JP2017112694A - Motor control device and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device and a motor control method capable of adjusting a magnitude of a torque current command to an appropriate value.SOLUTION: A motor control device according to an embodiment comprises an inverter, a detector, and a controller. The inverter drives a motor on the basis of a torque current command and an excitation current command. The detector detects a DC bus voltage value of the inverter. The controller, at regeneration of the motor, adjusts a magnitude of the torque current command depending on the DC bus voltage value detected by the detector.SELECTED DRAWING: Figure 1

Description

  Embodiments disclosed herein relate to a motor control device and a motor control method.

  In an inverter that drives a motor based on a torque current command and an excitation current command, the DC bus voltage of the inverter may increase due to regenerative power flowing from the motor during motor regeneration, and the inverter may become overvoltage. In particular, if the motor is rapidly decelerated while the motor is rotating at a high speed, the inverter may become overvoltage.

  Therefore, a technique for preventing an overvoltage of the inverter by limiting the magnitude of the torque current command when the motor is in a regenerative state has been proposed (for example, see Patent Document 1).

JP 2014-155255 A

  However, in the technique described in Patent Document 1, the limit value of the torque current command is a value determined in advance based on the torque characteristics of the motor. For this reason, in the technique described in Patent Document 1, when the DC bus voltage value of the inverter fluctuates, the torque current command may be limited excessively or insufficiently. If the torque current command limit is excessive, the motor deceleration time increases. On the other hand, if the torque current command limit is insufficient, an inverter overvoltage occurs.

  One aspect of the embodiment has been made in view of the above, and an object thereof is to provide a motor control device and a motor control method capable of adjusting the magnitude of a torque current command to an appropriate value.

  A motor control device according to an aspect of an embodiment includes an inverter, a detection unit, and a control unit. The inverter drives a motor based on a torque current command and an excitation current command. The detection unit detects a DC bus voltage value of the inverter. The control unit adjusts the magnitude of the torque current command according to the DC bus voltage value detected by the detection unit during regeneration of the motor.

  According to one aspect of the embodiment, it is possible to provide a motor control device and a motor control method that can adjust the magnitude of the torque current command to an appropriate value.

FIG. 1 is a diagram illustrating a configuration example of a motor control device according to the embodiment. FIG. 2 is a diagram illustrating a configuration example of the I _q control unit illustrated in FIG. 1. FIG. 3 is a diagram illustrating an example of voltage limitation according to the embodiment. FIG. 4 is a diagram illustrating a first configuration example of the adjustment unit illustrated in FIG. 2. FIG. 5 is a diagram for explaining the operation of the adjustment unit illustrated in FIG. 4. FIG. 6 is a diagram illustrating a second configuration example of the adjustment unit illustrated in FIG. 2. FIG. 7 is a diagram for explaining the operation of the adjustment unit illustrated in FIG. 6. FIG. 8 is a flowchart illustrating an example of a q-axis current command adjustment process according to the embodiment.

  Hereinafter, embodiments of a motor control device and a motor control method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

[1. Motor control device]
FIG. 1 is a diagram illustrating a configuration example of a motor control device according to the embodiment. An AC power supply 2 and a motor 3 are connected to the motor control device 1 shown in FIG. The motor control device 1 includes an _Iq control unit 11, an ACR (Auto Current Regulator) 13, a coordinate conversion unit 15, a PWM (Pulse Width Modulation) control unit 17, and an inverter 19. In addition, the motor control device 1 includes a current detection unit 21, an AD (Analog to Digital) conversion unit 23, and a coordinate conversion unit 25. In addition, the motor control device 1 includes a DC bus voltage detection unit 27, a speed calculation unit 29, and a regeneration determination unit 31.

A q-axis current command (that is, torque current command) I _qRef is input to the I _q control unit 11. The I _q control unit 11 _adjusts the magnitude of the q-axis current command I _qRef according to the DC bus voltage value of the inverter 19 during the regeneration of the motor 3, and _sends the adjusted q-axis current command I _qRef ′ to the ACR 13. Output. On the other hand, the I _q control unit 11 does not adjust the magnitude of the q-axis current command I _qRef during powering of the motor 3, and the input q-axis current command I _qRef is directly _used as the q-axis current command I _qRef ′. Output to ACR13. Details of the _Iq control unit 11 will be described later.

For example, when the motor 3 is rotating positively at the maximum rotation speed ω _max (that is, when the motor 3 is rotating at + ω _max ), the positive maximum value of the q-axis current (that is, torque current). + I _qmax is input to the I _q control unit 11 as the q-axis current command I _qRef . When the motor 3 rotating at + ω _max is suddenly stopped, for example, the negative maximum value −I _qmax of the q-axis current is input to the I _q control unit 11 as the q-axis current command I _qRef .

Further, for example, when the motor 3 is rotating backward at the maximum rotation speed ω _max (that is, when the motor 3 is rotating at −ω _max ), the negative maximum value −I _qmax of the q-axis current is The q-axis current command I _qRef is input to the I _q control unit 11. When the motor 3 rotating at −ω _max is suddenly stopped, for example, the positive maximum value + I _qmax of the q-axis current is input to the I _q control unit 11 as the q-axis current command I _qRef .

The ACR 13 receives a d-axis current command (that is, an excitation current command) I _dRef and a q-axis current command I _qRef ′. Further, the q-axis current value I _qFB and the d-axis current value I _dFB are input to the _{ACR 13} from the coordinate conversion unit 25. The ACR ₁₃ generates a d-axis voltage command (that is, an excitation voltage command) V _dRef based on the deviation between the d-axis current command I _dRef and the d-axis current value I _dFB, and _performs coordinate conversion of the generated d-axis voltage command V _dRef To the unit 15. Further, the ACR ₁₃ generates a q-axis voltage command (that is, a torque voltage command) V _qRef based on the deviation between the q-axis current command I _qRef ′ and the q-axis current value I _qFB, and the generated q-axis voltage command V _qRef Is output to the coordinate conversion unit 15.

The coordinate conversion unit 15 converts the d-axis voltage command V _dRef and the q-axis voltage command V _qRef into a three-phase voltage command of a U-phase voltage command V _u , a V-phase voltage command V _v and a W-phase voltage command V _w. The three-phase voltage command after the coordinate conversion is output to the PWM control unit 17.

The PWM control unit 17 performs PWM conversion based on a comparison between the three-phase voltage commands V _u , V _v , and V _w and a carrier wave generated inside the PWM control unit 17, and PWM drive signals corresponding to the three phases. And the generated PWM drive signal is output to the inverter 19.

  The inverter 19 is supplied with electric power of each phase of the R phase, the S phase, and the T phase from the AC power supply 2. The inverter 19 includes an AC / DC converter circuit that converts R-phase, S-phase, and T-phase AC to DC, a smoothing capacitor that smoothes the converted DC, and a plurality of switching units that convert the smoothed DC into AC. Device. In the inverter 19, the AC / DC conversion circuit, the smoothing capacitor, and the plurality of switching elements are connected in parallel to each other via a DC bus.

In the inverter 19, when the motor 3 is powered, the switching element is turned on / off based on the PWM drive signal input from the PWM control unit 17. When the motor 3 is powered, the inverter 19 once converts the R-phase, S-phase, and T-phase alternating currents into direct current, and then converts the converted direct current back into alternating current through the switching element. As a result, when the motor 3 is powered, the inverter 19 converts the power supplied from the AC power supply 2 into driving power for each of the U-phase, V-phase, and W-phase, and supplies the converted driving power to the motor 3. Then, the motor 3 is driven. The source of control for the inverter 19 is a q-axis current command I _qRef and a d-axis current command I _dRef . That is, the inverter 19 drives the motor 3 based on the q-axis current command I _qRef and the d-axis current command I _dRef .

  On the other hand, at the time of regeneration of the motor 3, induced electromotive force (that is, regenerative power) of each phase of the U phase, V phase, and W phase generated in the motor 3 due to the deceleration of the motor 3 flows from the motor 3 to the inverter 19. The DC bus voltage increases.

The current detector 21 detects the current values I _u , I _v , I _w of the driving power of each phase supplied from the inverter 19 to the motor 3, and AD detects the detected current values I _u , I _v , I _w . The data is output to the conversion unit 23.

In the configuration example of FIG. 1, the current detection unit 21 detects three-phase current values of the U phase, the V phase, and the W phase. However, the current detection unit 21 may detect a current value of any two phases of the U phase, the V phase, and the W phase. When any two-phase current value is detected, the remaining one-phase current value can be obtained from the relationship of “I _u + I _v + I _w = 0”.

The AD conversion unit 23 converts the analog current values I _u , I _v , I _w to digital current values I _u ′, I _v ′, I _w ′, and converts the converted current values I _u ′, I _v ′. , I _w ′ is output to the coordinate conversion unit 25.

The coordinate conversion unit 25 converts the current values I _u ′, I _v ′, and I _w ′ into the q-axis current value I _qFB and the d-axis current value I _dFB, and the q-axis current value I _qFB after the coordinate conversion. And the d-axis current value I _dFB is output to the _ACR 13.

The DC bus voltage detection unit 27 detects the DC bus voltage value V _dc of the inverter 19 and outputs the detected DC bus voltage value V _dc to the I _q control unit 11. For example, the DC bus voltage detection unit 27 detects the voltage value between terminals of the smoothing capacitor included in the inverter 19 as the DC bus voltage value V _dc .

  The encoder 4 detects the rotational position θ of the motor 3 and outputs the detected rotational position θ to the speed calculation unit 29.

The speed calculation unit 29 calculates the rotation speed ω _m of the motor 3 based on the rotation position θ detected by the encoder 4, and outputs the calculated rotation speed ω _m to the I _q control unit 11 and the regeneration determination unit 31. .

The regenerative determination unit 31 receives a q-axis current command I _qRef . Based on the q-axis current command I _qRef and the rotational speed ω _m , the regeneration determination unit 31 determines whether the motor 3 is in a power running state or a regeneration state, and outputs the determination result to the I _q control unit 11. To do. For example, the regeneration determination unit 31 determines that the motor 3 is in a power running state when “I _qRef > 0 and ω _m > 0” or when “I _qRef <0 and ω _m <0”. Further, for example, the regeneration determining unit 31 determines that the motor 3 is in the regenerative state when “I _qRef > 0 and ω _m <0” or “I _qRef <0 and ω _m > 0”. .

Here, the motor control device 1 includes, for example, a microcomputer such as a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory), a microcomputer having various input / output ports, and various circuits. The functions of the I _q control unit 11, the ACR 13, the coordinate conversion units 15 and 25, the PWM control unit 17, the speed calculation unit 29, and the regeneration determination unit 31, for example, the CPU reads out a program stored in the ROM. It is realized by executing. Note that some or all of the _Iq control unit 11, the ACR 13, the coordinate conversion units 15 and 25, the PWM control unit 17, the speed calculation unit 29, and the regeneration determination unit 31 are part of ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable). Gate Array) or the like.

[2. _Iq control unit 11]
Next, the I _q control unit 11 will be described in detail. FIG. 2 is a diagram illustrating a configuration example of the I _q control unit 11. The I _q control unit 11 includes a control value calculation unit 41, a parameter storage unit 43, a start speed calculation unit 45, and an adjustment unit 47. The control value calculation unit 41 includes a first calculation unit 411 and a second calculation unit 413.

The first calculation unit 411 receives the DC bus voltage value V _dc from the DC bus voltage detection unit 27. Here, the voltage V _A applied to the motor 3 (hereinafter sometimes referred to as “applied voltage”) V _A can be expressed as “V _A = √ (V _d ² + V _q ² )”. “V _d ” is a d-axis voltage (ie, excitation voltage) applied to the motor 3, and “V _q ” is a q-axis voltage (ie, torque voltage) applied to the motor 3. The upper limit value of the applied voltage _VA is the DC bus voltage value V _dc . That is, “V _A ≦ V _dc ”. Therefore, the upper limit value of the d-axis voltage V _d (hereinafter sometimes referred to as “d-axis voltage upper limit value”) V _dlim is determined according to the upper limit value of the applied voltage V _A , that is, the DC bus voltage value V _dc. , And fluctuates according to the fluctuation of the DC bus voltage value V _dc .

Further, when the applied voltage V _A is limited by, for example, the voltage limit circle “V _max = (V _dc × M) / √3” shown in FIG. 3, when the applied voltage V _A exceeds the voltage limit circle V _max , Each of the d-axis voltage V _d and the q-axis voltage V _q is limited by an excess ratio with respect to the voltage limit circle V _max . FIG. 3 is a diagram illustrating an example of voltage limitation according to the embodiment. Voltage limit circle _{V max} Oite shown in FIG. 3, "M" each modulation rate, "1 / √3" is U-phase -V phase, V phase -W phase, and, W-phase -U phase inverter 19 Is a conversion coefficient from the line voltage to the phase voltage in each of the U phase, the V phase, and the W phase. In FIG. 3, “V _qlim ” is the upper limit value of the q-axis voltage V _q (hereinafter sometimes referred to as “q-axis voltage upper limit value”), “V _dmax ” is the maximum value of the d-axis voltage V _d , “V _qmax ” is the maximum value of the q-axis voltage V _q . Therefore, the d-axis voltage upper limit value V _dlim after the limitation of the applied voltage V _A is expressed by the following equation (1).

Here, if each of the d-axis voltage V _d and the q-axis voltage V _q is to be maximized (ie, “V _dmax = V _qmax = V _max ”), the voltage limit circle V _max causes d to The shaft voltage V _d is limited to the d-axis voltage upper limit value V _dlim represented by the following equation (2). That is, when the d-axis voltage V _d is limited to the greatest extent, it is limited to “1 / √2 times” the maximum value V _dmax of the d-axis voltage V _d . That is, “√2” is the maximum limiting ratio with respect to the d-axis voltage V _d .

Therefore, the first calculation unit 411, for example, based on the voltage limit circle _{V max} shown in FIG. 3, the maximum limit ratio d-axis voltage _{V d} and the "1 / √2", the following equation (3 ) To calculate the d-axis voltage upper limit value V _dlim from the DC bus voltage value V _dc . The first calculation unit 411 outputs the calculated d-axis voltage upper limit value V _dlim to the second calculation unit 413 and the start speed calculation unit 45.

The limit ratio “√2” in the above equation (3) is an example, and the limit ratio with respect to the d-axis voltage V _d is set to any value between 1 and less than √2, and the DC bus voltage value V _{dc is changed} to the d-axis voltage. The upper limit value V _dlim may be calculated.

The parameter storage unit 43 stores various parameters. The parameter storage unit 43 includes, as parameters, for example, the number of pole pairs p of the motor 3, the inductance L _a of the motor 3, and the maximum value of the q-axis current applied to the motor 3 (hereinafter referred to as “q-axis current maximum value”). _Iqmax is stored. For example, the parameter storage unit 43 is realized by a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory).

The rotation speed ω _m is input from the speed calculation unit 29 to the second calculation unit 413. The second calculation unit 413 refers to the parameter storage unit 43, acquires pole logarithm p and the inductance _{L a} from the parameter storage unit 43. The second calculation unit 413, a d-axis voltage limit _{V Dlim,} a pole pair number p, the rotation speed omega _m, based on the inductance _{L a,} used for adjusting the magnitude of the q-axis current command _{I Qref} Control value (hereinafter, sometimes referred to as “q-axis current command control value”) is calculated. The second calculation unit 413 outputs the calculated q-axis current command control value to the adjustment unit 47. Details of the q-axis current command control value calculated by the second calculation unit 413 will be described later.

Start speed calculation unit 45 refers to the parameter storage unit 43, it acquires the number of pole pairs p, the inductance _{L a} and the q-axis current maximum value _{I qmax} from the parameter storage unit 43. Start speed calculation unit 45, the d-axis voltage limit _{V Dlim,} a pole pair number p, and the inductance _{L a,} based on the q-axis current maximum value _{I qmax,} the q-axis current command _{I Qref} magnitude of the adjustment A rotational speed (hereinafter sometimes referred to as “start speed”) ω _start corresponding to the start point is calculated. The start speed calculation unit 45 outputs the calculated start speed ω _start to the adjustment unit 47. Details of the _start speed ω _start calculated by the start speed calculation unit 45 will be described later.

The adjustment unit 47 receives a determination result from the regeneration determination unit 31 as to whether the motor 3 is in power running or regeneration. In addition, the rotation speed ω _m of the motor 3 is input from the speed calculation unit 29 to the adjustment unit 47. The adjustment unit 47 determines the magnitude of the q-axis current command I _qRef using the q-axis current command control value calculated by the second calculation unit 413 when the motor 3 is regenerated according to the determination result of the regeneration determination unit 31. The adjusted q-axis current command I _qRef ′ is output to the ACR ₁₃ after adjustment. However, when the rotation speed ω _m of the motor 3 is equal to or higher than the start speed ω _start , the adjustment unit 47 uses the q-axis current command control value calculated by the second calculation unit 413 to change the q-axis current command I _qRef. Adjust the size of.

On the other hand, the adjustment unit 47 does not adjust the magnitude of the q-axis current command I _qRef when the motor 3 is _powered according to the determination result in the regeneration determination unit 31. Further, even when the motor 3 is regenerating, the adjusting unit 47 does not adjust the magnitude of the q-axis current command I _qRef if the rotational speed ω _m of the motor 3 is less than the start speed ω _start . When the adjustment unit 47 does not adjust the magnitude of the q-axis current command I _qRef , the adjustment unit 47 _outputs the input q-axis current command I _{qRef as it is} to the _{ACR 13} as the q-axis current command I _qRef ′.

[2.1. Adjustment unit 47]
Next, the adjustment unit 47 will be described in detail. Hereinafter, the first configuration example (adjustment unit 47A) of the adjustment unit 47 and the second configuration example (adjustment unit 47B) of the adjustment unit 47 will be described separately.

[2.1.1. Adjustment unit 47A]
FIG. 4 is a diagram illustrating a first configuration example (adjustment unit 47A) of the adjustment unit 47. As illustrated in FIG. The adjustment unit 47A includes an adjustment control unit 471 and a limiter 473.

Here, the d-axis voltage (hereinafter sometimes referred to as “regenerative d-axis voltage”) V _dmot applied to the inverter 19 by the regenerative electric power when the motor 3 is regenerated is represented by the following expression (4). . When the regenerative d-axis voltage V _dmot represented by the following equation (4) is suppressed to be equal to or lower than the d-axis voltage upper limit value V _dlim (that is, by satisfying the condition of “V _dmot ≦ V _dlim ”), the motor 3, overvoltage of the inverter 19 can be prevented.

Here, pole pairs p in the above formula (4), the rotational speed omega _m, inductance _{L a,} and among the four parameters of the q-axis current _{I q,} the number of pole pairs p and the inductance _{L a} is the characteristics of the motor 3 This parameter is determined, and is a parameter specific to the motor 3. Accordingly, during regeneration of the motor 3, it is difficult to limit the number of pole pairs p and the inductance L _a to a desired value. Therefore, when the d-axis voltage V _dmot is expressed by the above equation (4), the condition of “V _dmot ≦ V _dlim ” is satisfied by limiting the q-axis current I _q in the above equation (4). preferable. q-axis current _{I q} is because they are controlled by q-axis current commands _{I Qref,} q-axis current _{I q} is limited by the q-axis current commands _{I Qref} is restricted.

Therefore, when the adjustment unit 47A adopts the configuration shown in FIG. 4, the second calculation unit 413 performs, for example, the following equation (5) to calculate a limit value (hereinafter referred to as “ _{qq” for} the magnitude of the q-axis current command I _qRef. I _{qlim (} which may be referred to as “axis current command limit value”) is calculated as a control value for q axis current command. The calculated q-axis current command limit value I _qlim is input to the adjustment control unit 471.

Further, _since the magnitude of the q-axis current command I _qRef is equal to or less than the q-axis current maximum value I _qmax , the start speed ω _start is expressed by the following formula (6).

Therefore, the adjustment control unit 471 receives the start speed ω _start calculated from the start speed calculation unit 45 according to the above equation (6). In addition, the adjustment control unit 471 receives from the regeneration determination unit 31 a determination result indicating whether the motor 3 is in a power running state or a regeneration state, and inputs the rotational speed ω _{m of the} motor 3 from the speed calculation unit 29. Is done.

Since the pole pairs p and the inductance L _a in the above formula (5) is a known fixed value, the second calculation unit 413, "p × L _a" is the coefficient alpha q-axis current command with specified in The limit value I _qlim may be calculated. Further, since the number of pole pairs in the above equation (6) p, inductance _{L a} and the q-axis current maximum value _{I qmax} is the known fixed value, the start speed calculation unit 45, defined by "p × _{L a} × _{I qmax"} Alternatively, the _start speed ω _start may be calculated using the coefficient β. When the second calculation unit 413 calculates the q-axis current command limit value I _qlim using the coefficient α, and the start speed calculation unit 45 calculates the start speed ω _start using the coefficient β, the I _q control unit 11 may not have the parameter storage unit 43.

When the motor 3 is regenerating and the rotational speed ω _m of the motor 3 is equal to or higher than the start speed ω _start , the adjustment control unit 471 calculates the q axis calculated by the second calculation unit 413 according to the above equation (5). The current command limit value I _qlim is set in the limiter 473 as the limit value of the limiter 473. Therefore, the limiter 473 to which the q-axis current command limit value I _qlim is set by the adjustment control unit 471 limits the magnitude of the q-axis current command I _qRef to the q-axis current command limit value I _qlim , thereby _{reducing the} q-axis current command. _Adjust the magnitude of I _qRef . By _limiting the magnitude of the q-axis current command I _qRef to the q-axis current command limit value I _qlim calculated according to the above equation (5), the d-axis voltage V _d applied to the motor 3 becomes the d-axis voltage upper limit. Control is performed so as not to exceed the value V _dlim . The limiter 473 outputs the adjusted q-axis current command I _qRef ′ (= I _qlim ) to the ACR 13.

On the other hand, the adjustment control unit 471 sets the maximum q-axis current value I _qmax in the limiter 473 as the limit value of the limiter 473 when the motor 3 is in power running. Since the magnitude of the q-axis current command _{I Qref} inputted to the limiter 473 is less than the q-axis current maximum value _{I qmax,} the limiter 473 from the adjustment control unit 471 is set to q-axis current maximum value _{I qmax,} the q-axis The size of current command I _qRef is not limited. Therefore, when the motor 3 is _powered , the limiter 473 outputs the input q-axis current command I _{qRef as it is} to the _{ACR 13} as the q-axis current command I _qRef '. Even when the motor 3 is regenerating, if the rotational speed ω _m of the motor 3 is less than the start speed ω _start , the adjustment control unit 471 and the limiter 473 operate in the same manner as when the motor 3 is powered.

FIG. 5 is a diagram for explaining the operation of the adjustment unit 47A. However, FIG. 5 shows a case where the q-axis current command limit value I _qlim is a positive value. In FIG. 5, for example, when the DC bus voltage value V _dc is “V _dc1 ”, the start speed ω _start calculated according to the above equation (3) and the above equation (6) is “ω _start1 ”. Further, for example, when the DC bus voltage value V _dc is “V _dc2 ”, it is _assumed that the start speed ω _start calculated according to the above equation (3) and the above equation (6) is “ω _start2 ”. Further, for example, when the DC bus voltage value V _dc is “V _dc3 ”, the start speed ω _start calculated according to the above formulas (3) and (6) is “ω _start3 ”. Here, “V _dc1 <V _dc2 <V _dc3 ” and “ω _start1 <ω _start2 <ω _start3 ”. The q-axis current command limit value I _qlim is calculated according to the above equation (5).

Therefore, the limiter 473 _limits the magnitude of the q-axis current command I _qRef when the motor 3 is regenerated as follows. That is, when the DC bus voltage value V _dc is V _dc1 , the limiter 473 _indicates the magnitude of the q-axis current command I _qRef when the rotational speed ω _m of the motor 3 is _{equal to} or higher than the start speed ω _start1. To the q-axis current command limit value I _{qlim shown} in FIG. Further, when the DC bus voltage value V _dc is V _dc2 , the limiter 473 _indicates the magnitude of the q-axis current command I _qRef when the rotational speed ω _m of the motor 3 is _{equal to} or higher than the start speed ω _start2 , and the graph G2 To the q-axis current command limit value I _{qlim shown} in FIG. Further, when the DC bus voltage value V _dc is V _dc3 , the limiter 473 _indicates the magnitude of the q-axis current command I _qRef when the rotational speed ω _m of the motor 3 is _{equal to} or higher than the start speed ω _start3 , in the graph G3 To the q-axis current command limit value I _{qlim shown} in FIG. The graphs G1, G2, and G3 are straight lines parallel to each other.

Further, when the q-axis current command limit value I _qlim when the rotation speed ω _m of the motor 3 is at the maximum rotation speed ω _max is _expressed as “I _qmin ”, the q-axis current command limit value I _qmin is _expressed by the following equation: It is represented by (7). Therefore, each of the q-axis current command limit values I _qmin1 , I _qmin2 , and I _qmin3 shown in FIG. 5 is given by the above equation (3) and the following equation (7).

That is, in the motor control device 1, the start speed ω _start increases as the DC bus voltage value V _dc increases. In the motor control device 1, as the start speed ω _start increases, the range of the rotational speed ω _m in which the magnitude of the q-axis current command I _qRef is adjusted _{decreases and} the magnitude of the q-axis current command I _{qRef increases} . The degree of adjustment becomes smaller.

[2.1.2. Adjustment unit 47B]
FIG. 6 is a diagram illustrating a second configuration example (adjustment unit 47B) of the adjustment unit 47. As illustrated in FIG. The adjustment unit 47B includes an adjustment control unit 475 and a correction unit 477. When the adjustment unit 47B adopts the configuration shown in FIG. 6, the second calculation unit 413 calculates a correction value (hereinafter referred to as “q-axis current” for the magnitude of the q-axis current command I _qRef by, for example, the calculation of the following equation (8). ΔI _{q (} which may be called “command correction value”) is calculated as a control value for q-axis current command. The calculated q-axis current command correction value ΔI _q is input to the adjustment control unit 475.

The adjustment control unit 475 receives a determination result indicating whether the motor 3 is in a power running or regeneration state from the regeneration determination unit 31, and receives a rotation speed ω _m of the motor 3 from the speed calculation unit 29. . The adjustment control unit 475 receives the start speed ω _start from the start speed calculation unit 45.

The adjustment control unit 475 is the q-axis calculated by the second calculation unit 413 according to the above equation (8) when the motor 3 is regenerating and the rotational speed ω _m of the motor 3 is equal to or higher than the start speed ω _start. The current command correction value ΔI _q is output to the correction unit 477. Accordingly, the correction unit 477 corrects the magnitude of the q-axis current command I _qRef by correcting the magnitude of the q-axis current command I _qRef using the q-axis current command correction value ΔI _q by, for example, the calculation of the following equation (9). Adjust the size. Correction unit 477 outputs adjusted q-axis current command I _qRef ′ to ACR 13.

On the other hand, the adjustment control unit 475 outputs “ΔI _q = 0” as the _q -axis current command correction value to the correction unit 477 during the power running of the motor 3, and the correction unit 477 is “ΔI _q = 0”. The magnitude of the q-axis current command I _qRef is not corrected. Therefore, at the time of power running of the motor 3, the correction unit 477 outputs the input q-axis current command I _{qRef as it is} to the _{ACR 13} as the q-axis current command I _qRef ′. Even when the motor 3 is regenerating, if the rotational speed ω _m of the motor 3 is less than the start speed ω _start , the adjustment control unit 475 and the correction unit 477 operate in the same manner as when the motor 3 is powered. .

FIG. 7 is a diagram for explaining the operation of the adjustment unit 47B. However, FIG. 7 shows a case where the q-axis current command limit value I _qlim is a positive value. In FIG. 7, the q-axis current command limit value I _qmin when the rotational speed ω _m of the motor 3 is at the maximum rotational speed ω _max is given by the above formula (3) and the above formula (7). As shown in FIG. 7, when the motor 3 is regenerating and the rotational speed ω _m of the motor 3 is equal to or higher than the start speed ω _start , the magnitude of the q-axis current command I _qRef is as shown in FIG. From the q-axis current command correction value ΔI _q , the correction is made according to the above equation (9). Thereby, in the adjustment part 47B, similarly to the adjustment part 47A, when the motor 3 is regenerating and the rotational speed ω _m of the motor 3 is equal to or higher than the start speed ω _start , the magnitude of the q-axis current command I _qRef Is limited to the q-axis current command limit value I _qlim . Although illustration in FIG. 7 is omitted, also in the adjustment unit 47B, as shown in FIG. 5, the q-axis current command limit value I _qlim is represented by a graph G1, depending on the magnitude of the DC bus voltage value V _dc . The change to G2 and G3 is the same as that of the adjustment unit 47A.

[3. q-axis current command adjustment process]
Next, an example of the adjustment process of the q-axis current command I _qRef by the motor control device 1 will be described. FIG. 8 is a flowchart illustrating an example of adjustment processing of the q-axis current command I _{qRef according to} the embodiment.

In FIG. 8, in step ST _< b> 101, the DC bus voltage detection unit 27 detects the DC bus voltage value V _dc of the inverter 19.

Next, in step ST103, the regeneration determination unit 31 determines whether the motor 3 is in a power running state or a regeneration state. When the motor 3 is in the power running state (step ST103: No), the magnitude of the q-axis current command I _qRef is not adjusted by the I _q control unit 11.

On the other hand, when the motor 3 is in the regenerative state (step ST103: Yes), the I _q control unit 11 _increases the q-axis current command I _qRef according to the DC bus voltage value V _dc detected in step ST101. The height is adjusted (step ST105). However, the I _q control unit 11 _adjusts the magnitude of the q-axis current command I _qRef when the rotation speed ω _m of the motor 3 is equal to or higher than the start speed ω _start .

As described above, the motor control device 1 according to the embodiment includes the inverter 19, the DC bus voltage detection unit 27, and the I _q control unit 11. The inverter 19 drives the motor 3 based on the q-axis current command I _qRef and the d-axis current command I _dRef . The DC bus voltage detector 27 detects the DC bus voltage value V _dc of the inverter 19. The I _q control unit 11 _adjusts the magnitude of the q-axis current command I _qRef according to the DC bus voltage value V _dc detected by the DC bus voltage detection unit 27 during regeneration of the motor 3.

In this way, by adjusting the magnitude of the q-axis current command I _qRef during regeneration of the motor 3, excessive torque during regeneration of the motor 3 can be suppressed and overvoltage of the inverter 19 can be prevented. Further, _since the magnitude of the q-axis current command I _qRef is adjusted according to the DC bus voltage value V _dc , the magnitude of the q-axis current command I _qRef can be adjusted to an appropriate value.

In addition, the I _q control unit 11 includes a control value calculation unit 41 and an adjustment unit 47. The control value calculation unit 41 calculates a q-axis current command control value based on the DC bus voltage value V _dc detected by the DC bus voltage detection unit 27. The adjustment unit 47 uses the q-axis current command control value calculated by the control value calculation unit 41 to adjust the magnitude of the q-axis current command I _qRef .

Thus, by adjusting the magnitude of the q-axis current command I _qRef using the q-axis current command control value calculated based on the DC bus voltage value V _dc , the magnitude of the q-axis current command I _qRef Adjustment can be performed with high accuracy.

Further, the control value calculation unit 41 includes a first calculation unit 411 and a second calculation unit 413. The first calculator 411 calculates the d-axis voltage upper limit value V _dlim from the DC bus voltage value V _dc detected by the DC bus voltage detector 27. The second calculation unit 413, a d-axis voltage limit _{V Dlim} calculated by the first calculation unit 411, and the pole pair number p of the motor 3, the rotation speed omega _m of the motor 3, the inductance _{L a} of the motor 3 Based on this, a q-axis current command control value is calculated.

DC bus voltage value V _dc, pole pairs p, the rotation speed omega _m, and, of the four parameters of inductance L _a, the variation depending on the characteristics of the individual motor occurs is the inductance L _a. Therefore, by calculating the q-axis current command control value based on the above four parameters, the degree of dependence on the motor characteristics can be reduced in adjusting the magnitude of the q-axis current command I _qRef .

In addition, the I _q control unit 11 includes a start speed calculation unit 45. Start speed calculation unit 45, the d-axis voltage limit _{V Dlim} calculated by the first calculation unit 411, and the pole pair number p of the motor 3, and the inductance _{L a} of the motor 3, to the q-axis current maximum value _{I qmax} Based on this, the start speed ω _start is calculated. The adjustment unit 47 adjusts the magnitude of the q-axis current command I _qRef when the motor 3 is regenerating and the rotational speed ω _m of the motor 3 is equal to or higher than the start speed ω _start .

Among the four parameters of the d-axis voltage upper limit value V _dlim , the number of pole pairs p, the inductance L _a , and the q-axis current maximum value I _qmax , it is the inductance L _a that varies depending on the characteristics of the individual motors. is there. Therefore, by calculating the _start speed ω _start based on the above four parameters, the dependency on the motor characteristics can be reduced in determining the start point of the adjustment of the magnitude of the q-axis current command I _qRef. it can.

Further, the control value calculation unit 41 calculates the q-axis current command limit value I _qlim as the q-axis current command control value. The adjustment unit 47A _limits the magnitude of the q-axis current command I _qRef by using the q-axis current command limit value I _qlim calculated by the control value calculation unit 41 to limit the magnitude of the q-axis current command I _qRef. adjust.

With this so adjusted by limiting the magnitude of the q-axis current command I _Qref, by limiting the magnitude of the q-axis current command I _Qref using, for example, the limiter 473, the q-axis current command with a simple configuration The magnitude of I _qRef can be adjusted.

Further, the control value calculation unit 41 calculates the q-axis current command correction value ΔI _q as the q-axis current command control value. The adjustment unit 47B _corrects the magnitude of the q-axis current command I _qRef by using the q-axis current command correction value ΔI _q calculated by the control value calculation unit 41, thereby _adjusting the magnitude of the q-axis current command I _qRef. adjust.

Thus, _when the magnitude of the q-axis current command I _qRef is adjusted by correction, the magnitude of the q-axis current command I _qRef can be adjusted by a simple process such as a subtraction process.

  As described above, the motor control device 1 includes the “inverter that drives the motor based on the torque current command and the excitation current command” and the “detection unit that detects the DC bus voltage value of the inverter”. Further, the motor control device 1 includes a “calculation unit that calculates an upper limit value of an excitation voltage applied to the motor from the DC bus voltage value detected by the detection unit”. Further, the motor control device 1 includes “means for adjusting the magnitude of the torque current command so that the excitation voltage does not exceed the upper limit value calculated by the calculation unit”. The inverter 19 is an example of “an inverter that drives a motor based on a torque current command and an excitation current command”. The DC bus voltage detection unit 27 is an example of a “detection unit that detects a DC bus voltage value of the inverter”. The first calculation unit 411 is an example of “a calculation unit that calculates an upper limit value of an excitation voltage applied to the motor from the DC bus voltage value detected by the detection unit”. The adjustment unit 47 is an example of “means for adjusting the magnitude of the torque current command so that the excitation voltage does not exceed the upper limit value calculated by the calculation unit”.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Motor control apparatus 3 Motor 4 Encoder 11 _Iq control part 19 Inverter 27 DC bus voltage detection part 29 Speed calculation part 31 Regenerative judgment part

Claims (8)

An inverter that drives the motor based on the torque current command and the excitation current command;
A detector for detecting a DC bus voltage value of the inverter;
A control unit that adjusts the magnitude of the torque current command according to the DC bus voltage value detected by the detection unit during regeneration of the motor;
A motor control device comprising: The controller is
A control value calculation unit that calculates a control value used to adjust the magnitude of the torque current command based on the DC bus voltage value detected by the detection unit;
An adjustment unit that adjusts the magnitude of the torque current command using the control value calculated by the control value calculation unit;
A motor control device according to claim 1. The control value calculation unit
A first calculation unit that calculates an upper limit value of an excitation voltage applied to the motor from the DC bus voltage value detected by the detection unit;
A second calculation unit that calculates the control value based on the upper limit value of the excitation voltage calculated by the first calculation unit, the number of pole pairs of the motor, the rotation speed of the motor, and the inductance of the motor. When,
A motor control device according to claim 2. The controller is
Based on the upper limit value of the excitation voltage calculated by the first calculation unit, the number of pole pairs, the inductance, and the maximum value of the torque current applied to the motor, the magnitude of the torque current command A rotation speed calculation unit that calculates a start speed that is a rotation speed corresponding to the start point of the adjustment;
The adjustment unit is
When the motor is regenerating and the rotational speed of the motor is equal to or higher than the start speed, the magnitude of the torque current command is adjusted.
The motor control device according to claim 3. The control value calculation unit
A limit value for the magnitude of the torque current command is calculated as the control value,
The adjustment unit is
Adjusting the magnitude of the torque current command by limiting the magnitude of the torque current command using the limit value calculated by the control value calculation unit;
The motor control apparatus as described in any one of Claim 2 to 4. The control value calculation unit
Calculating a correction value for the magnitude of the torque current command as the control value;
The adjustment unit is
Adjusting the magnitude of the torque current command by correcting the magnitude of the torque current command using the correction value calculated by the control value calculation unit;
The motor control apparatus as described in any one of Claim 2 to 4. An inverter that drives the motor based on the torque current command and the excitation current command;
A detector for detecting a DC bus voltage value of the inverter;
A calculation unit that calculates an upper limit value of an excitation voltage applied to the motor from the DC bus voltage value detected by the detection unit during regeneration of the motor;
Adjusting means for adjusting the magnitude of the torque current command so that the excitation voltage does not exceed the upper limit value calculated by the calculation unit;
A motor control device comprising: Detecting the DC bus voltage value of the inverter that drives the motor based on the torque current command and the excitation current command;
Adjusting the magnitude of the torque current command according to the detected DC bus voltage value during regeneration of the motor;
A motor control method including:

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