it becomes impossible to distinguish whether the change in the detected current pulsation is due to a change in the gain error correction value or a change in the frequency characteristics, which may result in a decrease in the accuracy of the gain error estimation.

[0100] Furthermore, when performing offline estimation, if the rotation speed of the three-phase motor 10 changes, the amplitude of the current pulsation changes depending on the rotation speed even for the same gain error, which breaks down the assumption that the gain error is proportional to the current pulsation, and this may result in a decrease in the accuracy of the gain error estimation. However, if the fluctuation in the amplitude component of the current pulsation value due to fluctuations in the rotation speed of the three-phase motor 10 is known in advance, the gain error can be estimated by correcting the amplitude of the current pulsation value in accordance with the rotation speed.

[0101] 10 is a diagram showing an example of a configuration for realizing the functions of the control device 100 in this embodiment. The functions of the control device 100 are realized by, for example, a processing circuit. The processing circuit may include a processor 301 and a memory 302. The processing circuit may be dedicated hardware 303. A part of the processing circuit may be formed as dedicated hardware 303, and the processing circuit may further include a processor 301 and a memory 302. In the example shown in the figure, a part of the processing circuit is formed as dedicated hardware 303. In addition, in the example shown in the figure, the processing circuit further includes a processor 301 and a memory 302.

[0102] The processing circuitry, part of which is at least one dedicated hardware 303, may be, for example, a single circuit, a multiple circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. If the processing circuitry comprises at least one processor 301 and at least one memory 302, the functionality of the control device 100 may be realized by software, firmware, or a combination of software and firmware.

[0103] The software and firmware are written as programs and stored in memory 302. Processor 301 realizes the functions of each unit by reading and executing the programs stored in memory 302. Processor 301 is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. Memory 302 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM, or a magnetic disk, flexible disk, optical disk, compact disk, minidisk, DVD, etc.

[0104] In this way, the processing circuit of the control device 100 can realize each function of the control device 100 by hardware, software, firmware, or a combination of these. When the processing circuit of the control device 100 includes at least the processor 301 and the memory 302, the processor 301 executes a program stored in the memory 302 in the control device 100, and the hardware and software of the control device 100 work together to realize the function of each unit included in the control device 100.

[0105] Embodiment 2 A second embodiment of the present disclosure will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a diagram showing an overall configuration of a control device for an electric motor. Fig. 12 is a diagram showing an example configuration of a gain error estimator included in the control device.

[0106] The following describes the motor control device according to this embodiment 2, focusing on the differences from embodiment 1. Configurations for which a description is omitted are basically the same as those in embodiment 1. In the following description, configurations that are the same as or correspond to those in embodiment 1 will be generally denoted by the same reference numerals as those used in the description of embodiment 1.

[0107] 11, the motor control device according to 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.

[0108] In this embodiment, gain error estimator 120 estimates the gain error of current detector 200 based on the d-axis current detection value output from first coordinate converter 111 and the speed detection value output from speed detector 20. More specifically, gain error estimator 120 outputs, as the gain error, a first gain error estimate estimated to minimize pulsation in the d-axis current and a third gain error estimate estimated to minimize pulsation in the speed detection value. The control device then performs gain error correction of current detector 200 based on the third gain error estimate. Furthermore, parameter error estimator 130 estimates the parameter error using the first gain error estimate and the third gain error estimate.

[0109] The equations (20) and (21) explained in the first embodiment are expressed as the q-axis current command value iq ref and the current pulsation components idpe and iqpe that the parameter errors affect on the d-axis and q-axis. When the control device 100 controls the speed 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 is the speed control gain Cω(s), the speed detection value ω, and the speed command value ω ref Using this, it can be expressed as the following equation (28).

[0110]

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[0111] According to equation (28), in particular, the speed command value ω ref is a constant speed, the speed command value ω ref contains only DC components, the q-axis current command value iq ref It can be seen that the pulsating component of is caused by the detected speed value ω. ref When is constant, instead of estimating the gain error using the pulsation component of the detected current of the q axis, the gain error can be estimated using the pulsation component of the detected speed value ω.

[0112] 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. With such a motor control device, it is possible to achieve the same effects as in the first embodiment.

[0113] 12, the gain error estimator 120 according to this embodiment may include a frequency analyzer 121 and a gain error estimation calculator 122. The frequency analyzer 121 receives the detected d-axis current value and detected speed value, and either time or the rotation angle of the three-phase electric motor 10 as inputs, and outputs amplitude information A and amplitude information B of the frequency of a current ripple component caused by a gain error and a parameter error, and amplitude information A and amplitude information B of the frequency of a speed ripple component caused by a gain error and a 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.

[0114] The amplitude information A and amplitude information B output from the frequency analyzer 121 are input to the gain error estimation calculator 122. Using the amplitude information A and amplitude information B of the input current and speed pulsation components, the gain error estimation calculator 122 calculates and outputs a first gain error estimate estimated to minimize d-axis current pulsation and a third gain error estimate estimated to minimize pulsation in the detected speed value. Therefore, the gain error estimator 120 of this embodiment can estimate gain errors in response to the input of both the current pulsation component and the speed detection value pulsation component. [Industrial Applicability]

[0115] The control device according to the present disclosure can be applied to the control of a three-phase electric motor. [Explanation of symbols]

[0116] 10 Three-phase electric motor 20 Speed ​​detector 100 control device 101 Speed ​​Controller 102 d-axis current command generator 103 d-axis current controller 104 q-axis current controller 111 First coordinate transformer 112 Second coordinate transformer 120 Gain Error Estimator 121 Frequency Analyzer 122 Gain error estimation calculator 130 Parameter Error Estimator 200 Current Detector 301 processor 302 memory 303 Dedicated Hardware

Claims

1. a speed detector for detecting the rotation speed of the electric motor; a speed controller that outputs a q-axis current command so that the speed detection value of the speed detector follows a speed command value; a current detector for detecting current values ​​of at least two of a u-phase, a v-phase, and a w-phase input to the electric motor; a first coordinate converter that converts the current detection value of the current detector into a d-axis and a q-axis current detection value; a d-axis current command generator that 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 that estimates a gain error of the current detector based on the d-axis and q-axis current detection values ​​output from the first coordinate converter; a parameter error estimator that estimates a parameter error due to a three-phase imbalance of an electrical parameter of the electric motor based on a gain error estimated by the gain error estimator; the gain error estimator outputs, as the gain error, a first gain error estimate estimated so as to minimize pulsation of a d-axis current and a second gain error estimate estimated so as to minimize pulsation of a q-axis current; the parameter error estimator estimates a parameter error using the first gain error estimate and the second gain error estimate; A motor control device that performs gain error correction of the current detector based on the second gain error estimate value.

2. a speed detector for detecting the rotation speed of the electric motor; a speed controller that outputs a q-axis current command so that the speed detection value of the speed detector follows a speed command value; a current detector for detecting current values ​​of at least two of a u-phase, a v-phase, and a w-phase input to the electric motor; a first coordinate converter that converts the current detection value of the current detector into a d-axis and a q-axis current detection value; a d-axis current command generator that 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 that estimates a gain error of the current detector based on the d-axis current detection value and the speed detection value output from the first coordinate converter; a parameter error estimator that estimates a parameter error due to a three-phase imbalance of an electrical parameter of the electric motor based on a gain error estimated by the gain error estimator; the gain error estimator outputs, as the gain error, a first gain error estimate that is estimated so as to minimize pulsation of the d-axis current and a third gain error estimate that is estimated so as to minimize pulsation of the detected speed value; the parameter error estimator estimates a parameter error using the first gain error estimate and the third gain error estimate; A motor control device that corrects the gain error of the current detector based on the third gain error estimate value.

3. 3. The motor control device according to claim 1, wherein said gain error estimator estimates the gain error of said current detector while said motor is rotating at a constant speed.

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

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