Motor control method and motor control device

Abstract

To surely suppress a torque fluctuation in a pulse shift in order to secure a detection time of a phase current.SOLUTION: The present invention provides a motor control method in which a three-phase current (iu, iv, and iw) is acquired from a DC bus current idc, a first phase voltage command value (v*u1, v*v1, and v*w1) is calculated from a predetermined torque command value T* by referring the acquired three-phase current (iu, iv, and iw), a shift objective phase in the first phase voltage command value is determined, a second phase voltage command value (v*u2, v*v2, and v*w2) is calculated by executing a correction processing for executing a plus shift in order to secure a detection time of the three-phase current to a phase voltage component of the shift object phase, and a driving signal of a power converter 6 is generated on the basis of the second phase voltage command value. Specifically, in the correction processing, a current vector fluctuation direction θc of a motor 9 by the pulse shift determines the shift objective phase so as to be moved to a contact line direction of the torque line CT such as an output torque T in a dq-shaft coordinate system.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a motor control method and a motor control device. [Background technology]

[0002] Conventionally, there has been known a motor control method in which the current (three-phase current) of a three-phase AC motor is estimated using the current (DC bus current) detected in a DC power system, and a three-phase voltage command value for the motor is determined based on the estimated three-phase current. In such a motor control method, in a scene in which two or more phase voltage components of the three-phase voltage command value are substantially equal to each other, the time during which it is possible to separate the estimated values ​​of the phase current components of the three-phase current from the DC bus current (hereinafter also simply referred to as "detection time") becomes short, making the detection difficult.

[0003] For this reason, a process (pulse shift) has been proposed that corrects each phase voltage component to ensure sufficient detection time while maintaining the average of the three-phase voltage command values ​​per carrier cycle. However, this pulse shift sets a phase voltage command value that differs from the desired torque command value at least within the carrier cycle. Therefore, executing the pulse shift causes unintended current fluctuations, resulting in high-frequency torque fluctuations that coincide with the carrier harmonics.

[0004] In response to this, Patent Document 1 proposes a control method for selecting, as the phase for executing pulse shift (shift target phase), the phase in which the d-axis voltage (d-axis component) is maximum or minimum among the phase voltage components of the three-phase voltage command value. According to this control method, pulse shift is executed so that the direction of voltage change (voltage vector fluctuation direction) before and after correction approaches the d-axis direction. As a result, the direction of current change before and after the correction can also approach the d-axis direction, which has relatively less effect on the output torque compared to the q-axis direction, thereby suppressing torque fluctuations. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 208652 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method of Patent Document 1 has a problem in that it is not possible to sufficiently suppress torque fluctuations during pulse shift in a motor control system that employs a motor structure or control logic in which the d-axis current contributes to the output torque.

[0007] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a motor control method and a motor control device that can more reliably suppress torque fluctuations during pulse shifting to ensure sufficient time for detecting three-phase currents. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a motor control method for calculating phase voltage command values ​​based on a predetermined torque command value, and generating, based on the phase voltage command values, drive signals for a power converter that converts DC power into multi-phase AC power and supplies it to a motor. The motor control method includes acquiring three-phase currents from a DC bus current, calculating a first phase voltage command value from the torque command value by referring to the acquired three-phase currents, determining phases to be shifted in the first phase voltage command value, performing correction processing to apply a pulse shift to the phase voltage components of the phases to be shifted in order to ensure detection time for the three-phase currents, calculating a second phase voltage command value, and generating a drive signal based on the second phase voltage command value.

[0009] In particular, in the correction process, the phase to be shifted is determined so that the direction of the current vector fluctuation of the motor due to the pulse shift is along the tangent direction of the equal torque line where the output torque is constant in the dq axis coordinate system. [Effects of the Invention]

[0010] According to the present invention, torque fluctuations can be more reliably suppressed during pulse shifting to ensure sufficient time for detecting phase currents. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the configuration of a motor control system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a timing chart illustrating the processing of the phase current reproducing unit. [Figure 3] FIG. 3 is a block diagram illustrating the processing of the voltage command calculation unit according to the first embodiment. [Figure 4] FIG. 4 is a block diagram illustrating the processing of the voltage command correction unit according to the first embodiment. [Figure 5] FIG. 5 is a timing chart illustrating the process (first correction mode) in the first voltage correction unit. [Figure 6] FIG. 6 is a flowchart showing a specific process of correction in the first correction mode. [Figure 7] FIG. 7 is a flowchart showing the process (second correction mode) in the second voltage correction unit. [Figure 8] FIG. 8 is a flowchart showing the voltage correction process I in the second correction mode. [Figure 9] FIG. 9 is a flowchart showing the voltage correction process II in the second correction mode. [Figure 10] FIG. 10 is a flowchart showing the voltage correction process III in the second correction mode. [Figure 11] FIG. 11 is a timing chart illustrating an example of each of the voltage correction processes I to III. [Figure 12] FIG. 12 is a block diagram illustrating the processing of the voltage shift phase determination unit according to the first embodiment. [Figure 13] FIG. 13 is a diagram showing an image of the defined voltage vector fluctuation direction. [Figure 14] FIG. 14 is a block diagram showing the configuration of a motor control system according to the second embodiment. [Figure 15]FIG. 15 is a block diagram illustrating the processing of the voltage command corrector according to the second embodiment. [Figure 16] FIG. 16 is a block diagram illustrating the processing of the voltage shift phase determination unit according to the second embodiment. [Figure 17] FIG. 17 is a diagram illustrating the problem of the comparative example. [Figure 18] FIG. 18 shows the results of frequency analysis in the control of the comparative example and the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] [First embodiment] 1 is a block diagram showing the configuration of a motor control system 100 for executing a motor control method according to this embodiment. As shown in the figure, the motor control system 100 mainly includes a motor 9 configured as a three-phase synchronous motor or the like, and a torque command value T * and a power conversion device (inverter 6) that supplies desired power based on the three-phase command voltage from a battery (DC power source) to the motor 9. In particular, the motor control system 100 is mounted on a vehicle such as an electric vehicle or a hybrid vehicle that uses the motor 9 as a driving source.

[0014] The motor 9 is configured by, for example, an IPM (Interior Permanent Magnet) type three-phase synchronous motor.

[0015] The motor control device is mainly composed of a voltage command calculation unit 1, a dq / uvw coordinate converter 2, a voltage command correction unit 3, a phase current reproduction unit 4, a PWM (Pulse Width Modulation) converter 5, a rotation speed calculation unit 11, and a uvw / dq coordinate converter 12.

[0016] The voltage command calculation unit 1 calculates the torque command value T* , the motor rotation speed N, the battery output voltage detected by the DC voltage sensor 7 (hereinafter referred to as "DC voltage V dc "), dq axis current detection value (i d ,i q ) is input, and the dq-axis voltage command value (v * d_fin ,v * q_fin ) and outputs it. In particular, the voltage command calculation unit 1 calculates and outputs the torque command value T * The dq-axis current detection value (i d ,i q ) is fed back to obtain the dq-axis voltage command value (v * d_fin ,v * q_fin ) is calculated.

[0017] The dq / uvw coordinate converter 2 uses the detected electrical angle θ to calculate the dq-axis voltage command value (v * d_fin ,v * q_fin ) to the first three-phase voltage command value (v * u1 ,v * v1 ,v * w1 ) and output.

[0018]

number

[0019] The voltage command correction unit 3 calculates the torque command value T * , motor rotation speed N, DC voltage V dc , the first three-phase voltage command value (v * u1 ,v * v1 ,v * w1 ), and dq axis current detection value (i d ,i q ) is input, and the DC bus current i dc to three-phase current (iu ,i v ,i w ) detection time (first correction mode or second correction mode, which will be described later) is performed to obtain the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) is calculated. In particular, in this correction process, correction is performed so that the mutual difference between each phase voltage component becomes equal to or greater than a predetermined value in the first half cycle of one cycle of the carrier related to PWM control. On the other hand, in the second half cycle of the carrier, correction is performed so that the correction voltage amount in the first half cycle is canceled out. This correction maintains the average voltage per carrier cycle of each phase voltage component (or each component of a duty command value, which will be described later) before and after correction. In other words, this correction shifts the pulse phase of the phase voltage component to be corrected. For simplicity's sake, this correction will be simply referred to as "pulse shift" below. Further details of the processing in voltage command correction unit 3 will be described later.

[0020] The phase current reproducing unit 4 reproduces the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) and DC bus current i dc From the above, the phase reproduction current (i u_rep ,i v_rep ,i w_rep ) is calculated. dc is detected by the DC current detector 8. Here, the DC bus current i dc From this, current information for up to two phases can be obtained for each half cycle of the carrier. Therefore, by using the relationship in the following equation (2), the DC bus current i dc From the phase reproduction current (i u_rep ,i v_rep ,i w_rep ) can be calculated.

[0021]

number

[0022] The processing in the phase current reproducing unit 4 will be described in further detail later.

[0023] The PWM converter 5 converts the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) and DC voltage V dc The inverter 6 receives the DC voltage V as an input, generates a drive signal for driving the switching element of the inverter 6, and outputs the drive signal. dc Each phase voltage component v * u2 , v * v2 , v * w2 The duty command value (D * u ,D * v ,D * w ) is determined based on the

[0024] The inverter 6 receives the drive signal and drives a power semiconductor element (not shown) to generate a second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) is supplied according to the three-phase current (i u ,i v ,i w ) while ensuring the detection time, the desired torque command value T * It is possible to realize an output of actual torque T according to the above.

[0025] The rotation speed calculator 11 calculates and outputs the motor rotation speed N from the amount of change per unit time of the detected electrical angle θ obtained from the rotor sensor 10.

[0026] The uvw / dq coordinate converter 12 converts the phase reproduced current (i u_rep ,i v_rep ,i w_rep ) to the dq axis current detection value (i d ,i q ) and output.

[0027]

number

[0028] The motor control device described above is realized by a computer that includes a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface) and is programmed to execute the above-mentioned components. The motor control device can also be configured by multiple computer hardware components that execute each process in a distributed manner.

[0029] Below, each part of the motor control device will be described in detail.

[0030] (Phase current reproduction section) 2 is a timing chart illustrating the processing in the phase current reproducing unit 4. The phase current reproducing unit 4 generates trg1 by adding Δd1 to the duty command value of the phase (hereinafter simply referred to as the "middle phase") whose duty command value (i.e., phase voltage component) is intermediate, and generates trg2 by subtracting Δd2 from the duty command value. The phase current reproducing unit 4 then calculates the DC bus current i at the timings when the carrier wave C crosses trg1 and trg2. dc and use this as the phase reproduction current (i u_rep ,i v_rep ,i w_rep ) are two components. Δd1 is set to a predetermined value equal to or greater than 0, and Δd2 is the minimum duty difference D required to ensure the detection time. min It is set to a desired value above.

[0031] In particular, Fig. 2 shows the process at successive control timings k-1, k, and k+1, assuming that the w-phase is an intermediate phase. In the illustrated example, the phase current reproducing unit 4 reproduces the previous w-phase duty command value D * w Then, the phase current reproducing unit 4 determines trg1 and trg2 based on the DC bus current i detected at the previous control timing. dc The DC bus current i at the timing when the carrier wave C crosses trg1 is dc From u phase reproduction current i u_rep , and the DC bus current i at the timing of crossing trg2 dc From v-phase reproduced current i v_rep are determined respectively.

[0032] More specifically, when the control timing k is the current time, the duty command value D calculated at the previous control timing k-1 is * w DC bus current i at the timing when trg1[k-1] based on [k-1] intersects with carrier wave C dc From the above, the u-phase reproduced current i obtained at the current control timing k u_rep On the other hand, the duty command value D at the previous control timing k-1 is * w DC bus current i at the timing when trg2[k-1] based on [k-1] and carrier wave C intersect dc From the above, the v-phase reproduced current i obtained at the current control timing k v_rep Define [k].

[0033] (Voltage command calculation unit) FIG. 3 is a block diagram illustrating the processing of the voltage command calculation unit 1. For the sake of simplicity, in FIG. 3, the d-axis voltage command value v * d_fin Only the calculation block in * q_fin The operation in can be performed similarly.

[0034] As shown in the figure, the voltage command calculation unit 1 includes a non-interference voltage calculator 101, a current target value calculator 102, and a current controller 103.

[0035] The decoupling voltage calculator 101 calculates the torque command value T * , motor rotation speed N, and DC voltage V dc is input, and the d-axis non-interacting voltage value v is calculated by referring to a predetermined table. * d_dcpl The current target value calculator 102 calculates and outputs the torque command value T * , motor rotation speed N, and DC voltage V dc is input, and the d-axis current target value i is calculated by referring to a specified table. * d Each table stores experimentally determined current values ​​that generate desired torque at maximum efficiency and corresponding interference voltage values.

[0036] The current controller 103 calculates the actual d-axis current as the d-axis current target value i * d In order to make it follow the d-axis current target value i * d and the d-axis current detection value i d The feedback calculation (equation (4) below) is performed to make the deviation of the current feedback d-axis voltage command value v di ´ is required.

[0037]

number

[0038] The current controller 103 also calculates the d-axis non-interacting voltage value v * d_dcpl The corrected d-axis non-interacting voltage value v obtained by applying a low-pass filter LPF1 with a time constant of the reference d-axis current response to d_dcpl_fit and the current feedback d-axis voltage command value v di The sum of ´ and is the d-axis voltage command value v *d_fin That is, the voltage command calculation unit 1 outputs the d-axis voltage command value v determined by the following equation (5): * d_fin Output.

[0039]

number

[0040] (Voltage command correction unit) 4 is a block diagram illustrating the processing of the voltage command correction unit 3. The voltage command correction unit 3 generates a correction mode signal based on various input parameters, and calculates the first three-phase voltage command value (v * u1 ,v * v1 ,v * w1 ) is obtained by selectively executing either the first correction mode or the second correction mode for the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) is calculated.

[0041] Specifically, the voltage command corrector 3 includes a first voltage corrector 301, a second voltage corrector 302, a correction mode signal generator 303, a correction voltage command value generator 304, and a voltage shift phase determiner 305.

[0042] The first voltage correction unit 301 corrects the DC voltage V dc and the first three-phase voltage command value (v * u1 ,v * v1 ,v * w1 ) is input, and the correction voltage value (v * u2_v ,v * v2_v ,v * w2_v ) and output it.

[0043] 5 is a timing chart illustrating the process (correction in the first correction mode) in the first voltage correction unit 301. As shown in the figure, the first voltage correction unit 301 corrects each phase voltage component v * u1 ,v * v1 ,v * w1 A pulse shift is performed on the phase voltage component of the phase (hereinafter also referred to as the "maximum phase") that has the maximum value (the u-phase voltage component shown by the dashed line in FIG. 5) and the phase voltage component of the phase (hereinafter also referred to as the "minimum phase") that has the minimum value (the v-phase voltage component shown by the dashed line in FIG. 5). That is, in the first correction mode, the maximum phase and the minimum phase are determined as the phases to be shifted.

[0044] More specifically, the first voltage correction unit 301 calculates the maximum phase voltage component (u-phase voltage component v * u ) and increase the phase voltage component of the smallest phase (v) * v ) is corrected to reduce the DC bus current i dc The detection time (in Fig. 5, the u-phase current component i u and v-phase current component i v (Estimated width of each of the above)

[0045] On the other hand, in the latter half of the carrier cycle, the phase voltage components of the maximum and minimum phases (the u-phase voltage component v in Fig. 5) * u and the v-phase voltage component v * v ) is corrected to cancel the correction amount of the first half. That is, the maximum phase voltage component (u-phase voltage component v * u ) by the amount of increase in the first half, and the phase voltage component of the minimum phase (v) * v ) is increased by the amount of decrease in the first half. This allows the DC bus current i dc Therefore, the detection time can be suitably secured.

[0046] 6 is a flowchart showing the specific process of correction in the first correction mode. min " is calculated by the following equation (6) as the minimum duty difference D min and DC voltage V dc That is, the minimum voltage difference V min is defined as the minimum voltage difference required to ensure the detection time.

[0047]

number

[0048] The first voltage correction unit 301 calculates the phase voltage component v of the maximum phase after correction obtained through the processes of steps S101 to S111. 2max * , the phase voltage component of the minimum phase after correction v 2min * , and the phase voltage component of the intermediate phase v that remains unchanged 1mid * From the correction voltage value (v * u2_v ,v * v2_v ,v * w2_v ) is established.

[0049] Next, the second voltage correction unit 302 will be described. The second voltage correction unit 302 calculates the fluctuation direction component magnitude relationship information I generated by the voltage shift phase determination unit 305. vshi refers to the DC voltage V dc and the first three-phase voltage command value (v * u1 ,v * v1 ,v * w1 ) to the corrected voltage value (v * u2_c ,v * v2_c ,v * w2_c ) and output it.

[0050] 7 is a flowchart showing a specific process of correction in the second correction mode. As shown in the figure, in the second correction mode, first, the fluctuation direction component magnitude relationship information I vshi The phase voltage components v of the phase where the phase fluctuation component described later is the maximum (hereinafter also referred to as the "maximum component phase"), the intermediate phase (hereinafter also referred to as the "intermediate component phase"), and the minimum phase (hereinafter also referred to as the "minimum component phase") are calculated with reference to t1max , v t1mid , v t1min is determined (S201).

[0051] And each phase voltage component v t1max , v t1mid , v t1min Depending on the result of the determination of the relative magnitudes of these voltages (S202, S203), one of voltage correction processes I to III is executed.

[0052] In each of the voltage correction processes I, II, and III, the phase voltage component v of the minimum component phase selected as the shift target phase is t1min and / or the phase voltage component v of the maximum component phase t1max In other words, in the first half of the carrier period, the DC bus current i dc To ensure the detection time of each phase voltage component v t1min ,v t1max Each of these is corrected by a predetermined amount (correction value v t1cmp ,v t2cmp ), while in the latter half of the carrier cycle, each phase voltage component v t1min ,v t1max In particular, each of the voltage correction processes I, II, and III corrects each phase voltage component v t1min ,v t1mid ,v t1max The selection is made according to the relative magnitude of the two.

[0053] FIG. 8 is a flowchart showing the details of the voltage correction process I. In the voltage correction process I, the phase voltage component v of the minimum component phase is calculated according to the processes in steps S301 to S318. t1min and the phase voltage component v of the maximum component phase t1max Correction is made for each of the above.

[0054] In particular, in voltage correction process I, the phase voltage component v of the minimum component phase t1min Correction value v t1cmp By adding these, the phase voltage component v of the intermediate phase t1mid The difference between the voltages is the minimum voltage difference V to ensure the current detection time described above. min As above, the phase voltage component v of the minimum component phase after correction t2min (S301~S307).

[0055] More specifically, the correction value v t1cmp is the phase voltage component v t1min to the phase voltage component v t1mid The voltage difference Δv obtained by subtracting t1 The absolute value of and the minimum voltage difference V min In particular, the absolute value of the voltage difference |Δv t1 | is the minimum voltage difference V min If it is less than (No in S302), the correction value v t1cmp is set to a predetermined value other than 0, and if not (Yes in S302), it is set to 0. That is, this means that the phase voltage component v is set to 0 only when the mutual voltage difference between the minimum component phase and the middle component phase does not reach a level required to ensure the current detection time. t1min otherwise, the phase voltage component v t1min This means that the value is maintained without correction.

[0056] In particular, the correction value v t1cmp is the phase voltage component v of the minimum component phase after correction. t2min and the phase voltage component v of the intermediate phase t1mid The difference Δv t1 ´(=v t2min -v t1mid ) is the minimum voltage difference V min (S303 to S305).

[0057] Furthermore, in voltage correction process I, the phase voltage component v of the maximum component phase t1max Correction value v t2cmpBy adding t2max and the phase voltage relatively close to this (the phase voltage component of the smallest component phase after correction v t2min or the phase voltage component v of the intermediate component phase t1mid ) and the difference Δv t2 ´(“v t2min -v t2max ”) or Δv t3 ´(“v t1mid -v t2max ”) is the minimum voltage difference V min The phase voltage component v t2max (S308 to S316). When the mutual voltage difference between the maximum component phase and the phases close to it reaches a level that can secure the current detection time, the phase voltage component v t1max is maintained without correction (Yes in S309 and S317).

[0058] 9 is a flowchart showing the details of the voltage correction process II. In the voltage correction process II, the phase voltage component v of the maximum component phase is corrected according to the processes in steps S401 to S418. t1max and the phase voltage component v of the minimum component phase t1min Correction is made for each of the above.

[0059] In particular, in voltage correction process II, the phase voltage component v of the maximum component phase t1max Correction value v t1cmp By adding these, the phase voltage component v of the intermediate phase t1mid The difference to the minimum voltage difference V min The phase voltage component v of the maximum component phase after correction is as above. t2max (S401 to S406). When the mutual voltage difference between the maximum component phase and the intermediate component phase reaches a level that can secure the current detection time, the phase voltage component v t1max is maintained without correction (Yes in S402 and S406).

[0060] In addition, in voltage correction process II, the phase voltage component v of the minimum component phase t1min Correction value v t2cmp By adding t2minand the phase voltage component v of the phase with a value relatively close to this (the maximum component after correction) t2max or the phase voltage component v of the intermediate component phase t1mid ) and the difference Δv t2 ´(“v t2max -v t2min ”) or Δv t3 ´(“v t1mid -v t2min ”) is the minimum voltage difference V min The phase voltage component v t2min (S408 to S416). When the mutual voltage difference between the minimum component phase and the phases close to it reaches a level that can secure the current detection time, the phase voltage component v t1min is maintained without correction (Yes in S409 and S417).

[0061] 10 is a flowchart showing the details of the voltage correction process III. In the voltage correction process III, the phase voltage component v of the maximum component phase is corrected according to the processes in steps S501 to S512. t1max and the phase voltage component v of the minimum component phase t1min Correction is made for each of the above.

[0062] In particular, in voltage correction process III, the phase voltage component v t1max and the phase voltage component v t1mid and the phase voltage component v t1min and the phase voltage component v t1mid The difference between these voltages is the minimum voltage difference V min The phase voltage component v of the maximum component phase after correction is as above. t2max and the phase voltage component v of the minimum component phase after correction t2min If the mutual voltage difference between the maximum component phase and the intermediate component phase and / or the minimum component phase and the intermediate component phase has reached a level that allows the current detection time to be ensured, the original value is maintained without correction (Yes in S502, Yes in S506 and S507, S511).

[0063] 11A and 11B are timing charts illustrating an example of the results of processing in the second correction mode. In particular, FIG. 11A shows the results of processing in voltage correction process I, FIG. 11B shows the results of processing in voltage correction process II, and FIG. 11C shows the results of processing in voltage correction process III.

[0064] FIG. 11(a) shows an example in which pulse shift is performed on each phase (u-phase and v-phase) other than the w-phase (middle component phase) in the voltage correction process I. In this example, the phase voltage component v of the v-phase (minimum component phase) in the first half of the carrier cycle is v * and the phase voltage component v of the u phase (maximum component phase) u * By increasing the DC bus current i dc In addition, in the latter half of the carrier cycle, a correction is made to cancel out the correction amount of each phase voltage component in the first half.

[0065] FIG. 11(b) shows an example in which pulse shift is performed on each phase (u-phase and w-phase) other than the v-phase (middle component phase) in voltage correction process II. In this example, the phase voltage component v of the w-phase (minimum component phase) in the first half of the carrier cycle is w * and the phase voltage component v of the u phase (maximum component phase) u * By increasing the DC bus current i dc In addition, in the latter half of the carrier cycle, a correction is made to cancel out the correction amount of each phase voltage component in the first half.

[0066] Furthermore, FIG. 11(c) shows an example in which pulse shift is performed on each phase (v phase and w phase) other than the u phase (middle component phase) in the voltage correction process III. In this example, the phase voltage component v of the v phase (minimum component phase) in the first half of the carrier cycle is v * and the w-phase (maximum component phase) phase voltage component v w * By increasing the DC bus current i dcIn addition, in the latter half of the carrier cycle, a correction is made to cancel out the correction amount of each phase voltage component in the first half.

[0067] Next, the correction mode signal generation unit 303 (see FIG. 4) will be described. The correction mode signal generation unit 303 receives the motor rotation speed N as an input, generates a correction mode signal, and outputs the signal to the correction voltage command value generation unit 304. Specifically, the correction mode signal generation unit 303 references the motor rotation speed N and generates the correction mode signal according to the logic shown in Table 1.

[0068] [Table 1]

[0069] Next, the correction voltage command value generating unit 304 will be described. The correction voltage command value generating unit 304 refers to the correction mode signal, selects either the first correction mode or the second correction mode, and generates the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 In particular, the correction voltage command value generating unit 304 outputs the correction voltage command value when the motor rotation speed N is equal to or exceeds a predetermined first threshold value N th1 If the value is less than or equal to the value (estimated to be in the low modulation rate region), the correction voltage value (v * u2_c ,v * v2_c ,v * w2_c ) to the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 ) and outputs the correction voltage command value. th2 If the value is greater than or equal to the value of the correction voltage (v * u2_v ,v * v2_v ,v * w2_v ) to the second three-phase voltage command value (v* u2 ,v * v2 ,v * w2 ) is output as the motor rotation speed N. th1 or more and the second threshold N th2 In the hysteresis region defined below, the previous correction mode signal is maintained and the second three-phase voltage command value (v * u2 ,v * v2 ,v * w2 )

[0070] Next, the voltage shift phase determination unit 305 will be described. The voltage shift phase determination unit 305 determines the torque command value T * and the electrical angle detection value θ are input, and the fluctuation direction component magnitude relationship information I vshi Generate.

[0071] 12 is a block diagram illustrating the processing of the voltage shift phase determination unit 305. As shown in the figure, the voltage shift phase determination unit 305 includes a voltage vector fluctuation direction calculation unit 3051 and a fluctuation direction component magnitude relationship determination unit 3052.

[0072] The filter processing unit 3050 calculates the torque command value T * A low-pass filter set to the time constant of the target torque response is applied to the

[0073] The voltage vector variation direction calculation unit 3051 calculates the torque command value T * Based on this, the voltage vector fluctuation direction θ shift The voltage vector fluctuation direction θ shift is a parameter indicating the direction in which the voltage of the motor 9 fluctuates in the dq-axis coordinate system due to the pulse shift. shift is defined as the angle between the vector representing the voltage fluctuation (hereinafter also referred to as "voltage fluctuation vector") and the d axis in the dq axis coordinate system.

[0074] In particular, in this embodiment, the voltage vector fluctuation direction calculation unit 3051 calculates the voltage vector fluctuation direction θ shift The direction in which the current of the motor 9 fluctuates due to the pulse shift (hereinafter referred to as the "current vector fluctuation direction θ c ") is the constant torque line C where the output torque T is constant in the dq-axis coordinate system. T The direction of the current vector fluctuation is defined as the tangential direction of the c is a parameter indicating the direction in which the current of the motor 9 fluctuates in the dq-axis coordinate system due to the pulse shift. In particular, in this embodiment, the current vector fluctuation direction θ c is defined as the angle between the vector representing the fluctuation of the current (hereinafter also referred to as "current fluctuation vector") and the d axis in the dq axis coordinate system.

[0075] FIG. 13 shows the voltage vector fluctuation direction θ shift In particular, in this embodiment, the torque command value T * Equivalent torque curve C according to T The voltage vector fluctuates along the direction θ shift is converted into a map and stored in a predetermined storage area. That is, the voltage vector variation direction calculation unit 3051 calculates the torque command value T * Voltage vector fluctuation direction θ shift The following is established.

[0076] The fluctuation direction component magnitude relation determination unit 3052 determines the voltage vector fluctuation direction θ shift The judgment parameter θ is obtained by adding the detected electrical angle θ (≒ rotor position of the motor 9) to t The magnitude relationship of the fluctuation direction components is determined by inputting the voltage vector fluctuation direction θ shiftThe three-phase voltage fluctuation vector is calculated by converting the voltage fluctuation components (i.e., voltage fluctuation vector) on the dq-axis coordinate system defined by the above into the three-phase AC coordinate system. Then, the magnitude relationship of each phase fluctuation component of the three-phase voltage fluctuation vector (u-phase fluctuation component, v-phase fluctuation component, and w-phase fluctuation component) is determined, and this is used as the fluctuation direction component magnitude relationship information I vshi Specifically, the fluctuation direction component magnitude relationship determination unit 3052 outputs the voltage vector fluctuation direction θ shift Based on the logic shown in Table 2 below, the fluctuation direction component magnitude relationship information I vshi and outputs it to the second voltage correction unit 302.

[0077] [Table 2]

[0078] The configuration of the motor control method of the present embodiment described above and the resulting effects will now be described.

[0079] In this embodiment, the predetermined torque command value T * Based on the phase voltage command value (v * u ,v * v ,v * w ) is calculated, and the drive signal of the power converter (inverter 6) that converts DC power into multi-phase AC power and supplies it to the motor 9 is converted into a phase voltage command value (v * u ,v * v ,v * w A motor control method is provided that generates a motor control signal based on the

[0080] In this motor control method, the DC bus current i dc to three-phase current (i u ,i v ,i w ) and obtain the three-phase current (i u ,i v ,i w ) to obtain the specified torque command value T *to the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) and calculates the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) to determine the phase to be shifted, and the three-phase current (i u ,i v ,i w ) detection time, a correction process is performed to apply a pulse shift to obtain the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) and calculates the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) to generate the drive signal.

[0081] Then, in the correction process (voltage command correction unit 3), the current vector fluctuation direction θ of the motor 9 due to the pulse shift is c The constant torque line C where the output torque T is constant in the dq-axis coordinate system T The phase to be shifted is determined so as to vary in the tangential direction of the

[0082] This makes it possible to determine the phase to be shifted so that the current fluctuation due to the pulse shift is changed in a direction that maintains the output torque T. Therefore, while suppressing the occurrence of high-frequency torque fluctuations due to the execution of the pulse shift, the DC bus current i dc A control logic is realized that enables estimation of three-phase currents (ensuring current detection time) based on the above.

[0083] In particular, with the motor control method of this embodiment, even in a motor 9 whose specifications allow not only the q-axis current but also the d-axis current to contribute to the output torque T (a motor 9 that actively utilizes reluctance torque), it is possible to suppress the occurrence of torque fluctuations while suitably ensuring the current detection time.

[0084] In addition, in the correction process, the input torque command value T * Equivalent torque curve C according to T The voltage vector fluctuation direction θ of the motor 9 due to the pulse shift is defined as follows. shift The torque is expressed as the torque constant C. T The voltage vector fluctuation direction is determined as the tangent direction of (Fig. 13). shift The phase to be shifted is determined by referring to (Table 2).

[0085] This allows the current fluctuation due to the pulse shift to be controlled by the equal torque curve C T The condition that follows is the input torque command value T * The voltage vector fluctuation direction θ changes depending on shift Therefore, the expected torque command value T * The current fluctuation is equal to the torque curve C T The voltage vector fluctuation direction θ satisfies the condition along shift As a result, a control logic is realized that can appropriately ensure the current detection time while suppressing the occurrence of torque fluctuations in a wide torque range.

[0086] In particular, in this correction process, the voltage vector fluctuation direction θ shift From the voltage fluctuation (voltage fluctuation vector) in the dq-axis coordinate system determined by the above, the magnitude relationship of each phase fluctuation component when the voltage fluctuation is converted into a three-phase coordinate system is estimated, and the phase to be shifted is determined based on the magnitude relationship of each phase fluctuation component (Table 2 and S201 in FIG. 7).

[0087] As a result, the voltage vector fluctuation direction θ shift A more specific calculation logic for determining the phase to be shifted is realized by referring to the above.

[0088] Furthermore, in this correction process, at least one of the phase having the maximum value (maximum component phase) and the phase having the minimum value (minimum component phase) among the phase fluctuation components is set as the phase to be shifted.

[0089] This allows the number of phases to be shifted to be determined as two or one, as appropriate. Therefore, for example, depending on the driving conditions (torque, rotation speed, and / or modulation rate) of the motor 9, the number of phases to be shifted can be set to two or one, and a shift pulse can be executed so as to ensure a current detection time.

[0090] In addition, the correction process of this embodiment is performed by adjusting the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) based on the magnitude relationship of the phase voltage components, and the current vector fluctuation direction θ c is the equal torque line C T and a second correction mode (second voltage correction unit 302, FIGS. 7 to 10) for determining the phase to be shifted so as to follow the tangential direction of the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) is corrected to obtain the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) is calculated.

[0091] As a result, in the first correction mode, which determines the phase to be shifted based on the magnitude relationship of each phase voltage component, the voltage components of each phase are directly referenced, and the difference between them is set to a value that can ensure the current detection time (minimum voltage difference V minOn the other hand, in the second compensation mode, the occurrence of high-frequency torque fluctuations is suppressed, but the current vector fluctuation direction θ c is the equal torque line C T Since the pulse shift is performed while imposing a constraint along the tangential direction of the torque command value T, the amount of pulse shift may be excessive. As a result, in the second correction mode, the second phase voltage command value is * It is also assumed that torque fluctuations may occur due to a large deviation from the first phase voltage command value corresponding to the first phase voltage command value. In contrast, in this embodiment, by appropriately switching between the first correction mode and the second correction mode according to the driving status of the motor 9, it is possible to more reliably suppress the occurrence of torque fluctuations and ensure the current detection time regardless of the driving status.

[0092] In particular, the driving conditions of the motor 9 include the rotation speed of the motor 9 (motor rotation speed N). This provides one embodiment of specific control parameters for distinguishing between scenes (driving conditions) suitable for executing the first correction mode and the second correction mode. Note that, instead of or in addition to the motor rotation speed N, any other parameters such as modulation rate and torque may be used as parameters indicating the driving conditions of the motor 9.

[0093] In addition, the pulse shift in this embodiment is performed by adjusting the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) or second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) based on the duty command value (D * u2 ,D * v2 ,D * w2 ) per carrier period is the first phase voltage command value (v * u1 ,v * v1,v * w1 ) is defined as a process of correcting the phase voltage component in the phase to be shifted so that it coincides with that based on

[0094] That is, the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) is the torque command value T * The first phase voltage command value (v * u1 ,v * v1 ,v * w1 ), but they can be integrated over one carrier period to match, so that unintended torque fluctuations can be suppressed.

[0095] Furthermore, this embodiment provides a motor control device suitable for executing the above motor control method.

[0096] In particular, this motor control device controls the DC bus current i dc to three-phase current (i u ,i v ,i w ) and obtain the three-phase current (i u ,i v ,i w ) to obtain the specified torque command value T * to the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) and the first phase voltage command value calculation unit (voltage command calculation unit 1) that calculates the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) to determine the phase to be shifted, and the three-phase current (i u ,iv ,i w ) detection time, a correction process is performed to apply a pulse shift to obtain the second phase voltage command value (v * u2 ,v * v2 ,v * w2 ) and a second-phase voltage command value calculation unit (voltage command correction unit 3) that calculates the second-phase voltage command value (v * u2 ,v * v2 ,v * w2 and a drive signal generating unit (PWM converter 5) that generates the drive signal based on the drive signal.

[0097] [Second embodiment] The second embodiment will be described below, with the same elements as those in the first embodiment being given the same reference numerals and their description omitted.

[0098] Fig. 14 is a block diagram showing the configuration of a motor control system 200 that executes a motor control method according to this embodiment, and Fig. 15 is a block diagram illustrating the processing of voltage command corrector 3 of this embodiment.

[0099] In this embodiment, the voltage command calculation unit 1 calculates the torque command value T * , motor rotation speed N, and DC voltage V dc is input, and the d-axis current command value i is calculated by referring to a predetermined map. * d and q-axis current command value i * q and outputs it to the voltage command correction unit 3.

[0100] In this embodiment, the voltage shift phase determination unit 305 of the voltage command correction unit 3 determines the electrical angle detection value θ, the d-axis current command value i * d , and the q-axis current command value i * q The magnitude relationship information of the fluctuation direction component I vshi That is, the fluctuation direction component magnitude relationship information Ivshi The torque command value T * Instead of the d-axis current command value i * d and q-axis current command value i * q This differs from the first embodiment in that it uses

[0101] 16 is a block diagram illustrating the processing of the voltage shift phase determination unit 305 according to this embodiment. As shown in the figure, the voltage shift phase determination unit 305 according to this embodiment includes a low-pass filter LP3, a low-pass filter LP4, a current fluctuation direction calculation unit 3053, a voltage vector fluctuation direction calculation unit 3051, and a fluctuation direction component magnitude relationship determination unit 3052.

[0102] The low-pass filter LP3 is used to calculate the d-axis current command value i * d The low-pass filter LP4 is set to the time constant of the target d-axis current. * q A low-pass filter set to the time constant of the target q-axis current is applied to this.

[0103] The current fluctuation direction calculation part 3053 is the d-axis current command value i * d and q-axis current command value i * q Based on this, the current vector variation direction θ c Calculate.

[0104]

number

[0105] However, "φ" in the formula a " is the magnetic flux of the magnet, "L d " is the d-axis inductance, and "L q" represents the q-axis inductance. Here, equation (7) is the relational expression between the current and output torque T in an IPM three-phase synchronous motor, and the angle between the tangent to the curve on the dq-axis coordinate system, which is determined when the output torque T is considered a constant, is the angle between the d-axis and the current vector fluctuation direction θ c The calculation is as follows.

[0106] Then, the voltage vector variation direction calculation unit 3051 calculates the current vector variation direction θ c is input, and the voltage vector fluctuation direction θ is calculated based on the following equation (8). shift Calculate.

[0107]

number

[0108] Here, equation (8) is the voltage vector fluctuation direction θ shift The current vector fluctuation direction θ c The calculation is performed taking into account the deviation according to the ratio of the q-axis inductance to the d-axis inductance (saliency ratio).

[0109] The processing in the fluctuation direction component magnitude relationship determination unit 3052 is the same as in the first embodiment.

[0110] According to the motor control method of the present embodiment described above, the voltage vector fluctuation direction θ for determining the shift target phase is calculated by a control logic different from that of the first embodiment. shift can be appropriately determined.

[0111] [Control results] The control results of the motor control method (example) of the above embodiment will be explained below while comparing them with the control results of a motor control method of a comparative example. Here, as the comparative example, instead of the control of the second voltage correction unit 302 in this embodiment, * u1 ,v * v1 ,v * w1) is assumed to be a control to shift the phases in which the d-axis direction component is maximum and minimum among the phase voltage components of the example (control described in Patent Document 1). Note that, to clarify the comparison, the same reference numerals are used to designate components common to the example and comparative example.

[0112] 17 is a diagram illustrating the problem of the comparative example. As shown in the figure, in the comparative example, the DC bus current i dc In order to detect the first phase voltage command value (v * u1 ,v * v1 ,v * w1 ) is pulse-shifted to ensure the current detection time, the current value also fluctuates accordingly, resulting in harmonic fluctuations being superimposed on the actual torque. Here, because the pulse shift is performed within one carrier cycle, the frequency of the torque fluctuations is often in the range of several kHz. Such torque fluctuations can cause noise or deterioration of peripheral elements such as gears mechanically connected to the motor 9.

[0113] In contrast, in the control of the embodiment, the current vector fluctuation direction θ c is the equal torque line C T By determining the phase to be shifted so as to be along the tangent direction of the torque fluctuation, the torque fluctuation can be suppressed.

[0114] 18 shows the results of frequency analysis for the control of the comparative example and the example. As shown in the figure, the torque near the carrier frequency (5000 Hz) is excessively large for the control of the comparative example. In contrast, it can be seen that the torque at that frequency is significantly reduced for the control of the example.

[0115] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0116] 1. Voltage command calculation section 2 dq / uvw coordinate converter 3 Voltage command correction section 4-phase current reproduction section 5 PWM converter 6 inverters 9 Motor 11. Rotation speed calculator 12 UVW / DQ Coordinate Transformer 100 Motor Control System 200 Motor Control System

Claims

1. 1. A motor control method comprising: calculating phase voltage command values ​​based on a predetermined torque command value; and generating, based on the phase voltage command values, drive signals for a power converter that converts DC power into polyphase AC power and supplies the power to a motor, the method comprising: acquiring three-phase currents from the DC bus current, and calculating a first-phase voltage command value from the torque command value by referring to the acquired three-phase currents; determining a phase to be shifted in the first phase voltage command value, and performing a correction process to apply a pulse shift to a phase voltage component of the phase to be shifted in order to ensure a detection time for the three-phase current, thereby calculating a second phase voltage command value; generating the drive signal based on the second phase voltage command value; In the correction process, The phase to be shifted is determined so that the direction of the current vector fluctuation of the motor due to the pulse shift is along a tangent direction of an equal torque line where the output torque is constant in a dq-axis coordinate system. Motor control methods.

2. 2. The motor control method of claim 1, In the correction process, defining the equal torque line according to the input torque command value; The direction of the voltage vector fluctuation of the motor due to the pulse shift is determined as a tangential direction of the defined equal torque line; determining the phase to be shifted by referring to the determined voltage vector variation direction; Motor control methods.

3. 3. The motor control method according to claim 2, In the correction process, Identifying a magnitude relationship between phase fluctuation components when the voltage fluctuation in the dq-axis coordinate system determined by the voltage vector fluctuation direction is transformed into a three-phase coordinate system; determining the phase to be shifted based on the magnitude relationship of the phase fluctuation components; Motor control methods.

4. 4. The motor control method according to claim 3, In the correction process, At least one of the phase having the maximum value and the phase having the minimum value among the phase fluctuation components is set as the shift target phase. Motor control methods.

5. The motor control method according to any one of claims 1 to 4, The correction process includes: a first correction mode in which the phase to be shifted is determined based on the magnitude of each phase voltage component of the first phase voltage command value, and a second correction mode in which the phase to be shifted is determined so that the current vector variation direction is along a tangential direction of the equal torque line, selectively executing either the first correction mode or the second correction mode depending on a driving state of the motor to correct the first phase voltage command value, thereby calculating the second phase voltage command value; Motor control methods.

6. 6. A motor control method according to claim 5, comprising: The driving conditions include the rotation speed of the motor. Motor control methods.

7. The motor control method according to any one of claims 1 to 4, the pulse shift is a process of correcting the phase voltage component in the phase to be shifted so that an average value per carrier period of the second phase voltage command value or a duty command value based on the second phase voltage command value coincides with an average value per carrier period of the second phase voltage command value or a duty command value based on the second phase voltage command value. Motor control methods.

8. 1. A motor control device that calculates phase voltage command values ​​based on a predetermined torque command value, and generates, based on the phase voltage command values, drive signals for a power converter that converts DC power into multi-phase AC power and supplies the power to a motor, a first-phase voltage command value calculation unit that acquires three-phase currents from the DC bus current and calculates a first-phase voltage command value from the torque command value by referring to the acquired three-phase currents; a second-phase voltage command value calculation unit that determines a phase to be shifted in the first-phase voltage command value, and calculates a second-phase voltage command value by performing a correction process to apply a pulse shift to a phase voltage component of the phase to be shifted in order to ensure a detection time for the three-phase current; a drive signal generation unit that generates the drive signal based on the second phase voltage command value, In the correction process, The phase to be shifted is determined so that the direction of the current vector fluctuation of the motor due to the pulse shift is along a tangent direction of an equal torque line where the output torque is constant in a dq-axis coordinate system. Motor control device.

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