JP2010252488A - Motor drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive control device that improves fuel consumption without deterioration in driveability performance by operating an AC motor using a sinusoidal wave PWM control system as much as possible. <P>SOLUTION: The motor drive control device 10 includes a converter 20, inverter 22 and a control unit 26 operating/controlling the converter and inverter to drive/control an AC motor M1 through sinusoidal wave PWM control or the like. The control unit 26 determines a modulation rate from a system voltage command value VH* and motor-required voltage calculated on the basis of a torque command value Tr*, and when the modulation rate reaches or exceeds the maximum modulation rate in sinusoidal wave PWM control during non-boosting operation of the converter 20, the start of the boosting operation by the converter 20 is requested. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motor drive control device, and more particularly to a motor drive control device that drives an AC motor by a sine wave PWM control method as much as possible when a converter is not boosted.

  2. Description of the Related Art Conventionally, a hybrid vehicle including an engine that outputs power using gasoline or the like as a fuel and a motor that is driven by electric power from a power source device such as a battery to output power is known as a driving power source. In general, a three-phase synchronous AC motor is used for the electric motor. This three-phase synchronous AC motor is driven by converting a DC voltage supplied from a power supply device into a three-phase AC voltage by an inverter and applying it.

  In the hybrid vehicle, the DC voltage supplied from the power supply device may not be supplied to the inverter as it is, but may be boosted to a predetermined command value by a step-up / down converter and then input to the inverter. Thus, by boosting with the buck-boost converter and setting the system voltage high, there is an advantage that it is possible to drive the AC motor at a higher torque and higher rotation.

  As a control method for the three-phase AC motor, sinusoidal pulse width modulation (PWM) control, overmodulation control, and rectangular wave control are well known. It is widely used that these control methods are selectively switched according to the driving conditions of the vehicle, a modulation factor described later, and the like.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 2006-31768) discloses that a motor driving system capable of variably controlling an input voltage to an inverter maintains a modulation rate in a specific control method at a target value. Yes. In this motor drive system, the inverter (14) converts the system voltage VH into an AC voltage and applies it to the AC motor (M1) in accordance with torque control by the PWM control block (200). The modulation factor target value setting unit (310) sets a modulation factor that reduces the loss of the entire system in a specific control method in the inverter (14) in which the modulation factor is not fixed. The modulation factor target value (Kmd #) Set as. The modulation factor calculation unit (330) calculates the ratio of the amplitude (Vamp) of the necessary motor voltage to the input voltage to the inverter (14), that is, the system voltage (VH), and obtains the actual modulation factor (Kmd). The voltage command value generation unit (340) generates a voltage command value (VH #) for the system voltage (VH) based on a comparison between the actual modulation factor (Kmd) and the modulation factor target value (Kmd #). The converter (12) variably controls the system voltage (VH) based on the voltage command value (VH #).

JP 2006-31768 A

  However, in the motor drive system disclosed in Patent Document 1, a modulation rate that reduces loss in the entire system is set as a modulation target value and controlled to be maintained. When such control is performed, since the rectangular wave control among the above three control methods can most reduce the switching loss in the converter or inverter, the operation region in which the rectangular wave control is selected as the AC motor drive method is relatively small. On the other hand, the operating area of the sine wave PWM control is reduced. As is well known, the rectangular wave control is inferior in control responsiveness compared to the sine wave PWM control, so that the drivability performance of the vehicle is deteriorated in the control according to Patent Document 1.

  Further, the voltage required for driving the AC motor (hereinafter referred to as “motor required voltage”) varies depending on variations in circuit constants and the environment (particularly temperature). Alternatively, when the motor rotation speed rapidly increases due to slip or the like, the required motor voltage also increases rapidly. In this way, even if the required motor voltage changes due to variations in circuit constants and the environment, the required motor voltage does not become insufficient, and control responsiveness can be ensured even when the motor speed changes suddenly. In some cases, the required voltage of the motor is set in advance by adding a voltage margin. In this case, the boost target voltage of the converter (which is the input voltage to the inverter and is hereinafter referred to as “system voltage”) calculated based on the necessary motor voltage is also set high. For this reason, if the above voltage margin is not taken into consideration, boosting by the converter may be started even at an operating point where the power supply voltage is used without being boosted and can be driven by sine wave PWM control. On the other hand, it is desirable that the drivability performance of the vehicle be as good as possible even when the converter is not boosted.

  The object of the present invention is to drive the AC motor by the sinusoidal PWM control system as much as possible when the converter is not boosted, so that the drivability performance is not impaired and the converter is not boosted as much as possible. It is an object of the present invention to provide a motor drive control device capable of improving energy efficiency by reducing electric loss in an inverter and thus improving fuel efficiency.

  A motor drive control device according to a first aspect of the present invention includes a converter capable of boosting a DC voltage supplied from a power supply device according to a system voltage command value, and converting a DC voltage as a system voltage output from the converter into an AC voltage. And selectively controlling the AC motor by at least one of sine wave PWM control, overmodulation control and rectangular wave control by controlling the operation of the converter and inverter based on the torque command value. A control unit that controls the driving of the converter, wherein the control unit obtains a modulation factor from the required motor voltage and the system voltage command value calculated based on the torque command value, and performs non-boosting of the converter A modulation rate comparison unit that compares the modulation rate with the maximum modulation rate value in the sinusoidal PWM control during operation; Rate comparing section the modulation rate comparison result of includes a step-up operation request unit that requests the start of the boost operation by the converter when it is the modulation rate maximum value or higher. Here, the “modulation rate” is defined as the ratio of the amplitude of the required motor voltage that is an AC voltage to the system voltage that is the inverter input voltage.

  The motor drive control device according to the second aspect of the present invention includes a converter capable of boosting a DC voltage supplied from a power supply device according to a system voltage command value, and a DC voltage as a system voltage output from the converter. The inverter is converted into the AC motor and applied to the AC motor, and the AC motor is controlled by at least one of sine wave PWM control, overmodulation control and rectangular wave control by controlling the operation of the converter and the inverter based on the torque command value. A motor drive control device including a control unit that selectively controls driving, wherein the control unit monitors a change state of the motor rotation speed during a non-boosting operation of the converter, and the motor rotation speed Boosting operation that requires the converter to start boosting operation when the motor speed changes suddenly based on the monitoring result of the monitoring unit Including a required part, a.

  According to the motor drive control device of the first aspect of the present invention, the drivability performance of the vehicle can be improved by driving the AC motor with sinusoidal PWM control with the best control response when possible during the non-boosting operation of the converter. By determining the start of boosting of the converter based on the modulation rate, it is possible to start boosting in a timely manner without being affected by the voltage margin. As a result, electric loss in the converter and inverter is reduced. It is possible to improve the energy efficiency rate and fuel consumption.

  According to the motor drive control device of the second aspect of the present invention, the control response of the AC motor can be controlled as much as possible by starting the boosting operation by the converter when the motor rotation speed suddenly changes during the non-boosting operation of the converter. It becomes possible to drive with good sine wave PWM control, and the drivability performance of the vehicle can be kept good even during slipping.

FIG. 1 is an overall configuration diagram of a motor drive system including a motor drive control device according to an embodiment of the present invention. FIG. 2 is a diagram showing a map that defines the relationship between the rotational speed of the motor and the torque, which is referred to by the control unit. FIG. 3 is a flowchart illustrating a processing procedure for boosting start determination executed in the control unit. FIG. 4 is a flowchart showing another boosting start determination processing procedure executed at the time of a sudden change in the motor rotation speed in the control unit. FIG. 5 is a flowchart showing a processing procedure of the motor rotation speed sudden change determination in FIG. FIG. 6A is a map showing a switching line from sine wave PWM control to overmodulation control, and FIG. 6B is a map showing a switching line from overmodulation control to sine wave PWM control.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like.

  FIG. 1 is a diagram showing an overall configuration of a motor drive system 100 including a motor drive control device 10 according to an embodiment of the present invention. The motor drive system 100 can be suitably applied to a hybrid vehicle, an electric vehicle, or the like that mounts a motor as a driving power source.

  The motor drive system 100 includes a battery 11 as a power supply device, voltage sensors 12 and 14, system main relays SMR1 and SMR2, smoothing capacitors 16 and 18, a step-up / down converter 20, an inverter 22, and a current sensor 24. The control unit 26 and the AC motor M1 are provided.

  AC motor M1 is, for example, a drive motor for generating torque for driving drive wheels of a hybrid vehicle or an electric vehicle. Alternatively, AC 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. Furthermore, AC motor M1 may operate as an electric motor for the engine, and may be incorporated into a hybrid vehicle so that the engine can be started, for example.

  The battery 11 is a secondary battery such as nickel metal hydride or lithium ion. Alternatively, in addition to the secondary battery, a capacitor without a chemical reaction or a fuel cell may be used as the power supply device. Voltage sensor 12 detects DC voltage Vb output from battery 11, and outputs the detected DC voltage Vb to control unit 26. The battery 11 is provided with a temperature sensor 28. The battery temperature Tb detected by the temperature sensor 28 is output to the control unit 26.

  System main relay SMR 1 is connected between the positive terminal of battery 11 and power line 30, and system main relay SMR 1 is connected between the negative terminal of battery 11 and ground line 32. System main relays SMR1 and SMR2 are turned on / off by a signal SE from control unit 26. More specifically, system main relays SMR1 and SMR2 are turned on by an H (logic high) level signal SE from control unit 26, and are turned off by an L (logic low) level signal SE from control unit 26. . Smoothing capacitor 16 is connected between power line 30 and ground line 32.

  Buck-boost converter 20 includes a reactor L, power semiconductor switching elements E1 and E2, and diodes D1 and D2. Power switching elements E 1 and E 2 are connected in series between power line 30 and ground line 32. On / off of power switching elements E1 and E2 is controlled by switching control signals S1 and S2 from control unit 26.

  As a power semiconductor switching element (hereinafter simply referred to as “switching element”), an IGBT (Insulated Gate Bipolar Transistor) or the like can be suitably used. Anti-parallel diodes D1 and D2 are arranged for switching elements E1 and E2.

  Reactor L is connected between a connection node of switching elements E1 and E2 and power line 30. The smoothing capacitor 16 is connected between the power line 30 and the ground line 32.

  Inverter 22 includes a U-phase arm 34, a V-phase arm 36, and a W-phase arm 38 that are provided in parallel between power line 30 and ground line 32. Each of the phase arms 34 to 38 includes a switching element connected in series between the power line 31 and the ground line 32. For example, the U-phase arm 34 includes switching elements E3 and E4, the V-phase arm 36 includes switching elements E5 and E6, and the W-phase arm 38 includes switching elements E7 and E8. Further, antiparallel diodes D3 to D8 are connected to the switching elements E3 to E8, respectively. On / off of the switching elements E3 to E8 is controlled by switching control signals S3 to S8 from the control unit 26.

The midpoint of each phase arm 34-38 is connected to each phase end of each phase coil of AC motor M1. In other words, AC motor M1 is a three-phase synchronous permanent magnet motor, and is configured such that one end of three coils of U, V, and W phases is commonly connected to a middle point N. Furthermore, the other end of each phase coil is connected to the midpoint of the switching elements of each phase arm 34-38.
During the step-up operation, the step-up / step-down converter 20 boosts a DC voltage (for example, 200 V) supplied from the battery 11 (this DC voltage corresponding to the input voltage to the inverter 22 is hereinafter referred to as “system voltage VH”). Is supplied to the inverter 22. More specifically, in response to the switching control signals S1 and S2 from the control unit 26, the ON period of the switching element E1 and the ON period of E2 are alternately provided, and the step-up ratio is equal to the ratio of these ON periods. It will be a response.

  The step-up / step-down converter 20 can boost the DC power supplied from the battery 11 up to a boost upper limit voltage of, for example, 600V. However, the boost upper limit voltage is not a fixed value, and may be variable according to, for example, the demand of the vehicle. For example, when the eco mode is selected by the driver's switch operation and the ECO signal is input to the control unit 26, the boost upper limit voltage of the converter 20 may be limited to, for example, 400V.

  Further, during the step-down operation, the step-up / step-down converter 20 steps down the DC voltage supplied from the inverter 22 via the smoothing capacitor 18 and charges the battery 11. More specifically, in response to the switching control signals S1, S2 from the control unit 26, a period in which only the switching element E1 is turned on and a period in which both the switching elements E1, E2 are turned off are alternately provided, The step-down ratio is in accordance with the duty ratio during the ON period.

  Smoothing capacitor 18 smoothes the DC voltage from buck-boost converter 20 and supplies the smoothed DC voltage to inverter 22. The voltage sensor 14 detects the voltage across the smoothing capacitor 18, that is, the system voltage VH, and outputs the detected value VH to the control unit 26.

  When the torque command value Tr * of AC motor M1 is positive (Tr *> 0), inverter 22 responds to switching control signals S3 to S8 from control unit 26 when DC voltage is supplied from smoothing capacitor 18. The AC motor M1 is driven so that the DC voltage is converted into an AC voltage by the switching operation of the switching elements E3 to E8 and a positive torque is output. Further, when the torque command value Tr * of the AC motor M1 is zero (Tr * = 0), the inverter 22 converts the DC voltage into the AC voltage by the switching operation in response to the switching control signals S3 to S8. The AC motor M1 is driven so that the torque becomes zero. As a result, AC motor M1 is driven to generate zero or positive torque designated by torque command value Tr *.

  Further, during regenerative braking of a hybrid vehicle or electric vehicle equipped with motor drive system 100, torque command value Tr * of AC motor M1 is set to a negative value (Tr * <0). In this case, the inverter 22 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 raises and lowers the converted DC voltage via the smoothing capacitor 18. Supply to the pressure converter 20. 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 a motor current flowing through AC motor M <b> 1 and outputs the detected motor current to control unit 26. Since the sum of instantaneous values of the three-phase currents iu, iv, and iw is zero, the current sensor 24 has two phases of motor current (for example, U-phase current iu and V-phase current iv) 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 motor M1, and sends the detected rotation angle θ to the control unit 26. The control unit 26 calculates the rotational speed (rotational speed) of the AC motor M1 based on the rotational angle θ.

  The control unit 26 includes a torque command value Tr * input from an electronic control unit (ECU) provided outside, a battery voltage Vb detected by the voltage sensor 12, a system voltage VH detected by the voltage sensor 14, and a current sensor. Based on the motor currents iu and iv from 24 and the rotation angle θ from the rotation angle sensor 40, the step-up / down converter 20 and the AC motor M1 output torque according to the torque command value Tr * by a method described later. The operation of the inverter 22 is controlled. That is, the switching control signals S1 to S8 for controlling the buck-boost converter 20 and the inverter 22 as described above are generated and output to the buck-boost converter 20 and the inverter 22.

  During the step-up operation of the step-up / step-down converter 20, the control unit 26 performs feedback control on the output voltage VH of the smoothing capacitor 18, and generates the switching control signals S1 and S2 so that the output voltage VH becomes the system voltage command value VH *.

  Further, when the control unit 26 receives a signal indicating that the hybrid vehicle or the electric vehicle has entered the regenerative braking mode from the external ECU, the control unit 26 converts the AC voltage generated by the AC motor M1 into a DC voltage. S <b> 3 to S <b> 8 are generated and output to the inverter 22. As a result, the inverter 22 converts the AC voltage generated by the AC motor M <b> 1 into a DC voltage and supplies it to the step-up / down converter 20.

  Further, when the control unit 26 receives a signal indicating that the hybrid vehicle or the electric vehicle has entered the regenerative braking mode from the external ECU, the control unit 26 outputs the switching control signals S1 and S2 so as to step down the DC voltage supplied from the inverter 22. Generated and output to the buck-boost converter 20. As a result, the AC voltage generated by AC motor M1 is converted into a stepped-down DC voltage and charged to battery 11.

  Next, power conversion in the inverter 22 controlled by the control unit 26 will be described in detail. In the motor drive system 100 of the present embodiment, three control methods are switched and used for power conversion in the inverter 22.

  The sine wave PWM control method is used as a general PWM control. The switching element in each phase arm is turned on / off by changing the voltage between a sine wave voltage command value and a carrier wave (typically, a triangular wave). Control according to the comparison. 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 fundamental wave component is a sinusoidal AC voltage (motor) within one control cycle. The duty ratio is controlled so as to be the required voltage. As is well known, in a general sine wave PWM control system, the maximum modulation rate defined as the ratio of the amplitude of the required motor voltage to the system voltage VH can only be increased to 0.61. However, it is known that the maximum modulation factor can be increased to 0.70 in the case of sinusoidal PWM control by the two-phase modulation method or the third harmonic superposition control.

  On the other hand, in the rectangular wave control method, the AC motor M1 is applied for one pulse of the rectangular wave whose ratio between the high level period and the low level period is 1: 1 within the one control period. As a result, the modulation rate is increased to 0.78.

  The overmodulation control method performs PWM control according to a voltage comparison between a sinusoidal voltage command value and a carrier wave as in the sine wave PWM control method. In this case, the voltage command value is larger than the carrier wave. As a result of generating a rectangular pulse having a relatively large duty ratio, the amplitude of the fundamental wave component having a substantially sinusoidal shape can be expanded, thereby increasing the modulation factor to a range of 0.61 to 0.78. it can.

  In AC motor M1, when the number of rotations and output torque increase, the induced voltage increases and the required motor voltage increases. The boosted voltage by the converter 20, that is, the system voltage VH needs to be set higher than this motor required voltage (induced voltage). On the other hand, the boosted voltage by the converter 20, that is, the system voltage has an upper limit value, that is, a boosted upper limit voltage.

  Therefore, in the region where the required motor voltage (induced voltage) is lower than the maximum value of the system voltage, the maximum torque control by the sine wave PWM control method or the over modulation control method is applied, and the output torque is controlled by the motor current control according to the vector control. Is controlled to the torque command value Tr *. On the other hand, when the required motor voltage (induced voltage) reaches the maximum value of the system voltage (VH maximum voltage), a rectangular wave control method according to field weakening control is applied while maintaining the system voltage VH. In the rectangular wave control method, since the amplitude of the fundamental wave component is fixed, torque control is executed by voltage phase control of the rectangular wave pulse based on the deviation between the actual torque value obtained by power calculation and the torque command value.

  The control unit 26 selects a control method from the three control methods as follows. In response to the torque command value Tr * of the AC motor M1 being calculated and inputted from the vehicle request output based on the accelerator opening etc. in an external ECU (not shown), the control unit 26 is based on a preset map or the like. Then, the required motor voltage is calculated from the torque command value Tr * of the AC motor M1 and the motor rotation speed.

  Then, the control unit 26 performs field-weakening control (rectangular wave control method) and maximum torque control (sine wave PWM control method / overmodulation) in accordance with the relationship between the required motor voltage and the maximum value of the system voltage VH (that is, the boost upper limit voltage). Select which of the control methods is to be used for motor control. Whether to use the sine wave PWM control method or the overmodulation control method when applying the maximum torque control is selected according to the modulation rate range of the voltage command value according to the vector control. That is, 0 <modulation rate <0.61 selects sinusoidal PWM control, 0.61 ≦ modulation rate <0.78 selects overmodulation control, and modulation rate = 0.78 selects rectangular wave control.

  As a result, as a control method for AC motor M1, sine wave PWM control method with small torque fluctuation and excellent control response is used in the low and medium rotation speed region, and overmodulation control method is used in the medium and high rotation speed region. A rectangular wave control method is used in the rotation speed region.

  Next, the boosting start determination process of the converter 26 executed in the control unit 26 of the motor drive control device 10 of the present embodiment will be described.

  In motor drive system 100, AC motor M <b> 1 can be driven and controlled by one of the above three control methods using battery voltage Vb (for example, 200 V) supplied from battery 11 as it is without causing converter 26 to perform a boost operation. There is an operating area. The operation area of each control is shown in the map of FIG.

  Referring to FIG. 2, in this map, the horizontal axis represents the motor rotation speed and the vertical axis represents the motor torque, and the outline line defining the substantially trapezoidal area together with the horizontal axis and the vertical axis represents when the converter 20 is not boosted This is the maximum torque line that the AC motor M1 can output. The inner region of the maximum torque line is divided into a sine wave PWM control region A1, an overmodulation control region A2, and a rectangular wave control region A3 according to the modulation factor value described above. A line where the boundary between the sine wave PWM control region A1 and the overmodulation control region A2 coincides with the modulation factor 0.61 which is the maximum modulation factor value of general sine wave PWM control (displayed as “boost start determination line”). This will be described later), and the boundary between the overmodulation control region A2 and the rectangular wave control region A3 is a line that matches the modulation factor 0.78 (constant) of the rectangular wave control.

  Note that the maximum torque line during boosting indicated by a broken line in FIG. 2 can be output by the AC motor M1 when the battery voltage Vb is boosted to the boosting upper limit voltage by the converter 20 and the system voltage VH is set to the maximum value (for example, 600V). The maximum torque line is shown. Similarly to the above, the inner region of the maximum torque line is divided into control regions A1, A2, and A3 by lines (not shown) defined by the modulation rate.

  Generally, the control unit in the motor drive system stops the boosting operation of the converter when the system voltage command value VH * calculated based on the torque command value Tr * becomes equal to or lower than the battery voltage Vb. When the value VH * exceeds the battery voltage Vb, the boosting operation of the converter is started and the boosting target voltage according to the system voltage command value VH * is output.

  However, when the system voltage command value VH * is calculated from the required motor voltage added with a voltage margin in consideration of variations in circuit constants of AC motors, environmental changes, sudden changes in the motor speed, etc., the system voltage command value VH * Will also be set high. Therefore, when the boosting start or stop of the converter is determined by comparing the system voltage command value VH * and the battery voltage Vb, the AC motor is sinusoidally used without boosting the battery voltage Vb unless the voltage margin is considered. Boosting by the converter may be started even at an operating point that can be driven by the wave PWM control, and in this case, electric loss occurs in the converter and the inverter.

  Therefore, the control unit 26 of the motor drive control device 10 of the present embodiment executes the boost start determination process of the first aspect as shown in FIG. This boosting start determination process is repeatedly executed, for example, every several msec when the boosting operation of the converter 20 is stopped, that is, when there is no boosting.

  First, when the converter 20 is not boosted, the modulation rate is compared with a preset threshold A (step S10: modulation rate comparison unit). Here, the modulation factor is obtained by the control unit 26 dividing the amplitude of the necessary motor voltage calculated based on the input torque command value Tr * by the system voltage command value VH *. The calculation of the necessary motor voltage and the system voltage command value VH * here can be performed by a known method. Further, as a specific example of the threshold A, 0.61 which is a maximum modulation rate value of general sine wave PWM control is used.

  When it is determined in step S10 that the modulation factor is equal to or greater than threshold A, the boost start request flag is set to ON (step S12: boost operation request unit), and the boost operation of converter 20 is started. On the other hand, if it is determined that the modulation factor is less than the threshold value A, the boost start request flag is set to OFF or maintained (step S14).

  As described above, the required modulation rate is obtained by dividing the required motor voltage (amplitude), which is set higher in advance by the voltage margin added in consideration of variations in motor circuit constants, etc., by the system voltage command value VH *. Thus, the influence of the voltage margin is offset. Therefore, by determining the boost start of the converter 20 based on the modulation rate, the boost start can be performed in a timely manner without being affected by the voltage margin, and as a result, the electric loss in the converter 20 and the inverter 22 is reduced. This can improve the energy efficiency rate and fuel consumption.

  Further, by using the maximum modulation factor value of sine wave PWM control as the threshold value A to be compared, AC motor M1 is driven with sine wave PWM control having as excellent control response as possible during non-boosting operation of converter 20. Therefore, the drivability performance of the vehicle can be maintained well.

  Next, the boosting start determination process of the second aspect executed by the control unit 26 of the motor drive control device 10 of the present embodiment will be described with reference to FIG.

  First, when the converter 20 is not boosted, it is determined whether or not the sudden rotation change determination flag is on (step S20). When the sudden rotation change determination flag is on, the boost start request flag is set to on (step S22: Step-up operation requesting unit), and thereby the step-up operation of the converter 20 is started. On the other hand, when the rapid rotation change determination flag is off, the boost start request flag is set off or maintained (step S24).

  The sudden rotation change determination flag is derived according to the processing procedure shown in FIG. First, the change rate of the motor rotation speed is calculated (step S30). The motor rotation speed change rate is obtained as a rate of change per unit time (for example, every second) of the rotation speed of the AC motor M1, which is calculated as needed based on the detection value θ of the rotation angle sensor 40.

  Next, it is determined whether or not the rotation speed change rate is equal to or higher than a preset threshold rate B (step S32: motor rotation speed monitoring unit). Thereby, the change state of the rotation speed of AC motor M1 is monitored by the rotation speed change rate. If it is determined that the rotational speed change rate is equal to or higher than the threshold rate B, the rapid rotation change determination flag is set to ON (step S34), and the sudden change determination counter is set to C (msec) (step S36).

  On the other hand, if it is determined in step S32 that the rotation speed change rate is less than the threshold rate B, the sudden change determination counter C is decremented by a predetermined time (for example, several msec) every time the process of FIG. 5 is repeated ( Step S40). Then, it is determined whether or not the sudden change determination counter has become 0 (step S42). If it is determined that the sudden change determination counter is 0, the rotation sudden change determination flag is set to OFF or maintained. On the other hand, the rotation sudden change determination flag is held at the previous value until the sudden change determination counter becomes 0 (step S46). Thus, when the previous value of the rotation sudden change determination flag is on, it is held as it is.

  As described above, according to the other boost determination process executed in the control unit 26, the converter 20 starts the boost operation when the motor rotation speed changes suddenly during the non-boosting operation of the converter 20, so that AC is possible as much as possible. The motor M1 can be driven by sinusoidal PWM control with excellent control response, and the drivability performance of the vehicle can be kept good even during slipping.

  The motor drive control device according to the present invention is not limited to the configuration and control processing procedure of the above-described embodiment, and various changes and improvements can be made.

  For example, as one of the control methods for the AC motor M1, the description has been made assuming that a general sine wave PWM control with a modulation factor of 0 to 0.61 is used. Instead, the modulation factor is set to a maximum value of 0.70. A sinusoidal PWM control based on a two-phase modulation method or a third harmonic superposition control may be used. Thereby, the drivability performance of the vehicle can be further improved. Further, when this sine wave PWM control is applied, 0.70 is used as the threshold A during the boosting start determination of the first aspect.

  Furthermore, the threshold A used in the boost start request determination of the first aspect may be set to a different value between the boost start determination and the boost stop determination. Specifically, as shown in FIG. 6A, while setting the threshold A of the modulation factor corresponding to the control method switching line from sine wave PWM control to overmodulation control, for example, 0.61, As shown in B), a modulation factor threshold A corresponding to a control method switching line from overmodulation control to sine wave PWM control is set to 0.59, for example. Thereby, it is possible to suppress the hunting phenomenon in which the start and stop of the boosting operation of converter 20 frequently occur.

  DESCRIPTION OF SYMBOLS 10 Motor drive control apparatus, 11 Battery, 12, 14 Voltage sensor, 16, 18 Smoothing capacitor, 20 Buck-boost converter, 22 Inverter, 24 Current sensor, 25 Rotation angle sensor, 26 Control part, 28 Temperature sensor, 40 Rotation angle sensor , 100 Motor drive system, M1 AC motor.

Claims (2)

A converter capable of boosting a DC voltage supplied from a power supply device according to a system voltage command value, an inverter for converting a DC voltage as a system voltage output from the converter into an AC voltage, and applying it to an AC motor, and a torque command value And a controller that selectively controls the AC motor by at least one of sine wave PWM control, overmodulation control, and rectangular wave control by controlling the operation of the converter and the inverter based on the motor drive control device. Because
The control unit
Modulation rate comparison for obtaining a modulation rate from the required motor voltage and system voltage command value calculated based on the torque command value and comparing the modulation rate with the maximum modulation rate value in sinusoidal PWM control during non-boosting operation of the converter And
And a step-up operation requesting unit that requests a converter to start a step-up operation when the modulation rate is equal to or greater than the modulation factor maximum value as a result of comparison by the modulation rate comparison unit. A converter capable of boosting a DC voltage supplied from a power supply device according to a system voltage command value, an inverter for converting a DC voltage as a system voltage output from the converter into an AC voltage, and applying it to an AC motor, and a torque command value And a controller that selectively controls the AC motor by at least one of sine wave PWM control, overmodulation control, and rectangular wave control by controlling the operation of the converter and the inverter based on the motor drive control device. Because
The control unit is a motor rotation number monitoring unit that monitors a change state of the motor rotation number during the non-boosting operation of the converter;
A step-up operation requesting unit that requests the start of the step-up operation by the converter when the motor rotation number suddenly changes according to the monitoring result of the motor rotation number monitoring unit;

Images