JP2007089264A - Motor drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent an inrush current from being generated in a motor driver using a secondary batter and a capacitor as a power supply. <P>SOLUTION: A controller 30 implements a voltage control for equalizing a voltage Vc across terminals of the capacitor C0 and a system voltage Vm before a vehicle system is activated. When the capacitor C0 is in an excessively discharged state, the controller 30 drives an engine ENG at a predetermined engine rotation speed after the engine ENG is activated by using power from a battery B and driving a motor generator MG1. When a back electromotive voltage is generated in the motor generator MG1 by a drive force from the engine ENG, a single-phase AC output voltage is extracted from a neutral point in the motor generator MG1, and supplied to the capacitor C0 through system relays SRP1, SRP2. When the capacitor C0 exits from the excessively discharged state, the controller 30 continuously charges the capacitor C0 using a multiphase AC output voltage in the back electromotive voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor drive device that drives a motor, and more particularly to a motor drive device that includes a secondary battery and a capacitor as a power source.

  Recently, hybrid vehicles and electric vehicles have attracted attention as environmentally friendly vehicles. A hybrid vehicle is a vehicle that uses a motor driven by a DC power supply via an inverter in addition to a conventional engine as a power source. In other words, a power source is obtained by driving the engine, a DC voltage from a DC power source is converted into an AC voltage by an inverter, and a motor is rotated by the converted AC voltage to obtain a power source.

  An electric vehicle is a vehicle that uses a motor driven by a DC power supply via an inverter as a power source.

  In such a hybrid vehicle or electric vehicle, in order to improve energy efficiency while driving the vehicle appropriately, power corresponding to the load on the motor is supplied and energy can be efficiently recovered during regeneration. Desired.

In order to meet such demands, for example, Patent Document 1 includes a battery and a large-capacity capacitor (electric double layer capacitor) as a power supply source of a motor. Disclosed is a power supply device for an electric vehicle having switching means for switching a connection state with a motor.
Japanese Patent Laid-Open No. 7-231511

  Here, in the electric double layer capacitor, the stored energy is proportional to the square of the voltage of the capacitor. That is, when an electric double layer capacitor is used as a DC power source, the voltage of the capacitor decreases as the consumed energy increases. When the overdischarge state is reached, the voltage of the electric double layer capacitor becomes almost zero.

  Therefore, in the above electric vehicle power supply device, when the electric double layer capacitor is overdischarged and the voltage of the capacitor reaches almost zero, the system voltage (corresponding to the voltage of the power supply line for supplying power to the motor) ) May cause an excessive current (inrush current) to flow into the electric double layer capacitor. In particular, when an excessive inrush current instantaneously flows through the electric double layer capacitor, the inside of the capacitor may be heated and damaged. Furthermore, a problem that the relay contacts are welded may occur.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a highly reliable motor drive device in which components are protected from inrush current.

  According to the present invention, the motor drive device is provided between the power supply line and the multiphase motor, and is configured to drive and control the multiphase motor, provided that the DC power can be supplied to the power supply line. A drive circuit that performs power conversion of the power source, a power storage device connected to the power supply line via first opening / closing means, and the multi-phase motor, and after the start, the multi-phase motor is rotated, And a voltage for controlling the power supply voltage of the power storage device to be substantially the same as the voltage of the power supply line when the back electromotive voltage generating means for generating a back electromotive voltage corresponding to the power supply voltage and the first opening / closing means are open. Control means. The voltage control unit generates a voltage for charging the power storage device from a single-phase AC output voltage of a counter electromotive voltage of the multiphase motor when the power supply voltage of the power storage device is equal to or lower than a predetermined voltage. Supply to power storage device.

  According to the motor drive device described above, since the voltage difference between the power storage device and the power supply line is eliminated, it is possible to prevent the occurrence of an inrush current when the opening / closing means is in the closed state, and protect the components. it can. In particular, when the power storage device is in an overdischarged state, charging is performed by limiting the supply voltage to the power storage device, so that inrush current can be reliably prevented. As a result, a highly reliable motor drive device can be realized.

  Preferably, the voltage control means charges the power storage device from the single-phase AC output voltage taken from the neutral point of the multiphase motor when the power supply voltage of the power storage device is equal to or lower than the predetermined voltage. Generate a voltage of

  According to the above motor drive device, when the power storage device is in an overdischarged state, the single-phase AC output voltage of the back electromotive voltage is taken out from the neutral point of the multiphase motor, and the power storage device is charged from the single-phase AC output voltage. By generating the voltage for this purpose, it is possible to easily prevent the inrush current from occurring.

  Preferably, the power storage device is connected to a neutral point of the multiphase motor via a second opening / closing means. When the power supply voltage of the power storage device is equal to or lower than the predetermined voltage, the voltage control means is configured such that a voltage difference between the voltage generated from the single-phase AC output voltage and the power supply voltage of the power storage device is greater than a predetermined threshold value. Is smaller, the second opening / closing means is closed, and the power storage device and the neutral point of the multiphase motor are electrically connected.

  According to the motor drive device described above, the voltage for charging the power storage device generated from the single-phase AC output voltage is started to be supplied to the power storage device in response to a small voltage difference from the power storage device. Inrush current can be reliably prevented.

  Preferably, the voltage control means closes the first opening / closing means when the power supply voltage of the power storage device is higher than the predetermined voltage and lower than the voltage of the power supply line, and With the second opening / closing means open, a voltage for charging the power storage device is generated from the multiphase AC output voltage of the back electromotive voltage of the multiphase motor and supplied to the power storage device.

  According to the motor drive device described above, when the power storage device is released from the overdischarge state, the inrush current is avoided by charging the power storage device with a voltage generated from the multiphase AC output voltage of the counter electromotive voltage of the multiphase motor. However, the power storage device can be charged quickly.

  Preferably, the counter electromotive voltage generating means is an internal combustion engine mounted on a vehicle. The internal combustion engine rotates at a predetermined rotational speed to rotate the multi-phase motor, and generates a back electromotive voltage corresponding to the predetermined rotational speed in the multi-phase motor.

  According to the motor drive device described above, a desired counter electromotive voltage can be generated in the multiphase motor by controlling the rotational speed of the internal combustion engine.

  Preferably, when the vehicle activation instruction is received, the vehicle is activated in response to the power supply voltage of the power storage device being substantially the same as the voltage of the power supply line.

  According to the motor drive device described above, since the vehicle is started in response to elimination of the voltage difference between the power storage device and the power supply line, it is possible to prevent an inrush current from being generated when the vehicle system is started. .

  Preferably, the motor drive device further includes a voltage conversion circuit that converts a DC voltage between the DC power supply and the power supply line.

  According to the above motor drive device, since the occurrence of an inrush current can be reliably prevented, a motor drive device having high reliability and energy efficiency can be constructed using a DC power source and a power storage device as a power source.

  According to the present invention, by controlling the voltage so as to eliminate the voltage difference between the power storage device and the power supply line, it is possible to reliably prevent the occurrence of an inrush current even when the power storage device is in an overdischarged state. As a result, a highly reliable motor drive device can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 1 is a schematic block diagram of a motor drive device according to an embodiment of the present invention.
Referring to FIG. 1, motor drive device 100 includes a battery B, a boost converter 12, a storage capacitor C0, smoothing capacitors C1 and C2, inverters 14 and 31, and voltage sensors 10, 20, 22, current sensors 24 and 28, system relays SRB 1, SRB 2, SRC 1, SRC 2, SRP 1, SRP 2, SRU, SRV, SRW, and a control device 30.

  Although motor generators MG1 and MG2 can function as both a generator and an electric motor, as will be described below, motor generator MG1 mainly operates as a generator, and motor generator MG2 mainly operates as an electric motor.

  Specifically, motor generator MG1 is a three-phase AC rotating machine, and is used as a starter for starting engine ENG (not shown) during acceleration. At this time, motor generator MG1 receives the supply of electric power from battery B, drives it as an electric motor, cranks engine ENG, and starts it.

  Further, after engine ENG is started, motor generator MG1 is rotated by the driving force of engine ENG transmitted via power split mechanism 50 to generate electric power.

  The electric power generated by motor generator MG1 is selectively used according to the driving state of the vehicle, the energy stored in capacitor C0, and the charge amount of battery B. For example, during normal traveling or sudden acceleration, the electric power generated by motor generator MG1 becomes electric power for driving motor generator MG2 as it is. On the other hand, when the stored energy of capacitor C0 or the charge amount of battery B is lower than a predetermined value, the electric power generated by motor generator MG1 is converted from AC power to DC power by inverter 14, and is transferred to capacitor C0 or battery B. Stored.

  Motor generator MG2 is a three-phase AC rotating machine, and is driven by at least one of the electric power stored in battery B and capacitor C0 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to the drive shaft of the wheel via the speed reducer. Thus, motor generator MG2 assists engine ENG to cause the vehicle to travel, or causes the vehicle to travel only by its own driving force.

  Further, at the time of regenerative braking of the vehicle, motor generator MG2 is rotated by a wheel via a speed reducer and operates as a generator. At this time, the regenerative electric power generated by motor generator MG2 is charged to capacitor C0 and battery B via inverter 31.

  System relay SRB 1 is connected between the positive electrode of battery B and boost converter 12. System relay SRB <b> 2 is connected between the negative electrode of battery B and boost converter 12.

  System relays SRB1 and SRB2 are turned on / off by a signal SEB from control device 30. More specifically, system relays SRB1 and SRB2 are turned on by H (logic high) level signal SEB from control device 30, and are turned off by L (logic low) level signal SEB from control device 30.

  Boost converter 12 includes a reactor L1, NPN transistors Q1, Q2, and diodes D1, D2. Reactor L1 has one end connected to the power supply line of DC power supply B, and the other end connected to an intermediate point between NPN transistor Q1 and NPN transistor Q2, that is, between the emitter of NPN transistor Q1 and the collector of NPN transistor Q2. The NPN transistors Q1, Q2 are connected in series between power supply line LN1 and ground line LN2. The collector of NPN transistor Q1 is connected to power supply line LN1, and the emitter of NPN transistor Q2 is connected to ground line LN2. Further, diodes D1 and D2 for flowing current from the emitter side to the collector side are connected between the collector and emitter of each NPN transistor Q1 and Q2.

  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 between power supply line LN1 and ground line LN2.

  The U-phase arm 15 includes NPN transistors Q3 and Q4 connected in series, the V-phase arm 16 includes NPN transistors Q5 and Q6 connected in series, and the W-phase arm 17 includes NPN transistors Q7 and Q7 connected in series. Consists of Q8. Further, diodes D3 to D8 that flow current from the emitter side to the collector side are connected between the collectors and emitters of the NPN transistors Q3 to Q8, respectively.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of motor generator MG1. That is, motor generator MG1 is configured such that one end of three coils of U, V, and W phases is commonly connected to neutral point N1, and the other end of U phase coil is at the intermediate point of NPN transistors Q3 and Q4. The other end of the phase coil is connected to the midpoint of NPN transistors Q5 and Q6, and the other end of the W phase coil is connected to the midpoint of NPN transistors Q7 and Q8.

The inverter 31 has the same configuration as the inverter 14.
The battery B is composed of a secondary battery such as nickel metal hydride or lithium ion. In addition, the battery B may be a fuel cell. Voltage sensor 10 detects DC voltage Vb output from battery B, and outputs the detected DC voltage Vb to control device 30.

  Capacitor C1 smoothes DC voltage Vb supplied from battery B, and supplies the smoothed DC voltage Vb to boost converter 12.

  Boost converter 12 boosts DC voltage Vb supplied from capacitor C1 and supplies the boosted voltage to capacitor C2. More specifically, when boosting converter 12 receives signal PWMC from control device 30, boosting converter 12 boosts DC voltage Vb according to the period during which NPN transistor Q2 is turned on by signal PWMC and supplies it to capacitor C2.

  Further, when boost converter 12 receives signal PWMC from control device 30, battery 12 is charged by stepping down the DC voltage supplied from inverter 14 and / or inverter 31 via capacitor C2.

  Capacitor C0 is formed of an electric double layer capacitor, for example, and is connected in parallel with battery B with respect to the power supply line and the earth line. Power supply line LN1 and ground line LN2 and capacitor C0 are electrically coupled / separated by system relays SRC1 and SRC2, respectively.

  System relay SRC1 is connected between boost converter 12 and the positive electrode of capacitor C0. System relay SRC2 is connected between boost converter 12 and the negative electrode of capacitor C0.

  System relays SRC1 and SRC2 are turned on / off by a signal SEC from control device 30. More specifically, system relays SRC1 and SRC2 are turned on by an H level signal SEC from control device 30 and turned off by an L level signal SEC from control device 30.

  The voltage sensor 22 detects the voltage Vc across the capacitor C0 and outputs the detected voltage Vc to the control device 30.

  In the present invention, capacitor C0 is further electrically coupled / separated from neutral point N1 of motor generator MG1 by system relays SRP1, SRP2.

  Specifically, system relay SRP1 is connected between the positive electrode of capacitor C0 and the W-phase coil of motor generator MG1 via diode D9 and system relay SRW described later. System relay SRP2 is connected between the negative electrode of capacitor C0 and neutral point N1 of motor generator MG1.

  System relays SRP1 and SRP2 are turned on / off by a signal SEP from control device 30. More specifically, system relays SRP 1, SRP 2 are turned on by H level signal SEP from control device 30 and turned off by L level signal SEP from control device 30.

  Capacitor C 2 smoothes the DC voltage from boost converter 12 and supplies the smoothed DC voltage to inverters 14 and 31. The voltage sensor 20 detects the voltage across the capacitor C2, that is, the output voltage Vm of the boost converter 12 (corresponding to the input voltage to the inverters 14 and 31, the same applies hereinafter), and controls the detected output voltage Vm. Output to device 30.

  When a DC voltage is supplied from boost converter 12 or capacitor C0 via capacitor C2, inverter 14 converts DC voltage into an AC voltage based on signal PWMI1 from control device 30 to drive motor generator MG1. Thereby, motor generator MG1 is driven to generate torque according to torque command value TR1.

  Further, inverter 14 converts the AC voltage generated by motor generator MG1 into a DC voltage based on signal PWMI1 from control device 30 during regenerative braking of the hybrid vehicle equipped with motor drive device 100, and the converted DC The voltage is supplied to the capacitor C0 or the boost converter 12 via the capacitor C2. Note that regenerative braking here refers to braking that involves regenerative power generation when the driver operating the hybrid vehicle performs a footbrake operation, or regenerative braking by turning off the accelerator pedal while the vehicle is running, although the footbrake is not operated. This includes decelerating (or stopping acceleration) the vehicle while generating electricity.

  When a DC voltage is supplied from boost converter 12 or capacitor C0 via capacitor C2, inverter 31 converts DC voltage to an AC voltage based on signal PWMI2 from control device 30 to drive motor generator MG2. Thereby, motor generator MG2 is driven so as to generate torque specified by torque command value TR2.

  Further, inverter 31 converts the AC voltage generated by motor generator MG2 into a DC voltage based on signal PWMI2 from control device 30 during regenerative braking of the hybrid vehicle equipped with motor drive device 100, and the converted DC The voltage is supplied to the capacitor C0 or the boost converter 12 via the capacitor C2.

  Current sensor 24 detects motor current MCRT1 flowing through motor generator MG1, and outputs the detected motor current MCRT1 to control device 30. Current sensor 28 detects motor current MCRT2 flowing through motor generator MG2, and outputs the detected motor current MCRT2 to control device 30.

  Here, in motor generator MG1, system relays SRU, SRV, and SRW are connected between the other end of each phase coil of U, V, and W phases and the intermediate point of each phase arm 15, 16, and 17, respectively. The

  More specifically, system relay SRU is connected between the other end of the U-phase coil and an intermediate point between NPN transistors Q3 and Q4. System relay SRV is connected between the other end of the V-phase coil and an intermediate point between NPN transistors Q5 and Q6. System relay SRW is connected between the other end of the W-phase coil and an intermediate point between NPN transistors Q7 and Q8.

  Of the three system relays SRU, SRV, and SRW, only the system relay SRW is connected to the other end of the W-phase coil according to the signal SEM from the control device 30, the intermediate point of the NPN transistors Q7 and Q8, and the diode D9. Selectively bonded to one of the anodes. Specifically, system relay SRW electrically couples the other end of the W-phase coil and the intermediate point of NPN transistors Q7 and Q8 by H level signal SEM from control device 30. On the other hand, system relay SRW electrically couples the other end of the W-phase coil and the anode of diode D9 by L level signal SEM from control device 30.

  The other system relays SRU and SRV are turned on by the H level signal SEM from the control device 30 and turned off by the L level signal SEM from the control device 30.

  Therefore, when motor generator MG 1 receives H-level signal SEM from control device 30, the other end of each phase coil and the midpoint of each phase arm 15, 16, 17 are all electrically coupled. On the other hand, when an L level signal SEM is received from control device 30, the other end of the U-phase coil and V-phase coil and the midpoint of U-phase arm 15 and V-phase arm 16 are electrically separated, while W Only the other end of the phase coil is electrically coupled to the anode of diode D9.

  As described above, motor drive device 100 according to the present invention has a configuration in which the connection relationship between motor generator MG1, inverter 14 and capacitor C0 is switched using system relays SRU, SRV, SRW and system relays SRP1, SRP2. This configuration is intended to protect capacitor C0, system relays SRC1, SRC2, boost converter 12 and the like from inrush current in the voltage control means of capacitor C0, as will be described later.

  Based on input voltage Vm of inverter 14, torque command value TR1 and motor current MCRT1, control device 30 controls switching of NPN transistors Q3-Q8 of inverter 14 when inverter 14 drives motor generator MG1. PWMI1 is generated, and the generated signal PWM1 is output to the inverter 14.

  Control device 30 performs switching control of NPN transistors Q3-Q8 of inverter 31 when inverter 31 drives motor generator MG2 based on input voltage Vm of inverter 31, torque command value TR2 and motor current MCRT2. The signal PWMI2 is generated, and the generated signal PWMI2 is output to the inverter 31.

  Furthermore, when inverter 14 drives motor generator MG1, control device 30 determines NPN of boost converter 12 based on DC voltage Vb of battery B, input voltage Vm of inverter 14, torque command value TR1, and motor rotational speed MRN1. A signal PWMC for switching control of transistors Q1 and Q2 is generated, and the generated signal PWMC is output to boost converter 12.

  Further, when inverter 31 drives motor generator MG2, control device 30 determines NPN of boost converter 12 based on DC voltage Vb of battery B, input voltage Vm of inverter 31, torque command value TR2, and motor rotational speed MRN2. Signal PWMC for switching control of transistors Q1 and Q2 is generated, and the generated signal PWMC is output to boost converter 12.

  Further, control device 30 generates an AC voltage generated by motor generator MG2 based on input voltage Vm of inverter 31, torque command value TR2 and motor current MCRT2 during regenerative braking of a hybrid vehicle equipped with motor drive device 100. A signal PWMI2 for conversion to a DC voltage is generated, and the generated signal PWMI2 is output to the inverter 31. In this case, the NPN transistors Q3 to Q8 of the inverter 31 are subjected to switching control by the signal PWMI2. Thereby, inverter 31 converts the AC voltage generated by motor generator MG2 into a DC voltage and supplies it to capacitor C0 or boost converter 12.

  In the configuration described above, motor drive device 100 according to the present invention uses the power stored in capacitor C0 in addition to the power of battery B as the power required to drive motor generators MG1 and MG2 in the powering mode. . Further, the battery B and the capacitor C0 are charged with the electric power generated when the motor generators MG1 and MG2 are driven in the regeneration mode. In particular, since a large-capacity electric double layer capacitor is employed as capacitor C0, electric power can be quickly supplied to motor generators MG1 and MG2, and the responsiveness when driving the motor can be improved. As a result, the running performance of the vehicle can be ensured.

  On the other hand, when the electric double layer capacitor is mounted on the motor driving device 100, as described above, it is caused by the voltage difference between the terminal voltage Vc of the capacitor C0 and the system voltage (corresponding to the voltage of the power supply line of the motor driving device 100). As a result, an inrush current is generated, which may damage the battery B, the inverters 14 and 31, the boost converter 12, and the like. Further, in system relays SRC1 and SRC2, there is a possibility that welding occurs between the contacts.

  Therefore, the motor drive device 100 according to the present invention is characterized by including the voltage control means for the capacitor C0 described below as means for avoiding the inrush current caused by the capacitor C0. According to this, a highly reliable motor drive device can be realized.

  Specifically, the voltage control means according to the present invention executes voltage control for eliminating a voltage difference between the terminal voltage Vc of the capacitor C0 and the system voltage. As the system voltage, the detected value of the input voltage Vm of the inverters 14 and 31 from the voltage sensor 20 is used.

  When the vehicle system is started, the capacitor C0 may be in an overdischarged state, and an excessive inrush current may flow into the capacitor C0 due to a voltage difference between the terminal voltage Vc of the capacitor C0 and the system voltage Vm. .

  Therefore, when the vehicle system is started, voltage control is performed so that the voltage Vc between terminals of the capacitor C1 is substantially the same as the system voltage Vm in response to the ignition key IG being turned on. It is assumed that it is activated.

  FIG. 2 is a flowchart for illustrating voltage control when the vehicle system is activated according to the embodiment of the present invention. The following voltage control is executed by the control device 30 that controls the entire motor drive device 100.

  Referring to FIG. 2, first, in response to ignition key IG being turned on (step S01), control device 30 provides H level signal SEM to system relays SRU, SRV, SRW on motor generator MG1 side. Output. Thereby, system relays SRU and SRV are turned on (step S02). Further, system relay SRW electrically couples the other end of the W-phase coil and the intermediate point of W-phase arm 17 (step S03). In other words, motor generator MG1 is electrically connected to inverter 14.

  Next, control device 30 outputs H level signal SEB to system relays SRB1 to SRB3 on the battery B side, and turns on system relays SRB1 to SRB3 (step S04).

  At this time, if the high-voltage battery B is suddenly connected to the load, an excessive inrush current may instantaneously flow. Therefore, at the start of power supply, system relays SRB1 to SRB3 are turned on / off in a procedure that prevents an inrush current by resistor R1 provided in system relay SRB1. Specifically, first, system relay SRB1 and system relay SRB3 are turned on simultaneously. Thereby, system relay SRB1 supplies the direct current from battery B to boost converter 12 via resistor R1. Subsequently, system relay SRB2 is turned on with system relays SRB1 and SRB3 being turned on. System SRB2 directly supplies DC current from battery B to boost converter 12. Finally, only system relay SRB1 is turned off.

  Next, when control device 30 receives voltage Vc between terminals of capacitor C0 from voltage sensor 18, based on the voltage level of voltage Vc between terminals, control device 30 performs system relays SRC1, SRC2 on capacitor C0 side according to the procedure described below. And the capacitor C0 is connected to the motor drive device 100.

  Specifically, control device 30 determines whether or not voltage Vc between terminals of capacitor C0 is within a voltage range that does not cause an inrush current when capacitor C0 is connected. When the capacitor C0 is suddenly connected when the capacitor C0 is in an overdischarged state, an excessive inrush current flows into the capacitor C0 due to a voltage difference from the system voltage Vm.

  Specifically, first, control device 30 determines whether or not inter-terminal voltage Vc of capacitor C0 is greater than a predetermined voltage V1 indicating an overdischarge state (hereinafter also referred to as overdischarge voltage) (see FIG. Step S05).

  In step S05, when it is determined that inter-terminal voltage Vc of capacitor C0 is equal to or lower than overdischarge voltage V1, control device 30 performs a charging operation of capacitor C0 according to the flowchart after step S06.

  On the other hand, if it is determined in step S05 that the inter-terminal voltage Vc of the capacitor C1 is greater than the overdischarge voltage V1, the control device 30 subsequently determines that the inter-terminal voltage Vc is a predetermined voltage lower limit value (hereinafter referred to as the lower limit voltage). (Also referred to as V2) is determined (step S15). The lower limit voltage V2 at this time is preset to the lower limit value of the inter-terminal voltage Vc when the voltage difference between the inter-terminal voltage Vc of the capacitor C0 and the system voltage Vm does not generate an inrush current exceeding the allowable value. Yes. Therefore, the lower limit value V2 is higher than the overdischarge voltage V1, but is lower than the system voltage Vm.

  In step S15, when it is determined that the voltage Vc between terminals of capacitor C0 is larger than lower limit voltage V2, control device 30 outputs H level signal SEC and turns on system relays SRC1 and SRC2 (step S16). When capacitor C0 is connected, motor drive device 100 enters an RDY state in which vehicle system activation can be started (step S17), and thereafter performs normal vehicle system activation operation.

  On the other hand, when it is determined in step S15 that the terminal voltage Vc of the capacitor C0 is equal to or lower than the lower limit voltage V2, that is, it is determined that the terminal voltage Vc is larger than the overdischarge voltage V1 and lower than the lower limit voltage V2. Then, control device 30 performs the charging operation of capacitor C0 according to the flowchart of FIG.

  As described above, in the flowchart of FIG. 2, the charging operation of the capacitor C0 is performed when (1) the inter-terminal voltage Vc is equal to or lower than the overdischarge voltage V1, and (2) the inter-terminal voltage Vc is larger than the overdischarge voltage V1. , And the lower limit voltage V2 or less. The two charging operations are common in that they are performed using the counter electromotive voltage generated in motor generator MG1, as described below, but differ in the configuration for supplying the counter electromotive voltage. This is in consideration of the voltage difference between the counter electromotive voltage and the inter-terminal voltage Vc of the capacitor C0.

(1) When Terminal Voltage Vc of Capacitor C0 is Less than Overdischarge Voltage V1 First, charging operation of the capacitor C0 when the terminal voltage Vc of the capacitor C0 is less than the overdischarge voltage V1 will be described.

  Referring to FIG. 2, when it is determined in step S05 that terminal voltage Vc is equal to or lower than overdischarge voltage V1, control device 30 follows the steps S06 to S14 described below to drive the motor generator as the engine ENG is driven. Capacitor C0 is charged by the back electromotive voltage generated in MG1. The counter electromotive voltage is generally represented by the product of the rotational angular velocity of the rotor and the magnetic flux of the permanent magnet. Therefore, the counter electromotive voltage generated increases in proportion to the rotational angular velocity of motor generator MG1, that is, the engine speed.

  Specifically, first, motor generator MG1 is used as a starter for starting engine ENG. At this time, a command (torque command value TR1) for driving motor generator MG1 is given from external ECU to control device 30 such that the engine speed is set to the idle speed.

  Control device 30 generates signal PWMI1 based on torque command value TR1, motor current MCRT1 and voltage Vm, and outputs the generated signal PWMI1 to inverter 14.

  Inverter 14 converts the DC voltage from boost converter 12 into an AC voltage according to signal PWMI1, and drives motor generator MG1 so as to output torque according to torque command value TR1. Motor generator MG1 is supplied with electric power from battery B and is driven as an electric motor, and cranks engine ENG via power split mechanism 50 to start it (step S06).

  When the engine ENG has been started up in response to the engine speed reaching a predetermined idle speed after the engine has been started (step S07), the control device 30 outputs an L-level signal SEB and the battery B Side system relays SRB2 and SRB3 are turned off (step S08). Thereby, the battery B is electrically disconnected from the motor drive device 100.

  Here, when startup of engine ENG is completed, motor generator MG1 is rotated by the driving force of engine ENG transmitted through power split mechanism 50. At this time, a counter electromotive voltage proportional to the engine speed is generated in motor generator MG1. In the present invention, capacitor C0 is charged using the back electromotive voltage generated in motor generator MG1.

  Specifically, as shown in FIG. 4, a counter electromotive voltage composed of three-phase AC output voltages Vu, Vv, and Vw is generated in motor generator MG1. The three-phase AC output voltages Vu, Vv, Vw having an electrical angle of 360 ° as one cycle have equal amplitudes and phases different from each other by an electrical angle of 120 °. Then, the capacitor C2 arranged on the input side of the inverter 14 rectifies the three-phase AC output voltages Vu, Vv, and Vw, thereby obtaining the terminal voltage Vm having the output waveform shown in the middle stage of FIG. .

  When system relays SRC1 and SRC2 are turned on at time t0 in FIG. 4, capacitor C0 is electrically connected to capacitor C2 and receives inter-terminal voltage Vm having an output waveform in the middle of FIG. Charging will be started.

  However, at this time, the capacitor C0 is in an overdischarged state and the inter-terminal voltage Vc is substantially zero as described in step S05 above. Therefore, an excessive inrush current may flow into the capacitor C0 instantaneously due to a voltage difference between the terminal voltage Vm of the capacitor C2 and the terminal voltage Vc of the capacitor C0.

  In view of this, in the configuration in which the capacitor C0 is charged with the counter electromotive voltage of the motor generator MG1, the present invention further generates a single-phase AC output voltage from the counter electromotive voltage when the capacitor C0 is in an overdischarged state. The capacitor C0 is charged using the single-phase AC output voltage.

  Specifically, when a counter electromotive voltage is generated in motor generator MG1, control device 30 uses neutral point N1 of motor generator MG1 to select one of the three-phase AC output voltages Vu, Vv, and Vw. AC output voltage (single-phase AC output voltage) is generated. In the present embodiment, for example, a W-phase AC output voltage is generated. Then, control device 30 applies the generated W-phase AC output voltage to capacitor C0 via diodes D9 and D10 and system relays SRP1 and SRP2.

  Here, the generation of the single-phase AC output voltage is specifically performed in the motor drive device 100 of FIG. 1 by using the other end of each phase coil of the motor generator MG1 and the intermediate point of each phase arm 15-17 of the inverter 14. Is performed by switching system relays SRU, SRV, SRW provided between the two.

  Specifically, as shown in step S10 of FIG. 2, system relays SRU, SRV are turned off in response to signal SEM to L level from control device 30, and neutral point N1 of motor generator MG1 and U-phase arm 15 are turned off. And the middle point of the V-phase arm 16 is electrically separated.

  On the other hand, system relay SRW switches the other end of the W-phase coil from the middle point of W-phase arm 17 to the anode of diode D9 in accordance with L level signal SEM from control device 30 (step S11). . Thereby, neutral point N1, which is one end of the W-phase coil, is connected to the negative electrode of capacitor C0 via system relay SRP2. The other end of the W-phase coil is connected to the positive electrode of capacitor C0 via system relay SRW, diode D9, and system relay SRP1. That is, capacitor C0 is connected in parallel to the W-phase coil via system relays SRP1, SRP2. Therefore, when system relays SRP1 and SRP2 are turned on, single-phase AC output voltage Vw generated in the W-phase coil is rectified and supplied to capacitor C0.

  FIG. 5 is a schematic diagram for explaining the voltage control at the time of starting the vehicle system according to the embodiment of the present invention.

  Referring to FIG. 5, the single-phase AC output voltage (= W-phase AC output voltage Vw) generated from the three-phase AC output voltages Vu, Vv, Vw (see the uppermost stage in the figure) is composed of diodes D9, D10. By passing through a rectifier circuit, it is converted into an output waveform that has been half-wave rectified as shown in the middle of the figure. That is, the W-phase AC output voltage Vw has a period T1 in which the voltage level becomes approximately zero every half cycle.

  The supply of the W-phase AC output voltage Vw to the capacitor C0 is performed by taking the system relays SRP1 and SRP2 into consideration in consideration of the voltage difference between the W-phase AC output voltage Vw and the inter-terminal voltage Vc from the viewpoint of preventing an inrush current. It starts by turning it on.

  Specifically, in step S12 of FIG. 2, control device 30 calculates W-phase AC output voltage Vw from motor rotational speed MRN1 of motor generator MG1, and detects voltage Vc between terminals by voltage sensor 20. Then, when determining the voltage difference | Vw−Vc |, the control device 30 generates an H level signal SEP at a timing when the voltage difference becomes equal to or less than a predetermined threshold value V_std, and system relays SRP1, SRP2 Is turned on (step S13).

  In FIG. 5, since the inter-terminal voltage Vc shows substantially zero, the system relays SRP1, SRP2 are turned on at the timing t1 of the period T1 when the W-phase AC output voltage Vw becomes substantially zero. In the period after the timing t1 when the system relays SRP1, SRP2 are turned on, the capacitor C0 is supplied with the W-phase AC output voltage Vw shown in the middle stage in the figure.

  Then, when charging of the capacitor C0 is started in response to the supply of the W-phase AC output voltage Vw (step S14), the inter-terminal voltage Vm of the capacitor C0 is as shown in the lowermost stage of FIG. The increase and decrease are repeated gently according to the amplitude of the W-phase AC output voltage Vw. That is, the capacitor C0 is repeatedly charged and discharged with the periodicity of the W-phase AC output voltage Vw. At this time, the inter-terminal voltage Vc gradually increases as the energy stored in the capacitor C0 gradually increases.

  Then, returning to step S05, if it is determined that the inter-terminal voltage Vc has exceeded the overdischarge voltage V1, that is, if it is determined that the capacitor C0 has escaped the overdischarge state, the control device 30 determines that the inter-terminal voltage In response to Vc being equal to or lower than the lower limit voltage V2, the operation proceeds to the charging operation of the capacitor C0 described in (2) below, and the capacitor C0 is charged more rapidly.

(2) When the inter-terminal voltage Vc of the capacitor C0 is greater than the overdischarge voltage V1 and less than or equal to the lower limit voltage V2, if it is determined that the capacitor C0 has escaped the overdischarge state by the charging operation of (1), the control The device 30 continues the charging operation of the capacitor C0 according to the flowchart of FIG. The charging operation shown below is not limited to the case where the charging operation of (1) is continued, but the terminal voltage Vc of the capacitor C0 when the vehicle system is started is larger than the overdischarge voltage V1 and the lower limit. In the case where the voltage is V2 or less, it is performed independently.

  FIG. 3 is a flowchart for illustrating voltage control at the time of starting the vehicle system according to the embodiment of the present invention.

  Referring to FIG. 3, the charging operation of capacitor C0 is performed using the back electromotive voltage generated in motor generator MG1 in the same manner as described in (1) above. However, the charging operation (2) is performed by supplying all of the three-phase AC output voltages Vu, Vv, and Vw to the capacitor C0, and the capacitor C0 is charged using the single-phase AC output voltage. This is different from the charging operation of (1) above.

  Specifically, when control device 30 determines in step S15 of FIG. 2 that terminal voltage Vc of capacitor C0 is lower than lower limit voltage V2, back electromotive force generated in motor generator MG1 in accordance with the following steps S20 to S30. The capacitor C0 is charged with the voltage. Since the engine ENG starting operation shown in step S20 is performed in the same procedure as described in step S06 of FIG. 2, detailed description will not be repeated.

  In the case of shifting from the charging operation (1) to the charging operation (2), since the engine is already started and the battery B is disconnected from the motor drive device 100, the operations of steps S20 and S21 are performed. Control device 30 outputs H level signal SEB and turns on system relays SRB2 and SRB3 on the battery B side (step S22). Further, control device 30 generates H level signal SEM, turns on system relays SRU and SRV on the motor generator MG1 side (step S23), and connects system relay SRW to inverter 14 side. (Step S24).

  Next, prior to charging operation of capacitor C0, control device 30 determines whether or not input voltage Vm of inverter 14 is lower than a predetermined voltage level V3 (step S25). The predetermined voltage level V3 at this time is a voltage level that can prevent the occurrence of an inrush current due to a voltage difference between the terminal voltage Vc and the input voltage Vm when the system relays SRC1 and SRC2 are turned on and the capacitor C0 is connected. And This is because the input voltage Vm is boosted to a high voltage level by starting the engine in step S20.

  If it is determined in step S23 that input voltage Vm of inverter 14 is lower than predetermined voltage V3, control device 30 outputs H level signal SEC and turns on system relays SRC1 and SRC2 (step S26). .

  On the other hand, when it is determined in step S25 that the input voltage Vm of the inverter 14 is equal to or higher than the predetermined voltage V3, the control device 30 consumes the energy accumulated in the capacitor C2 and changes the input voltage Vm to the predetermined voltage V3. The voltage is reduced to the voltage V3 level (step S30). As a specific method of energy consumption, there is a method of increasing the on-duty of the NPN transistor on the upper side of the inverter 31 and providing a path through which energy flows from the capacitor C2 to the motor generator MG2 via the inverter 31. .

  Next, when system relays SRC1 and SRC2 are turned on and capacitor C0 is connected to motor drive device 100, back electromotive voltage generated in motor generator MG1 by the driving force of engine ENG is charged in capacitor C0. Further, the power supply from the battery B is received and the capacitor C0 is charged.

  Specifically, control device 30 determines a target engine speed for generating a desired counter electromotive voltage in motor generator MG1 (step S27). The desired counter electromotive voltage is obtained from the amount of electric power that must be supplied to the capacitor C0 in order to set the inter-terminal voltage Vc of the capacitor C0 and the input voltage Vm of the inverter 14 to substantially the same voltage level. In step S25, the control device 30 stores the correlation between the engine speed and the counter electromotive voltage as a map in advance, and selects the engine speed corresponding to the desired counter electromotive voltage from the map. Also good.

  Back electromotive voltage generated in motor generator MG1 is converted from AC power to DC power in inverter 14 and stored in capacitor C0. As a result, the terminal voltage Vc of the capacitor C0 increases.

  The control device 30 continues the above charging operation of the capacitor C0 until the voltage difference between the input voltage Vm of the inverter 14 and the terminal voltage Vc of the capacitor C0 becomes equal to or lower than a predetermined threshold value V_std. Finally, the control device 30 confirms that the voltage difference between the output voltage Vm and the inter-terminal voltage Vc has been reduced to a predetermined threshold value V_std or less (step S28), and the motor drive device 100 is moved to the vehicle. An RDY state in which system start can be started is set (step S29). The motor drive device 100 executes a normal vehicle system activation operation in response to the RDY state.

  As described above, according to the motor drive device 100 of the present invention, when the vehicle system is started, it is confirmed that the voltage difference between the terminal voltage Vc of the capacitor C0 and the system voltage Vm has been eliminated, and normal system start-up is performed. Since the operation shifts, the components can be protected from the inrush current. In particular, when the capacitor C0 is in an overdischarged state, charging is performed by limiting the voltage applied to the capacitor C0, so that an inrush current can be reliably prevented. As a result, a highly reliable motor drive device can be realized.

  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.

  The present invention can be applied to a motor drive device mounted on a hybrid vehicle.

1 is a schematic block diagram of a motor drive device according to an embodiment of the present invention. It is a flowchart for demonstrating the voltage control at the time of vehicle system starting by embodiment of this invention. It is a flowchart for demonstrating the voltage control at the time of vehicle system starting by embodiment of this invention. It is a schematic diagram for demonstrating the voltage control at the time of vehicle system starting by embodiment of this invention. It is a schematic diagram for demonstrating the voltage control at the time of vehicle system starting by embodiment of this invention.

Explanation of symbols

  10, 20, 22 Voltage sensor, 12 Boost converter, 14, 31 Inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm, 24, 28 Current sensor, 30 Control device, 50 Power split mechanism, 100 Motor drive Device, B battery, Q1-Q8 NPN transistor, D1-D10 diode, C0 capacitor, C1, C2 capacitor, L1 inductor, LN1 power line, LN2 ground line, MG1, MG2 motor generator, SRB1, SRB2, SRC1, SRC2, SRP1 , SRP2, SRU, SRV, SRW System relay, ENG engine.

Claims (7)

A DC power source provided to supply DC power to the power line;
A drive circuit that is provided between the power line and the multiphase motor and performs power conversion for driving and controlling the multiphase motor;
A power storage device connected to the power line via first opening and closing means;
Back electromotive force generating means that is started by the multi-phase motor, rotates the multi-phase motor after starting, and generates a back electromotive voltage according to the number of rotations;
Voltage control means for controlling the power supply voltage of the power storage device to be substantially the same as the voltage of the power supply line when the first opening / closing means is in an open state;
The voltage control unit generates a voltage for charging the power storage device from a single-phase AC output voltage of a counter electromotive voltage of the multiphase motor when the power supply voltage of the power storage device is equal to or lower than a predetermined voltage. A motor driving device that supplies the power storage device.   The voltage control means, when the power supply voltage of the power storage device is equal to or less than the predetermined voltage, a voltage for charging the power storage device from the single-phase AC output voltage taken from the neutral point of the multiphase motor The motor drive device according to claim 1, wherein the motor drive device is generated. The power storage device is connected to a neutral point of the multiphase motor via a second opening / closing means,
When the power supply voltage of the power storage device is equal to or lower than the predetermined voltage, the voltage control means is configured such that a voltage difference between the voltage generated from the single-phase AC output voltage and the power supply voltage of the power storage device is greater than a predetermined threshold value. 3. The motor driving device according to claim 2, wherein the second opening / closing means is closed to electrically connect the power storage device and a neutral point of the multiphase motor according to the fact that the second opening / closing means is closed.   The voltage control means closes the first opening and closing means when the power supply voltage of the power storage device is higher than the predetermined voltage and lower than the voltage of the power supply line, and the second control means 4. The motor drive according to claim 3, wherein a voltage for charging the power storage device is generated from a multiphase AC output voltage of a counter electromotive voltage of the multiphase motor and supplied to the power storage device by opening and closing means. apparatus. The counter electromotive voltage generating means is an internal combustion engine mounted on a vehicle,
5. The motor drive device according to claim 4, wherein the internal combustion engine rotates at a predetermined rotation speed to rotate the multiphase motor, and generates a back electromotive voltage corresponding to the predetermined rotation speed in the multiphase motor. .   The said voltage control means will start the said vehicle according to the power supply voltage of the said electrical storage apparatus having become substantially the same as the voltage of the said power supply line, if the starting instruction | indication of the said vehicle is received. Motor drive device.   The motor drive device according to any one of claims 1 to 6, further comprising a voltage conversion circuit that converts a DC voltage between the DC power supply and the power supply line.

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