JP2011067010A - Motor drive of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive of a vehicle having improved energy efficiency while maintaining stability of motor control. <P>SOLUTION: The motor drive of a vehicle is provided with a voltage converter 12, and a controller 30 controlling an inverter 14 by using rectangular wave control mode and overmodulation control mode and switching a control mode from the rectangular wave control mode to the overmodulation control mode based on whether a relation between an actual current value of a motor M1 and a current command value when the overmodulation control mode is applied satisfies a switching condition or not. The controller 30 changes the switching condition so that the control mode is easily switched just after the voltage converter 12 starts a boosting operation, as compared to a normal state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle motor drive device, and more particularly to a vehicle motor drive device having a plurality of switchable control modes.

  A configuration in which a DC motor is driven and controlled by converting a DC voltage into an AC voltage by an inverter is generally used. In such a configuration, in order to drive the motor with high efficiency, the motor current is generally controlled according to pulse width modulation (PWM) based on vector control. In addition, in order to improve the motor output, a configuration in which the motor is controlled by switching between a rectangular wave voltage phase control mode in which a rectangular wave voltage is applied to the motor for driving control and a PWM current control mode in accordance with the PWM control, for example, It is known as shown in Japanese Patent Application Laid-Open No. 2007-306699.

  In the motor drive control device disclosed in this document, basically, a PWM current control mode (hereinafter also simply referred to as a PWM control mode) and a motor state, more specifically, based on the voltage amplitude and current phase thereof, and Mode switching determination during the rectangular wave voltage phase control mode (hereinafter also simply referred to as a rectangular wave voltage control mode) is executed.

JP 2007-306699 A JP 2007-020383 A JP 2008-253000 A

  When driving a motor, a configuration is also known in which the voltage of a DC power supply is boosted by a voltage converter and supplied to an inverter. In such a configuration in which the voltage of the inverter is variably controlled, if the voltage of the inverter is changed during execution of the rectangular wave voltage control mode, the rectangular wave is distorted and an imbalance occurs in the voltage applied to the three-phase coil. Then, an offset occurs in the currents of the U, V, and W phases of the motor. Therefore, in the rectangular wave control mode, the inverter voltage is generally fixed at the maximum boosted voltage. In this case, when the voltage of the inverter is changed using the voltage converter, it is performed in the PWM control mode.

  In recent years, fine control over inverters has become possible as technology advances. Therefore, there is a possibility that the rectangular wave control mode is applied even when the inverter voltage is being changed by the voltage converter to reduce the switching loss and further improve the energy efficiency. This leads to improved fuel efficiency in hybrid vehicles, and extended cruising distance by charging power in electric vehicles and plug-in hybrid vehicles.

  However, immediately after the boosting of the inverter voltage is started by the voltage converter, the dq axis current value of the motor current greatly changes in the positive direction. When this change is large, torque disturbance (torque shortage) occurs in the rectangular wave control mode, and the battery current is greatly disturbed. Therefore, it is necessary to quickly switch the control mode from the rectangular wave control mode to the PWM control mode with good controllability. In other words, in the conventional specification, the setting of the switching condition from the rectangular wave control mode to the overmodulation PWM control mode is set on the premise that “in the rectangular wave control mode, the inverter voltage is fixed at the maximum boosted voltage”. It was. For this reason, it is necessary to review the switching conditions in order to increase the energy efficiency by expanding the range in which the rectangular wave control mode is applied.

  An object of the present invention is to provide a motor drive device for a vehicle with improved energy efficiency while maintaining stability of motor control.

  In summary, the present invention relates to a motor drive device for a vehicle, which includes a voltage converter that boosts the voltage of a DC power supply, an inverter that is supplied with a voltage from the voltage converter, and that drives the motor. Overmodulation control from the rectangular wave control mode based on whether the relationship between the actual current value of the motor and the current command value when the overmodulation control mode is applied satisfies the switching condition. And a control device for switching the control mode to the mode. Immediately after the voltage converter starts the boosting operation, the control device is in a control mode more than the normal mode including when the voltage converter is not performing the boosting operation and when the voltage converter starts the boosting operation and a predetermined time has elapsed. The switching condition is changed so that the switching is likely to occur.

  Preferably, the switching condition includes a condition that the switching is generated when the deviation amount indicating the deviation of the actual current value from the current command value is larger than the threshold value. The control device changes the threshold value immediately after the voltage converter starts the step-up operation so that switching of the control mode is more likely to occur than during normal operation.

  More preferably, the threshold value includes a first threshold value for determining a difference in d-axis current of the motor current and a second threshold value for determining a difference in phase angle of the motor current in the dq plane. . The control device changes the first or second threshold value so that the switching of the control mode is more likely to occur than usual, immediately after the voltage converter starts the boosting operation.

  Preferably, the switching condition is a first condition that the switching is generated when either one of the difference between the d-axis current of the motor current and the difference between the phase angles of the motor current in the dq plane satisfies a predetermined condition. Immediately after the voltage converter starts the step-up operation, the second condition for generating the switching based only on the phase angle difference is included.

  More preferably, when the value obtained by subtracting the phase angle of the actual current value of the motor from the phase angle of the current command value when the overmodulation control mode is applied is ΔIφ and the positive threshold is Iφt1, the first condition Includes a condition that ΔIφ> Iφt1 is satisfied, and the second condition includes a condition that ΔIφ> 0 is satisfied.

  Preferably, the switching condition is a first condition that the switching is generated when either one of the difference between the d-axis current of the motor current and the difference between the phase angles of the motor current in the dq plane satisfies a predetermined condition. Immediately after the voltage converter starts the step-up operation, a second condition for generating a switch based on the difference between the d-axis current of the motor current and the difference of the q-axis current of the motor current is included.

  More preferably, a value obtained by subtracting the d-axis current value of the actual current value of the motor from the d-axis current value of the current command value when the overmodulation control mode is applied is ΔId, and the current when the overmodulation control mode is applied Assuming that a value obtained by subtracting the q-axis current value of the actual motor current value from the q-axis current value of the command value is ΔIq, the second condition includes a condition that ΔId <0 or ΔIq> 0 is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, in vehicles which mount motors, such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle, energy efficiency can be improved, maintaining the stability of motor control.

1 is an overall configuration diagram of a motor drive control system controlled by a motor drive control device according to an embodiment of the present invention. It is a figure which illustrates schematically the control mode of the motor M1 in the motor drive control system by embodiment of this invention. It is a figure explaining the correspondence of the operation state of motor M1, and the above-mentioned control mode. It is a block diagram for demonstrating the drive control apparatus of the motor implement | achieved by the control apparatus 30 of FIG. It is a flowchart for demonstrating the process performed in the mode switching determination part of FIG. It is a wave form diagram for demonstrating the electric current value at the time of switching from a rectangular wave voltage control mode to an overmodulation control mode. It is a flowchart for demonstrating the detail of the process of FIG.5 S4. It is a figure for demonstrating (DELTA) Iphi and (DELTA) Id. It is a flowchart for demonstrating the content of step S4A which is a modification of step S4. FIG. 10 is a diagram for describing control mode switching determination in a second embodiment. It is a flowchart for demonstrating the content of step S4B which is a modification of step S4. FIG. 10 is a diagram for describing control mode switching determination in a third embodiment.

  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 detailed description thereof will not be repeated in principle.

[Overall system configuration]
FIG. 1 is an overall configuration diagram of a motor drive control system controlled by a motor drive control device according to an embodiment of the present invention.

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

  The motor M1 is, for example, a drive motor for generating torque for driving drive wheels of a hybrid vehicle or an electric vehicle. Or this motor M1 may be comprised so that it may have the function of the generator driven with an engine, and may be comprised so that it may have the function of an electric motor and a generator together. Furthermore, the motor M1 may operate as an electric motor for the engine, and may be incorporated in a hybrid vehicle so that the engine can be started, for example. That is, in the present embodiment, the “motor” may include an AC-driven 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 voltage 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 SR1 is connected between the positive terminal of DC power supply B and positive electrode bus 6, and system relay SR1 is connected between the negative terminal of DC power supply B and negative electrode bus 5. System relays SR1 and SR2 are turned on / off by signal SE from control device 30.

  Voltage converter 12 includes a reactor L1, power semiconductor switching elements Q1, Q2, and diodes D1, D2. Power switching elements Q 1 and Q 2 are connected in series between positive electrode bus 7 and negative electrode bus 5. On / off of power switching elements Q1 and Q2 is controlled by switching control signals S1 and S2 from control device 30.

  In the embodiment of the present invention, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or a power bipolar transistor is used as a power semiconductor switching element (hereinafter simply referred to as “switching element”). Etc. 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 positive electrode bus 6. Smoothing capacitor C 0 is connected between positive electrode bus 7 and negative electrode bus 5.

  Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are provided in parallel with each other between positive electrode bus 7 and negative electrode bus 5. Each phase arm includes a switching element connected in series between positive electrode bus 7 and negative electrode bus 5. U-phase arm 15 includes switching elements Q3 and Q4. V-phase arm 16 includes switching elements Q5 and Q6. W-phase arm 17 includes 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, the motor M1 is a three-phase permanent magnet motor. One ends of the three coils of the U, V, and W phases are commonly connected to the neutral point. Furthermore, the other end of each phase coil is connected to the midpoint of the switching elements of each phase arm 15-17.

  During the boost operation, the voltage converter 12 boosts the DC voltage Vb supplied from the DC power supply B (hereinafter referred to as “system voltage” or “inverter voltage”). Also referred to as an inverter 14. More specifically, in response to switching control signals S1 and S2 from control device 30, an ON period of switching element Q1 and an ON period of Q2 are alternately provided, and the step-up ratio is equal to the ratio of these ON periods. It will be a response.

  Further, during the step-down operation, the voltage converter 12 steps down the DC voltage VH (system voltage) supplied from the inverter 14 via the smoothing capacitor C0 and charges the DC power supply B. More specifically, in response to switching control signals S1 and S2 from control device 30, a period in which only switching element Q1 is turned on and a period in which both switching elements Q1 and Q2 are turned off are alternately provided, The step-down ratio is in accordance with the duty ratio during the ON period.

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

  Furthermore, during regenerative braking of a hybrid vehicle or electric vehicle equipped with motor drive control system 100, torque command value Trqcom of motor M1 is set to a negative value (Trqcom <0). In this case, the inverter 14 converts the AC voltage generated by the 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 voltage converter 12. Note that regenerative braking here refers to braking with regenerative power generation when the driver driving a hybrid vehicle or electric vehicle performs foot braking, or turning off the accelerator pedal while driving, although the foot brake is not operated. This includes decelerating the vehicle (or stopping acceleration) while generating regenerative power.

  Current sensor 24 detects motor current MCRT flowing through motor M1 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 motor M1 and sends the detected rotation angle θ to the control device 30. The control device 30 can calculate the rotational speed (rotational speed) and angular speed ω (rad / s) of the motor M1 based on the 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.

  Control device 30 corresponding to the drive control device in the embodiment of the present invention is configured by an electronic control unit (ECU), and performs motor drive control by software processing according to a program stored in advance and / or hardware processing by an electronic circuit. Control the operation of the system 100.

  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, the motor currents iv and iw from the current sensor 24, the rotation angle θ from the rotation angle sensor 25, etc., the voltage is set so that the motor M1 outputs a torque according to the 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 voltage converter 12 and inverter 14 as described above are generated and output to voltage converter 12 and inverter 14.

  During the boosting operation of voltage converter 12, control device 30 feedback-controls system voltage VH output to smoothing capacitor C0, and generates switching control signals S1 and S2 so that system voltage VH becomes a voltage command value.

  Further, when receiving a signal RGE indicating that the hybrid vehicle or the electric vehicle has entered the regenerative braking mode from another ECU, the control device 30 performs switching control so as to convert the AC voltage generated by the motor M1 into a DC voltage. Signals S3 to S8 are generated and output to inverter 14. Thus, the inverter 14 converts the AC voltage generated by the motor M1 into a DC voltage and supplies the DC voltage to the voltage converter 12.

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

[Description of control mode]
The control of the motor M1 by the control device 30 will be described in further detail.

  FIG. 2 is a diagram schematically illustrating a control mode of the motor M1 in the motor drive control 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 motor M1, that is, power conversion in the inverter.

  The sine wave PWM control is used as a general PWM control, and on / off of each phase arm element is controlled 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. The ratio is controlled. As is well known, in the sine wave PWM control mode in which the correlation waveform of the voltage command is a sine wave, the amplitude of the fundamental wave component can be increased only to about 0.61 times the inverter input voltage.

  On the other hand, in the rectangular wave voltage control, one pulse of a rectangular wave whose ratio between the high level period and the low level period is 1: 1 is applied to the motor 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 after distorting the amplitude of the voltage command. As a result, the fundamental wave component can be distorted, and the modulation rate can be increased from the maximum modulation rate in the sine wave PWM control mode to a range of 0.78.

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

  Conventionally, in the region where the required motor voltage is lower than the VH maximum voltage, the PWM control mode by the sine wave PWM control or the overmodulation PWM control is applied, and the output torque is the torque command value by the feedback control of the motor current according to the vector control. It was controlled by Trqcom. On the other hand, when the required motor voltage reaches the VH maximum voltage, the rectangular wave voltage control mode is applied after setting the system voltage VH to the VH maximum voltage. In the rectangular wave voltage control, since the amplitude of the fundamental wave component 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.

[Embodiment 1]
The motor control device of the present embodiment performs a sine wave PWM control mode → overmodulation PWM control mode → rectangular wave control mode based on the modulation rate even before the required motor voltage reaches the VH maximum voltage. Then, the control mode switching determination method is changed immediately after the voltage change so that the mode change occurs earlier than usual when the voltage is changed.

FIG. 3 is a diagram for explaining the correspondence between the operation state of the motor M1 and the above-described control mode.
As shown in FIG. 3, generally, the sine wave PWM control mode is used in the low rotational speed range R1 to reduce the torque fluctuation, and the overmodulation PWM control mode and the high rotational speed are used in the middle rotational speed range R2. In the region R3, the rectangular wave voltage control mode is applied. In particular, the output of the motor M1 is improved by applying the overmodulation PWM control mode and the rectangular wave voltage control mode. In this way, which of the control modes shown in FIG. 2 is used is determined within the range of the realizable modulation rate.

  FIG. 4 is a block diagram for explaining a motor drive control device realized by the control device 30 of FIG. Each block for motor control shown in FIG. 4 is realized by hardware or software processing by the control device 30.

  Referring to FIG. 4, PWM control unit 200 performs switching control of inverter 14 according to pulse width modulation (PWM) control so that motor M1 outputs torque according to torque command value Trqcom when PWM control mode is selected. Signals S3 to S8 are generated. The PWM control unit 200 includes a current command generation unit 210, a current control unit 220, and a PWM circuit 230.

  When the rectangular wave voltage control mode is selected, the rectangular wave voltage control unit 300 performs switching of the inverter 14 so that a rectangular wave voltage having a voltage phase such that the motor M1 outputs a torque according to the torque command value Trqcom is generated. Control signals S3 to S8 are generated. The rectangular wave voltage control unit 300 includes a calculation unit 305, a torque detection unit 310, a voltage phase control unit 320, and a rectangular wave generation unit 330.

  Mode switching determination unit 400 determines mode switching between the PWM control mode and the rectangular wave voltage control mode shown in FIG. Further, the mode switching determination unit 400 has a function of determining switching between the sine wave PWM control mode and the overmodulation PWM control even in the PWM control mode. When overmodulation PWM control is selected, the control signal OM is turned on.

  The changeover switch 410 is set to either the I side or the II side according to the control mode selected by the mode change determination unit 400.

  When the PWM control mode is selected, the changeover switch 410 is set to the I side, and a pseudo sine wave voltage is applied to the motor M1 in accordance with the switching control signals S3 to S8 set by the PWM control unit 200. On the other hand, when the rectangular wave voltage control mode is selected, the changeover switch 410 is set to the II side, and the rectangular wave voltage is set to the motor M1 by the inverter 14 in accordance with the switching control signals S3 to S8 set by the rectangular wave voltage control unit 300. To be applied.

Next, the details of the function of each block will be described.
In PWM control unit 200, current command generation unit 210 generates current amplitude | I | and current phase φi based on torque command value Trqcom. Current controller 220 is based on, for example, proportional-integral (PI) control to determine the difference between motor current MCRT detected by current sensor 24 and current amplitude | I | and current phase φi generated by current command generator 210. In response, a command value (hereinafter also simply referred to as a voltage command) for the voltage applied to the motor M1 is generated. The voltage command is represented by its voltage amplitude | V | and voltage phase φv. Here, the voltage phase φv is an angle of a voltage vector with respect to the q axis.

  When the overmodulation control mode in which the control signal OM is turned on is selected, the current control unit 220 distorts the voltage amplitude | V | of the voltage command so that the modulation rate becomes larger than 0.61. Generate.

  The PWM circuit 230 controls on / off of the elements of each phase arm of the inverter 14 based on the comparison between the voltage command indicated by the voltage amplitude | V | and the voltage phase φv from the current control unit 220 and the carrier wave. The pseudo sine wave voltage is generated for each phase of the motor M1.

  In this manner, the PWM control unit 200 performs feedback control for making the motor current MCRT of the motor M1 coincide with the motor current set by the current command generation unit 210.

On the other hand, in the rectangular wave voltage control unit 300, the torque detection unit 310 detects the output torque of the motor M1. The torque detection unit 310 can be configured using a known torque sensor, but can also be configured to detect the output torque Tq according to the calculation shown in the following equation (1).
Tq = Pm / ω
= (Iu · vu + iv · vv + iw · vw) / ω (1)
Here, Pm represents the electric power supplied to the motor M1, and ω represents the angular velocity of the motor M1. Further, iu, iv, and iw represent respective phase current values of the motor M1, and vu, vv, and vw represent respective phase voltages supplied to the motor M1. For vu, vv, and vw, a voltage command set in the inverter 14 may be used, or an actual value supplied from the inverter 14 to the motor M1 may be detected by a voltage sensor. Further, since the output torque Tq is determined by the design value of the motor M1, it may be estimated from the current amplitude and phase.

  The calculation unit 305 calculates a torque deviation ΔTq that is a deviation of the output torque Tq detected by the torque detection unit 310 with respect to the torque command value Trqcom. Torque deviation ΔTq generated by calculation unit 305 is supplied to voltage phase control unit 320.

  Voltage phase control unit 320 generates voltage phase φv in accordance with torque deviation ΔTq. This voltage phase φv indicates the phase of a rectangular wave voltage to be applied to the motor M1. Specifically, the voltage phase control unit 320 uses the system voltage VH input to the inverter 14 and the angular velocity ω of the motor M1 together with the torque deviation ΔTq as parameters when generating the voltage phase φv, and performs a predetermined calculation on them. A necessary voltage phase φv is generated by substituting it into the equation or performing equivalent processing.

  The rectangular wave generator 330 generates the switching control signals S3 to S8 of the inverter 14 so as to generate a rectangular wave voltage according to the voltage phase φv from the voltage phase controller 320. In this manner, the rectangular wave voltage control unit 300 performs feedback control that adjusts the phase of the rectangular wave voltage in accordance with the torque deviation of the motor M1.

  FIG. 5 is a flowchart for explaining processing executed in the mode switching determination unit of FIG. The processing of this flowchart is called and executed from a predetermined main routine every predetermined time or every time a predetermined condition is satisfied.

  Referring to FIG. 5, first, in step S1, it is determined whether or not the current control mode is a PWM control mode. In step S1, if the current control mode is the PWM control mode, the process proceeds to step S2, and if the control mode is not the PWM control mode, that is, the rectangular wave control mode, the process proceeds to step S4. .

  In step S2, the modulation factor is calculated based on the voltage command | V |, φv. In step S3, it is determined whether a switching condition from the PWM control mode to the rectangular wave control mode is satisfied. The condition for switching can be, for example, the case where the modulation factor calculated in step S2 is 0.78 or more.

  If the switching condition is satisfied in step S3, the process proceeds to step S6, and the rectangular wave control mode is selected. On the other hand, if the switching condition is not satisfied, the process proceeds to step S5 and the PWM control mode is selected.

  If the PWM control mode is selected in step S5, it is further determined in step S7 whether or not the modulation rate satisfies the condition for selecting the sine wave PWM control. For example, the modulation rate may be 0.61 or less. If the condition is satisfied in step S7, the sine wave PWM control mode is selected in step S9, and if not satisfied, the overmodulation PWM control mode is selected in step S8.

  In step S1, if the current control mode is the rectangular wave control mode, the process proceeds to step S4, and it is determined whether or not a switching condition from the rectangular wave control mode to the PWM control mode is satisfied. The switching condition from the rectangular wave control mode to the PWM control mode will be described in detail later with reference to FIG.

  If the switching condition is satisfied in step S4, the process proceeds to step S8, and the overmodulation PWM control mode is selected. On the other hand, if the switching condition is not satisfied in step S4, the process proceeds to step S6 and the rectangular wave voltage control mode is maintained.

  If the control mode is determined in any of steps S6, S8, and S9, the process proceeds to step S10 and the control is transferred to the main routine.

  FIG. 6 is a waveform diagram for explaining a current value at the time of switching from the rectangular wave voltage control mode to the overmodulation control mode.

  In FIG. 6, the voltage command value VH * and the voltage values VH and Vb are shown in an overlapping manner, below which the timing of the boost start command and the switching condition of the present embodiment are applied (before improvement) and applied. The switching timing of the later (after improvement) control mode is shown. Further below, a current value Id and a current command value Id *, and a current value Iq and a current command value Iq * are shown superimposed.

  First, at times t0 to t1, each voltage and current value is in a state that matches the command value. At time t1, the boost command value starts to increase with respect to battery voltage Vb. However, the voltage converter 12 does not immediately start the boosting operation. Therefore, during times t1 to t2, the current values Id and Iq are reduced with respect to the current command values Id * and Iq *.

  Here, in response to the deviation between voltage command value VH * and battery voltage value Vb becoming larger than threshold value ΔVt at time t2, the boost start command changes from the off state to the on state. In response to this, at time t2 to t3, voltage converter 12 starts the boost operation voltage, and system voltage VH suddenly increases to coincide with command value VH *.

  The amount of increase in voltage command value VH * at times t1 to t4 is limited at a constant rate in order to prevent disturbance of the motor current due to a rapid voltage increase. However, the operation of the voltage converter 12 does not occur unless the threshold value ΔVt is exceeded. Therefore, the increase in the system voltage VH from the time t2 to the time t3 occurs at a speed much faster than the increase speed of the limited voltage command value VH *. Conventionally, the switching speed of the control mode is slow, and the motor control is executed in the rectangular wave control mode with poor followability between times t2 and t3. During that time, the currents Id1 and Iq1 increased rapidly and a large peak was generated. When the control mode is changed from the rectangular wave control mode to the overmodulation control mode at time t3, current feedback control is applied. As a result, the current value decreases at times t3 to t4, and the current values Id1 and Iq1 after time t4 are The current command values coincide with the current command values Id * and Iq *, respectively.

  In the present embodiment, since the switching condition from the rectangular wave mode to the overmodulation mode immediately after the start of boosting is changed, the timing for switching from the rectangular mode to the overmodulation mode is between time t4 and t3 as shown in FIG. It is expedited. As a result, the current peak becomes small as indicated by the current values Id2 and Iq2.

FIG. 7 is a flowchart for explaining details of the process in step S4 of FIG.
Referring to FIG. 7, first, in step S21, it is determined whether or not it is immediately after the start of boosting. Specifically, it is determined that the pressure increase start command is immediately after the pressure increase within a predetermined time from the time when the pressure increase start command changes from the OFF state to the ON state at time t2 in FIG.

If it is determined in step S21 that it is not immediately after the start of boosting, normal switching determination conditions are applied in step S22. In step S22, it is determined whether or not the following conditions are satisfied for the current phase angle difference ΔIφ and the Id current value difference ΔId.
ΔIφ> Iφt1 (2)
ΔId <Idt1 (3)
FIG. 8 is a diagram for explaining ΔIφ and ΔId.

Referring to FIG. 8, arrow A1 indicates a current command value I * calculated when the overmodulation control mode is applied, and arrow A2 indicates an actual current at the time when the rectangular wave control mode is switched to the overmodulation control mode. The value I is indicated. ΔIφ and ΔId are defined by the following equations (4) and (5).
ΔIφ = Iφ * −Iφ (4)
ΔId = Id * −Id (5)
A line L1 indicates a control line for a current command value when overmodulation control is executed, and a line L2 indicates a locus on which the actual current value moves on the dq plane when switching from rectangular wave control to overmodulation control. ing.

  In the state shown in FIG. 8, in the region where Iq is on the plus side and Id is on the plus side with respect to the line L1, the current is disturbed and the control is lost, and the rectangular wave control cannot be executed. However, the rectangular wave control can be maintained even if the line L1 is slightly off.

  From the definitions shown in the equations (4) and (5), the case of FIG. 8 is in a state of ΔId <0 and ΔIφ> 0.

  In order to indicate that there is an actual current value in the region where the rectangular wave control cannot be performed, particularly in the movement direction of the locus indicated by the line L2, when the thresholds Idt1 and Iφt1 are used, the above formula (2) or ( This can be determined when at least one of 3) holds.

  Referring to FIG. 7 again, if at least one of equations (2) or (3) is established in step S22, the process proceeds to step S23, and if none is established, the process proceeds to step S24. Advances. In step S23, overmodulation PWM control is selected as the control mode, and in step S24, rectangular control is maintained as the control mode.

If it is determined in step S21 that the boosting has just started, the process proceeds to step S25. The determination condition in step S25 is whether or not any of the following expressions (6) and (7) is satisfied.
ΔIφ> Iφt2 (6)
ΔId> Idt2 (7)
The threshold value of step S25 is different from that of step S22. The threshold values Iφt2 and Idt2 used in step S25 are set so that switching is more likely to occur than the threshold value in step S22.

  Specifically, since ΔIφ and ΔId have different signs as described in FIG. 8 and equations (4) and (5), the threshold values are set so that Iφt2 <Iφt1 and Idt2> Idt1. However, from the relationship that ΔId is a negative value, | Idt2 | <| Idt1 |.

  If at least one of the expressions (6) and (7) is established in step S25, the process proceeds to step S26, and if none is established, the process proceeds to step S27. In step S26, overmodulation PWM control is selected as the control mode, and in step S27, rectangular control is maintained as the control mode.

  After any one of steps S23, S24, S26, and S27 is completed and the control mode is determined, the process proceeds to step S28, and the control is transferred to the flowchart of FIG.

  As described above, in the first embodiment, the threshold value is changed so that the switching from the rectangular wave control to the overmodulation PWM control is likely to occur for a while immediately after the start of boosting. In this way, switching occurs early and the peaks (current disturbance) of Id2 and Iq2 can be suppressed to a small level.

[Embodiment 2]
In the first embodiment, the threshold value of the determination condition is changed (the threshold value is reduced) immediately after the start of boosting so that the switching from the rectangular wave control mode to the overmodulation PWM control is likely to occur. Stated. However, other modifications are also conceivable to facilitate mode switching.

  FIG. 9 is a flowchart for explaining the content of step S4A, which is a modification of step S4.

  The flowchart in FIG. 9 includes step S25A instead of step S25 in the flowchart in FIG. 7 for explaining the switching condition of the first embodiment. The other parts of the flowchart of FIG. 9 are the same as those of FIG. 7, and description thereof will not be repeated.

In step S25A, it is determined whether or not the following equation (8) is satisfied.
ΔIφ> 0 (8)
In the first embodiment, the control mode is switched from the rectangular wave control to the overmodulation control when either ΔIφ or ΔId satisfies the condition of the expression (2) or (3). On the other hand, in the second embodiment, the determination condition is further simplified, and zero, which is the strictest determination value, is adopted as the threshold value Iφt in Expression (2).

  FIG. 10 is a diagram for describing control mode switching determination according to the second embodiment.

  Referring to FIG. 10, arrow B1 indicates a current command value I * calculated when the overmodulation control mode is applied, and arrow B2 indicates an actual current at the time of switching from the rectangular wave control mode to the overmodulation control mode. The value I is indicated. As shown in FIG. 10, immediately after the locus L1 of the current command value calculated when the overmodulation control mode is applied and the locus L3 of the actual current value during the rectangular wave control, ΔIφ> 0. It becomes. As a result, the mode immediately shifts to the overmodulation control mode before the current is greatly disturbed. For this reason, similar effects can be obtained even with simpler determination conditions than in the first embodiment.

[Embodiment 3]
In the third embodiment, still another modification example of the switching determination condition will be described.

  FIG. 11 is a flowchart for explaining the contents of step S4B, which is a modification of step S4.

  The flowchart in FIG. 11 includes step S25B instead of step S25 in the flowchart in FIG. 7 for explaining the switching condition of the first embodiment. The other parts of the flowchart of FIG. 9 are the same as those of FIG. 7, and description thereof will not be repeated.

In step S25B, it is determined whether or not the following expressions (9) and (10) are satisfied.
ΔId <0 (9)
ΔIq> 0 (10)
FIG. 12 is a diagram for describing control mode switching determination according to the third embodiment.

  Referring to FIG. 12, arrow C1 indicates a current command value I * calculated when the overmodulation control mode is applied, and arrow C2 indicates an actual current at the time of switching from the rectangular wave control mode to the overmodulation control mode. The value I is indicated. As shown in FIG. 12, immediately after the locus L1 of the current command value calculated when the overmodulation control mode is applied and the locus L4 of the actual current value during the rectangular wave control, ΔId <0. , ΔIq> 0. As a result, the mode immediately shifts to the overmodulation control mode before the current is greatly disturbed. For this reason, the same effect as Embodiment 1 and 2 can be acquired.

Finally, this embodiment will be summarized with reference to FIG. 1 again.
The motor drive device for a vehicle includes a voltage converter 12 that boosts the voltage of a DC power supply (battery B), an inverter 14 that is supplied with a voltage from the voltage converter 12 and that drives a motor M1, and an inverter 14 that has a rectangular wave control mode. Overmodulation from the rectangular wave control mode based on whether the relationship between the actual current value of the motor M1 and the current command value when the overmodulation control mode is applied satisfies the switching condition. And a control device 30 that switches the control mode to the control mode. The control device 30 immediately after the voltage converter 12 starts the boosting operation, from the normal time including when the voltage converter 12 is not performing the boosting operation and when a predetermined time has elapsed since the voltage converter 12 started the boosting operation. Also, the switching condition is changed so that the switching of the control mode is likely to occur.

  Preferably, the switching condition includes a condition that the switching is generated when the deviation amount indicating the deviation of the actual current value I from the current command value I * is larger than the threshold value. Control device 30 changes the threshold value immediately after the voltage converter starts the step-up operation so that switching of the control mode is more likely to occur than during normal operation.

  More preferably, as shown in FIG. 7, the threshold value is a first threshold value Idt for determining a difference in d-axis current of the motor current and a first threshold value for determining a phase angle difference in the dq plane of the motor current. 2 threshold Iφt. The control device makes it easier to switch the control mode to the first or second threshold value immediately after the voltage converter starts the step-up operation than at the normal time (step S22: threshold values Idt1, Iφt1). (Step S25: Threshold values Idt2, Iφt2) are changed.

  Preferably, as shown in FIG. 9, the switching condition is normally set when the difference between the d-axis current of the motor current or the phase angle difference of the motor current in the dq plane satisfies a predetermined condition. The first condition is generated (step S22), and immediately after the voltage converter starts the step-up operation, the second condition is generated that causes switching based only on the phase angle difference (step S25A).

  More preferably, when the value obtained by subtracting the phase angle of the actual current value of the motor from the phase angle of the current command value when the overmodulation control mode is applied is ΔIφ and the positive threshold is Iφt1, the first condition Includes a condition that ΔIφ> Iφt1 is satisfied (step S22), and the second condition includes a condition that ΔIφ> 0 is satisfied (step S25A).

  Preferably, as shown in FIG. 11, the switching condition is normally switched when either one of the motor current d-axis current difference and the motor current dq plane phase angle difference satisfies a predetermined condition. The first condition is generated (step S22). Immediately after the voltage converter starts the boosting operation, switching is generated based on the difference between the d-axis current of the motor current and the difference of the q-axis current of the motor current. The second condition to be included is included (step S25B).

  More preferably, a value obtained by subtracting the d-axis current value of the actual current value of the motor from the d-axis current value of the current command value when the overmodulation control mode is applied is ΔId, and the current when the overmodulation control mode is applied If the value obtained by subtracting the q-axis current value of the motor actual current value from the q-axis current value of the command value is ΔIq, the second condition includes a condition that ΔId <0 or ΔIq> 0 is satisfied (step S25B). ).

  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.

  5 Negative bus, 6, 7 Positive bus, 10 Voltage sensor, 10 # DC voltage generator, 11 Current sensor, 12 Voltage converter, 13 Voltage sensor, 14 Inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm , 24 current sensor, 25 rotation angle sensor, 30 control device, 100 motor drive control system, 200 PWM control unit, 210 current command generation unit, 220 current control unit, 230 PWM circuit, 300 rectangular wave voltage control unit, 305 calculation unit 310 torque detection unit 320 voltage phase control unit 330 rectangular wave generation unit 400 mode switching determination unit 410 switching switch B DC power source C0, C1 smoothing capacitor D1-D8 diode L1 reactor M1 motor Q1 ~ Q8 switching element, SR1, SR2 system Over.

Claims (7)

A voltage converter that boosts the voltage of the DC power supply;
An inverter which is supplied with voltage from the voltage converter and drives a motor;
Whether the inverter is controlled using a rectangular wave control mode and an overmodulation control mode, and whether the relationship between the actual current value of the motor and the current command value when the overmodulation control mode is applied satisfies a switching condition. And a control device for switching the control mode from the rectangular wave control mode to the overmodulation control mode,
The control device is configured so that immediately after the voltage converter starts the boosting operation, the normal time including when the voltage converter is not performing the boosting operation and when a predetermined time has elapsed since the voltage converter started the boosting operation. And a motor drive device for a vehicle that changes the switching condition so that the switching of the control mode is likely to occur. The switching condition includes a condition of causing switching when a deviation amount indicating a deviation of the actual current value from the current command value is larger than a threshold value,
2. The vehicle according to claim 1, wherein the control device changes the threshold so that switching of the control mode is more likely to occur than in the normal time immediately after the voltage converter starts a boost operation. Motor drive device. The threshold value includes a first threshold value for determining a difference in d-axis current of motor current and a second threshold value for determining a difference in phase angle of the motor current in the dq plane,
The control device changes the first or second threshold so that the switching of the control mode is more likely to occur than in the normal time immediately after the voltage converter starts a boosting operation. The motor drive apparatus for vehicles described in 1.   In the normal condition, the switching condition is a first condition in which switching is generated when either a difference in d-axis current of the motor current or a phase angle difference in the dq plane of the motor current satisfies a predetermined condition. 2. The vehicle motor drive device according to claim 1, further comprising a second condition for generating the switching based only on the phase angle difference immediately after the voltage converter starts the boosting operation. When the value obtained by subtracting the phase angle of the actual current value of the motor from the phase angle of the current command value when the overmodulation control mode is applied is ΔIφ, and the positive threshold is Iφt1,
The first condition includes a condition that ΔIφ> Iφt1 is satisfied,
The motor drive apparatus for a vehicle according to claim 4, wherein the second condition includes a condition that ΔIφ> 0 is satisfied.   In the normal condition, the switching condition is a first condition in which switching is generated when either a difference in d-axis current of the motor current or a phase angle difference in the dq plane of the motor current satisfies a predetermined condition. And immediately after the voltage converter starts the step-up operation, a second condition for generating the switching based on the difference between the d-axis current of the motor current and the difference of the q-axis current of the motor current is included. The motor drive device for a vehicle according to claim 1. A value obtained by subtracting the d-axis current value of the actual current value of the motor from the d-axis current value of the current command value when the overmodulation control mode is applied is denoted by ΔId, and when the overmodulation control mode is applied When ΔIq is a value obtained by subtracting the q-axis current value of the actual current value of the motor from the q-axis current value of the current command value,
The motor drive apparatus for a vehicle according to claim 6, wherein the second condition includes a condition that ΔId <0 or ΔIq> 0 is satisfied.

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