Motor control device and power conversion device

Abstract

To provide a motor control device and a power conversion device capable of suppressing field failure at the time of field weakening inrush.SOLUTION: The magnetic flux command value generation unit includes an interlinkage flux command calculator that calculates an interlinkage flux command value based on a torque command value, an interlinkage flux optimal command limit calculator that obtains a maximum interlinkage flux value that can be set for the torque command value, an interlinkage flux command limit calculator that calculates a limit magnetic flux obtained by adding a predetermined value to the maximum interlinkage flux value, and a limit limiter that limits an upper limit value of the interlinkage flux command value based on a difference between an output of the interlinkage flux command limit calculator and an output of the interlinkage flux optimal command limit calculator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 listed below discloses a motor control device that performs vector control and is capable of suppressing the occurrence of field failure. This motor control device includes a flux command value generation unit that generates a flux command value based on a torque command value, and a current command value generation unit that generates a current command value based on the flux command value, and the flux command value generation unit includes a flux linkage command calculator that calculates a pre-compensation flux linkage command value based on the torque command value, a flux linkage calculator that calculates a flux linkage feedback value based on the motor rotation speed, a PI controller that calculates a flux compensation value based on the deviation between the pre-compensation flux linkage command value and the flux linkage feedback value, and an adder that calculates the flux command value from the pre-compensation flux linkage command value based on the flux compensation value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-179990 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the above-described background art, in order to satisfy torque accuracy even in the field region (voltage saturation region), it is necessary to operate a flux linkage command, which is an input command of a control map (TI-MAP) that defines the relationship between flux linkage and a torque command value, and to aim for a current command (idiq command) on an equal torque line. However, due to fluctuations in power supply voltage, variations in sensors, temperature changes, etc., there is a risk that a point where a field is faulty or a current vector is not optimal will be aimed for using only a predetermined flux linkage command.

[0005] The flux linkage command limit calculator in the background art specifies a line voltage modulation rate limit value based on torque, rotation speed, and power supply voltage, i.e., the modulation rate in the field region, and it is necessary to adjust the flux linkage command in order to suppress field defects during field weakening inrush.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a motor control device and a power conversion device that are capable of suppressing field failure during field-weakening inrush. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs, as a first solution related to a motor control device, a motor control device comprising: a flux command value generation unit that generates a flux command value based on a torque command value; and a current command value generation unit that generates a current command value based on the flux command value, wherein the flux command value generation unit comprises: a flux linkage command calculator that calculates a flux linkage command value based on the torque command value; a flux linkage optimum command limit calculator that determines a maximum flux linkage value that can be set for the torque command value; a flux linkage command limit calculator that calculates a limit flux by adding a predetermined value to the maximum flux linkage value; and a limit limiter that limits an upper limit of the flux command value based on the difference between the output of the flux linkage command limit calculator and the output of the flux linkage optimum command limit calculator.

[0008] The present invention employs, as a second solution related to a motor control device, a solution in which, in the first solution described above, the flux linkage command limit calculator is set by adding the flux in the MTPA (Maximum Torque Per Ampere) control region and the flux having control toughness.

[0009] The present invention employs, as a third solution related to a motor control device, the second solution described above, in which the flux linkage optimum command limit calculator is configured as a one-dimensional map, and includes a limiting section that sets an optimum flux that becomes an MTPA (Maximum Torque Per Ampere) control region based on a torque command, calculates the difference between this and the output value of the flux linkage command limit calculator, and limits the result to zero if it is negative.

[0010] The present invention employs, as a fourth solution related to a motor control device, a solution in which, in the above-mentioned third solution, the flux linkage optimal command limit calculator is set at a flux in the MTPA (Maximum Torque Per Ampere) control region.

[0011] The present invention employs a solution relating to a power conversion device, which comprises a motor control device according to any one of the first to fourth solutions. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a motor control device and a power conversion device that are capable of suppressing field failure during field-weakening inrush. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a circuit diagram showing a schematic configuration of a control device that functions as a motor control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a functional configuration of a power converter control unit as a motor control device. [Figure 3] FIG. 2 is a block diagram of a magnetic flux command value generating unit included in the motor control device according to an embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram showing the transition of the current operating point on the id-iq plane when the motor is driven at maximum output. [Figure 5]1 is a schematic diagram showing the transition of the current operating point on the id-iq plane when the motor M is driven at maximum output. FIG. [Figure 6] FIG. 10 is a characteristic diagram showing the effect of one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a power conversion device 1 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, this power conversion device 1 includes a power converter 2 and a power converter control unit 3. The power converter control unit 3 corresponds to the motor control device according to this embodiment.

[0015] The power converter 2 includes a step-up / step-down converter 2a, a drive inverter 2b, and a power generation inverter 2c. As shown in the figure, a battery P, a motor M, and a generator G are connected to the power converter 2. The power converter 2 includes a pair of battery terminals (a positive battery terminal E1 and a negative battery terminal E2) to which the battery P is connected as external connection terminals.

[0016] As shown in the figure, the positive electrode of the battery P is connected to the positive battery terminal E1, and the negative electrode is connected to the negative battery terminal E2. The battery P is a secondary battery such as a lithium ion battery, and discharges DC power to the control device 1 and charges DC power via the control device 1.

[0017] The power converter 2 also has three motor terminals (U-phase motor terminal Fu, V-phase motor terminal Fv, and W-phase motor terminal Fw) to which the motor M is connected. The power converter 2 also has three generator terminals (U-phase generator terminal Hu, V-phase generator terminal Hv, and W-phase generator terminal Hw) to which the generator G is connected.

[0018] The motor M is a three-phase motor having three phases and is a load of the drive inverter 2b. The U-phase input terminal of this motor M is connected to the U-phase motor terminal Fu, the V-phase input terminal is connected to the V-phase motor terminal Fv, and the W-phase input terminal is connected to the W-phase motor terminal Fw. The rotating shaft (drive shaft) of this motor M is connected directly or indirectly to the wheels of an electric vehicle, and applies rotational power to the wheels to rotate them.

[0019] The generator G is a three-phase generator, with a U-phase output terminal connected to a U-phase generator terminal Hu, a V-phase output terminal connected to a V-phase generator terminal Hv, and a W-phase output terminal connected to a W-phase generator terminal Hw. The generator G is connected to the output shaft of a power source such as an engine mounted on an electric vehicle, and outputs three-phase AC power to the control device 1.

[0020] In the power converter 2, the step-up / step-down converter 2a steps up the DC voltage output from the battery P and outputs it to the drive inverter 2b based on a PWM (Pulse Width Modulation) signal input from the power converter control unit 3. The PWM signal is a control signal that controls the step-up operation of the step-up / step-down converter 2a, i.e., a step-up / step-down PWM signal.

[0021] In addition, based on a PWM signal (boost / buck PWM signal) input from the power converter control unit 3, the boost / buck converter 2a reduces the regenerative power (DC power) input from the drive inverter 2b or the generated power (DC voltage) output from the power generation inverter 2c at a predetermined step-down ratio and outputs it to the battery P.

[0022] The buck-boost converter 2a includes a plurality of capacitors, a transformer, and a plurality of transformer IGBTs (Insulated Gate Bipolar Transistors), as shown in Fig. 1. Such a buck-boost converter 2a is a power circuit known as a magnetically coupled interleaved chopper circuit.

[0023] The step-up / step-down converter 2a selectively performs a step-up operation in which it steps up battery power (DC power) input from the battery P via a pair of battery terminals E1, E2 and outputs the power to the drive inverter 2b, or a step-down operation in which it steps down DC power input from the drive inverter 2b or the power generation inverter 2c and outputs the DC power to the battery P via a pair of battery terminals E1, E2. In other words, the step-up / step-down converter 2a is a power conversion circuit that steps up and down DC power in both directions between the battery P and the drive inverter 2b or the power generation inverter 2c.

[0024] Based on a PWM signal (driving PWM signal) input from the power converter control unit 3, the driving inverter 2b converts the battery power (DC power) output from the battery P into three-phase AC power (motor driving power) and supplies it to the motor M.

[0025] Furthermore, the drive inverter 2b converts the regenerative power (three-phase AC power) input from the motor M into DC power and outputs it to the step-up / step-down converter 2a based on a PWM signal (regenerative PWM signal) input from the power converter control unit 3. As shown in Fig. 1, the drive inverter 2b has three switching legs corresponding to the number of phases (three phases) of the motor M, i.e., a total of six drive IGBTs.

[0026] The drive inverter 2b is a power conversion circuit that selectively performs power running and regeneration. Power running is a forward operation that converts battery power (DC power) input from the step-up / step-down converter 2a into motor drive power (three-phase AC power) and outputs it to the motor M via three motor terminals Fu, Fv, and Fw.

[0027] In contrast, the regenerative operation is a reverse operation in which regenerative power (three-phase AC power) input from the motor M via the three motor terminals Fu, Fv, and Fw is converted into DC power and output to the step-up / step-down converter 2a. In other words, the drive inverter 2b is a power circuit that converts DC power and three-phase AC power between the step-up / step-down converter 2a and the motor M.

[0028] The power generation inverter 2c converts the generated power (AC power) output from the generator G into DC power and outputs it to the step-up / step-down converter 2a based on a PWM signal (power generation PWM signal) input from the power converter control unit 3. The power generation inverter 2c has three switching legs corresponding to the number of phases (three phases) of the generator G, i.e., a total of six power generation IGBTs.

[0029] The power generation inverter 2c is a power conversion circuit that converts the generated power (three-phase AC power) input from the generator G via three generator terminals Hu, Hv, and Hw into DC power and outputs it to the step-up / step-down converter 2a. In other words, the power generation inverter 2c is a power circuit that converts the generated power (three-phase AC power) into DC power between the step-up / step-down converter 2a and the generator G.

[0030] The power converter control unit 3 includes a gate driver and an ECU (Electronic Control Unit). The gate driver is a circuit that generates gate signals based on various duty command values ​​(transformation duty command value, drive duty command value, and power generation duty command value) input from the ECU.

[0031] For example, the gate driver generates a gate signal to be supplied to the step-up / step-down converter 2a based on a voltage transformation duty command value input from the ECU. The gate driver also generates a gate signal to be supplied to the drive inverter 2b based on a drive duty command value input from the ECU. The gate driver also generates a gate signal to be supplied to the power generation inverter 2c based on a power generation duty command value input from the ECU.

[0032] The ECU is a control circuit that performs predetermined control processing based on a pre-stored control program. The ECU outputs various duty command values ​​(transformation duty command value, drive duty command value, and power generation duty command value) generated based on the control processing to the gate driver.

[0033] Such an ECU performs drive control of the motor M and charge control of the battery P via the power converter 2 and the gate driver. That is, this ECU generates various duty command values ​​(a duty command value for voltage transformation, a duty command value for driving, and a duty command value for power generation) related to the step-up / step-down converter 2a, the drive inverter 2b, and the power generation inverter 2c based on detection values ​​(detected voltage values) of voltage sensors and detection values ​​(detected current values) of current sensors incidentally provided to the step-up / step-down converter 2a, the drive inverter 2b, and the power generation inverter 2c, as well as operation information of the electric vehicle, etc.

[0034] Such a power conversion device 1 is an electric device provided in an electrically powered vehicle such as a hybrid car or an electric car. A power converter 2 in the power conversion device 1 drives and controls a motor M, which is a rotating electric machine, and also charges a battery P with AC power generated by a generator G. A power converter control unit 3 in the power conversion device 1 functions as a motor control device that controls the power converter 2, and controls the drive of the motor M based on the output of the battery P (battery power), and controls the charging of the battery P based on the power generated by the generator G or the regenerative power of the motor M.

[0035] Next, the detailed configuration of the power converter control unit 3 in this embodiment will be described with reference to Fig. 2. As described above, this power converter control unit 3 corresponds to the motor control device according to this embodiment.

[0036] First, we will explain the additional components of the power conversion device 1 related to this power converter control unit 3. The power conversion device 1 includes a current sensor 4 and a rotation angle sensor 5 as components related to the control of the power converter 2 by the power converter control unit 3. That is, the power conversion device 1 according to this embodiment includes the current sensor 4 and the rotation angle sensor 5 in addition to the power converter 2 and the power converter control unit 3.

[0037] The current sensor 4 detects each phase current between the motor M and the power converter 2, and outputs the detection result as a current detection signal to the power converter control unit 3. Note that multiple current sensors 4 may be provided between the power converter 2 and the motor M, or may be provided inside the power converter 2. The current sensor 4 is not particularly limited as long as it is configured to detect the phase current of each phase, and may include, for example, a current transformer (CT) with a transformer or a Hall element. Alternatively, the current sensor 4 may be a shunt resistor.

[0038] The rotation angle sensor 5 detects the rotation angle θ of the motor M. The rotation angle θ of the motor M is the electrical angle of the rotor from a predetermined reference rotation position. The rotation angle sensor 5 outputs a rotation detection signal indicating the rotation angle θ to the power converter control unit 3. For example, the rotation angle sensor 5 may include a resolver. The rotation speed of the motor M (motor rotation speed) is calculated based on the rotation detection signal output from the rotation angle sensor 5. In other words, the rotation angle sensor 5 outputs a rotation detection signal that includes the motor rotation speed as information.

[0039] The power converter control unit 3 includes functional components embodied by, for example, the above-mentioned gate driver or ECU, such as a torque control unit 11, a current detection unit 12, a three-phase / dq conversion unit 13, an angular velocity calculation unit 14, a current control unit 15, a dq / three-phase conversion unit 16, and a PWM control unit 17.

[0040] The torque control unit 11 acquires a torque command value T* from an external higher-level control device, and generates a d-axis current command value id* and a q-axis current command value iq* based on the torque command value T*. The d-axis current command value id* is a target value for the d-axis current of the motor M, and the q-axis current command value iq* is a target value for the q-axis current of the motor M. The torque control unit 11 outputs the d-axis current command value id* and the q-axis current command value iq* to the current control unit 15.

[0041] The torque control unit 11 includes a magnetic flux command value generating unit 20 and a current command value generating unit 30. The magnetic flux command value generating unit 20 generates a flux linkage command value Ψocmp* based on the torque command value T*. The current command value generating unit 30 generates current command values ​​(a d-axis current command value id* and a q-axis current command value iq*) based on the flux linkage command value Ψocmp*.

[0042] Based on the rotation detection signals input from the current sensors 4, the current detection unit 12 detects a U-phase current value iu flowing in the U-phase coil of the motor M, a V-phase current value iv flowing in the V-phase coil of the motor M, and a W-phase current value iw flowing in the W-phase coil of the motor M. The current detection unit 12 outputs the U-phase current value iu, the V-phase current value iv, and the W-phase current value iw to the three-phase / dq conversion unit 13.

[0043] The three-phase / dq converter 13 converts the U-phase current value iu, the V-phase current value iv, and the W-phase current value iw into d-axis current value id and q-axis current value iq in a dq coordinate system corresponding to the rotation angle θ based on the rotation detection signal input from the rotation angle sensor 5. The three-phase / dq converter 13 outputs the d-axis current value id and the q-axis current value iq to the current controller 15.

[0044] The angular velocity calculation unit 14 calculates an angular velocity ω corresponding to the rotation angle θ based on the rotation detection signal input from the rotation angle sensor 5. The angular velocity calculation unit 14 outputs the angular velocity ω to the current control unit 15. The current control unit 15 calculates a d-axis voltage command value Vd* based on the d-axis current command value id*. The current control unit 15 calculates a q-axis voltage command value Vq* based on the q-axis current command value iq*. The current control unit 15 outputs the d-axis voltage command value Vd* and the q-axis voltage command value Vq* to the dq / three-phase conversion unit 16.

[0045] The dq / three-phase converter 16 performs coordinate conversion of the d-axis voltage command value Vd* and the q-axis voltage command value Vq* into a U-phase voltage command value Vu*, a V-phase voltage command value Vv*, and a W-phase voltage command value Vw* based on the rotation detection signal input from the rotation angle sensor 5. That is, the dq / three-phase converter 16 uses the rotation angle θ of the motor M to convert the d-axis voltage command value Vd* and the q-axis voltage command value Vq* in the dq coordinate system into a U-phase voltage command value Vu*, a V-phase voltage command value Vv*, and a W-phase voltage command value Vw* in the three-phase coordinate system. The dq / three-phase converter 16 outputs the U-phase voltage command value Vu*, the V-phase voltage command value Vv*, and the W-phase voltage command value Vw* to the PWM controller 17.

[0046] PWM control unit 17 generates U-phase PWM signal Du, V-phase PWM signal Dv, and W-phase PWM signal Dw based on U-phase voltage command value Vu*, V-phase voltage command value Vv*, W-phase voltage command value Vw*, and the rotation angle θ and angular velocity ω of motor M. That is, PWM control unit 17 generates U-phase PWM signal Du, V-phase PWM signal Dv, and W-phase PWM signal Dw by comparing a carrier wave of a predetermined carrier frequency with the U-phase voltage command value Vu*, V-phase voltage command value Vv*, and W-phase voltage command value Vw* that change over time.

[0047] The U-phase PWM signal Du, the V-phase PWM signal Dv, and the W-phase PWM signal Dw are pulse width modulation signals that are at a high level when the U-phase voltage command value Vu*, the V-phase voltage command value Vv*, and the W-phase voltage command value Vw* are greater than the carrier wave, and are at a low level when they are smaller than the carrier wave. The PWM control unit 17 outputs the U-phase PWM signal Du, the V-phase PWM signal Dv, and the W-phase PWM signal Dw to the power converter 2.

[0048] Next, the detailed configuration of the magnetic flux command value generating unit 20 will be described with reference to FIG. As shown in FIG. 3, the flux command value generation unit 20 includes a flux linkage command calculator 21, a flux linkage command limit calculator 22, a flux linkage command limit restriction unit 23, a flux linkage calculator 24, a subtractor 25, a PI controller 26, a flux linkage compensation limit calculator 27, a flux linkage compensation limit restriction unit 28, an adder-subtractor 29, a flux linkage optimum command limit calculator 20a, a subtractor 20b, a constant generator 20c, and a limit restriction unit 20d.

[0049] The torque command value T*, angular velocity ω, and DC bus voltage Vdcf are input to the flux linkage command calculator 21. The flux linkage command calculator 21 calculates a pre-compensation flux linkage command value Ψo* based on the torque command value T*, angular velocity ω, and DC bus voltage Vdcf. That is, the flux linkage command calculator 21 determines a modulation factor coefficient using the torque command value T*, angular velocity ω, and DC bus voltage Vdcf as parameters, and calculates the pre-compensation flux linkage command value Ψo* based on the modulation factor coefficient, angular velocity ω, and DC bus voltage Vdcf.

[0050] The flux linkage command limit calculator 22 receives the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf as input to the flux linkage command calculator 21. The flux linkage command limit calculator 22 calculates the flux linkage command upper limit value Ψomax and the flux linkage command lower limit value Ψomin based on the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf.

[0051] That is, the flux linkage command limit calculator 22 acquires the flux linkage command upper limit value Ψomax and the flux linkage command lower limit value Ψomin corresponding to the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf by using the flux linkage limit map for field control. The flux linkage command upper limit value Ψomax is the maximum value of the flux linkage command value Ψocmp* that can be set for the torque command value T*.

[0052] Here, the field control flux linkage limit map is a one-dimensional map as shown in Fig. 4(a), and sets the flux linkage command upper limit value Ψomax by adding the offset flux ofs to the basic fluxes Wb1, Wb2, Wb3, .... The basic fluxes Wb1, Wb2, Wb3, ... are set as fluxes in the MTPA (Maximum Torque Per Ampere) control region.

[0053] That is, the flux linkage command upper limit value Ψomax is set as a value obtained by adding a predetermined offset flux ofs to the basic fluxes Wb1, Wb2, Wb3, ... (magnetic flux in the MTPA control region) corresponding to the torque command value T*. This offset flux ofs is set taking into consideration fluctuations in the power supply voltage, variations in sensors, temperature changes, etc. Such a flux linkage command upper limit value Ψomax is a limit flux (restricted flux) obtained by adding a predetermined value of the offset flux ofs to the basic fluxes Wb1, Wb2, Wb3, ..., which are the maximum flux linkage values.

[0054] On the other hand, the flux linkage command lower limit value Ψomin is the minimum value of the flux linkage command value Ψocmp* that can be set for the torque command value T*, assuming that field weakening control is possible. Note that the flux linkage command lower limit value Ψomin may be a preset fixed value.

[0055] The flux linkage command limit restricting unit 23 restricts the upper and lower limits of the pre-compensation flux linkage command value Ψo* calculated by the flux linkage command calculator 21 based on the flux linkage command upper limit value Ψomax calculated by the flux linkage command limit calculator 22 and the flux linkage command lower limit value Ψomin.

[0056] That is, when the pre-compensation flux linkage command value Ψo* input from the flux linkage command calculator 21 is greater than the flux linkage command upper limit value Ψomax, the flux linkage command limit restriction unit 23 replaces the value of the pre-compensation flux linkage command value Ψo* with the value of the flux linkage command upper limit value Ψomax and outputs it.

[0057] Furthermore, when the pre-compensation flux linkage command value Ψo* input from the flux linkage command calculator 21 is smaller than the flux linkage command lower limit value Ψomin, the flux linkage command limit restriction unit 23 replaces the value of the pre-compensation flux linkage command value Ψo* with the value of the flux linkage command lower limit value Ψomin and outputs it. Note that the pre-compensation flux linkage command value Ψo* output from the flux linkage command limit restriction unit 23 is referred to as the pre-compensation flux linkage command value Ψoff*.

[0058] The flux linkage calculator 24 calculates a flux linkage feedback value Ψof based on the angular velocity ω of the motor M. The flux linkage calculator 24 calculates a voltage command value V* (d-axis voltage command value Vd* and q-axis voltage command value Vq*) from the current control unit 15. The flux linkage calculator 24 calculates the flux linkage feedback value Ψof based on the angular velocity ω of the motor M input from the angular velocity calculation unit 14 and the voltage command value V* calculated by the current control unit 15.

[0059] The subtractor 25 calculates the deviation Ψoerr by subtracting the flux linkage feedback value Ψof input via a low-pass filter (LPF) from the pre-compensation flux linkage command value Ψoff* input via the low-pass filter (LPF). The subtractor 25 outputs the deviation Ψoerr to the PI controller 26.

[0060] The PI controller 26 calculates the magnetic flux compensation value dΨobuf* based on the deviation Ψoerr input from the subtractor 25. That is, the PI controller 26 calculates the magnetic flux compensation value dΨobuf* by adding a value obtained by multiplying the deviation Ψoerr by a proportional gain and a value obtained by multiplying the deviation Ψoerr by an integral gain and then integrating the result.

[0061] It should be noted that feedback anti-windup processing may be performed to prevent the integral term from saturating. In this case, a value is obtained by subtracting a flux compensation value dΨo* (described later) output from an interlinkage flux compensation limiting unit 28 from the pre-compensation interlinkage flux command value Ψoff* output from the PI controller 26. This value is then multiplied by the reciprocal of the proportional gain used in the PI controller 26, and the obtained value is subtracted from the deviation Ψoerr, and then the calculation is performed in which the result is multiplied by the integral gain as described above.

[0062] The flux linkage compensation limit calculator 27 calculates an upper limit value dΨomax and a lower limit value dΨomin based on the flux linkage command upper limit value Ψomax, the pre-compensation flux linkage command value Ψo*, and the pre-compensation flux linkage command value Ψoff*. The upper limit value dΨomax is the upper limit value of the flux compensation value dΨobuf*. The lower limit value dΨomin is the lower limit value of the flux compensation value dΨobuf*.

[0063] The interlinkage flux compensation limiting unit 28 calculates the flux compensation value dΨo* based on the upper limit value dΨomax and the lower limit value dΨomin as well as the flux compensation value dΨobuf* input from the PI controller 26. This flux compensation value dΨo* is obtained by limiting the flux compensation value dΨobuf* using the upper limit value dΨomax and the lower limit value dΨomin.

[0064] Such a flux compensation value dΨo* is effective when performing field-weakening control on the motor M. When the pre-compensation flux linkage command value Ψo* is smaller than the flux linkage command upper limit value Ψomax, it can be determined that field-weakening control is necessary. When the pre-compensation flux linkage command value Ψo* is smaller than the flux linkage command upper limit value Ψomax, the flux linkage compensation limit calculator 27 calculates an upper limit value dΨomax and a lower limit value dΨomin so that the upper and lower limit values ​​of the flux compensation value dΨobuf* are limited.

[0065] That is, when the pre-compensation flux linkage command value Ψo* is greater than the flux linkage command upper limit value Ψomax and field weakening control is not necessary, the flux linkage compensation limit calculator 27 sets the upper limit value dΨomax and the lower limit value dΨomin so that the upper and lower limit values ​​of the flux compensation value dΨobuf* become zero.

[0066] Note that instead of the pre-compensation flux linkage command value Ψo*, the upper limit value dΨomax and the lower limit value dΨomin may be calculated using the pre-compensation flux linkage command value Ψoff* output from the flux linkage command limiting unit 23. Also, the upper limit value dΨomax and the lower limit value dΨomin may be calculated using the pre-compensation flux linkage command value Ψo* and the pre-compensation flux linkage command value Ψoff*.

[0067] When the flux compensation value dΨobuf* input from the PI controller 26 is larger than the upper limit value dΨomax, the flux linkage compensation limiting unit 28 replaces the value of the flux compensation value dΨobuf* with the upper limit value dΨomax and outputs it. When the flux compensation value dΨobuf* input from the PI controller 26 is smaller than the lower limit value dΨomin, the flux linkage compensation limiting unit 28 replaces the value of the flux compensation value dΨobuf* with the lower limit value dΨomin and outputs it.

[0068] The flux linkage optimum command limit calculator 20a is provided to cancel the offset flux ofs in the field control flux linkage limit map of the above-mentioned flux linkage command limit calculator 22, and calculates the flux linkage command upper limit value Ψomax*. This flux linkage command upper limit value Ψomax* is the maximum flux linkage value that can be set for the torque command value T*.

[0069] That is, the flux linkage optimum command limit calculator 20a has a one-dimensional map configuration as shown in FIG. 4(b), and is provided with an offset cancellation flux linkage limit map set so that the basic fluxes Wb1, Wb2, Wb3, ... correspond to the respective torque command values ​​Nm1, Nm2, Nm3, ....

[0070] By using such an offset cancellation flux linkage limit map, the flux linkage optimum command limit calculator 20a outputs the flux linkage command upper limit value Ψomax* corresponding to the torque command value T* input from the upper control device to the subtractor 20b.

[0071] The subtractor 20b generates the offset flux ofst by subtracting the flux linkage command upper limit value Ψomax* input from the flux linkage optimum command limit calculator 20a from the flux linkage command upper limit value Ψomax input from the flux linkage command limit calculator 22. The subtractor 20b outputs this offset flux ofst to the limiter 20d.

[0072] The constant generator 20c generates "0" as an example of a constant. The constant generator 20c outputs "0" to the limiter 20d. The limiter 20d is a limiter that performs limiting processing on the offset magnetic flux ofst, with "0" as the lower limit value and the offset magnetic flux ofst as the upper limit value. The limiter 20d outputs the offset magnetic flux ofst after limiting processing to the adder / subtractor 29.

[0073] The adder-subtractor 29 calculates the flux linkage command value Ψocmp* by adding or subtracting the pre-compensation flux linkage command value Ψoff*, the flux compensation value dΨo*, and the offset flux ofst. That is, the adder-subtractor 29 compensates the pre-compensation flux linkage command value Ψoff* with the flux compensation value dΨo*, and also calculates the flux linkage command value Ψocmp* by compensating the pre-compensation flux linkage command value Ψoff* with the offset flux ofst.

[0074] In the flux command value generating unit 20 configured as above, the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf are sequentially input at predetermined time intervals to the flux linkage command calculator 21. The flux linkage command calculator 21 sequentially calculates the pre-compensation flux linkage command value Ψo* based on the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf.

[0075] Meanwhile, the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf are also sequentially input to a flux linkage command limit calculator 22. The flux linkage command limit calculator 22 sequentially calculates a flux linkage command upper limit value Ψomax and a flux linkage command lower limit value Ψomin based on the torque command value T*, the angular velocity ω, and the DC bus voltage Vdcf.

[0076] The pre-compensation flux linkage command value Ψo* is limited in value by a flux linkage command limiting unit 23 based on the flux linkage command upper limit value Ψomax or the flux linkage command lower limit value Ψomin as necessary, and is calculated as a pre-compensation flux linkage command value Ψoff*. Meanwhile, the angular velocity ω and voltage command value V* (d-axis voltage command value Vd* and q-axis voltage command value Vq*) of the motor M are input to a flux linkage calculator 24. The flux linkage calculator 24 calculates a flux linkage feedback value Ψof based on the angular velocity ω and the voltage command value V*.

[0077] The pre-compensation flux linkage command value Ψoff* is input to the subtractor 25 via a low-pass filter. The flux linkage feedback value Ψof is also input to the subtractor 25 via a low-pass filter. The subtractor 25 calculates the deviation Ψoerr by subtracting the flux linkage feedback value Ψof from the pre-compensation flux linkage command value Ψoff*.

[0078] The deviation Ψoerr is input to the PI controller 26. The PI controller 26 calculates the magnetic flux compensation value dΨobuf* by adding a value obtained by multiplying the deviation Ψoerr by a proportional gain and a value obtained by multiplying the deviation Ψoerr by an integral gain and then integrating the result.

[0079] On the other hand, the pre-compensation flux linkage command value Ψo* and the flux linkage command upper limit value Ψomax are input to a flux linkage compensation limit calculator 27. The flux linkage compensation limit calculator 27 calculates an upper limit value dΨomax that limits the upper limit of the flux compensation value dΨobuf* based on the pre-compensation flux linkage command value Ψo* and the flux linkage command upper limit value Ψomax. The flux linkage compensation limit calculator 27 also calculates a lower limit value dΨomin of the flux compensation value dΨobuf* based on the pre-compensation flux linkage command value Ψo* and the flux linkage command upper limit value Ψomax.

[0080] The flux compensation value dΨobuf* is limited by an interlinkage flux compensation limiting unit 28 based on an upper limit value dΨomax or a lower limit value dΨomin as necessary, and the limited value is output as a flux compensation value dΨo*. The pre-compensation interlinkage flux command value Ψoff* and the flux compensation value dΨo* are input to an adder / subtractor 29, which adds the pre-compensation interlinkage flux command value Ψoff* and the flux compensation value dΨo* and subtracts the offset flux ofst from the pre-compensation interlinkage flux command value Ψoff* to calculate an interlinkage flux command value Ψocmp*. This flux command value Ψocmp* is input to a current command value generating unit 30, which generates a d-axis current command value id* and a q-axis current command value iq* based on the flux command value Ψocmp*.

[0081] FIG. 5 is a schematic diagram showing the transition of the current operating point on the id-iq plane when the motor M is driven at maximum output. In FIG. 5, the arrows indicate the transition of the current operating point. As shown in this figure, when the control device 1 of this embodiment drives the motor M at maximum output, the current operating point is shifted so as to follow the minimum current maximum torque line that provides the highest efficiency, and after the current operating point reaches the magnetic flux limit (the edge of the magnetic flux limit circle), field weakening control is performed to weaken the field force. In such field weakening, the current operating point is shifted so as to follow the edge of the magnetic flux limit circle.

[0082] Here, according to the power conversion device 1 and motor control device (power converter control unit 3) of this embodiment, the flux linkage calculator 24 calculates the flux linkage feedback value Ψof based on the angular velocity ω of the motor M and the voltage command value V* (the d-axis voltage command value Vd* and the q-axis voltage command value Vq*).

[0083] Furthermore, the PI controller 26 calculates the deviation Ψoerr by subtracting the flux linkage feedback value Ψof from the pre-compensation flux linkage command value Ψoff*. The PI controller 26 also calculates a flux compensation value dΨobuf* corresponding to the deviation Ψoerr. Furthermore, an adder / subtractor 29 adds the pre-compensation flux linkage command value Ψoff* and the flux compensation value dΨo* together and subtracts the offset flux ofst from the pre-compensation flux linkage command value Ψoff* to calculate the flux linkage command value Ψocmp*.

[0084] In such a power conversion device 1 and motor control device (power converter control unit 3), feedback control is performed based on the flux linkage feedback value Ψof, making it possible to suppress fluctuations in the current operating point. That is, as shown in FIG. 5, even when the current operating point shifts so as to follow the edge of the flux limit circle, the current operating point can move outside the flux limit circle. Therefore, according to this embodiment, it is possible to prevent the current operating point from deviating from the range of the flux limit circle and to suppress field failure during field-weakening inrush.

[0085] Furthermore, in the power conversion device 1 and motor control device (power converter control unit 3) according to this embodiment, the limiter 20d limits the upper limit of the flux linkage command value Ψocmp* based on the difference between the output of the flux linkage command limit calculator 22 (flux linkage command upper limit value Ψomax) and the output of the flux linkage optimum command limit calculator 20a (flux linkage command upper limit value Ψomax*), so it is possible to cancel the influence of the offset flux ofs in the flux linkage limit map for field control of the flux linkage command limit calculator 22.

[0086] That is, according to this embodiment, as shown in Fig. 6, a clear improvement is seen in the d-axis current command value id* and the q-axis current command value iq* by subtracting the offset flux ofst from the pre-compensation interlinkage flux command value Ψoff*. Therefore, according to this embodiment, it is possible to further suppress field failure during field-weakening inrush.

[0087] Furthermore, in the power conversion device 1 and motor control device (power converter control unit 3) according to this embodiment, the flux linkage command limit calculator 22 sets the field control flux linkage limit map by adding the basic fluxes Wb1, Wb2, Wb3, ... in the MTPA (Maximum Torque Per Ampere) control region and the offset flux ofs that provides control toughness. Therefore, according to this embodiment, it is possible to prevent the current operating point from deviating from the range of the flux limit circle and to suppress field failure during field-weakening inrush.

[0088] Furthermore, in the power conversion device 1 and motor control device (power converter control unit 3) according to this embodiment, the flux linkage optimum command limit calculator 20a is configured as a one-dimensional map, and includes a limiting unit 20d that sets optimal basic fluxes Wb1, Wb2, Wb3, ... that become the MTPA control region based on the torque command, calculates the difference between this and the output value (flux linkage command upper limit value Ψomax) of the flux linkage command limit calculator 22, and limits the result to zero if it is negative. According to this embodiment, it is possible to accurately suppress field failure when the current operating point deviates from the range of the flux limit circle and field weakening inrush occurs.

[0089] Furthermore, in the power conversion device 1 and motor control device (power converter control unit 3) according to this embodiment, the flux linkage optimum command limit calculator 20a is set at the basic fluxes Wb1, Wb2, Wb3, ... of the MTPA control region. Therefore, according to this embodiment, it is possible to prevent the current operating point from deviating from the range of the flux limit circle and to suppress field failure during field-weakening inrush.

[0090] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0091] For example, in the above embodiment, the configuration has been described in which the upper and lower limits of the flux compensation value dΨobuf* are limited based on the limit values ​​by the flux linkage compensation limit limiting unit 28. However, the present invention is not limited to this. It is also possible to adopt a configuration that does not include the flux linkage compensation limit limiting unit 28 and the flux linkage compensation limit calculator 27.

[0092] In the above embodiment, a configuration including the PI controller 26 has been described. However, instead of the PI controller, it is also possible to adopt a configuration that performs feedback control by including a controller that performs P control or a controller that performs PID control.

[0093] In the above embodiment, the step-up / step-down converter 2a is a power circuit known as a magnetically coupled interleaved chopper circuit. However, the present invention is not limited to this. For example, a single chopper type or other step-up type converter may be used.

[0094] In the above embodiment, a configuration has been described in which the motor M and the generator G are connected to the power converter 2. However, the present invention is not limited to this. For example, a configuration in which the generator G is not connected to the power converter 2, or a configuration in which two or more motors M are connected to the power converter 2 may also be used. [Explanation of symbols]

[0095] 1...power conversion device, 2...power converter, 3...power converter control unit, 4...current sensor, 5...rotation angle sensor, 11...torque control unit, 12...current detection unit, 13...three-phase / dq conversion unit, 14...angular velocity calculation unit, 15...current control unit, 16...dq / three-phase conversion unit, 17...PWM control unit, 20...flux command value generation unit, 21...flux linkage command calculator, 22...flux linkage command limit calculator, 23...flux linkage command limit restriction unit, 24...flux linkage calculator, 25...subtractor, 26...PI controller, 27...flux linkage compensation limit calculator, 28...flux linkage compensation limit restriction unit, 29...adder / subtractor, 20a...flux linkage optimal command limit calculator, 20b...subtractor, 20c...constant generator, 20d...limit limiter, 30...current command value generation unit

Claims

1. a magnetic flux command value generation unit that generates a magnetic flux command value based on a torque command value; a current command value generating unit that generates a current command value based on the magnetic flux command value; A motor control device comprising: the magnetic flux command value generating unit includes a magnetic flux linkage command calculator that calculates a magnetic flux linkage command value based on the torque command value; a flux linkage optimum command limit calculator for calculating a maximum flux linkage value that can be set for the torque command value; a flux linkage command limit calculator that calculates a limit flux by adding a predetermined value to the maximum flux linkage value; a limiter that limits an upper limit of the magnetic flux command value based on a difference between an output of the magnetic flux linkage command limit calculator and an output of the magnetic flux linkage optimum command limit calculator; A motor control device comprising:

2. 2. The motor control device according to claim 1, wherein the flux linkage command limit calculator is set by adding together a flux in an MTPA (Maximum Torque Per Ampere) control region and a flux having control toughness.

3. 3. The motor control device according to claim 2, further comprising a limiting unit, wherein the flux linkage optimum command limit calculator is configured as a one-dimensional map, and sets an optimum flux that becomes a maximum torque per ampere (MTPA) control region based on a torque command, calculates a difference between the output value of the flux linkage optimum command limit calculator, and limits the result to zero if the result is negative.

4. 4. The motor control device according to claim 3, wherein the flux linkage optimum command limit calculator is set at a flux in an MTPA (Maximum Torque Per Ampere) control region.

5. A power conversion device comprising the motor control device according to claim 1 or 2.

Images