JP2010207030A - Motor drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive control device that prevents high-frequency noise from being generated from a motor driven by over-modulation control. <P>SOLUTION: The motor drive control device includes: a converter 48; inverters 44 and 46; and a motor ECU60 that controls the operation thereof to selectively drive and control motors MG1 and MG2 in sine wave PWM control, over-modulation control, or rectangular wave control. The motor ECU60 includes; a converter operation decision part (step S10) that decides whether boost by the converter 48 is prohibited or not; a motor drive method decision part (step S12) that decides whether the motor drive method is over-modulation control or not; and a motor drive method switch part (step S14) that starts boost operation by the converter 48 to change the drive method of the motors MG1 and MG2 from the over-modulation control to the sine wave PWM control. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor drive control device, and more particularly to a motor drive control device capable of suppressing high-frequency noise generated from a motor driven by overmodulation control.

  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 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 some cases, the hybrid vehicle includes a generator that generates power by receiving all or part of the power output from the engine, and a three-phase synchronous AC motor is also used for the generator. . The electric power generated by the generator is charged in the power storage device or used as electric power for driving the electric motor. Hereinafter, the three-phase synchronous AC motor used for the electric motor and generator will be referred to as “motor” as appropriate.

  As the motor drive control system, sine wave PWM (Pulse Width Modulation) control, overmodulation control and rectangular wave control are known, and any of the above controls according to the output torque, rotation speed, etc. required for the motor. The method is selectively set.

  When executing the sine wave PWM control or overmodulation control, the PWM signal for turning on / off the power switching element (eg, IGBT) included in the inverter fluctuates periodically as shown in FIG. 11A. For example, it is generated by voltage comparison between a triangular wave carrier 1 and a sinusoidal voltage command 2.

  When the three-phase AC voltage converted by the inverter that is controlled by the PWM signal generated in this way is applied to the motor and driven, the motor generates an integer-order high-frequency sound such as a primary or secondary carrier frequency f. May occur. FIG. 10 schematically shows the state, in which a three-phase AC voltage is applied from the inverter 3 to the motor 5 through three power wirings 4 corresponding to the three phases of the U phase, the V phase, and the W phase. In particular, a phenomenon was observed in which high-frequency sound 7 was generated from the vicinity of the input terminal portion 6 of the motor 5, which is a motor drive voltage input portion.

  The high frequency sound resulting from the carrier frequency f as described above may be perceived as annoying noise for a user in a car. In particular, when the vehicle is running at low speeds or when the level of sound generated when the vehicle is running, including engine noise, motor noise, and the sound generated when the tire rolls on the road surface, becomes relatively low and the interior is quieter. Sometimes it becomes easy to feel high-frequency sound generated from the motor as noise.

  In order to solve the problem of high-frequency noise caused by the carrier frequency f described above, as shown in FIG. 11B, a carrier having a high frequency band exceeding an audible frequency band (for example, an upper limit of about 5 kHz) that is a sound range that can be heard by humans is used. Control is performed such that the frequency f of 1 is changed or switched.

  For example, Patent Document 1 discloses a technique for changing a carrier frequency used for inverter control according to a load state of an air conditioner, and describes that the carrier sound is reduced by changing to a high carrier frequency at a light load. Has been.

JP 2002-272126 A

  However, in the hybrid vehicle described above, there may be a situation where the carrier frequency cannot be arbitrarily set according to the motor load in order to suppress high-frequency noise caused by the carrier. For example, overmodulation control, which is one of the motor drive systems, is inferior in control responsiveness compared to sine wave PWM control, but in order to achieve good control responsiveness as close as possible to sine wave PWM control, FIG. As shown in FIG. 5, the control in which the electrical cycle (or control cycle) of the voltage command 2 and an integral multiple of the triangular wave constituting the carrier 1 (here, 8 times as an example) are synchronized (hereinafter simply referred to as “synchronous control”). )) Is required.

  Therefore, when the motor is in the overmodulation control state, the carrier frequency cannot be arbitrarily set to a high frequency exceeding the audible band in order to suppress high frequency noise. In contrast, sine wave PWM control does not impair good control responsiveness even in asynchronous control where the voltage command and carrier are not synchronized, and rectangular wave control is more control responsive than overmodulation control. However, since no carrier is used for inverter control, the problem of high frequency noise caused by the carrier frequency does not occur.

  An object of the present invention is to provide a motor drive control device capable of suppressing high-frequency noise generated from a motor driven by overmodulation control.

  A motor drive control device according to the present invention includes a converter capable of boosting a DC voltage received from a power supply device, an inverter that converts a DC voltage output from the converter into an AC voltage, and applies the drive voltage to an AC motor, a converter, A control unit capable of selectively driving and controlling the AC motor by any one of sine wave PWM control, overmodulation control and rectangular wave control by operating an inverter, and a motor drive control device comprising: The control unit determines whether or not boosting by the converter is prohibited or restricted, and whether or not the AC motor drive system is overmodulation control according to the determination result of the converter operation determination unit. It is determined that the AC motor is being driven by overmodulation control by the motor drive method determination unit and the motor drive method determination unit. Characterized in that it comprises a motor drive system switching unit to shift to the sine wave PWM control or rectangular wave control from the overmodulation control the driving method of the AC motor starts or stops the boosting operation by the converter when.

  In the motor drive control device according to the present invention, the control unit is configured such that the frequency of the carrier used for generating the PWM signal for controlling the operation of the switching element included in the inverter is a frequency in the audible frequency band and a frequency exceeding the audible range. A carrier frequency switching unit for switching to a band type, and when the control unit determines that boosting by the converter is prohibited by the converter operation determining unit, the motor drive system switching unit cancels the boost prohibition by the converter. In addition, the boosting operation may be started to shift the AC motor driving method from overmodulation control to sine wave PWM control, and the carrier frequency switching unit may switch the carrier frequency to a high frequency exceeding the audible range.

  In the motor drive control device according to the present invention, the control unit further includes a shift position determination unit that determines whether or not the shift position of the vehicle is neutral, and the shift position determination unit determines that the shift position is neutral. When it is determined, the boost prohibition release of the converter, the start of the boost operation, and the transition to the sine wave PWM control may be executed.

  In the motor drive control device according to the present invention, the control unit may cancel the boost prohibition of the converter and start the boost operation when the shift position is neutral and the vehicle speed or the motor speed is equal to or less than the threshold value, and the sine Transition to wave PWM control may be executed.

  Furthermore, in the motor drive control device according to the present invention, when the controller determines that the boosting by the converter is restricted by the converter operation determining unit, the motor drive system switching unit stops the boosting operation by the converter. The driving method of the AC motor may be shifted from overmodulation control to rectangular wave control.

  According to the motor drive control device of the present invention, the AC motor drive method is changed from overmodulation control to sine wave PWM control or rectangular wave control according to the determination result of whether or not boosting by the converter is prohibited or restricted. The control to be transferred is executed. As a result, the carrier frequency can be arbitrarily set to a high frequency exceeding the audible range when shifting to sine wave PWM control capable of asynchronous control, and inverter control is performed when shifting to rectangular wave control. Since no carrier is used, high frequency noise caused by the carrier frequency can be suppressed or eliminated in any case.

1 is a schematic configuration diagram of a hybrid vehicle to which a motor drive control device according to an embodiment of the present invention is applied. It is a figure which shows the converter, inverter, and motor ECU which comprise the motor drive control apparatus of FIG. It is a figure which shows the 1st map which prescribes | regulates the relationship between the rotation speed of a motor, and a torque referred in motor ECU. It is a graph which shows a voltage waveform and a modulation factor about each of sine wave PWM control, overmodulation control, and rectangular wave control. It is a 2nd map which prescribes | regulates the relationship between the rotation speed of a motor, and a torque referred in motor ECU. It is a flowchart which shows the process sequence which switches a motor drive system from over modulation control to sine wave PWM control performed in motor ECU. It is a flowchart which shows the modification of the process sequence shown in FIG. It is a flowchart which shows the process sequence which switches a motor drive system from overmodulation control to rectangular wave control performed in motor ECU. It is a figure which shows the map applied by the process shown in FIG. It is a figure which shows typically a mode that the high frequency sound has generate | occur | produced from the motor. It is a figure which shows each waveform of a comparatively low frequency carrier and voltage command. It is a figure which shows each waveform of a comparatively high frequency carrier and voltage command. It is a figure for demonstrating the synchronous control in overmodulation 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 a schematic configuration of a hybrid vehicle 10 including a motor drive control device according to an embodiment of the present invention. In FIG. 1, the power transmission system is indicated by a solid line, the power line is indicated by a one-dot chain line, and the signal line is indicated by a dotted line. The hybrid vehicle 10 includes an engine 12 capable of outputting driving power, two three-phase AC synchronous motor generators (hereinafter simply referred to as “motors”) MG 1 and MG 2, and a power distribution and integration mechanism 14.

  The engine 12 is an internal combustion engine that uses gasoline, light oil, or the like as fuel. The engine 12 is electrically connected to an engine ECU (Electronic Control Unit) (hereinafter referred to as “engine ECU”) 16 and receives a control signal from the engine ECU 16 to inject fuel, ignite, intake air amount, and the like. The operation is controlled by adjusting. The rotational speed Ne of the engine 12 is calculated by the engine ECU 16 based on a detection value by the rotational position sensor 11 provided in the vicinity of the output shaft 13 that outputs power from the engine 12.

  The power distribution and integration mechanism 14 meshes with both the sun gear 18 disposed in the center, the ring gear 20 disposed concentrically with the sun gear 18 and having inner teeth on the inner periphery of the annular ring, and both the sun gear 18 and the ring gear 20. The planetary gear mechanism is configured to include a plurality of planetary gears 22. The plurality of planetary gears 22 are rotatably attached to end portions of the carrier 26, respectively.

  In the power distribution and integration mechanism 14, the output shaft 13 of the engine 12 is connected to the carrier 26 via a damper 24 for reducing torque impact, and the rotary shaft 30 connected to the rotor 29 of the motor MG 1 is connected to the sun gear 18. The reduction gear 34 is connected to the ring gear 20 via the ring gear shaft 32. Thus, in the power distribution and integration mechanism 14, when the motor MG1 functions as a generator, the power from the engine 12 input from the carrier 26 is distributed to the sun gear 18 side and the ring gear 20 side according to the gear ratio. When the MG 1 functions as an electric motor, the power of the engine 12 input from the carrier 26 and the power from the MG 1 input from the sun gear 18 are integrated to reduce the speed including a gear train having a predetermined reduction ratio from the ring gear 20 via the ring gear shaft 32. It is input to the machine 34.

  A rotary shaft 38 connected to the rotor 36 of the motor MG2 is also connected to the speed reducer 34. When the motor MG2 functions as an electric motor, power from the motor MG2 is input to the speed reducer 34.

  The power input from at least one of the ring gear shaft 32 and the rotation shaft 38 of the MG 2 is transmitted to the axle 40 through the speed reducer 34, whereby the wheels 42 are rotationally driven. On the other hand, when power is input from the wheel 42 and the axle 40 to the rotary shaft 38 via the speed reducer 34 during regenerative braking, the MG 2 functions as a generator. Here, during regenerative braking, not only when the driver brakes the vehicle to reduce the vehicle speed, but also when the driver releases the accelerator pedal and stops vehicle acceleration, or when the vehicle goes downhill. This includes cases where the vehicle is traveling by gravity.

  Motors MG1 and MG2 are electrically connected to corresponding inverters 44 and 46, respectively, and each inverter 44 and 46 functions as a power supply device via a DC / DC converter (hereinafter simply referred to as "converter") 48. The battery 50 is electrically connected. As the battery 50, a secondary battery such as a lithium ion battery or a capacitor that can store electricity without causing a chemical reaction is preferably used.

  When motors MG1 and MG2 function as an electric motor, converter 48 is supplied with DC voltage Vb, which is a battery voltage, from battery 50 via smoothing capacitor 52. The converter 48 has a function of boosting the input voltage Vb to a predetermined value Vc and outputting it. Further, the converter 48 has a maximum boostable voltage determined by the standard. For example, the battery voltage Vb of 200V can be boosted to a maximum of 600V. However, when the eco mode is selected as the vehicle travel mode as will be described later, the boosting operation of the converter 48 is prohibited, and the battery voltage Vb is output from the inoperative converter 48 as it is.

  The DC voltage Vc output from the converter 48 is input to the inverters 44 and 46 via the smoothing capacitor 54. Each inverter 44, 46 converts the input DC voltage Vc into a three-phase AC voltage and applies it to the motors MG1, MG2, whereby the motors MG1, MG2 are rotationally driven as electric motors. . As described above, the converter output voltage Vc is an inverter input voltage, which may be hereinafter referred to as a system voltage VH.

  Further, since the motor MG1 is connected to the engine 12 via the power distribution and integration mechanism 14, it can be driven as an electric motor and used as a cell motor at the time of starting the engine. It can also be used as a transmission for shifting the rotational speed Ne of the engine 12 by performing control.

  On the other hand, when the motors MG1 and MG2 function as generators, the three-phase AC voltage output from the motors MG1 and MG2 is converted into DC by the inverters 44 and 46, and then the voltage is stepped down by the converter 48 to charge the battery 50. Since inverters 44 and 46 share power line 56 and ground line 58 connected to converter 48, the power generated by one of motors MG 1 and MG 2 is not transmitted through converter 48 but the other. It can also be driven to rotate by being supplied to this motor.

  The inverters 44 and 46 are electrically connected to a motor ECU (hereinafter referred to as “motor ECU”) 60 as a control unit, respectively, and are operated and controlled based on a control signal transmitted from the motor ECU 60. The motors MG1 and MG2 are provided with rotation angle sensors 31 and 37 for detecting the rotation angles of the rotors 29 and 36, respectively. The rotation angle sensors 31 and 37 are preferably configured by, for example, a resolver. The detection values by the rotation angle sensors 31 and 37 are input to the motor ECU 60 and used for calculating the motor rotation speeds Nm1 and Nm2.

  The motor ECU 60 can be constituted by a microcomputer including a CPU that executes a control program described later, a ROM that stores a control program, a control map, and the like, and a RAM that can store and read various detection values as needed. The map stored in the ROM includes a first map (see FIG. 3) that is referred to in the normal travel mode, and a second map (see FIG. 5) that is referred to in the eco mode, which is the fuel efficiency-oriented travel mode. Is included.

  The eco mode may be configured to be manually selected by turning on an eco switch provided near the driver's seat and easily operated by the driver, or When the hybrid ECU 66 (hereinafter referred to as “hybrid ECU”) 66 that comprehensively monitors the driving state of the vehicle travels only by the power of the motor MG2, the vehicle speed and the torque request to the motor MG2 are stable. It may be configured to be automatically selected in some cases.

  The battery 50 is provided with an SOC sensor 62 for detecting a state of charge (SOC). The SOC sensor 62 can be configured by a current sensor that detects a charge / discharge current of the battery 50. The value detected by the SOC sensor 62 is input to a battery ECU (hereinafter referred to as “battery ECU”) 64. The battery ECU 64 is input with a battery voltage Vb detected by a voltage sensor, a battery temperature detected by a temperature sensor (not shown), and the like. The battery ECU 64 monitors the remaining battery capacity SOC based on the integrated value of the charge / discharge current detected by the SOC sensor 62 so that the remaining battery capacity SOC is maintained in an appropriate range. A limit signal is output to hybrid ECU 66.

  The hybrid ECU 66 is electrically connected to the engine ECU 16, the motor ECU 60, and the battery ECU 64, respectively, and has a function of comprehensively controlling the engine 12 and the motors MG1 and MG2 and managing the battery 50. The hybrid ECU 66 transmits an engine control signal to and from the engine ECU 16 as necessary, and receives data relating to the engine operating state (for example, engine speed Ne) as necessary. Further, the hybrid ECU 66 transmits a required torque command Tr * to the motor ECU 60 as necessary, and receives data relating to the motor operating state (for example, motor rotation speeds Nm1, Nm2, motor current, etc.) as necessary. To do. Further, the hybrid ECU 66 receives data necessary for battery management such as the remaining battery capacity SOC, battery voltage, battery temperature, and charge / discharge restriction signal from the battery ECU 64.

  The hybrid ECU 66 is also electrically connected to a vehicle speed sensor 68, an accelerator opening sensor 70, and a shift position sensor 71. The vehicle speed Sv, which is the traveling speed of the hybrid vehicle 10, and the depression amount of an accelerator pedal (not shown). Corresponding accelerator opening information Ac and shift position information R in which the shift lever is operated are respectively input.

  FIG. 2 is a diagram showing the converter 48, the inverters 44 and 46, and the motor ECU 60 that constitute the motor drive control device 100 of this embodiment in more detail. Since inverter 44 for motor MG1 has the same configuration as inverter 46 for motor MG2, only inverter 46 will be described here.

  Converter 48 is connected to battery 50 via system main relays SMR1, SMR2. System main relays SMR1, SMR2 are turned on / off in response to a switching signal from motor ECU 60.

  Converter 48 includes a reactor L, power switching elements (hereinafter simply referred to as “switching elements”) E1 and E2, and diodes D1 and D2. Switching elements E 1 and E 2 are connected in series between power line 56 and ground line 58. As the switching elements E1 and E2, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used. The diodes D1 and D2 are connected in parallel to the switching elements E1 and E2, respectively, so that a current flows from the emitter side to the collector side. Reactor L has one end connected to connection line 74 between switching elements E1 and E2, and the other end connected to the positive electrode of battery 50 via system main relay SMR1. The switching elements E1, E2 are turned on / off in response to the switching signals S1, S2 from the motor ECU 60.

  The voltage across the smoothing capacitor 54 arranged between the converter 48 and the inverter 46, that is, the system voltage VH is detected by the voltage sensor 55 and input to the motor ECU 60.

  Inverter 46 includes a U-phase arm 78, a V-phase arm 80, and a W-phase arm 82 provided in parallel with each other between power line 56 and ground line 58. Each of the phase arms 78 to 82 includes two switching elements connected in series between the power line 56 and the ground line 58 and two diodes respectively connected in antiparallel to the switching elements. Specifically, U-phase arm 78 includes switching elements E3 and E4 and diodes D3 and D4, V-phase arm 80 includes switching elements E5 and E6 and diodes D5 and D6, and W-phase arm 82 includes switching elements E7 and E8. And diodes D7 and D8. For example, an IGBT or the like can be suitably used for each of the switching elements E3 to E8. Switching elements E3 to E8 are switched on / off in response to switching signals S3 to S8 from motor ECU 60.

  An intermediate point of each phase arm 78, 80, 82 is connected to one end of each phase coil of U phase, V phase and W phase (hereinafter simply referred to as “three phases”) of motor MG2. Each other end of each phase coil is commonly connected to a neutral point N in the motor MG2. Further, the currents flowing through the U-phase and V-phase coils are detected by the current sensor 84 and input to the motor ECU 60. The current flowing through the W-phase coil can be calculated from the relationship that the sum of the three-phase currents becomes zero.

  Next, with reference to FIGS. 3 to 5, the driving method of the motors MG <b> 1 and MG <b> 2 and map switching between the normal travel mode and the eco mode will be described. FIG. 3 shows a first map referred to in the motor ECU 60 in the normal travel mode. FIG. 4 schematically shows a voltage waveform and a modulation factor for each of three typical motor drive systems, ie, sine wave PWM control, overmodulation control, and rectangular wave control. FIG. 5 shows a second map referred to in the motor ECU 60 during the eco mode.

  The motor ECU 60 refers to the first map in the normal travel mode, and the motor MG1, using any one of the sine wave PWM control, overmodulation control, and rectangular wave control according to the input torque command Tr *. Drive control of MG2.

  The sine wave PWM control is the most commonly used PWM control in an AC motor, and is applied from a low rotation range to a middle rotation range as shown in FIG. In this control, as shown in FIG. 4, the on / off control of the switching elements E3-E8 in the respective phase arms 78-82 of the inverters 44, 46 is performed using a sinusoidal voltage command and a carrier (typically a triangular wave). This is performed by PWM signals S3-S8 generated in accordance with voltage comparison with a carrier wave. As a result, the fundamental wave component of the AC voltage applied to the motors MG1 and MG2 is a sine wave, which is a drive system that can produce a smooth output with little torque fluctuation and good control response. However, the modulation rate (ratio of the amplitude of the fundamental wave component to the system voltage VH, which is the same hereinafter) can only be increased from 0 to a maximum of 0.61, and the motor output becomes smaller than other driving methods.

  In addition, since the amplitude of the voltage command does not exceed the amplitude of the carrier and fine PWM signals can be generated in the sine wave PWM control, the motor electrical cycle or control cycle and the carrier frequency are not necessarily synchronized. Since the controllability does not deteriorate, the carrier frequency can be arbitrarily set or switched from one having a frequency in the audible band to one having a high frequency exceeding the audible band.

  On the other hand, in the rectangular wave control, under the field weakening control, as shown in FIG. 4, the switching element E3 of the inverters 44 and 46 applies only one rectangular wave pulse with a duty ratio of 50% to the motor within the one electrical cycle as shown in FIG. -E8 is on / off controlled. Thus, the modulation factor can be increased to 0.78 (constant), and is applied to control in a high output / high rotation range as shown in FIG. Further, in the rectangular wave control, a carrier is not used for generating the switching signals S3-S8, so that a problem that high-frequency noise caused by the carrier frequency is generated from the motor does not occur.

  On the other hand, as shown in FIGS. 3 and 4, the overmodulation control is applied from the middle rotation region to the high rotation region between the sine wave PWM control and the rectangular wave control, and the modulation factor is 0.61 to 0.78. It is variable between. This overmodulation control is also referred to as overmodulation PWM control because the PWM signals S3-S8 for the switching elements E3-E8 of the inverters 44, 46 are generated in accordance with the voltage comparison between the sinusoidal voltage command and the carrier. When the amplitude of the voltage command exceeds the amplitude of the carrier, the PWM signals S3 to S8 include a rectangular wave pulse having a relatively large duty ratio, which causes a large torque fluctuation compared to the sine wave PWM control and control response. It will be inferior to Therefore, in order to realize good control response close to sine wave PWM control as much as possible even in overmodulation control, it is necessary to perform synchronous control that synchronizes the electric cycle of the motor and the frequency of the carrier.

  In the normal running mode in which the motor drive method is selected with reference to the first map, the boost value by the converter 46 becomes the system voltage target value VH * required according to the motor drive method and its modulation factor. The switching signals S1 and S2 of the switching elements E1 and E2 are generated and output by the motor ECU 60. In this case, system voltage target value VH * is not less than battery voltage Vb (for example, 200 V) and not more than converter maximum boosted voltage Vcmax (for example, 600 V).

  However, when the eco mode is selected as described above, motor ECU 60 receives the input of the ECO signal and inhibits the boost operation by converter 48. Thereby, the boosting operation by converter 48 is prohibited, and system voltage VH becomes equal to battery voltage Vb. By prohibiting the boosting operation by the converter 48 in this way, it is possible to eliminate the occurrence of reactor loss and switching loss in the converter 48, and it is possible to improve energy efficiency and consequently improve fuel efficiency.

  When the eco mode is selected, the motor ECU 60 sets the drive system of the motors MG1 and MG2 with reference to the second map shown in FIG. The dotted line shown in FIG. 5 shows the outline of the first map shown in FIG. Since the boost of the converter 48 is prohibited and the battery voltage Vb is applied as the system voltage VH, the second map is a map that is reduced to the low torque side and the low rotation region side as a whole compared to the first map. It has become. Therefore, even at the same operation point A indicated by “X”, the sine wave PWM control is applied in the first map, whereas the overmodulation control is applied in the second map.

  When the motors MG1 and MG2 are driven by the rectangular wave control in the state where the eco mode is selected and the boosting of the converter 48 is prohibited in this way, the primary, secondary, etc. of the carrier frequency f from the motors MG1 and MG2. Integer order high frequency sound may be generated. The high frequency sound resulting from the carrier frequency f may be perceived as annoying noise for a user riding in an automobile. In particular, at low speeds (for example, 10 km / h), the level of sound generated when the vehicle travels, including motor sound and the sound generated when the tire rolls on the road surface, becomes relatively low and the quietness in the vehicle becomes high. In the following, it becomes easy to feel high-frequency sound generated from the motor MG2 that outputs the driving power as noise.

  Therefore, in the motor drive control device 100 of the present embodiment, the motor ECU 60 executes control as shown in the flowchart of FIG. 6 in order to eliminate high-frequency noise caused by the carrier frequency at a low speed equal to or less than a predetermined threshold value Svth.

  First, it is determined whether or not boosting by the converter 48 is prohibited (step S10: converter operation determining unit). This determination can be made based on whether or not an ECO signal is input to the motor ECU 60, that is, whether or not the eco mode is selected.

  Here, if it is determined that the boosting of the converter 48 is not prohibited, that is, the normal running mode is selected, the processing is ended as it is. On the other hand, if it is determined that boosting of the converter 48 is prohibited, it is then determined whether or not the motor drive system is overmodulation control (step S12: motor drive system determination unit). This determination is made based on which control method region the current motor operation point is located on the second map.

  Here, if it is determined that the motor drive system is other than overmodulation control, that is, sine wave PWM control or imposed modulation control, the processing is terminated as it is. On the other hand, when it is determined that the overmodulation control is performed, the map to be referred to for selecting the driving method of the motor MG2 is temporarily switched from the second map to the first map, and the boost prohibition of the converter 48 is once canceled. The step-up operation is started, and the motor drive system is shifted from overmodulation control to sine wave PWM control (step S14: motor drive system switching unit). Then, the carrier frequency is switched from one in the audible range to one having a high frequency exceeding the audible range (step S16: motor drive system switching unit), and the process is terminated.

  As described above, according to the motor drive control device 100 of the present embodiment, when it is determined that the drive method of the motor MG2 is overmodulation control while the boosting by the converter 48 is prohibited by the eco mode setting, the converter 48 is temporarily canceled to start boosting operation and the reference map is temporarily switched from the second map in the eco mode to the first map in the normal running mode to change the driving method of the motor MG2 from overmodulation control. Control to shift to sine wave PWM control is executed. Thereby, in the sine wave PWM control capable of asynchronous control, the carrier frequency can be arbitrarily set to a high frequency exceeding the audible range, so that the high frequency noise caused by the carrier frequency can be suppressed or eliminated.

  When the vehicle speed becomes equal to or higher than the predetermined threshold value Svth or a threshold value higher than the predetermined threshold value Svth, the state is restored to the state in the eco mode before switching, that is, the reference map is switched to the second map and the boosting by the converter 48 is prohibited. Then, the control of returning the carrier frequency may be performed.

  Next, a modified example of the control described above will be described with reference to the flowchart of FIG. This modification is applied when the shift position is in the neutral position and the motor MG1 is driven to control the engine speed at which the engine is operating for warm-up operation or the like. The map that is referred to when the driving method of the motor MG1 is selected by setting the eco mode is also the second map.

  In the hybrid vehicle 10, when the shift lever is operated, for example, from the drive position to the neutral position during traveling, the motor MG2 that outputs the traveling power is brought into a no-load rotation state when the inverter 46 is shut down. At this time, the high frequency sound resulting from the carrier frequency is not generated from the motor MG2.

  The processing procedure shown in FIG. 7 differs from FIG. 6 only in that a step for determining whether or not the shift position is the neutral position is added between step S12 and step S14.

  That is, when it is determined that the converter 48 is in the step-up prohibited state and the driving method of motor MG1 is overmodulation control (both YES in steps S10 and S12), it is determined whether or not the shift position is the neutral position. (Step S18: Shift position determination unit). This determination is made based on a shift position signal R input from the shift position sensor 71 to the hybrid ECU 66.

  Here, if it is determined that the shift position is not the neutral position, the process is terminated. On the other hand, if it is determined that the shift position is the neutral position, the reference map is once switched from the second map to the first map, and the boost prohibition cancellation and the boost operation start of the converter 48 are executed as described above ( In step S14, the carrier frequency is switched from one in the audible range to one having a high frequency exceeding the audible range (step S16).

  As described above, according to the control shown in FIG. 7, the level of the sound generated when the vehicle travels including the engine sound, the motor sound, and the sound generated when the tire rolls on the road surface becomes relatively small. It is possible to suppress or eliminate the generation of high-frequency noise from the motor MG1 due to the carrier frequency when the vehicle is stopped or when the vehicle is at a low speed close to the stopped state.

  In the control example described with reference to FIGS. 6 and 7, it is described that the control is executed when the vehicle speed is equal to or lower than the predetermined threshold value Svth. However, the present invention is not limited to this, and the motor rotation speeds Nm1 and Nm2 are set to the predetermined threshold value. You may make it perform when it becomes below Nmth.

  Next, another control example in the motor drive control device 100 of this embodiment will be described with reference to FIGS. FIG. 8 is a flowchart showing another example of the control, and FIG. 9 is a diagram showing a third map switched from the second map (see FIG. 5) in the another example of control.

  Here, the dotted line shown in FIG. 9 is the outline of the second map referred to in the eco mode. The eco mode in the control example described here is different from prohibiting boosting of the converter 48 and setting the system voltage VH to the battery voltage Vb as described above, and when the eco mode is selected, the boosting upper limit value of the converter 48 is selected. It is assumed that Vcrim (for example, 300 V) is set and converter 48 is allowed to perform a boost operation from battery voltage Vb to boost upper limit value Vcrim.

  Further, the third map shown in FIG. 9 is a map when boosting by the converter 48 is stopped and the system voltage VH is set to the battery voltage Vb (for example, 200 V), and in the eco mode in which the boosting upper limit value Vcrim is set. Compared to the second map to be referred to, it has been reduced to the low torque side and the low rotation range side, and overmodulation control is applied in the second map even at the same operation point A indicated by “X”. It can be seen that rectangular wave control is applied in the third map.

  Referring to FIG. 8, it is first determined whether or not the boosting by the converter 48 is limited (step S20: converter operation determining unit). Here, it is determined whether or not the eco mode is selected and the boost upper limit value Vcrim is set.

  Here, when it is determined that the boosting by the converter 48 is not restricted, that is, the eco mode is not selected, the processing is ended as it is. On the other hand, if it is determined that the boosting by the converter 48 is limited, it is then determined whether or not the motor drive system is overmodulation control (step S22: motor drive system determination unit). This determination is made based on which control method region the current motor operation point is located on the second map.

  Here, if it is determined that the motor drive system is other than overmodulation, that is, sine wave PWM control or rectangular wave control, the process is terminated. On the other hand, if it is determined that the motor drive system is overmodulation control, the reference map is switched from the second map to the third map, and the boosting by the converter 48 is stopped to change the motor drive system from overmodulation control to rectangular. The process proceeds to wave control (step S24: motor drive system switching unit), and the process ends.

  According to another control example described above, when the eco mode is selected, boosting by the converter 48 is limited, and when it is determined that the driving method of the motors MG1 and MG2 is overmodulation control, Control for shifting the motor drive system from overmodulation control to rectangular wave control is executed. Thus, by shifting to the rectangular wave control which does not use a carrier for inverter control, it can eliminate that the high frequency noise resulting from a carrier frequency generate | occur | produces from motor MG1, MG2.

  In another control example described with reference to FIGS. 8 and 9, the process may be executed when the vehicle speed or the motor rotational speed becomes a predetermined threshold value or less, and the process shown in FIG. Similarly to the above, when the shift position is the neutral position, the overmodulation control may be switched to the rectangular wave control.

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 11 Rotation position sensor, 12 Engine, 13 Output shaft, 14 Power distribution integration mechanism, 16 Engine ECU, 18 Sun gear, 20 Ring gear, 22 Planetary gear, 24 Damper, 26 Carrier, 29 Rotor, 30 Rotating shaft, 31, 37 rotation angle sensor, 32 ring gear shaft, 34 speed reducer, 36 rotor, 38 rotation shaft, 40 axle, 42 wheels, 44, 46 inverter, 48 converter, 50 battery, 52, 54 smoothing capacitor, 55 voltage sensor, 56 power line , 58 ground line, 60 motor ECU, 62 SOC sensor, 64 battery ECU, 66 hybrid ECU, 68 vehicle speed sensor, 70 accelerator opening sensor, 71 shift position sensor, MG1, MG2 three-phase synchronous AC motor.

Claims (5)

A converter capable of boosting a DC voltage received from a power supply device, an inverter that converts a DC voltage output from the converter into an AC voltage, and applies the drive voltage to an AC motor, and the AC motor by controlling the operation of the converter and the inverter A motor drive control device comprising: a control unit capable of selectively driving control by any one of sine wave PWM control, overmodulation control and rectangular wave control,
The control unit is a converter operation determination unit that determines whether or not boosting by the converter is prohibited or restricted, and the drive method of the AC motor is overmodulation control according to a determination result of the converter operation determination unit A motor drive system determination unit that determines whether or not the AC motor is driven by overmodulation control by the motor drive system determination unit, and starts or stops the step-up operation by the converter, and A motor drive control apparatus comprising: a motor drive system switching unit that shifts the drive system of the AC motor from overmodulation control to sine wave PWM control or rectangular wave control. The motor drive control device according to claim 1,
The control unit switches a carrier frequency used for generating a PWM signal for controlling the operation of a switching element included in the inverter between an audible frequency band and an audible frequency band. A switching unit,
In the control unit, when the converter operation determination unit determines that the boosting by the converter is prohibited, the motor drive system switching unit starts the boost prohibition release and the boosting operation by the converter, and the AC motor And a carrier frequency switching unit that switches the carrier frequency to a high frequency exceeding the audible range. The motor drive control device according to claim 2,
The control unit further includes a shift position determination unit that determines whether or not the shift position of the vehicle is neutral. A motor drive control device that executes a release and start of a boost operation and a transition to the sine wave PWM control. In the motor drive control device according to claim 3,
When the shift position is neutral and the vehicle speed or the motor rotation speed is equal to or less than a threshold value, the control unit executes the boost prohibition release of the converter, starts the boost operation, and shifts to the sine wave PWM control. A motor drive control device. The motor control device according to claim 1,
In the control unit, when the converter operation determination unit determines that the boosting by the converter is limited, the motor driving method switching unit stops the boosting operation by the converter and sets the driving method of the AC motor. A motor drive control device characterized in that a transition is made from overmodulation control to rectangular wave control.

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