WO2023243087A1

WO2023243087A1 - Electric motor control device

Info

Publication number: WO2023243087A1
Application number: PCT/JP2022/024355
Authority: WO
Inventors: 健岡本; 浩行榎嶋; 盛臣見延
Original assignee: 三菱電機株式会社
Priority date: 2022-06-17
Filing date: 2022-06-17
Publication date: 2023-12-21

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

Electric motor control device

The present disclosure relates to a control device for an electric motor.

In a motor control device, a pulsating component is extracted from at least one of the d-axis current value and the q-axis current value, and the sensor conversion coefficient setting value is used to calculate the current sensor's current sensor from the change in the amplitude value of the extracted pulsating component. A device is known that has a configuration that determines whether or not the correction made to the output error is incorrect, and determines the sensor conversion coefficient setting value according to the determination result (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2016-158414

It is known that current detectors used when controlling electric motors have gain errors. The gain error includes an offset error and an error due to variations in detection sensitivity. In such a control system, current pulsations due to errors occur due to control based on detected values that include errors. In addition, in a motor control system, there are parameter errors caused by imbalances in the electrical parameters of the three-phase motor, such as resistance and inductance among the three phases. If there is a parameter error in the three-phase motor, current pulsation will occur due to this parameter error.

In a motor control device as shown in Patent Document 1, a gain error of a current detector is corrected based on pulsating components of the d-axis and q-axis current values. However, the frequency of current pulsation due to gain error and the frequency of current pulsation due to parameter error are both twice the electrical angular frequency of the three-phase motor, and are 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 both is the same, so it is difficult to estimate the gain error and the parameter error at the same time. In this case, it is not possible to separate the estimated values of the gain error and parameter error, resulting in a decrease in the estimation accuracy of the gain error and parameter error. Furthermore, if the gain error and parameter error are estimated separately, it takes time to estimate each error and to adjust the three-phase motor, control device, etc., resulting in a decrease in work efficiency.

The present disclosure has been made to solve such problems. The 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.

An electric motor control device according to the present disclosure includes a speed detector that detects the rotational speed of the electric motor, and 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 among the u-phase, v-phase, and w-phase input to the motor; a d-axis current command generator that generates a d-axis current command; and a d-axis current command output from the d-axis current command generator, which A d-axis current controller that outputs a voltage command value and a q-axis current command value output from the speed controller are output from the first coordinate converter so that the output d-axis current detection value follows. A q-axis current controller outputs a voltage command value and the d-axis and q-axis current detection values outputted from the first coordinate converter so that the q-axis current detection value follows a gain error estimator that estimates a gain error of a current detector; a parameter error estimator that estimates a parameter error due to three-phase imbalance of electrical parameters of the motor based on a gain error estimate by the gain error estimator; The gain error estimator includes, as the gain error, a first gain error estimate estimated to minimize pulsations in the d-axis current, and a first gain error estimate estimated to minimize pulsations in the q-axis current. The parameter error estimator estimates a parameter error using the first gain error estimate and the second gain error estimate, and outputs the second gain error estimate. The gain error correction of the current detector is performed based on.

Alternatively, the electric motor control device according to the present disclosure includes a speed detector that detects the rotational speed of the electric motor, and a speed control 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 among the u-phase, v-phase, and w-phase that are input to the motor; a first coordinate converter that performs coordinate conversion to a detected value; a d-axis current command generator that generates a d-axis current command; and a first coordinate conversion to the d-axis current command output from the d-axis current command generator. a d-axis current controller that outputs a voltage command value, and a q-axis current command value output from the speed controller, so that the d-axis current detected value output from the speed controller follows the first coordinate converter. a q-axis current controller that outputs a voltage command value so that the q-axis current detected value outputted from the first coordinate converter follows the d-axis current detected value outputted from the first coordinate converter and the speed detected value; a gain error estimator that estimates a gain error of the current detector based on the gain error estimator; and a parameter that estimates a parameter error due to three-phase imbalance of electrical parameters of the motor based on the gain error estimate by the gain error estimator. an error estimator, the gain error estimator includes a first gain error estimate estimated to minimize pulsations in the d-axis current as the gain error, and a first gain error estimate estimated to minimize pulsations in the detected speed value. The parameter error estimator estimates a parameter error using the first gain error estimate and the third gain error estimate, and outputs a third gain error estimate estimated to make the parameter error. Gain error correction of the current detector is performed based on the third gain error estimate.

According to the electric motor control device according to 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 it is possible to improve the accuracy of estimating these errors.

1 is a diagram showing the overall configuration of a control device for an electric motor according to a first embodiment; FIG. FIG. 3 is a diagram illustrating a configuration example of a gain error estimator included in the control device according to the first embodiment. FIG. 2 is a block diagram showing a configuration equivalent to the control system of the electric motor control device according to Embodiment 1, converted to dq axes. FIG. 3 is a diagram showing frequency characteristics of a q-axis current command value related to a d-axis current detection value in the electric motor control device according to the first embodiment. FIG. 3 is a diagram showing frequency characteristics of a parameter error component of a d-axis current related to a detected d-axis current value in the motor control device according to the first embodiment. FIG. 3 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 motor control device according to the first embodiment. 3 is a diagram showing frequency characteristics of a q-axis current command value related to a q-axis current detected value in the electric motor control device according to the first embodiment. FIG. FIG. 3 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 motor control device according to the first embodiment. FIG. 3 is a diagram showing frequency characteristics of a parameter error component of a q-axis current related to a detected q-axis current value in the motor control device according to the first embodiment. FIG. 2 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. FIG. 3 is a diagram showing the overall configuration of a control device for an electric motor according to a second embodiment. 7 is a diagram illustrating a configuration example of a gain error estimator included in a control device according to a second embodiment. FIG.

Embodiments for implementing the electric motor control device according to the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are given the same reference numerals, and overlapping explanations will be simplified or omitted as appropriate. In the following description, for convenience, the positional relationship of each structure may be expressed based on the illustrated state. Note that the present disclosure is not limited to the following embodiments, and any combination of embodiments, modification of any component of each embodiment, or modification of each embodiment may be made without departing from the spirit of the present disclosure. Any component of the embodiment can be omitted.

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

A motor control device 100 according to this embodiment controls a three-phase motor 10. As shown in FIG. 1, a speed detector 20 is attached to the three-phase electric motor 10. Speed detector 20 detects the rotation speed of three-phase electric motor 10. The speed detector 20 outputs the detected rotation 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 of the control device 100 is input to the control device 100 . The speed command value is a command value of the rotational speed of the three-phase electric motor 10. The control device 100 controls the power supply to the three-phase motor 10 so that the speed detected by the speed detector 20 follows the speed command value.

The control system of the electric motor according to this embodiment is provided with a current detector 200, as shown in FIG. Current detector 200 detects the u-phase, v-phase, and w-phase current values supplied from control device 100 to three-phase motor 10 . Current detector 200 outputs the detected current value as a current detection value. Note that the current detector 200 only needs to detect current values of at least two of the three phases, the u phase, the v phase, and the w phase, which are input to the three-phase motor 10. When 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 from the three-phase equilibrium relationship, and estimates the current value of the one phase. The detected current value is output as the detected current value. In this disclosure, in order to simplify the explanation, it is not distinguished whether the estimated current value is included or not, and in either case, it is referred to as a current detected value.

As shown in FIG. 1, a 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, and a first coordinate system. A converter 111 and a second coordinate converter 112 are provided.

The difference between the speed command value input to the control device 100 and the speed detected value by the speed detector 20 is input to the speed controller 101. The speed controller 101 outputs a q-axis current command value based on the difference between the speed command value and the detected speed value so that the detected speed value follows the detected speed value. The q-axis current command value is a torque current command value.

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. Further, the d-axis current command value may be any negative value for field weakening control. The d-axis current command value may be any positive value for field strengthening control.

The first coordinate converter 111 coordinately transforms the current detection value of the current detector 200 into d-axis and q-axis current detection values. The first coordinate converter 111 receives three phase current detection values output from the current detector 200, that is, the u-phase, the v-phase, and the w-phase. Then, the first coordinate converter 111 converts the input three-phase current detection values into current values in the d-axis and q-axis coordinate systems, and outputs them as d-axis current detection values and q-axis current detection values. .

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

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 is input to the d-axis current controller 103. 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. .

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 is input to the q-axis current controller 104. 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. .

The second coordinate converter 112 converts the voltage command values of the d-axis and q-axis into voltage command values of three phases: u-phase, v-phase, and 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 three-phase voltage command values, and converts them into three-phase voltage command values of the u-phase, v-phase, and w-phase. Output.

Here, similarly to the coordinate transformation in the first coordinate converter 111, the coordinate transformation in the second coordinate converter 112 requires the magnetic pole position information of the three-phase electric motor 10. In FIG. 1, input of 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.

The control device 100 supplies three-phase power to the three-phase electric motor 10 based on the three-phase voltage command values output from the second coordinate converter 112. The three-phase electric motor 10 is driven by three-phase power supplied from the control device 100, and generates rotational torque and rotational speed.

The electric motor control device 100 according to this embodiment further includes a gain error estimator 120 and a parameter error estimator 130, as shown in FIG. Gain error estimator 120 estimates the gain error of current detector 200.

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

If 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, if there is a gain error in the current detector 200, the current detection gains of the three phases will not match. If there is a gain error in the current detector 200, current pulsations occur due to this gain error. The frequency of current pulsation caused by the gain error is twice the electrical angular frequency (energization frequency) of the three-phase motor 10. Note that if the gains of the three phases match each other with numerical values other than 1, this corresponds to a situation where no unbalanced three-phase current occurs and the efficiency of the three-phase motor 10 changes equivalently.

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. The gain error estimator 120 then outputs the gain error estimate to the current detector 200 and the parameter error estimator 130. The current detector 200 uses the gain error estimate output from the gain error estimator 120 to correct the u-phase current detection gain Gu, the v-phase current detection gain Gv, and the w-phase current detection gain Gw. A method for estimating the gain error by the gain error estimator 120 will be described later.

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 caused by the electrical parameters of the three-phase motor 10, that is, the resistance, inductance, etc., being unbalanced among the three phases. If there is a parameter error in the three-phase motor 10, current pulsations occur due to this parameter error. The frequency of current pulsations caused by parameter errors is twice the electrical angular frequency (energization frequency) of the three-phase motor 10, similar to the frequency of current pulsations caused by gain errors.

The parameter error estimator 130 converts the estimated parameter error value into a three-phase voltage and outputs it. In this disclosure, a parameter error estimate value converted into a three-phase voltage is also referred to as an electrical parameter error voltage. A method for estimating parameter errors by the parameter error estimator 130 will be described later.

The control device 100 corrects the three-phase voltage command values output from the second coordinate converter 112 using the electric parameter error voltage output from the parameter error estimator 130. More specifically, the control device 100 calculates the difference between the voltage command value and the electrical parameter error voltage so as to remove the electrical parameter error voltage from the three-phase voltage command value. Then, the control device 100 corrects the difference between the voltage command value and the electrical parameter error voltage so that it becomes the input voltage of the three-phase motor 10.

Note that in this embodiment, the parameter error of the three-phase electric motor 10 is assumed to be an error that occurs when the phase impedances are unbalanced. Therefore, it is assumed that an imbalance occurs in the three-phase current and three-phase voltage in the three-phase motor 10 due to this parameter error.

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

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 inputs the d-axis and q-axis currents and either time or the rotation angle of the three-phase motor 10, and calculates the amplitude information A of the cosine (cos) component and the sine of a desired frequency. (sin) component amplitude information B is output. Here, the "desired frequency" is the frequency of the current pulsation component caused by the gain error and parameter error. Therefore, the "desired frequency" is twice the electrical angular frequency (energization frequency) of the three-phase motor 10, as described above. Thereby, the frequency analyzer 121 outputs amplitude information A and amplitude information B of the pulsating components of the d-axis and q-axis currents. Amplitude information A and amplitude information B output from the frequency analyzer 121 are input to a gain error estimation calculator 122. The gain error estimation calculator 122 uses the input amplitude information A and amplitude information B of the pulsating component of the current to calculate and output a gain error estimated value.

When inputting time to the frequency analyzer 121, the frequency analyzer 121 outputs amplitude information A and amplitude information B at the time frequency of current pulsation due to gain error. When inputting the rotation angle of the three-phase electric motor 10 to the frequency analyzer 121, the frequency analyzer 121 outputs amplitude information A and amplitude information B at the spatial frequency of current pulsation caused by a gain error.

The time frequency here is the number of waves per second expressed as the reciprocal of the period. Furthermore, the spatial frequency is the number of waves per period of mechanical rotation of the three-phase motor 10 or per electrical angle rotation of the three-phase motor 10 in a determined interval, for example. For example, when the frequency of the electrical angle is 50 Hz, the frequency of current pulsation due to gain error is 100 Hz in the temporal frequency, and is the second harmonic of the electrical angle in the spatial frequency.

When offline estimating the gain error using prior drive data, the estimation is performed using the following steps.
Step 1. The three-phase motor 10 is driven with an arbitrarily set gain error setting value, and the frequency component of the current pulsation value at that time is obtained. This is repeated with at least three patterns of gain error setting values, and frequency component information of the gain error setting value and current pulsation value is obtained for each pattern.
Step 2. Using the obtained at least three patterns of gain error setting values and the frequency component information of the current pulsation value, the initial value of the gain error when no gain error is set is set as the gain error estimated value.

Note that 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 the unknown gain error by the gain error setting value. This means driving the three-phase electric motor 10. The gain error setting value is an arbitrarily set constant magnification.

When the V-phase gain error setting value is α _n , the W-phase gain error setting value is β _n , the V-phase gain error is α ₀ , and the W-phase gain error is β ₀ , the actual gain including the error is , can be expressed by the following equations (1) and (2).

If it is assumed that the error components in equations (1) and (2) are independently proportional to the amplitude of the pulsating component of the current in each of the V and W phases without correlation, then from the following equation (3), equation ( 6) holds true. In these equations, α _d0 with a hat (^) is the V-phase gain error estimate based on the d-axis current, and α _q0 with a hat is the V-phase gain error estimate based on the q-axis current, with a hat. β _d0 represents the W-phase gain error estimate based on the d-axis current, and β _q0 with a hat represents the W-phase gain error estimate based on the q-axis current.

However, A _dn , B _dn , A _qn , and B _qn are frequencies twice the electrical angle of the d-axis current and q-axis current, as shown in equations (7) and (8), respectively, when θ is the energization phase. represents the amplitude component of

Here, the subscript n represents the pattern of the gain error setting values (α _n , β _n ). Equations (3) to (8) are generalized for pattern n. The pulsation amplitude components A _dn , B _dn , A _qn , and B _qn represent the amplitude components at the gain error setting value of pattern n. For example, when three patterns of gain error setting values (α _n , β _n ) are set, n becomes 1 to 3, and Equations (3) to (8) represent the three equations where n = 1, 2, and 3, respectively. It will be included.

In equation (3), three variables with hats, α _d0 , K _dAα , and K _dBα , are unknown. Since α _n in equation (3) is a set value, it is known. Further, A _dn and B _dn in Equation (3) are known because they are obtained as a result of frequency analysis. Furthermore, in Equation (4), three variables with hats, β _d0 , K _dAβ , and K _dBβ , are unknown quantities. Since β _n in equation (4) is a set value, it is known. Further, A _dn and B _dn in Equation (4) are known because they are obtained as a result of frequency analysis. Similarly, equations (5) and (6) each include three unknowns. Therefore, each of these equations (3) to (6) is a combination of three equations, and by solving these simultaneous equations, the unknown quantity can be obtained. That is, in order to obtain the unknown quantity, at least three patterns of gain error setting values are required. In this way, each of equations (3) to (6) is calculated using at least three patterns of gain error setting values set in advance and the current pulsation components A _dn , B _dn , A _qn , and B _qn at that time. By solving simultaneous equations for the current detector 200, α _d0 with a hat, α _q0 with a hat, β _d0 with a hat, and β _q0 with a hat can be obtained.

When estimating the gain error online while driving the three-phase electric 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 becomes large, the gain correction value is changed in the opposite direction. On the other hand, if the current ripple value becomes smaller, the gain correction value is changed in the same direction as now. In this way, the gain correction value when the current pulsation value becomes the minimum is set as the gain error estimated value. Note that each of the offline estimation and the online estimation may be performed independently, or the offline estimation and the online estimation may be performed in combination.

Next, current pulsations appearing in the dq-axis current detection values will be explained with reference to FIGS. 3 to 9. Next, the main factors of the current pulsation value and their frequency characteristics will be clarified, and the effect that the control device 100 according to this embodiment can simultaneously estimate the gain error and the parameter error will be explained. What is shown in FIG. 3 is a control block equivalently expressed on the dq axes when the current detector 200 has a gain error. In the figure, the internal model of the three-phase electric motor 10 is represented by dq axes. Further, in the same figure, the current converted to the dq axis is detected by an equivalent block of the current detector 200 and the first coordinate converter 111 in FIG. 1.

The d-axis current controller 103 gives a voltage command to the three-phase motor 10 so that the d-axis current command id _ref created by the d-axis current command generator 102 and the d-axis current detected value ids match. The voltage applied to the three-phase motor 10 is converted into a current by the d-axis magnetic circuit P _md (s) inside the three-phase motor 10 . At this time, the actual d-axis current ida is influenced by the influence id _pe on the d-axis current due to the parameter error. Then, this actual d-axis current ida detected by the current detector 200 becomes the d-axis current detection value ids.

Further, the speed controller 101 gives 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) matches the speed command. The d-axis current controller 103 gives a voltage command to the three-phase motor 10 so that the axis current command iq _ref output from the speed controller 101 and the detected value iqs of the q-axis current match. The voltage applied to the three-phase motor 10 is converted into a current by the q-axis magnetic circuit P _mq (s) inside the three-phase motor 10 . At this time, the actual q-axis current _iqa is influenced by the influence of the parameter error on the q-axis current iq_pe. Then, this actual q-axis current iqa detected by the current detector 200 becomes the q-axis current detection value iqs.

As shown in Fig. 3, the d-axis current that actually flows in the three-phase motor is ida, the q-axis current that actually flows is iqa, the d-axis detected current converted to dq-axis is ids, and the q-axis detected current is iqs. shall be. As shown in the figure, when there is a difference between the current value actually flowing through the three-phase motor 10 and the current value detected by the current detector 200 due to the gain error of the current detector 200, the currents on the d and q axes are mutually different. affect. At this time, the relationship between the detected current values ids and iqs and the actually flowing dq-axis current values ida and iqa is expressed by the following equation (9).

Here, G _dd (s), G _dq (s), G _qd (s), and G _qq (s) are as follows.
G _dd (s): Coefficient that simulates the influence of the actual d-axis current on the detected d-axis current G _dq (s): Coefficient that simulates the influence that the actual d-axis current has on the detected q-axis current G _qd (s) ): Coefficient that simulates the effect that the actual q-axis current has on the detected d-axis current G _qq (s): Coefficient that simulates the effect that the actual q-axis current has on the detected q-axis current

Then, G _dd (s), G _dq (s), G _qd (s), and G _qq (s) are expressed by the following equations (10) to (13).

Note that α, β, and θ are as follows.
α: Gain error of v phase with respect to u phase β: Gain error of w phase with respect to u phase θ: Phase during coordinate transformation

Further, the u-phase current detection gain Gu, the v-phase current detection gain Gv, and the w-phase current detection gain Gw are expressed by the following equation (14).

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.

In addition, each variable is 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 value due to parameter error iq _pe : q-axis current due to parameter error Pulsation value ida: Actual d-axis current iqa: Actual q-axis current

Here, for the sake of simplicity, the three-phase electric motor 10 is assumed to be an SPM motor (Surface Permanent Magnet Motor). In this case, the d-axis and q-axis magnetic circuits are equal. Further, it is assumed that the gains of the current control of the d-axis and the q-axis are the same, that is, C _id (s)=C _iq (s), and control as shown in the following equation (17) is performed. However, ωc is the response angular frequency of current control.

Normally, in d-axis control, the current command value is often a fixed value. In particular, in an SPM motor when field weakening control is not performed, id=0 is normally controlled. In this way, when controlled to a fixed value, the d-axis current command value does not have a pulsating component. Assuming that the d-axis current command id _ref is controlled to be 0, equations (15) and (16) can be rewritten into the following equations (18) and (19), respectively.

Equations (18) and (19) include actual current values ida and iqa that cannot be detected, so these are deleted and the current command values of the d- and q-axes and the influence of parameter errors idpe, When iqpe is input, equations (18) and (19) can be rewritten into equations (20) and (21), respectively.

Note that H _d (s), J _d (s), K _d (s), H _q (s), J _q (s), and K _q (s) are calculated from the following equations (22) to (27), respectively. ) as shown.

Here, since the equation is complicated, we use approximations such as G _dd = G _qq ≒1, G _dq ≒G _qd ≒0.05, and G _dq *G _qd ≒0 to calculate Equation (20) and Equation (21). 4 to 9 show the frequency characteristics of the detected currents on the d and q axes of 2. 4 shows the frequency characteristics of H _d (s), FIG. 5 shows the frequency characteristics of J _d (s), and FIG. 6 shows the frequency characteristics of K _d (s), FIG. 7 shows the frequency characteristics of H _q (s), and FIG. 8 shows the frequency characteristics of J _q (s), and FIG. 9 shows the frequency characteristics of K _q (s), respectively.

As shown in FIG. 4, the frequency characteristics of H _d (s) are similar to those of a BPF (Band Pass Filter). As shown in FIG. 5, the frequency characteristics of J _d (s) are those of a first-order HPF (High Pass Filter) whose cutoff frequency is the current control response frequency ωc. As shown in FIG. 6, the frequency characteristics of K _d (s) are those of a first-order HPF whose cutoff frequency is the current control response frequency ωc. As shown in FIG. 7, the frequency characteristics of H _q (s) are those of an LPF (Low Pass Filter) whose cutoff frequency is the current control response frequency ωc. As shown in FIG. 8, the frequency characteristics of J _q (s) are those of a second-order HPF whose cutoff frequency is the current control response frequency ωc. As shown in FIG. 9, the frequency characteristics of K _q (s) are those of a 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 effects of the gain error.

In the case of having the HPF characteristics, if the frequency of the current ripple component is sufficiently lower than the response of current control, the gain becomes small and the ripple component of the detected current becomes small. H _q (s) in Fig. 7 is an LPF characteristic, and the pulsating value of the q-axis current is strongly influenced by the pulsating component of the q-axis current command and the gain error, and the pulsating component due to the parameter error is affected by the q-axis current detected value. It can be seen that the influence exerted is relatively small.

On the other hand, in the d-axis current detection value, H _d _, J _d , _and K _d all exhibit HPF characteristics, and the current pulsation value itself becomes small _. When compared visually, H _d becomes relatively small, and J _d and K _d become relatively large. Therefore, it can be seen that the pulsating component of the d-axis current remains influenced by the pulsating component due to the parameter error, and the pulsating component of the d-axis current is affected by both the parameter error and the gain error.

Therefore, the detected value of current pulsation on the q-axis has a small influence of the parameter error and the influence of the gain error is large, and the detected value of the d-axis current pulsation has the influence of both gain error and parameter error. I know it's coming out. Therefore, if the gain error is estimated based on the q-axis current pulsation value, it can be estimated without including the influence of the parameter error. On the other hand, when the gain error is estimated based on the d-axis current pulsation value, the estimated value also includes the influence of the parameter error.

Therefore, in the control device 100 according to the present disclosure, the gain error estimator 120 uses, as the gain error of the current detector 200, a first gain error estimate estimated to minimize the pulsation of the d-axis current; A second gain error estimate estimated to minimize pulsation of the q-axis current is output. Then, as shown in FIG. 1, the control device 100 corrects the gain error of the current detector 200 based only on the second gain error estimate without using the first gain error estimate to correct the gain error of the current detector 200. Make corrections.

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

In this way, in the control device 100 according to this embodiment, the d-axis current pulsations include the effects of both the gain error and the parameter error, and the q-axis current pulsations include the effects of the parameter errors relatively. Utilizing the characteristic that the gain error is small and the influence of the gain error is relatively large, the parameter error estimator 130 can estimate the parameter error from the difference between the d-axis and q-axis gain errors.

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%. Note that the v-phase gain error of +5% means that the detected current value of the v-phase is 105% when the same current as that of the u-phase is detected with the u-phase as a reference phase. In this case, the gain error correction of the current detector 200 is performed using the q-axis gain error +5%. Further, the parameter error estimator 130 estimates that the parameter error is -2% from the difference between the d-axis gain error +3% and the q-axis gain error +5%. Note that a parameter error of -2% means that the impedance of the v phase is 2% larger than the reference phase.

According to the electric motor control device 100 configured as described above, it is possible to simultaneously estimate the gain error and the parameter error with high accuracy. Therefore, it is possible to shorten the time required for adjustment work that was performed separately for gain errors and parameter errors, and it is also possible to reduce the influence of estimation errors due to the use of detection data that includes errors. .

The frequency characteristics of the dq-axis current ripple values output using the current detector 200 and first coordinate converter 111 shown in FIGS. 4 to 9 are based on the d-axis current controller 103 and the q-axis current controller 104. to be influenced. Then, depending on the HPF characteristics of the dq-axis current pulsation value, the magnitude of the current pulsation due to the influence of both parameter error and gain error appearing in the current detection value changes.

When estimating a gain error using the gain error estimator 120, the magnitude of current pulsation can be changed by changing the current control gain. This characteristic may be utilized to improve the estimation error. As described above, the d-axis current tends to have a smaller current pulsation value due to the HPF characteristics. From this, if the detection resolution of the current detector 200 is low and it is difficult to detect the current ripple value, lowering the d-axis current control gain will increase the gain on the low frequency side compared to before the change, and the current ripple value will increase. The value increases. Therefore, the d-axis current pulsation value can be increased, and detection can be made even when the resolution is low.

On the other hand, the main component of the q-axis current pulsation value is the q-axis current command value, and it has LPF characteristics. From this, by increasing the q-axis current control gain as much as possible, it is possible to reduce the pulsation component due to parameter error, and it is possible to reduce the estimation error in gain error estimation. 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.

Note that the gain error estimation is preferably performed while keeping the rotational speed of the three-phase motor 10 constant. That is, the gain error estimator 120 preferably estimates 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 electric motor 10 changes, the frequency of current pulsations due to gain error changes. For this reason, the frequency characteristics shown in FIGS. 4 to 9 change, and the amplitude of the pulsating component changes. Therefore, when performing online estimation, when the rotational speed of the three-phase motor 10 changes, it is not possible to distinguish whether the detected change in current pulsation is due to a change in the gain error correction value or a change in frequency characteristics. This may lead to a deterioration in the accuracy of gain error estimation.

In addition, when performing offline estimation, if the rotational speed of the three-phase motor 10 changes, the amplitude of current pulsation changes depending on the rotational speed even with the same gain error, so the assumption that the gain error and current pulsation are proportional breaks down. , there is a risk that the estimation accuracy of the gain error will decrease. However, if the fluctuation in the amplitude component of the current pulsation value due to the rotational speed fluctuation of the three-phase motor 10 is known in advance, the gain error estimation can be performed by correcting the amplitude of the current pulsation value according to the rotational speed. Can be done.

Note that FIG. 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 circuitry may be dedicated hardware 303. Part of the processing circuitry may be formed as dedicated hardware 303 and may further include a processor 301 and a memory 302 . In the example shown in the figure, part of the processing circuit is formed as dedicated hardware 303. Furthermore, in the example shown in the figure, the processing circuit further includes a processor 301 and a memory 302.

The processing circuitry, a part of which is at least one dedicated hardware 303, may be, 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 includes at least one processor 301 and at least one memory 302, the functions of the control device 100 are realized by software, firmware, or a combination of software and firmware.

Software and firmware are written as programs and stored in the memory 302. The processor 301 implements the functions of each section by reading and executing programs stored in the memory 302. The processor 301 is also referred to as a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. Examples of the memory 302 include nonvolatile or volatile semiconductor memories such as RAM, ROM, flash memory, EPROM, and EEPROM, or magnetic disks, flexible disks, optical disks, compact disks, minidisks, and DVDs.

In this way, the processing circuit of the control device 100 can realize each function of the control device 100 using hardware, software, firmware, or a combination thereof. Note that when the processing circuit of the control device 100 includes at least a processor 301 and a 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 cooperate. By doing so, the functions of each part included in the control device 100 are realized.

Embodiment 2.
Embodiment 2 of the present disclosure will be described with reference to FIGS. 11 and 12. FIG. 11 is a diagram showing the overall configuration of the electric motor control device. FIG. 12 is a diagram showing a configuration example of a gain error estimator included in the control device.

Hereinafter, the electric motor control device according to the second embodiment will be explained, focusing on the differences from the first embodiment. The configuration whose description is omitted is basically the same as that of the first embodiment. In the following description, structures similar to or corresponding to those of the first embodiment will be described with the same reference numerals used in the description of the first embodiment.

As shown in FIG. 11, the electric 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, and a first coordinate transformation. 111, a second coordinate transformer 112, a gain error estimator 120, and a parameter error estimator 130. The speed controller 101, d-axis current command generator 102, d-axis current controller 103, q-axis current controller 104, first coordinate converter 111, and second coordinate converter 112 are basically the same as in the first embodiment. The same is true for

In this embodiment, the gain error estimator 120 detects current 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. The gain error of the device 200 is estimated. More specifically, the gain error estimator 120 uses a first gain error estimate estimated to minimize pulsations in the d-axis current and a first gain error estimate estimated to minimize pulsations in the detected speed value as gain errors. and a third gain error estimated value. The control device then performs gain error correction of the current detector 200 based on the third gain error estimate. Furthermore, the parameter error estimator 130 estimates a parameter error using the first gain error estimate and the third gain error estimate.

Equations (20) and (21) described in Embodiment 1 are equations written using the q-axis current command value iq _ref and the current pulsation components idpe and iqpe that parameter errors exert on the d-axis and q-axis. there were. Here, when the control device 100 is controlling the speed of the three-phase motor 10, the speed controller 101 uses the difference between the speed detection value of the three-phase motor 10 detected by the speed detector 20 and the speed command value. Based on this, the q-axis current command value is calculated. The q-axis current command value iq _ref can be expressed by the following equation (28) using the speed control gain Cω(s), the detected speed value ω, and the speed command value ω _ref .

According to equation (28), especially when the speed command value ω _ref is a constant speed, the speed command value ω _ref includes only a DC component, so the pulsating component of the q-axis current command value iq _ref is equal to the detected speed value ω It can be seen that this is caused by Therefore, when the speed command value ω _ref is constant, the gain error can be estimated using the pulsating component of the detected speed value ω instead of estimating the gain error using the pulsating component of the detected current on the q-axis. .

Therefore, in this embodiment, as described above, the gain error estimator 120 uses the d-axis current detection value output from the first coordinate converter 111 and the speed detection value output from the speed detector 20. Based on this, the gain error of the current detector 200 is estimated. Even with such an electric motor control device, it is possible to achieve the same effects as in the first embodiment.

Note that the gain error estimator 120 according to this embodiment may include a frequency analyzer 121 and a gain error estimation calculator 122, as shown in FIG. The frequency analyzer 121 inputs the d-axis current detection value, speed detection value, and either time or the rotation angle of the three-phase motor 10, and calculates the frequency of the current pulsation component caused by the gain error and parameter error. Amplitude information A and amplitude information B, and amplitude information A and amplitude information B of the frequency of the speed pulsation component caused by the gain error and parameter error are output. Here, amplitude information A is amplitude information of a cosine (cos) component, and amplitude information B is amplitude information of a sine (sin) component.

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 uses the input amplitude information A and amplitude information B of the pulsation components of the current and speed to calculate a first gain error estimate estimated to minimize the pulsation of the d-axis current. , and a third gain error estimate estimated to minimize the pulsation of the detected speed value. Therefore, the gain error estimator 120 of this embodiment can estimate the gain error in response to inputs of both the pulsating component of the current and the pulsating component of the detected speed value.

The control device according to the present disclosure can be applied to control a three-phase electric motor.

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 converter 112 second coordinate converter 120 gain error estimation device 121 frequency analyzer 122 gain error estimation calculator 130 parameter error estimator 200 current detector 301 processor 302 memory 303 dedicated hardware

Claims

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 the speed command value;
a current detector that detects current values of at least two phases among the u-phase, v-phase, and w-phase input to the electric motor;
a first coordinate converter that 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; ,
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 three-phase imbalance of electrical parameters of the motor based on a gain error estimated value by the gain error estimator;
The gain error estimator includes, as the gain error, a first gain error estimate estimated to minimize pulsations in the d-axis current, and a second gain error estimated to minimize pulsations in the q-axis current. output the gain error estimate and
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.
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 the speed command value;
a current detector that detects current values of at least two phases among the u-phase, v-phase, and w-phase input to the electric motor;
a first coordinate converter that 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; ,
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 output from the first coordinate converter and the speed detection value;
a parameter error estimator that estimates a parameter error due to three-phase imbalance of electrical parameters of the motor based on a gain error estimated value by the gain error estimator;
The gain error estimator includes, as the gain errors, a first gain error estimate estimated to minimize pulsations in the d-axis current, and a first gain error estimate estimated to minimize pulsations in the detected speed value. 3 output the gain error estimate,
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 performs gain error correction of the current detector based on the third gain error estimate.
3. The electric motor control device according to claim 1, wherein the gain error estimator estimates the gain error of the current detector while the electric motor is rotating at a constant speed.
3. The electric 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 electric motor.