JP5281370B2 - AC motor control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance stability in control by appropriate setting of current commands, in the control of an AC motor to which current feedback is applied. <P>SOLUTION: In the current feedback control of the AC motor, usually current commands on d axis and q axis are set to correspond to the intersection between a maximum torque control line 610, which is shown by the aggregate of current operating points 611-613 of such current phases that the output torque may be the largest to the same current amplitude, and an equal torque line 600, which corresponds to torque commands. On the other hand, in an operation state where it is feared that the disorder of a motor current might occur, current commands on d axis and q axis are set to correspond to the intersections between a control line 620 for avoidance, which is shown as the aggregate of current operating points 621, 622 and 623 the current phases of which are slid so as to enlarge field angles from each current operating point on the maximum torque control line 610, and an equal torque line 600, which corresponds to the torque commands. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a control device for an AC motor, and more particularly to control of an AC motor to which current feedback control according to a current command value set based on a torque command value is applied.

  In order to drive and control an AC motor using a DC power source, a driving method using an inverter is employed. The inverter is switching-controlled by an inverter drive circuit. For example, a voltage switched according to PWM control is applied to the AC motor.

  As described in Japanese Patent Application Laid-Open No. 11-332298 (Patent Document 1), in such AC motor control, current command values for the d-axis and the q-axis are set according to the required torque of the motor, and the current command In general, torque control is executed by feedback control of a motor current based on a value.

  In such current feedback control, Japanese Patent Application Laid-Open No. 2007-151336 (Patent Document 2) sets a current command value so as to select an optimum current phase that maximizes output torque for the same current amplitude. On the other hand, it is described that the current command value is set so that the current phase is changed from the optimum value in order to intentionally increase the power loss in the AC motor.

In addition to the above Patent Document 2, JP 2000-358393 A (Patent Document 3), JP 2007-159368 A (Patent Document 4) and JP 2007-20383 A (Patent Document 5) include: It is described that pulse width modulation (PWM control) including sine wave control and overmodulation control and rectangular wave voltage control are switched and applied according to the operating state of the AC motor.
JP-A-11-332298 JP 2007-151336 A JP 2000-358393 A JP 2007-159368 A JP 2007-20383 A

  As described above, in consideration of energy efficiency, the current command value in the pulse width modulation control is usually set in correspondence with the current phase that maximizes the output torque with respect to the motor current having the same amplitude. On the other hand, in the operation region at the boundary where the output (rotation speed / torque) of the motor is increased and switched from PWM control to rectangular wave voltage control, the control current becomes unstable due to the relatively large motor current. It is expected that current disturbance will increase when Particularly in such a region, the modulation rate (voltage utilization rate) defined by the ratio of the effective value of the motor applied voltage (line voltage) to the inverter input voltage also increases, so current control tends to be relatively unstable. .

  Generally, overmodulation PWM control in which the fundamental wave component amplitude of each phase voltage is larger than the carrier wave amplitude in PWM control is used in the boundary region with rectangular wave voltage control in the application region of PWM control. However, in overmodulation PWM control, the number of times of switching in the inverter is relatively small, so that the switching timing may be slightly shifted due to the influence of sensor error or the like, and the motor applied voltage may fluctuate and current control may become unstable. There is. Further, in the overmodulation PWM control, since harmonic components are superimposed on the motor current, the current feedback control is executed after filtering the motor current, so it is difficult to improve the control response. Yes.

  The present invention has been made to solve such problems, and an object of the present invention is to improve control stability by appropriately setting a current command value in AC motor control to which current feedback is applied. Is to increase.

  An AC motor control apparatus according to the present invention is an AC motor control apparatus in which an applied voltage is controlled by an inverter, and includes a current detector and a pulse width modulation control unit. The current detector is configured to detect a current flowing between the inverter and the AC motor. The pulse width modulation control unit generates an inverter control command by pulse width modulation control based on a comparison between an AC voltage command for operating the AC motor according to a torque command value and a carrier wave. The pulse width modulation control unit includes a sine wave modulation control unit and an overmodulation control unit. The sine wave modulation control unit is configured to generate a control command according to a deviation between the motor current detected by the current detector and the current command corresponding to the torque command value according to the sine wave pulse width modulation method. The The overmodulation control unit outputs a control command according to the motor current and the current deviation of the current command according to the overmodulation pulse width modulation method for outputting an applied voltage having a larger amplitude of the fundamental wave component than the sine wave pulse width modulation method. Configured to occur. The overmodulation control unit includes a current command generation unit, a voltage command generation unit, and a modulation unit. The current command generation unit is configured to generate a current command corresponding to the torque command value. The voltage command generation unit is configured to generate a voltage command in accordance with a deviation between the current command and the motor current. The modulation unit is configured to generate a control command based on a comparison between the voltage command and the carrier wave. The current command generation unit includes a first control line for setting a current command corresponding to the torque command value according to a current phase at which the torque of the AC motor is maximized with respect to the same current amplitude, and a first control line And selecting one of the second control lines for setting the current command corresponding to the torque command value according to the current phase in which the current amplitude with respect to the same torque becomes larger as compared with the AC motor, A current command corresponding to the torque command value is generated according to the selected control line.

  Preferably, when the AC motor is operating in a predetermined region of a high output corresponding to each voltage, among the operation regions defined by the voltage, torque and rotation speed of the AC motor, the current command generator is On the other hand, when the AC motor is operating outside the predetermined area, the first control line is selected.

  According to the above AC motor control device, when overmodulation PWM control is applied, the first control line (maximum torque control line) in which the output torque is maximum for the same motor current amplitude in the high output region of the AC motor. The current command corresponding to the torque command value can be set according to the second control line (avoidance control line) having a lower modulation rate (voltage utilization rate) than the same torque. As a result, it is possible to improve the stability of the motor control in the high output region.

  More preferably, the current command generation unit selects the second control line when the temperature of the AC motor is higher than the determination temperature, and selects the first control line when the temperature of the AC motor is equal to or lower than the determination temperature.

  In this case, the modulation rate is intended by selecting the second control line (avoidance control line) in an operating state in which the current behavior is likely to be unstable due to the effect of demagnetization accompanying an increase in motor temperature. Therefore, the motor control can be relatively stabilized based on the current command that has been reduced.

  A control device for an AC motor according to another aspect of the present invention is a control device for an AC motor in which an applied voltage is controlled by an inverter, and includes a current detector and a pulse width modulation control unit. The current detector is configured to detect a current flowing between the inverter and the AC motor. The pulse width modulation control unit generates an inverter control command by pulse width modulation control based on a comparison between an AC voltage command for operating the AC motor according to a torque command value and a carrier wave. The pulse width modulation control unit includes a sine wave modulation control unit and an overmodulation control unit. The sine wave modulation control unit is configured to generate a control command according to a deviation between the motor current detected by the current detector and the current command corresponding to the torque command value according to the sine wave pulse width modulation method. The The overmodulation control unit outputs a control command according to the motor current and the current deviation of the current command according to the overmodulation pulse width modulation method for outputting an applied voltage having a larger amplitude of the fundamental wave component than the sine wave pulse width modulation method. Configured to occur. The overmodulation control unit includes a current command generation unit, a voltage command generation unit, and a modulation unit. The current command generation unit is configured to generate a current command corresponding to the torque command value. The voltage command generation unit is configured to generate a voltage command in accordance with a deviation between the current command and the motor current. The modulation unit is configured to generate a control command based on a comparison between the voltage command and the carrier wave. The current command generation unit includes a first control line for setting a current command corresponding to the torque command value according to a current phase at which the torque of the AC motor is maximized with respect to the same current amplitude, and a first control line And selecting one of the second control lines for setting the current command corresponding to the torque command value according to the current phase in which the current amplitude with respect to the same torque is larger than the current torque, A current command corresponding to the torque command value is generated according to the selected control line.

  Preferably, the current command generation unit selects the second control line when the current deviation is larger than the determination value, and selects the first control line when the current deviation is equal to or less than the determination value.

  According to the control apparatus for an AC motor, when the current deviation due to the current feedback control becomes large, the modulation rate (voltage utilization rate) is equal to the same torque than the first control line (maximum torque control line). A current command corresponding to the torque command value can be set according to the low second control line (avoidance control line). As a result, the control stability can be improved by detecting a sign of instability of the current feedback control based on the current deviation and setting the motor control with a reduced modulation rate in the inverter.

  Preferably, the current command generation unit sets the current command so that the sinusoidal pulse width modulation method is applied in correspondence with a target torque lower than the torque command value when the current deviation is larger than the determination value. In addition to executing the process, a return process for generating a current command in accordance with the second control line is executed so as to gradually increase the torque from the target torque to the original torque command value after the execution of the evacuation process.

  In this way, when the current deviation is equal to or greater than the determination value and the current turbulence becomes large, the current control is stabilized by a saving process that reduces the torque to the operating point where the sine wave PWM control with high control stability is applied. The return torque of the AC motor can be returned to the original torque command value while ensuring the control stability by the return process of gradually increasing the torque along the second control line.

  More preferably, the current command includes a d-axis current command value and a q-axis current command value. Then, the current command generator generates torque according to the first map in which the torque command value and the set of the d-axis current command value and the q-axis current command value are associated in advance according to the first control line, and the second control line. The current command corresponding to the torque command value is generated by selectively referring to the second map in which the command value and the set of the d-axis current command value and the q-axis current command value are associated in advance.

  In this way, setting of the current command value according to the first or second control line can be realized by referring to a map in which the torque value is associated with a set of d-axis and q-axis current command values in advance. it can.

  More preferably, the current command includes a d-axis current command value and a q-axis current command value. Then, when the first control line is selected, the current command generator generates a first map in which a set of a torque command value, a d-axis current command value, and a q-axis current command value is associated in advance according to the first control line. While generating the current command by reference, when selecting the second control line, by multiplying one of the d-axis current command value and the q-axis current command value obtained by referring to the first map by the adjustment coefficient One current command value is generated, and on the basis of the one current command value and the torque command value, the other current command value is generated according to the combination of the d-axis current command value and the q-axis current command value for realizing the torque command value. A current command value is generated.

  In this case, the current according to the second control line (avoidance control line) is based on the multiplication of the adjustment coefficient to the current command value according to the uniquely determined first control line (maximum torque control line). A command value can be generated. As a result, since the second control line can be adjusted using only the adjustment coefficient as a parameter, adaptation of the second control line can be simplified.

  According to the present invention, in AC motor control to which current feedback is applied, control stability can be improved by appropriately setting the current command value.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

[Embodiment 1]
(General configuration of motor control)
FIG. 1 is an overall configuration diagram of a motor drive control system to which an AC motor control device according to an embodiment of the present invention is applied.

  Referring to FIG. 1, motor drive control system 100 includes a DC voltage generation unit 10 #, a smoothing capacitor C0, an inverter 14, an AC motor M1, and a control device 30.

  For example, AC electric motor M1 generates torque for driving drive wheels of an electric vehicle (referred to as a vehicle that generates vehicle driving force by electric energy such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle). This is an electric motor for driving. Alternatively, AC electric motor M1 may be configured to have a function of a generator driven by an engine, or may be configured to have both functions of an electric motor and a generator. Further, AC electric motor M1 may operate as an electric motor for the engine, and may be incorporated in a hybrid vehicle as one that can start the engine, for example. That is, in the present embodiment, the “AC motor” includes an AC drive motor, a generator, and a motor generator (motor generator).

  DC voltage generation unit 10 # includes a DC power supply B, system relays SR1 and SR2, a smoothing capacitor C1, and a converter 12.

  The DC power supply B is typically constituted by a secondary battery such as nickel metal hydride or lithium ion, or a power storage device such as an electric double layer capacitor. The DC voltage Vb output from the DC power supply B and the input / output DC current Ib are detected by the voltage sensor 10 and the current sensor 11, respectively.

  System relay SR 1 is connected between the positive terminal of DC power supply B and power line 6, and system relay SR 1 is connected between the negative terminal of DC power supply B and ground line 5. System relays SR1 and SR2 are turned on / off by signal SE from control device 30.

  Converter 12 includes a reactor L1, power semiconductor switching elements Q1, Q2, and diodes D1, D2. Power semiconductor switching elements Q 1 and Q 2 are connected in series between power line 7 and ground line 5. On / off of power semiconductor switching elements Q 1 and Q 2 is controlled by switching control signals S 1 and S 2 from control device 30.

In the embodiment of the present invention, as a power semiconductor switching element (hereinafter, simply referred to as “switching element”), an IGBT (Insulated Gate Bipolar Transistor),
A power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used. Anti-parallel diodes D1, D2 are arranged for switching elements Q1, Q2. Reactor L1 is connected between a connection node of switching elements Q1 and Q2 and power line 6. Further, the smoothing capacitor C 0 is connected between the power line 7 and the ground line 5.

  Inverter 14 includes a U-phase upper and lower arm 15, a V-phase upper and lower arm 16, and a W-phase upper and lower arm 17 provided in parallel between power line 7 and ground line 5. Each phase upper and lower arm is constituted by a switching element connected in series between the power line 7 and the ground line 5. For example, the U-phase upper and lower arms 15 are composed of switching elements Q3 and Q4, the V-phase upper and lower arms 16 are composed of switching elements Q5 and Q6, and the W-phase upper and lower arms 17 are composed of switching elements Q7 and Q8. Further, antiparallel diodes D3 to D8 are connected to switching elements Q3 to Q8, respectively. Switching elements Q3 to Q8 are turned on / off by switching control signals S3 to S8 from control device 30.

  Typically, AC motor M1 is a three-phase permanent magnet type synchronous motor, and is configured by commonly connecting one end of three coils of U, V, and W phases to a neutral point. Furthermore, the other end of each phase coil is connected to the midpoint of the switching elements of the upper and lower arms 15 to 17 of each phase.

  Converter 12 is basically controlled such that switching elements Q1 and Q2 are turned on and off in a complementary manner in each switching period. During the boosting operation, converter 12 boosts DC voltage Vb supplied from DC power supply B to DC voltage VH (hereinafter, this DC voltage corresponding to the input voltage to inverter 14 is also referred to as “system voltage”). This step-up operation is performed by supplying the electromagnetic energy stored in reactor L1 during the ON period of switching element Q2 to power line 7 via switching element Q1 and antiparallel diode D1.

  Further, converter 12 steps down DC voltage VH to DC voltage Vb during the step-down operation. This step-down operation is performed by supplying the electromagnetic energy accumulated in the reactor L1 during the ON period of the switching element Q1 to the power line 6 via the switching element Q2 and the antiparallel diode D2. The voltage conversion ratio (ratio of VH and Vb) in these step-up or step-down operations is controlled by the on-period ratio (duty ratio) of the switching elements Q1 and Q2 with respect to the switching period. If switching elements Q1 and Q2 are fixed to ON and OFF, respectively, VH = Vb (voltage conversion ratio = 1.0) can be obtained.

  Smoothing capacitor C 0 smoothes the DC voltage from converter 12 and supplies the smoothed DC voltage to inverter 14. The voltage sensor 13 detects the voltage across the smoothing capacitor C 0, that is, the system voltage VH, and outputs the detected value to the control device 30.

  When the torque command value of AC motor M1 is positive (Trqcom> 0), inverter 14 responds to switching control signals S3 to S8 from control device 30 when a DC voltage is supplied from smoothing capacitor C0. AC motor M1 is driven so as to output a positive torque by converting a DC voltage into an AC voltage by switching operation of elements Q3 to Q8. Further, when the torque command value of AC electric motor M1 is zero (Trqcom = 0), inverter 14 converts the DC voltage to the AC voltage by the switching operation in response to switching control signals S3 to S8, and the torque is zero. The AC motor M1 is driven so that Thus, AC electric motor M1 is driven to generate zero or positive torque designated by torque command value Trqcom.

  Further, during regenerative braking of an electric vehicle equipped with motor drive control system 100, torque command value Trqcom of AC electric motor M1 is set to a negative value (Trqcom <0). In this case, the inverter 14 converts the AC voltage generated by the AC motor M1 into a DC voltage by a switching operation in response to the switching control signals S3 to S8, and converts the converted DC voltage (system voltage) to the smoothing capacitor C0. To the converter 12 via The regenerative braking here refers to braking with regenerative power generation when the driver operating the electric vehicle performs a footbrake operation, or regenerative braking by turning off the accelerator pedal while driving, although the footbrake is not operated. This includes decelerating (or stopping acceleration) the vehicle while generating electricity.

  Current sensor 24 detects motor current MCRT flowing through AC electric motor M <b> 1 and outputs the detected motor current to control device 30. Since the sum of instantaneous values of the three-phase currents iu, iv, and iw is zero, the current sensor 24 has a motor current for two phases (for example, a V-phase current iv and a W-phase current iw) as shown in FIG. It is sufficient to arrange it so as to detect.

  The rotation angle sensor (resolver) 25 detects the rotor rotation angle θ of the AC electric motor M 1 and sends the detected rotation angle θ to the control device 30. Control device 30 can calculate the rotational speed (rotational speed) and angular speed ω (rad / s) of AC electric motor M1 based on rotational angle θ. Note that the rotation angle sensor 25 may be omitted by directly calculating the rotation angle θ from the motor voltage or current by the control device 30.

  The control device 30 is configured by an electronic control unit (ECU), and performs software processing by executing a program stored in advance by a CPU (not shown) and / or hardware processing by a dedicated electronic circuit. Control the behavior.

  As a representative function, the control device 30 includes the input torque command value Trqcom, the DC voltage Vb detected by the voltage sensor 10, the DC current Ib detected by the current sensor 11, and the system voltage detected by the voltage sensor 13. Based on VH, motor currents iv and iw from current sensor 24, rotation angle θ from rotation angle sensor 25, etc., AC motor M1 outputs torque according to torque command value Trqcom by a control method described later. The operations of the converter 12 and the inverter 14 are controlled. That is, switching control signals S1 to S8 for controlling converter 12 and inverter 14 as described above are generated and output to converter 12 and inverter 14.

  During the boost operation of converter 12, control device 30 performs feedback control of system voltage VH, and generates switching control signals S1 and S2 so that system voltage VH matches the voltage command value.

  In addition, when control device 30 receives signal RGE indicating that the electric vehicle has entered the regenerative braking mode from an external ECU, switching control signal S3-3 converts AC voltage generated by AC motor M1 into DC voltage. S8 is generated and output to the inverter 14. Thereby, the inverter 14 converts the AC voltage generated by the AC motor M <b> 1 into a DC voltage and supplies it to the converter 12.

  Further, when receiving a signal RGE indicating that the electric vehicle has entered the regenerative braking mode from the external ECU, control device 30 generates switching control signals S1 and S2 so as to step down the DC voltage supplied from inverter 14. And output to the converter 12. As a result, the AC voltage generated by AC motor M1 is converted to a DC voltage, stepped down, and supplied to DC power supply B.

(Description of control mode)
The control of AC motor M1 by control device 30 will be described in further detail.

  FIG. 2 is a diagram schematically illustrating a control mode of AC electric motor M1 in the motor drive system according to the embodiment of the present invention.

  As shown in FIG. 2, in the motor drive control system 100 according to the embodiment of the present invention, three control modes are switched and used for control of the AC motor M1, that is, power conversion in the inverter.

  The sine wave PWM control is used as a general PWM control, and controls on / off of each phase upper and lower arm elements according to a voltage comparison between a sine wave voltage command and a carrier wave (typically a triangular wave). . As a result, for a set of a high level period corresponding to the on period of the upper arm element and a low level period corresponding to the on period of the lower arm element, the duty is set so that the fundamental wave component becomes a sine wave within a certain period. Is controlled. As is well known, in the sinusoidal PWM control in which the amplitude of the sinusoidal voltage command is limited to a range below the carrier wave amplitude, the fundamental wave of the applied voltage to the AC motor M1 (hereinafter also simply referred to as “motor applied voltage”). The component can only be increased to about 0.61 times the DC link voltage of the inverter. Hereinafter, in this specification, the ratio of the fundamental component (effective value) of the motor applied voltage (line voltage) to the DC link voltage (that is, the system voltage VH) of the inverter 14 is referred to as “modulation rate”.

  On the other hand, in the rectangular wave voltage control, an AC motor is applied for one pulse of a rectangular wave whose ratio between the high level period and the low level period is 1: 1 within the predetermined period. As a result, the modulation rate is increased to 0.78.

  The overmodulation PWM control performs PWM control similar to the sine wave PWM control in a range where the amplitude of the voltage command (sine wave component) is larger than the carrier wave amplitude. In particular, the fundamental wave component can be increased by distorting the voltage command from the original sine wave waveform (amplitude correction), and the modulation rate is increased from the maximum modulation rate in the sine wave PWM control mode to a range of 0.78. Can do. In overmodulation PWM control, since the amplitude of the voltage command (sine wave component) is greater than the carrier wave amplitude, the line voltage applied to AC motor M1 is not a sine wave but a distorted voltage.

  In the AC motor M1, the induced voltage increases as the rotational speed and output torque increase, so that the required drive voltage (motor required voltage) increases. The boosted voltage by the converter 12, that is, the system voltage VH needs to be set higher than the required voltage of the motor. On the other hand, there is a limit value (VH maximum voltage) in the boosted voltage by converter 12, that is, system voltage VH.

  Therefore, a PWM control mode by sine wave PWM control or overmodulation PWM control that controls the amplitude and phase of the motor applied voltage (AC) by feedback of the motor current according to the operating state of AC motor M1, and rectangular wave voltage One of the control modes is selectively applied. In the rectangular wave voltage control, since the amplitude of the motor applied voltage is fixed, the torque control is executed by the phase control of the rectangular wave voltage pulse based on the deviation between the actual torque value and the torque command value.

FIG. 3 shows the correspondence between the operating state of AC electric motor M1 and the control mode described above.
Referring to FIG. 3, schematically, sinusoidal PWM control is used in order to reduce the torque fluctuation in the low rotational speed range A1, overmodulation PWM control in the intermediate rotational speed range A2, and in the high rotational speed range A3. Square wave voltage control is applied. In particular, application of overmodulation PWM control and rectangular wave voltage control can improve the output of AC electric motor M1. As described above, which one of the control modes shown in FIG. 2 is used is basically determined within the range of the realizable modulation rate.

(Description of control configuration in each control mode)
FIG. 4 is a block diagram illustrating a motor control configuration based on sinusoidal PWM control, which is a basic control configuration by the AC motor control apparatus according to the embodiment of the present invention. Each functional block for motor control described in the block diagrams described below including FIG. 4 is realized by hardware or software processing by the control device 30.

  Referring to FIG. 4, sine wave PWM control unit 200 switches switching control signals S <b> 3 to S <b> 3 of inverter 14 such that AC motor M <b> 1 outputs torque according to torque command value Trqcom when sine wave PWM control mode is selected. S8 is generated.

  The sine wave PWM control unit 200 includes a current command generation unit 210, coordinate conversion units 220 and 250, a voltage command generation unit 240, and a PWM modulation unit 260.

  Current command generation unit 210 generates a d-axis current command value Idcom and a q-axis current command value Iqcom corresponding to torque command value Trqcom of AC electric motor M1 according to a map created in advance. The generation of current command values Idcom and Iqcom by the current command generation unit 210 will be described in detail later.

  The coordinate conversion unit 220 converts the v-phase current v and W-phase detected by the current sensor 24 by coordinate conversion using the rotation angle θ of the AC motor M1 detected by the rotation angle sensor 25 (3 phase → 2 phase). Based on the current iw, a d-axis current Id and a q-axis current Iq are calculated.

  Deviation ΔId (ΔId = Idcom−Id) relative to the command value of the d-axis current and deviation ΔIq (ΔIq = Iqcom−Iq) relative to the command value of the q-axis current are input to the voltage command generation unit 240. The voltage command generation unit 240 obtains a control deviation by performing PI (proportional integration) calculation with a predetermined gain for each of the d-axis current deviation ΔId and the q-axis current deviation ΔIq, and a d-axis voltage command value corresponding to the control deviation. Vd # and q-axis voltage command value Vq # are generated.

  The coordinate conversion unit 250 converts the d-axis voltage command value Vd # and the q-axis voltage command value Vq # into the U-phase, V-phase, W-phase by coordinate conversion (2 phase → 3 phase) using the rotation angle θ of the AC motor M1. Each phase voltage command Vu, Vv, Vw of the phase is converted.

  As shown in FIG. 5, the PWM modulation unit 260 is based on a comparison between the carrier wave 262 and the AC voltage command 264 (which comprehensively indicates Vu, Vv, Vw). By controlling on / off, a pseudo sine wave voltage is generated in each phase of AC electric motor M1. The carrier wave 262 is constituted by a triangular wave or a sawtooth wave having a predetermined frequency.

  In the PWM modulation for inverter control, the amplitude of the carrier wave 262 corresponds to the input DC voltage (system voltage VH) of the inverter 14. However, if the amplitude of the AC voltage command 264 to be PWM-modulated is converted into one obtained by dividing the amplitude of each original phase voltage command Vu, Vv, Vw by the system voltage VH, the amplitude of the carrier wave 262 used in the PWM modulation unit 260 is changed. Can be fixed.

  Referring to FIG. 4 again, the inverter 14 is subjected to switching control in accordance with the switching control signals S3 to S8 generated by the sine wave PWM control unit 200, whereby the torque according to the torque command value Trqcom is applied to the AC motor M1. An AC voltage for outputting is applied.

  FIG. 6 is a block diagram illustrating a motor control configuration based on rectangular wave voltage control that is executed when the rectangular wave voltage control mode is applied.

  Referring to FIG. 6, rectangular wave voltage control unit 400 includes a power calculation unit 410, a torque calculation unit 420, a PI calculation unit 430, a rectangular wave generator 440, and a signal generation unit 450.

  The power calculation unit 410 uses the phase currents obtained from the V-phase current iv and the W-phase current iw by the current sensor 24 and the voltages (u-phase, v-phase, w-phase) voltages Vu, Vv, Vw as follows ( 1) Calculate the power supplied to the motor (motor power) Pmt according to the equation (1). At this time, filter processing for removing distortion components from the detected motor current (iv, iw) is also executed.

Pmt = iu · Vu + iv · Vv + iw · Vw (1)
The torque calculation unit 420 uses the motor power Pmt obtained by the power calculation unit 410 and the angular velocity ω calculated from the rotation angle θ of the AC electric motor M1 detected by the rotation angle sensor 25, according to the following equation (2). Estimated value Tq is calculated.

Tq = Pmt / ω (2)
Torque deviation ΔTq (ΔTq = Trqcom−Tq) with respect to torque command value Trqcom is input to PI calculation unit 430. PI calculation unit 430 performs PI calculation with a predetermined gain on torque deviation ΔTq to obtain a control deviation, and sets phase φv of rectangular wave voltage according to the obtained control deviation. Specifically, when positive torque is generated (Trqcom> 0), the voltage phase is advanced when torque is insufficient, while when the torque is excessive, the voltage phase is delayed, and when negative torque is generated (Trqcom <0), the voltage phase is increased when torque is insufficient While delaying, the voltage phase is advanced when the torque is excessive.

  The rectangular wave generator 440 generates each phase voltage command value (rectangular wave pulse) Vu, Vv, Vw according to the voltage phase φv set by the PI calculation unit 430. The signal generator 450 generates switching control signals S3 to S8 according to the phase voltage command values Vu, Vv, and Vw. When inverter 14 performs a switching operation according to switching control signals S3 to S8, a rectangular wave pulse according to voltage phase φv is applied as each phase voltage of the motor.

  As described above, in the rectangular wave voltage control method, the motor torque control can be performed by the feedback control of the torque (electric power). However, since the operation amount of the motor applied voltage is only the phase in the rectangular wave voltage control method, the control responsiveness is reduced as compared with the PWM control method in which the amplitude and phase of the motor applied voltage can be the operation amount.

  Note that a torque deviation ΔTq may be obtained based on a detection value of the torque sensor by arranging a torque sensor instead of the power calculation unit 410 and the torque calculation unit 420.

  FIG. 7 is a block diagram for explaining a general example of a motor control configuration based on overmodulation PWM control.

  Referring to FIG. 7, overmodulation PWM control unit 201 includes a current filter 230 and a voltage amplitude correction unit 270 in addition to the configuration of sine wave PWM control unit 200 shown in FIG. 4.

  The current filter 230 executes a process of smoothing the d-axis current Id and the q-axis current Iq calculated by the coordinate conversion unit 220 in the time axis direction. Thereby, the actual currents Id and Iq based on the sensor detection values are converted into the filtered currents Idf and Iqf.

  In the overmodulation PWM control unit 201, the current deviations ΔId and ΔIq are calculated using the filtered currents Idf and Iqf. That is, ΔId = Idcom−Idf and ΔIq = Iqcom−Iqf.

  Voltage amplitude correction unit 270 performs correction processing for expanding the amplitude of the motor applied voltage with respect to original d-axis voltage command value Vd # and q-axis voltage command value Vq # calculated by voltage command generation unit 240. Execute. The coordinate conversion unit 250 and the modulation unit 260 generate the switching control signals S3 to S8 of the inverter 14 in accordance with the voltage command subjected to the correction process by the voltage amplitude correction unit 270.

  When the overmodulation PWM control is applied, the amplitude of each phase voltage command obtained by converting the voltage command values Vd # and Vq # into two-phase to three-phase is larger than the inverter input voltage (system voltage VH). This state corresponds to a state in which the amplitude of the AC voltage command 264 is larger than the amplitude of the carrier wave 262 in the waveform diagram shown in FIG. In this case, since the inverter 14 cannot apply a voltage exceeding the system voltage VH to the AC motor M1, the PWM according to each phase voltage command signal according to the original voltage command values Vd # and Vq #. Depending on the control, the original modulation rate corresponding to the voltage command values Vd # and Vq # cannot be secured.

Therefore, with respect to the AC voltage command based on the voltage command values Vd # and Vq #, the voltage command is performed by performing a correction process for expanding the voltage amplitude (× k times, k> 1) so that the voltage application interval is increased. The original modulation rate based on the values Vd # and Vq # can be secured. The voltage amplitude expansion ratio k in the voltage amplitude correction unit 270 can be theoretically derived based on the original modulation rate.
(Setting of current command value in PWM control)
In the PWM control including the sine wave PWM control shown in FIG. 4 and the overmodulation PWM control shown in FIG. 7, AC motor control is executed according to the processing procedure shown in FIG. Note that the control processing at each step in each flowchart described below is either software processing by execution of a predetermined program (subroutine) by the control device 30 or hardware processing in which a dedicated electronic circuit is constructed. Can be realized.

  Referring to FIG. 8, in step S100, control device 30 sets torque command value Trqcom in accordance with an output request to AC electric motor M1, and further, in step S200, control device 30 sets current command value Idcom, corresponding to torque command value Trqcom, Iqcom is determined. That is, the processing in step S200 corresponds to the function of current command generation unit 210 in FIGS.

  Further, in step S300, control device 30 determines a voltage command value based on a current deviation between current command values Idcom, Iqcom set in step S200 and d-axis current Id and q-axis current Iq converted from the motor current. Vd # and Vq # are determined. That is, the process of step S300 corresponds to the function of voltage command generation unit 240 in FIGS.

  In step S400, control device 30 converts input voltage VH of inverter 14 into a voltage applied to AC motor M1 based on voltage command values Vd # and Vq # obtained in step S300 and system voltage VH. The modulation rate when calculating is calculated. For example, the modulation rate FM is calculated by the following equation (3).

FM = (Vd # ² + Vq # ² ) ^1/2 / VH (3)
In step S500, control device 30 further determines a control mode in accordance with the modulation factor calculated in step S400. Specifically, when the modulation rate ≧ 0.78, the control mode switching from PWM control to rectangular wave voltage control is instructed. When the modulation rate <0.78, the calculated modulation rate is compared with a predetermined determination value (for example, 0.61 which is the theoretical value of the upper limit of the modulation rate to which the sine wave PWM control can be applied). Either sine wave PWM control or overmodulation PWM control is selected.

  In step S600, control device 30 generates a switching command (switching control signals S3 to S8) for inverter 14 based on voltage command values Vd # and Vq # in accordance with the control mode determined in step S500. That is, the process of step S600 corresponds to the functions of the coordinate conversion unit 250 and the PWM modulation unit 260 in FIG. 4, or the functions of the voltage amplitude correction unit 270, the coordinate conversion unit 250, and the PWM modulation unit 260 in FIG.

  Thus, in the PWM control, current command values Idcom and Iqcom are generated from the torque command value Trqcom, and current feedback control using the current command value as a reference value is executed. The AC motor control according to the present embodiment is characterized in that the setting of such a current command value is switched according to the operating state or control state of the AC motor M1.

  FIG. 9 is a flowchart illustrating a procedure for setting a current command value in AC motor control according to the first embodiment of the present invention. That is, FIG. 9 explains details of step S200 of FIG.

  Referring to FIG. 9, control device 30 determines an operation region of AC electric motor M <b> 1 in step S <b> 212. For example, as shown in FIG. 10, the operation region is defined by the voltage, torque, and rotation speed of AC electric motor M1, and the predetermined high output region 500 in region A2 to which overmodulation PWM control is applied. When the operating point (torque, rotation speed) of AC electric motor M1 exists, step S212 (FIG. 9) is determined as YES, while when the operating point of AC electric motor M1 is outside the high output region 500, Step S212 can be determined as NO. Note that the torque command value Trqcom may be used for the torque for determining the operating point. Further, the high output region 500 is set according to the voltage of AC motor M1 (specifically, system voltage VH that is an inverter input voltage corresponding to the amplitude of the voltage applied to AC motor M1).

  Referring to FIG. 9 again, in step S214, control device 30 further determines the temperature (motor temperature) of AC electric motor M1. For example, regarding the determination in step S214, when the temperature detected by a temperature sensor (not shown) arranged to measure the temperature of the stator coil and lubricating oil of AC electric motor M1 rises above a predetermined determination temperature. While it is determined as YES, it can be determined as NO when it is not.

  For example, when the AC motor M1 is a permanent magnet motor, this determination temperature can be set in correspondence with a temperature region in which demagnetization due to a temperature increase of the permanent magnet occurs. That is, the motor temperature is preferably an estimated temperature of the magnet temperature.

  Control device 30 avoids by step S230 when AC electric motor M1 is operating in high output region 500 (YES at S212) and the motor temperature is rising (YES at S214). Adopt control line. On the other hand, the controller 30 increases the motor temperature when the AC motor M1 is not operating in the high output region 500 (NO in S212) or even when the AC motor M1 is operating in the high output region 500. If not (NO in S214), the process proceeds to step S240 to employ the maximum torque control line.

  Note that the temperature determination in step S214 can be omitted. However, by adding the temperature determination, the current behavior becomes unstable due to the effect of demagnetization accompanying the increase in the motor temperature during operation in the high output region 500. It is possible to employ an avoidance control line that reduces the motor efficiency by narrowing down in an easy operation state.

  Next, the maximum torque control line and the avoidance control line will be described with reference to FIG.

  Referring to FIG. 11, a current operating point is indicated by a combination of current command values Idcom and Iqcom on a plane having a d-axis current on the horizontal axis and a q-axis current on the vertical axis. An isotorque line 600 is drawn by a set of current operating points for realizing the same torque. FIG. 11 representatively shows an equal torque line when output torque = T1, T2, and T3.

  Thus, when the current command values Idcom and Iqcom are generated in correspondence with the torque command value Trqcom, one of the current operation points on the equal torque line 600 is selected, and there is a degree of freedom of selection. It will be. Here, for each equal torque line 600, the current operating points 611, 612, and 613 at which the distance from the origin is the minimum, that is, the set of current operating points at a current phase that maximizes the output torque of the AC motor M1. The maximum torque control line 610 is uniquely defined. If the current command values Idcom and Iqcom are set according to the maximum torque control line 610, the current operating point is set at a current phase at which the current amplitude is minimized with respect to the same torque output.

  Basically, since the maximum torque control line 610 can be determined by prior analysis, the torque command value Trqcom is used as an argument according to the current operation point corresponding to the intersection of each equal torque line 600 and the maximum torque control line 610. A map for extracting the current command values Idcom and Iqcom can be configured.

  On the other hand, on each equal torque line 600, current operating points 621, 622, 623 are shifted from the current operating points 611, 612, 613 on the maximum torque control line 610 so as to increase the field angle. As a set, an avoidance control line 620 is defined.

  Compared with the current operating point on the maximum torque control line 610, the current operating point on the avoidance control line 620 increases the current amplitude for the same torque output. Therefore, from the viewpoint of energy efficiency, it is preferable to set the current command values Idcom and Iqcom according to the maximum torque control line 610. On the other hand, from the viewpoint of stabilizing the control operation by suppressing the current disturbance, the avoidance control is performed. It is advantageous to set the current command values Idcom and Iqcom according to the line 620.

  Also, at the current operating point on the avoidance control line 620, the modulation factor (voltage utilization factor) is lower than the current operating point on the maximum torque control line 610 for the same torque output for the following reason. Become.

  As is well known, the voltage equations on the d and q axes of the AC motor M1 are represented by the following (4) and (5). In the equations (4) and (5), R represents armature winding resistance, Ld and Lq represent d-axis and q-axis inductances, and Ψ represents the number of armature linkage magnetic fluxes of the permanent magnet. . Further, ω represents the electrical angular velocity of the AC motor M1, and can be obtained by ω = 2π · (Nm / 60) · P) using the motor rotation speed Nm (rpm) (P: the AC motor M1) Number of pole pairs).

Vd = R · Id + L · (dId / dt) −ω · Lq · Iq (4)
Vq = R · Iq + L · (dIq / dt) + ω · Ld · Id + ω · Ψ (5)
As can be seen from FIG. 11, the movement from the maximum torque control line 610 to the avoidance control line 620 for the same torque decreases the absolute value of the q-axis current while increasing the absolute value of the d-axis current. .

  In the equations (4) and (5), since the voltage component depending on the winding resistance R contributes in a very low speed region, the first term can be ignored, and in the examination of the steady operating point, the second term is used. Terms can also be ignored. In the equation (5), in general, | ω · Ld · Id | <| ω · Ψ |

Therefore, from the equation (4), the decrease in the absolute value of the q-axis current leads to a decrease in Vd ² , and from the equation (5), considering that the increase in the absolute value of the d-axis current is Id <0, It leads to a reduction of Vq ^2. As a result, for the same torque, the modulation factor expressed by the expression (3) is lower at the current operating point on the avoidance control line 620 than at the current operating point on the maximum torque control line 610.

  Since the avoidance control line 620 can also be obtained based on the actual machine experiment results, the torque command value Trqcom is determined according to the current operation point corresponding to the intersection of each equal torque line 600 and the avoidance control line 620. It is possible to configure a map for extracting current command values Idcom and Iqcom as arguments.

  As a result, when it is determined in steps S230 and S240 in FIG. 9 which of the avoidance control line and the maximum torque control line is to be adopted, the current command corresponding to the torque command value Trqcom is determined according to the flowchart shown in FIG. Values Idcom and Iqcom can be set.

  Referring to FIG. 12, in step S250, control device 30 determines whether or not the avoidance control line is applied in accordance with steps S230 and S240. Then, when the avoidance control line is applied (YES in S250), the control device 30 refers to the avoidance control line map in step S251 to refer to the current on the avoidance control line 620 (FIG. 11). Current command values Idcom and Iqcom corresponding to the torque command value Trqcom are generated so as to select the operating point.

  In contrast, when applying the maximum torque control line (when NO is determined in S250), control device 30 refers to the maximum torque control line map 610 (FIG. 11) by referring to the map for maximum torque control line in step S252. Current command values Idcom and Iqcom corresponding to the torque command value Trqcom are generated so as to select the upper current operating point.

  As described above, according to AC motor control according to the first embodiment, during PWM control in which current feedback control is performed, particularly during overmodulation PWM control with a relatively high output, it depends on the operating state of AC motor M1. Thus, it is possible to preventively apply current feedback control in which a current operating point (current command values Idcom, Iqcom) at which the modulation factor (voltage utilization factor) in the inverter 14 decreases is set. As a result, in an operating state where the output level of AC electric motor M1 is high, such as when operating in high output region 500 (FIG. 10) or when the motor temperature is rising, and there is a concern that the motor current may be disturbed, Control stability can be improved by appropriately setting the current command value so as to prevent the occurrence.

[Modification of Embodiment 1]
As shown in FIG. 12, the current command values Idcom and Iqcom according to the avoidance control line 620 can be generated by referring to a map created in advance. However, while the maximum torque control line 610 is uniquely determined, the setting of the avoidance control line 620 needs to be adjusted in consideration of the balance between the decrease in the modulation factor and the stability of the current control. For this reason, if both the current command values Idcom and Iqcom are mapped on the avoidance control line 620, there is a concern that the adjustment load increases.

  Therefore, in the modification of the first embodiment, a method will be described in which the adjustment load is reduced for the generation of the current command value according to the avoidance control line 620. In the modification of the first embodiment, only the generation of the current command values Idcom and Iqcom corresponding to the torque command value Trqcom, selected by the maximum torque control line 610 and the avoidance control line 620, is the same as in the first embodiment. Since they are different, description of other common parts will not be repeated.

  FIG. 13 is a flowchart illustrating a modification of the current command value setting processing procedure according to the control line selection result, as compared with FIG.

  Referring to FIG. 13, in the modification of the first embodiment, control device 30 executes steps S245, S250, S253 to S255 described below instead of steps S250 to S252 in FIG.

  When the control line adopted in step S230 or S240 (FIG. 9) is determined, control device 30 refers to the above-described maximum torque control line map and corresponds to torque command value Trqcom in step S245. Map values Idcom (M) and Iqcom (M) of current command values Idcom, Iqcom are read in accordance with maximum torque control line 610 (FIG. 11).

  Then, in step S250, the control device 30 determines whether or not the avoidance control line is applied. When maximum torque control is applied (NO in S250), control device 30 proceeds to step S253, and generates current command values Idcom and Iqcom using the map values read in step S245 as they are. To do. That is, Idcom = Idcom (M) and Iqcom = Iqcom (M) are set.

  In contrast, when the avoidance control line is applied (YES in S250), control device 30 advances the process to step S253, and sets one current command value of current command values Idcom and Iqcom to step S253. This is determined by correcting the map value read in S245. For example, for the d-axis current, Idcom = Idcom (M) · k (k> 1).

  Then, control device 30 can proceed to step S254 to realize torque command value Trqcom by a combination with d-axis current command value Idcom (one current command value) determined in step S253. The q-axis current command value (the other current command value) is calculated backward. This reverse calculation operation corresponds to obtaining the other of Id and Iq when one of Id and Iq is determined on the equal torque line 600 shown in FIG. According to this reverse calculation result, the other current command value that forms a pair with one current command value determined in step S253 is determined.

  Here, with regard to the above reverse calculation processing, an equal torque conversion map is created in advance, in which one current command value and torque command value are used as arguments, and the other current command value for realizing the torque command value is extracted. It can be realized by doing. As described above, the equal torque conversion map can be configured based on the equal torque line 600 on FIG.

  Alternatively, in steps S254 and S255, contrary to the above, in step S253, Iqcom = Iqcom (M) · k ′ (k ′ <1) is determined, and in step S254, the q-axis current command value Iqcom and the torque command are determined. The d-axis current command value Idcom may be obtained from the value Trqcom. Even in this case, the current command values Idcom and Iqcom are generated so as to set the current operation points 621 to 623 (FIG. 11) where the modulation rate in the inverter 14 is lower than that of the maximum torque control line 610. be able to.

  In this way, by setting only the coefficient k (or k ′), it is possible to set the avoidance control line 620 in consideration of the relationship between the degree of decrease in the modulation rate and the stability of the current control. As a result, the adjustment load for determining the current operating point can be reduced as compared with the method of directly mapping the combination of the current command values Idcom and Iqcom.

[Embodiment 2]
In the first embodiment, the control configuration for preventing the switching from the maximum torque control line to the avoidance control line in the operating state of AC electric motor M1 in which current disturbance is likely to occur has been described. In the following, a control configuration that considers switching from the maximum torque control line to the avoidance control line to the minimum according to the actual control state will be described.

  In the AC motor control according to the second embodiment, the selection of the avoidance control line and the maximum torque control line in generating the current command values Idcom and Iqcom is replaced with the flowchart of FIG. 9 as compared with the first embodiment. The difference is that it is executed according to the flowchart shown in FIG. The description of other parts common to the first embodiment will not be repeated.

  FIG. 14 is a flowchart illustrating a procedure for setting a current command value in AC motor control according to the second embodiment of the present invention.

  Referring to FIG. 14, in step S <b> 220, control device 30 determines the presence or absence of actual current disturbance by comparing the current deviation with a predetermined determination value. In step S220, the current disturbance may be detected when both the d-axis current and the current deviation of the q-axis current exceed the respective determination values, or one of the current deviation of the d-axis current and the q-axis current. The current disturbance may be detected when the value exceeds the determination value.

  When current disturbance occurs (YES in S220), control device 30 employs the avoidance control line in step S230, while when current disturbance does not occur (NO in S220), step S240. By adopting the maximum torque control line.

  When it is determined in step S230 or S240 which of the avoidance control line / maximum torque control line is to be adopted, according to the flowchart of FIG. 12 or FIG. 13 described above, as in the first embodiment or its modification, Current command values Idcom and Iqcom corresponding to the torque command value Trqcom can be generated.

  According to the AC motor control according to the second embodiment, the avoidance control line is employed only when current disturbance actually occurs. Therefore, the control stability is controlled by setting the current command value so that the modulation rate is intentionally reduced when current disturbance occurs while minimizing the use of avoidance control lines that reduce efficiency. Can be increased.

[Embodiment 3]
FIG. 15 is a flowchart illustrating a procedure for setting a current command value in AC motor control according to the third embodiment of the present invention. Also in the AC motor control according to the third embodiment, the description common to the first embodiment will not be repeated.

  Referring to FIG. 15, control device 30 determines whether or not current disturbance has occurred based on the current deviation in step S <b> 220 similar to FIG. 14.

  When current turbulence does not occur (NO in S220), the process proceeds to step S290, and the control is continued using the maximum torque control line. That is, according to the flowchart of FIG. 12 or FIG. 13, the current command values Idcom and Iqcom corresponding to the torque command value Trqcom are generated by referring to the map for maximum torque control, and the current feedback control is executed according to the current command value. The

  On the other hand, when current disturbance occurs (when YES is determined in S220), control device 30 advances the process to step S270 to execute a save process for once stabilizing current control. Specifically, the current operating point is changed to a region where the modulation factor is low and sine wave PWM control is applied.

  For example, as shown in FIG. 16, when current disturbance occurs due to overmodulation PWM control at the current operating point 613, the operation in the sine wave PWM control is guaranteed and the modulation factor is relatively low. At 630, the current operating point is changed. Then, current feedback control is executed according to the current command values Idcom and Iqcom corresponding to the current operating point 630.

  Thereby, the output torque of AC electric motor M1 falls instantaneously. Therefore, the time during which the current operating point 630 is selected is within a range necessary for stabilization of current control so that no problem occurs in load driving (for example, driving comfort of a hybrid vehicle or the like) by the AC motor M1. It is preferable to set a very short time.

  Referring to FIG. 15 again, control device 30 executes the saving process for changing the current operating point in step S270, and then proceeds to step S280 to execute the return process.

  Referring to FIG. 16 again, in the return process, the avoidance control line 620 is set so that the torque gradually increases from the current operating point where the output torque is forcibly reduced toward the original torque command value Trqcom. The current operating point moves along. That is, during the return process in step S270, the current command values Idcom and Iqcom are set according to the avoidance control line 620, and the current feedback control is executed according to the current command value. Also in the third embodiment, the generation of the current command values Idcom and Iqcom according to the avoidance control line 620 is the first embodiment (both Idcom and Iqcom are map values) or a modification (adjustment) of the first embodiment. This can be realized in the same manner as the introduction of coefficients.

  The avoidance control line 620 is prepared to include a current operating point 621 (modulation factor = 0.78) corresponding to a switching point with the rectangular wave voltage control. Therefore, even after the return process is completed, the current command values Idcom and Iqcom can be set according to the avoidance control line 620 in response to the change in the torque command value Trqcom. Thereby, the current feedback control once the current disturbance has occurred can be stabilized. Then, when the modulation factor = 0.78 (current operation point 621) on the avoidance control line 620 due to the increase of the torque command value Trqcom, the control mode is switched to the rectangular wave voltage control, and again from the rectangular wave voltage control. When switching to PWM control (overmodulation PWM control) occurs, a current operating point is set along the maximum torque control line 610. That is, when the control mode is switched to overmodulation PWM control, the current operating point is set near the current operating point 612.

  As described above, according to the AC motor control according to the third embodiment, when the current deviation is equal to or greater than the determination value and the current disturbance becomes large, the change to the current operating point to which the sine wave PWM control is applied. Thus, the control stability can be enhanced by executing a saving process that forcibly applies the current feedback control under a highly stable control condition.

  Furthermore, also in the return process for recovering the output torque reduced by the save process, the control stability can be ensured by changing the current operating point along the avoidance control line.

  In the present embodiment, as a preferred configuration example, DC voltage generation unit 10 # of the motor drive system includes buck-boost converter 12 so that the input voltage (system voltage VH) to inverter 14 can be variably controlled. However, as long as the input voltage to inverter 14 can be variably controlled, DC voltage generation unit 10 # is not limited to the configuration exemplified in this embodiment. Further, it is not essential that the inverter input voltage is variable, and the present invention is also applied to a configuration in which the output voltage of the DC power supply B is directly input to the inverter 14 (for example, a configuration in which the step-up / down converter 12 is omitted). Is applicable.

  Further, with regard to the AC motor serving as a load of the motor drive system, in the present embodiment, a permanent magnet motor mounted for driving a vehicle in an electric vehicle (hybrid vehicle, electric vehicle, etc.) is assumed. The present invention can also be applied to a configuration in which an arbitrary AC motor used in the above is used as a load.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an overall configuration diagram of a motor drive control system to which an AC motor control device and a control method according to an embodiment of the present invention are applied. It is a figure which illustrates schematically the control mode of the AC motor in the motor drive system by embodiment of this invention. It is a figure explaining the correspondence of the operation state of an AC motor, and the control mode shown in FIG. It is a block diagram explaining the motor control structure by the sine wave PWM control in the control apparatus of the alternating current motor by embodiment of this invention. FIG. 5 is a waveform diagram for explaining the operation of the PWM modulation unit in FIG. 4. It is a block diagram explaining the motor control structure by the rectangular wave voltage control in the control apparatus of the alternating current motor by embodiment of this invention. It is a block diagram explaining the motor control structure by the overmodulation PWM control in the control apparatus of the alternating current motor by embodiment of this invention. It is a flowchart which shows the process sequence in PWM control. It is a flowchart explaining the setting procedure of the electric current command value in the alternating current motor control by Embodiment 1 of this invention. It is a conceptual diagram explaining the operation area | region determination of AC electric motor M1. It is a conceptual diagram explaining the maximum torque control line and the avoidance control line in the setting of the current command value. It is a flowchart explaining the setting process procedure of the electric current command value according to the selection result of a control line. It is a flowchart explaining the modification of the setting process sequence of the electric current command value according to the selection result of a control line. It is a flowchart explaining the setting procedure of the electric current command value in the alternating current motor control by Embodiment 2 of this invention. It is a flowchart explaining the setting procedure of the electric current command value in the alternating current motor control by Embodiment 3 of this invention. It is a conceptual diagram explaining the setting of the electric current operating point in the alternating current motor control by Embodiment 3 of this invention.

Explanation of symbols

  5 Ground wire, 6, 7 Power line, 10, 13 Voltage sensor, 10 # DC voltage generator, 11, 24 Current sensor, 12 Converter, 14 Inverter, 15 U phase upper and lower arm, 16 V phase upper and lower arm, 17 W phase upper and lower Arm, 25 rotation angle sensor, 30 control unit (ECU), 100 motor drive control system, 200 sine wave PWM control unit, 201 overmodulation PWM control unit, 210 current command generation unit, 220, 250 coordinate conversion unit, 230 current filter , 240 voltage command generation unit, 250 coordinate conversion unit, 260 PWM modulation unit, 262 carrier wave, 264 AC voltage command, 270 voltage amplitude correction unit, 400 rectangular wave voltage control unit, 410 power calculation unit, 420 torque calculation unit, 430 calculation 440 square wave generator 450 signal generator 500 high output area 00 equal torque line, 610 maximum torque control line, 611, 612, 613 current operating point (maximum torque control line), 620 avoidance control line, 621, 622, 623 current operating point (evasion control line), 630 current operation Point (during the save process), B DC power supply, C0, C1 smoothing capacitor, D1 to D8 antiparallel diode, Ib DC current, Id d axis current, Idcom d axis current command value, Idf, Iqf d, q axis current Processing), Iqcom q-axis current command value, iu, iv, iw three-phase current, L1 reactor, M1 AC motor, MCRT motor current, Q1-Q8 power semiconductor switching element, S1-S8 switching control signal, SR1, SR2 system Relay, Trqcom torque command value, Vb DC voltage, Vd # d-axis power Pressure command value, VH system voltage, Vq q-axis voltage command value, Vu, Vv, Vw Phase voltage command, ΔId d-axis current deviation, ΔIq q-axis current deviation, θ rotor rotation angle, φv voltage phase, ω angular velocity.

Claims (8)

An AC motor control device in which an applied voltage is controlled by an inverter,
A current detector for detecting a current flowing between the inverter and the AC motor;
A pulse width modulation control unit that generates a control command for the inverter by pulse width modulation control based on a comparison between an AC voltage command and a carrier wave for operating the AC motor according to a torque command value;
The pulse width modulation control unit
Sine wave modulation control for generating the control command according to a current deviation which is a deviation between the motor current detected by the current detector and the current command corresponding to the torque command value according to a sine wave pulse width modulation method And
According overmodulation pulse width modulation scheme for outputting an applied voltage amplitude is large of the fundamental wave component than the sinusoidal pulse width modulation method, and the overmodulation control unit to generate the control command in accordance with the prior SL current deviation Including
The overmodulation control unit
A current command generator that generates the current command in correspondence with the torque command value;
Depending on the electrostatic Nagarehen difference, voltage command generation unit that generates a voltage command,
Based on a comparison between the voltage command and the carrier, and a modulator for generating the control command,
The current command generation unit includes a first control line for setting the current command corresponding to the torque command value according to a current phase at which the torque of the AC motor is maximized with respect to the same current amplitude, and the first control line. One of the second control line for setting the current command corresponding to the torque command value according to the current phase in which the current amplitude for the same torque is larger than the control line of Selecting according to the selected control line and generating the current command corresponding to the torque command value ,
The AC motor control device , wherein the current command in the sine wave modulation control unit is set according to the first control line .   The current command generator is configured to operate the AC motor when the AC motor is operating in a predetermined range of high output corresponding to each voltage in an operating region defined by the voltage, torque, and rotational speed of the AC motor. 2. The control device for an AC motor according to claim 1, wherein the first control line is selected when the AC motor is operating outside the predetermined region while the second control line is selected. The current command generation unit selects the second control line when the AC motor is operating in the predetermined region and the temperature of the AC motor is higher than a determination temperature, 3. The control of the AC motor according to claim 2, wherein the first control line is selected when the temperature of the AC motor is equal to or lower than the determination temperature even when the AC motor is operating within the predetermined region. apparatus. An AC motor control device in which an applied voltage is controlled by an inverter,
A current detector for detecting a current flowing between the inverter and the AC motor;
A pulse width modulation control unit that generates a control command for the inverter by pulse width modulation control based on a comparison between an AC voltage command and a carrier wave for operating the AC motor according to a torque command value;
The pulse width modulation control unit
Sine wave modulation control for generating the control command according to a current deviation which is a deviation between the motor current detected by the current detector and the current command corresponding to the torque command value according to a sine wave pulse width modulation method And
According overmodulation pulse width modulation scheme for outputting an applied voltage amplitude is large of the fundamental wave component than the sinusoidal pulse width modulation method, and the overmodulation control unit to generate the control command in accordance with the prior SL current deviation Including
The overmodulation control unit
A current command generator that generates the current command in correspondence with the torque command value;
Depending on the electrostatic Nagarehen difference, voltage command generation unit that generates a voltage command,
Based on a comparison between the voltage command and the carrier, and a modulator for generating the control command,
The current command generation unit includes a first control line for setting the current command corresponding to the torque command value according to a current phase at which the torque of the AC motor is maximized with respect to the same current amplitude, and the first control line. One of the second control line for setting the current command corresponding to the torque command value according to the current phase in which the current amplitude for the same torque is larger than that of the control line is set to the magnitude of the current deviation. A control apparatus for an AC motor that selects according to the selected control line and generates the current command corresponding to the torque command value.   The current command generation unit selects the second control line when the current deviation is larger than a determination value, and selects the first control line when the current deviation is equal to or less than the determination value. 4. The control apparatus for an AC motor according to 4.   The current command generation unit sets the current command so that the sine wave pulse width modulation method is applied in correspondence with a target torque lower than the torque command value when the current deviation is larger than a determination value. In addition to executing a retreat process, a return process for generating the current command according to the second control line so as to gradually increase the torque from the target torque to the original torque command value after the retreat process is performed. The control apparatus for an AC motor according to claim 4, which is executed. The current command includes a d-axis current command value and a q-axis current command value,
The current command generation unit includes a first map in which the set of the torque command value and the d-axis current command value and the q-axis current command value are associated in advance according to the first control line, and the second control. According to the line, the torque command value and the second map in which the set of the d-axis current command value and the q-axis current command value are preliminarily associated are selectively referred to, so that the torque command value corresponds to the torque command value. The control device for an AC motor according to claim 1, wherein the current command is generated. The current command includes a d-axis current command value and a q-axis current command value,
When the first control line is selected, the current command generation unit associates a set of the torque command value and the d-axis current command value and the q-axis current command value in advance according to the first control line. While the current command is generated by referring to one map, the d-axis current command value and the q-axis current command value obtained by referring to the first map are selected when the second control line is selected. One current command value is generated by multiplying one by an adjustment coefficient, and the d-axis current command value for realizing the torque command value based on the one current command value and the torque command value, and The control device for an AC motor according to any one of claims 1 to 6, wherein the other current command value is generated according to the combination of the q-axis current command values.

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