JP2006325322A - Vehicle driving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle driving apparatus reduced in failure occurrence probability. <P>SOLUTION: The vehicle driving apparatus is provided with a battery B, a voltage boosting converter 12 for converting a voltage from the battery B, a capacitor C2 for smoothing a voltage at an output node in the voltage boosting converter 12, an inverter 14 supplied with power from the voltage boosting converter 12 and the capacitor C2 and driving a motor generator M1, a voltage sensor 13 for sensing a voltage across terminals of the capacitor C2, a current sensor 11 for sensing a current transferred between the battery B and the voltage boosting converter 12, and a controller 30 for receiving an output from the voltage sensor 13 and controlling the voltage boosting converter 12. If the voltage sensor 13 is abnormal, the controller 30 determines a discharge state in the capacitor C2 in response to an output from the current sensor 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle drive device, and more particularly to a vehicle drive device that converts a DC voltage into a voltage of a DC power supply to drive a rotating electrical machine.

  In recent years, hybrid vehicles, electric vehicles, and fuel cell vehicles have attracted much attention as environmentally friendly vehicles.

  In such a vehicle, it has also been proposed to boost a DC voltage from a DC power source by a boost converter and supply the boosted DC voltage to an inverter that drives a motor.

Japanese Patent Application Laid-Open No. 2004-222362 (Patent Document 1) discloses that when the control device detects a failure of the boost converter, the inverter and the AC motor are controlled so as to prohibit the regenerative power generation of the AC motor.
JP 2004-222362 A JP 2003-189599 A

  In a hybrid vehicle, when a failure occurs in the boost voltage sensor that detects the voltage on the output side of the boost converter, the boost control of the boost converter is stopped, and the battery voltage is not boosted and supplied to the inverter as it is, so that the vehicle is not driven. It is possible to continue.

  However, if the voltage sensor on the boost output side is broken, the current boost voltage value cannot be detected. For example, if the difference between the voltage value on the boost output side, that is, the inverter side, and the battery voltage value is large, if the inverter side and the battery side are coupled inside the boost converter, an abrupt surge current flows and the boost converter fails. May occur. Therefore, it is desirable to combine the boost voltage and the battery voltage within the boost converter after the difference between the boost voltage and the battery voltage has become sufficiently small.

  An object of the present invention is to provide a vehicle drive device with reduced failure occurrence probability.

  In summary, the present invention is a vehicle drive device, which is a DC power supply, a DC voltage conversion unit that performs voltage conversion of the DC power supply, a first capacitor that smoothes a voltage at an output node of the DC voltage conversion unit, A drive unit that receives electric power from the DC voltage conversion unit and the first capacitor to drive the rotating electrical machine, a first voltage detection unit that detects a voltage between terminals of the first capacitor, a DC power source, and a DC voltage conversion unit; A current detection unit that detects a current exchanged between the first voltage detection unit and a control unit that receives the output of the first voltage detection unit and controls the DC voltage conversion unit. When an abnormality occurs in the first voltage detection unit, the control unit determines the discharge state of the first capacitor according to the output of the current detection unit.

  In another aspect, the present invention is a vehicle drive device, wherein a DC power source, a DC voltage converter that performs voltage conversion of the DC power source, and a voltage at an output node of the DC voltage converter are first smoothed. A capacitor, a second capacitor that smoothes the voltage at the input node of the DC voltage converter, a drive unit that receives electric power from the DC voltage converter and the first capacitor, and drives the rotating electrical machine, and a first capacitor DC voltage conversion is performed by receiving outputs of a first voltage detection unit that detects a voltage between terminals, a second voltage detection unit that detects a voltage between terminals of the second capacitor, and the first and second voltage detection units. A control unit for controlling the unit. When an abnormality occurs in the first voltage detection unit, the control unit determines the discharge state of the first capacitor according to the output of the second voltage detection unit.

  Preferably, when an abnormality occurs in the first voltage detection unit, the control unit gives a command to stop the operation of the DC voltage conversion unit and cause the drive unit to perform a power running operation of the rotating electrical machine. Discharge the capacitor.

  Preferably, the DC voltage conversion unit is configured to be capable of performing a step-up operation from a DC power source toward the drive unit and a step-down operation from the drive unit toward the DC voltage. When an abnormality occurs in the first voltage detection unit, the control unit causes the DC voltage conversion unit to perform a step-down operation to discharge the first capacitor.

  Preferably, the DC voltage conversion unit is configured to be capable of performing a step-up operation from a DC power source toward the drive unit and a step-down operation from the drive unit toward the DC voltage. The control unit stops the operation of the DC voltage conversion unit and causes the drive unit to continue the power running operation of the rotating electrical machine when the rotating electrical machine is performing the power running operation when an abnormality occurs in the first voltage detection unit. A command is given to discharge the first capacitor. The controller causes the DC voltage converter to perform a step-down operation to discharge the first capacitor when the rotating electrical machine is not performing a power running operation when an abnormality occurs in the first voltage detector. .

  Preferably, the DC voltage conversion unit includes a reactor having one end connected to the input node of the DC voltage conversion unit, and a first switching element that conducts the output node and the other end of the reactor under the control of the control unit. And a second switching element for conducting the other end of the reactor and the ground node under the control of the control unit. The control unit fixes the first switching element in the conducting state and the second switching element in the non-conducting state when the discharge state of the first capacitor becomes a predetermined state.

  According to the present invention, when shifting from driving with a boosted voltage to battery voltage driving, the deviation between the voltage value on the boosting side and the voltage value on the battery side can be reliably within a predetermined range. Therefore, problems at the time of battery voltage driving can be avoided.

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

[Embodiment 1]
FIG. 1 is a circuit diagram showing a configuration of a vehicle 100 according to an embodiment of the present invention. The vehicle 100 may be any of an electric vehicle that drives wheels with a motor, a fuel cell vehicle, and a hybrid vehicle that uses a motor and an engine in combination for driving the vehicle.

  Referring to FIG. 1, vehicle 100 includes a battery B, a voltage sensor 10, system main relays SR1 and SR2, a capacitor C1, an inverter 14, a temperature sensor 35, a current sensor 24, and a control device 30. Is provided.

  The battery B is a secondary battery such as nickel metal hydride or lithium ion. Voltage sensor 10 detects DC voltage value VB output from battery B, and outputs the detected DC voltage value VB to control device 30. System main relays SR1, SR2 are turned on / off by a signal SE from control device 30. More specifically, system main relays SR1 and SR2 are turned on by signal SE of H (logic high) level and turned off by signal SE of L (logic low) level. Capacitor C1 smoothes the voltage across terminals of battery B when system main relays SR1 and SR2 are on.

  Vehicle 100 further includes a voltage sensor 21, a current sensor 11, a boost converter 12, a capacitor C <b> 2, and a voltage sensor 13.

  Current sensor 11 detects a direct current flowing between battery B and boost converter 12 and outputs the detected current to control device 30 as a direct current value IB.

  Boost converter 12 has a first end connected to reactor L1 connected to the positive electrode of battery B via system main relay SR1, and IGBT elements Q1, Q2 connected in series between the output terminals of boost converter 12 that outputs voltage VH. And diodes D1, D2 connected in parallel to IGBT elements Q1, Q2, respectively.

  Reactor L1 has the other end connected to the emitter of IGBT element Q1 and the collector of IGBT element Q2. The cathode of diode D1 is connected to the collector of IGBT element Q1, and the anode of diode D1 is connected to the emitter of IGBT element Q1. The cathode of diode D2 is connected to the collector of IGBT element Q2, and the anode of diode D2 is connected to the emitter of IGBT element Q2.

  Voltage sensor 21 detects the voltage on the input side of boost converter 12 as voltage value VL. Current sensor 11 detects the current flowing through reactor L1 as current value IB. Capacitor C2 is connected to the output side of boost converter 12 and accumulates energy sent from boost converter 12, and smoothes the voltage. Voltage sensor 13 detects the voltage on the output side of boost converter 12, that is, the voltage between electrodes of capacitor C2, as voltage value VH.

  Inverter 14 receives the boosted voltage from boost converter 12 and drives motor generator M1. Further, inverter 14 returns the electric power generated in motor generator M <b> 1 due to regenerative braking to boost converter 12. At this time, boost converter 12 is controlled by control device 30 to operate as a step-down circuit.

  Motor generator M1 is a motor for generating torque for driving drive wheels (not shown) of vehicle 100. This motor may be incorporated in a hybrid vehicle, for example, having a function of a generator driven by an engine and operating as an electric motor for the engine so that the engine can be started.

  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 connected in parallel between the output lines of boost converter 12.

  U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series, and diodes D3 and D4 connected in parallel with IGBT elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of IGBT element Q3, and the anode of diode D3 is connected to the emitter of IGBT element Q3. The cathode of diode D4 is connected to the collector of IGBT element Q4, and the anode of diode D4 is connected to the emitter of IGBT element Q4.

  V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series, and diodes D5 and D6 connected in parallel with IGBT elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of IGBT element Q5, and the anode of diode D5 is connected to the emitter of IGBT element Q5. The cathode of diode D6 is connected to the collector of IGBT element Q6, and the anode of diode D6 is connected to the emitter of IGBT element Q6.

  W-phase arm 17 includes IGBT elements Q7, Q8 connected in series, and diodes D7, D8 connected in parallel with IGBT elements Q7, Q8, respectively. The cathode of diode D7 is connected to the collector of IGBT element Q7, and the anode of diode D7 is connected to the emitter of IGBT element Q7. The cathode of diode D8 is connected to the collector of IGBT element Q8, and the anode of diode D8 is connected to the emitter of IGBT element Q8.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of motor generator M1. That is, the motor generator M1 is a three-phase permanent magnet motor, and one end of each of the three coils of the U, V, and W phases is connected to the middle point. The other end of the U-phase coil is connected to the connection node of IGBT elements Q3 and Q4. The other end of the V-phase coil is connected to a connection node of IGBT elements Q5 and Q6. The other end of the W-phase coil is connected to a connection node of IGBT elements Q7 and Q8.

  Current sensor 24 detects the current flowing through motor generator M1 as motor current value MCRT1, and outputs motor current value MCRT1 to control device 30.

  Control device 30 receives torque command value TR1, motor rotation speed MRN1, voltage values VB, VL, VH, current value IB, and motor current value MCRT1. Control device 30 then outputs a boost instruction PWU and a step-down instruction PWD to boost converter 12. Furthermore, control device 30 provides inverter 14 with a drive instruction PWMI1 for converting a DC voltage output from boost converter 12 into an AC voltage for driving motor generator M1, and an AC voltage generated by motor generator M1. A regenerative instruction PWMC1 which is converted into a DC voltage and returned to the boost converter 12 side is output.

  Next, the operation of boost converter 12 will be briefly described. Boost converter 12 operates as a boost circuit serving as a forward conversion circuit that supplies power from battery B to inverter 14 during powering operation. Conversely, during regenerative operation, boost converter 12 also operates as a step-down circuit as a reverse conversion circuit that regenerates power generated by motor generator M1 in battery B.

  Boost converter 12 operates as a booster circuit by turning on and off IGBT element Q2 with IGBT element Q1 turned off. That is, when IGBT element Q2 is on, a path is formed in which a current flows from the positive electrode of battery B to the negative electrode of battery B via reactor L1 and IGBT element Q2. While this current is flowing, energy is accumulated in the reactor L1.

  When IGBT element Q2 is turned off, the energy stored in reactor L1 flows to inverter 14 side through diode D1. As a result, the voltage between the electrodes of the capacitor C2 increases. Therefore, the output voltage of boost converter 12 applied to inverter 14 is boosted.

  On the other hand, boost converter 12 operates as a step-down circuit by turning on and off IGBT element Q1 with IGBT element Q2 turned off. That is, when the IGBT element Q1 is on, the current regenerated from the inverter 14 flows to the IGBT element Q1, the reactor, and the battery B.

  In the state where IGBT element Q1 is off, a loop including reactor L1, battery B, and diode D2 is formed, and the energy stored in reactor L1 is regenerated in battery B. In this reverse conversion, the time during which the battery B receives power is longer than the time during which the inverter 14 supplies power, and the voltage at the inverter 14 is stepped down and regenerated by the battery B. The operation of boost converter 12 is performed by appropriately controlling the above power running operation and regenerative operation.

  In order to further reduce the loss, synchronous control may be performed in which the IGBT elements Q1 and Q2 are made conductive in synchronization with the timing when forward current flows through the diodes D1 and D2, respectively, in the above operation.

  The regenerative control includes braking accompanied by regenerative power generation when a foot brake operation is performed by a driver driving a hybrid vehicle or an electric vehicle. Moreover, even when the foot brake is not operated, it includes a case where the vehicle is decelerated or accelerated while regenerative power generation is performed by turning off the accelerator pedal during traveling.

  In summary, vehicle 100 receives power from battery B, boost converter 12 that performs voltage conversion of battery B, capacitor C2 that smoothes the voltage at the output node of boost converter 12, boost converter 12 and capacitor C2. An inverter 14 that drives motor generator M 1, a voltage sensor 13 that detects a voltage across terminals of capacitor C 2, a current sensor 11 that detects a current exchanged between battery B and boost converter 12, and voltage sensor 13 And a control device 30 that receives the output and controls the boost converter 12.

  When abnormality occurs in voltage sensor 13, control device 30 determines the discharge state of capacitor C <b> 2 according to the output of current sensor 11.

  FIG. 2 is a flowchart showing a control structure of a program executed by control device 30 in the first embodiment. The process of this flowchart is called and executed every time a predetermined time elapses from a predetermined main routine or every time a predetermined condition is satisfied.

  Referring to FIG. 2, first, when the process is started, control device 30 determines whether or not an abnormality has occurred in voltage sensor 13 in step S1. For example, by detecting that the voltage value VH output from the voltage sensor 13 is a fixed value, or that the voltage value VH is out of an appropriate predetermined range, the voltage sensor 13 is abnormal. It is judged that.

  If there is no abnormality in the voltage sensor 13 and the correct voltage value VH is measured, the process proceeds to step S6, and the control is returned to the main routine again.

  On the other hand, if it is determined in step S1 that an abnormality has occurred in the voltage sensor 13, the process proceeds to step S2.

  In step S2, the upper arm, that is, IGBT Q1 in FIG. 1 and the lower arm, that is, IGBT element Q2 in FIG. 1, are both controlled to be in a non-conductive state. In step S3, the motor generator M1 shown in FIG. By performing the power running operation, electric power is consumed by the motor generator M1. As a result, the charge stored in the capacitor C2 is consumed and the voltage drops.

  Subsequently, in step S4, it is determined whether or not the current value IB detected by the current sensor 11 is positive. If the current value IB is not positive, step S4 is repeated until the current value IB becomes a positive value.

  On the other hand, if it is determined in step S4 that the current value IB detected by the current sensor 11 has become a positive value, the process proceeds to step S5.

  In step S5, the upper arm, that is, IGBT element Q1 in boost converter 12 is fixed in a conductive state, and the lower arm, that is, IGBT element Q2, is fixed in a nonconductive state. Then, the process proceeds to step S6, and the control is returned to the main routine.

FIG. 3 is an operation waveform diagram for illustrating the control performed in the first embodiment.
In FIG. 3, the boosted voltage VH is not the value measured by the voltage sensor 13 of FIG. 1, but the actual voltage value between the terminals of the capacitor C2.

  It is assumed that an abnormality is detected in the output value of the voltage sensor 13 in FIG. 1 at time t1 (step S1 in FIG. 2). Then, IGBT elements Q1, Q2 are both fixed to a non-conductive state, and the boosting operation of boost converter 12 is stopped.

FIG. 4 is a diagram for explaining the direction of current flow at time t1 in FIG.
As shown in FIG. 4, if the voltage VH between the electrodes of the capacitor C2 is larger than the battery voltage VB, the diodes D1 and D2 are both biased in the reverse direction when both the IGBT elements Q1 and Q2 are fixed to the off state. Become. Therefore, when motor generator M1 performs a power running operation, current is consumed in inverter 14 and motor generator M1, and this current is supplied from capacitor C2 as current I1 indicated by an arrow. As a result, the voltage VH between the electrodes of the capacitor C2 gradually decreases.

  Referring to FIG. 3 again, when the interelectrode voltage VH of capacitor C2 becomes smaller than battery voltage VB at time t2, battery current IB starts to flow.

  FIG. 5 is a diagram for explaining that battery current IB starts to flow at time t2 in FIG.

  As shown in FIG. 5, when the interelectrode voltage VH of the capacitor C2 becomes smaller than the battery voltage VB, the diode D1 is forward biased. As a result, the forward current I2 can flow through the diode D1 as indicated by the arrow. Therefore, battery current IB is detected as a positive value also in current sensor 11.

  Thus, when it is detected in the current sensor 11 that the battery current value IB has exceeded a predetermined threshold value slightly larger than 0 in order to confirm that the battery current value IB is a positive value, the control device of FIG. 30 fixes the IGBT element Q1 in a conductive state and fixes the IGBT element Q2 in a non-conductive state.

FIG. 6 is a diagram for explaining a state after time t2 in FIG.
As shown in FIG. 6, when IGBT element Q1 is turned on and IGBT element Q2 is turned off, the inverter is connected to battery B through reactor L1 by IGBT element Q1. Accordingly, current is supplied from the battery to the inverter during the power running operation of the motor generator M1 along the path indicated by the arrow in FIG. 6, and on the contrary, a charging current can flow from the inverter toward the battery during the regenerative operation of the motor generator M1. It becomes.

  As described above, in the first embodiment, the voltage on the boost side can be controlled to be equal to the battery voltage value. After confirming that the actual boost voltage value has reached the battery voltage value by the output of the current sensor, the motor can be driven by the battery voltage by conducting the upper arm of the boost converter. No current flows. For this reason, surge current and overcurrent do not occur, and it is possible to prevent destruction of the intelligent power module incorporating the boost converter due to overcurrent.

[Embodiment 2]
FIG. 7 is a flowchart showing a control structure of a program executed by control device 30 in the second embodiment.

  Referring to FIG. 7, when the process is started, whether or not voltage sensor 13 is abnormal is determined in step S11. For example, when the voltage value VH is always a fixed value, or when the voltage value VH is out of a predetermined range, it is determined that the voltage sensor 13 is abnormal.

  If it is determined in step S11 that there is no abnormality in the voltage sensor 13, the process proceeds to step S15, and the control returns to the main routine.

  On the other hand, if it is determined in step S11 that the voltage sensor 13 is abnormal, the process proceeds to step S12. In step S12, control is performed so that the upper arm, that is, the IGBT element Q1 in FIG. 1 performs a switching operation, and the lower arm, that is, the IGBT element Q2, is turned off. As a result, a current flows from the capacitor C2 toward the reactor and is interrupted. As a result, a commutation current flows through the diode D2, so that the boost converter 12 performs a step-down operation from the capacitor C2 toward the battery B.

  Subsequently, in step S13, the control device 30 determines whether or not the current value IB observed by the current sensor 11 is positive. If the battery current value IB is not a positive value, the observation in step S13 is continued until the battery current value IB becomes a positive value.

  If it is observed in step S13 that the battery current value IB has become a positive value, the process proceeds to step S14.

  In step S14, the upper arm, that is, the IGBT element Q1, is controlled to be conductive, and the lower arm, that is, the IGBT element Q2, is controlled to be nonconductive. Then, the process proceeds to step S15, and the control is returned to the main routine.

  FIG. 8 is an operation waveform diagram for explaining a change in battery current IB in the second embodiment.

  Referring to FIG. 8, assume that abnormality of voltage sensor 13 is first detected at time t1. Then, in step S12 in FIG. 7, the upper arm is switched and the lower arm is controlled to be in a non-conducting state.

FIG. 9 is a diagram for explaining the direction of the battery current at time t1 in FIG.
Referring to FIG. 9, at time t1, voltage VH between terminals of capacitor C2 is still higher than battery voltage VB. Therefore, when IGBT element Q1 is turned on, battery current IB is applied to reactor L1 in the direction indicated by the arrow in FIG. Flowing. The energy stored in reactor L1 by this current is released during the off period of IGBT element Q1. At this time, a commutation current flows in the forward direction of the diode D2, and a battery current IB flows as indicated by an arrow. By causing the boost converter 12 to perform such a step-down operation, the charge stored in the capacitor C2 is discharged, and the inter-terminal voltage VH gradually decreases.

  Referring to FIG. 8 again, the voltage value VH gradually decreases by the step-down operation and becomes equal to the battery voltage VB at time t2, and when VH <VB after time t2, the current detected by the current sensor 11 is reduced. The direction changes from negative to positive.

FIG. 10 is a diagram for explaining the direction of current flow after time t2 in FIG.
In FIG. 10, even when the IGBT element Q1 continues switching at the moment when the voltage value becomes VH <VB, a current as shown by an arrow in FIG. When Q1 is non-conductive, a similar current flows as a forward current of the diode D1.

  In such a state, control device 30 detects IB> 0, puts the upper arm, ie, IGBT element Q1, in the conductive state, and fixes the lower arm, ie, IGBT element Q2, in the non-conductive state. As a result, as described above with reference to FIG. 6, the motor generator M1 can be caused to perform a power running operation and a regenerative operation.

  In the second embodiment, the same effects as those described in the first embodiment can be obtained. In addition, even when the motor generator M1 is not in the power running operation, the charge stored in the capacitor C2 can be discharged to reduce the voltage on the output side of the boost converter.

[Embodiment 3]
FIG. 11 is a flowchart showing a control structure of a program executed by control device 30 in the third embodiment.

  Referring to FIG. 11, first, when the process is started, control device 30 determines whether or not an abnormality has occurred in voltage sensor 13 in step S31. For example, by detecting that the voltage value VH output from the voltage sensor 13 is a fixed value, or that the voltage value VH is out of an appropriate predetermined range, the voltage sensor 13 is abnormal. It is judged that.

  If there is no abnormality in the voltage sensor 13 and the correct voltage value VH is measured, the process proceeds to step S36, and the control is returned to the main routine again.

  On the other hand, if it is determined in step S31 that an abnormality has occurred in the voltage sensor 13, the process proceeds to step S32.

  In step S32, the upper arm, ie, the IGBT Q1 in FIG. 1 and the lower arm, ie, the IGBT element Q2 in FIG. 1, are both controlled to be in a non-conductive (OFF) state. In step S33, the motor generator M1 shown in FIG. By performing the power running operation, electric power is consumed by the motor generator M1. As a result, the charge stored in the capacitor C2 is consumed and the voltage drops.

  When step S33 ends, the process of step S34 is performed. In step S34, the voltage value VL output from the voltage sensor 21 and the voltage value VB output from the voltage sensor 10 are compared, and it is determined whether or not VL <VB is satisfied. If VL <VB is not established, observation is performed in step S34 until this is established.

  On the other hand, if VL <VB is satisfied in step S34, the process proceeds to step S35.

  In step S35, the upper arm, that is, IGBT element Q1 in boost converter 12 is fixed in a conductive state, and the lower arm, that is, IGBT element Q2, is fixed in a nonconductive state. Then, the process returns to step S36, and the control is returned to the main routine.

  FIG. 12 is an operation waveform diagram for explaining the voltage comparison in step S34 in FIG.

  In FIG. 12, the voltage VH indicates an actual voltage, not an observation value of the voltage sensor 13. At time t1, an abnormality is detected in voltage sensor 13 that observes voltage VH, and the motor generator is operated in a power manner so as to discharge the charge accumulated in capacitor C2 between times t1 and t2. At this time, in the first and second embodiments, the example is shown in which the upper arm of the boost converter is switched to the conductive state when the battery current IB observed by the current sensor 11 becomes a positive value.

  However, a system without a current sensor is also conceivable, and a case where the current sensor has failed is also conceivable. In such a case, it is only necessary to detect that the voltage value VL observed by the voltage sensor 21 decreases for a moment.

  That is, at the moment when the battery current that has been zero until now starts flowing, the current is compensated from the capacitor C1, so the voltage VL across the capacitor C1 drops momentarily. By monitoring this moment, it can be detected that the voltage across the capacitor C2 has dropped below the voltage across the capacitor C1 and the battery voltage. As a result, the same effect as in the first embodiment can be obtained.

[Embodiment 4]
FIG. 13 is a flowchart showing a control structure of a program executed by control device 30 in the fourth embodiment.

  Referring to FIG. 13, when the process is started, it is determined whether or not voltage sensor 13 is abnormal in step S41. For example, when the voltage value VH is always a fixed value, or when the voltage value VH is out of a predetermined range, it is determined that the voltage sensor 13 is abnormal.

  If it is determined in step S41 that there is no abnormality in the voltage sensor 13, the process proceeds to step S45 and the control returns to the main routine.

  On the other hand, if it is determined in step S41 that the voltage sensor 13 is abnormal, the process proceeds to step S42. In step S42, control is performed so that the upper arm, that is, the IGBT element Q1 in FIG. 1, performs a switching operation, and the lower arm, that is, the IGBT element Q2, is turned off. As a result, a current flows from the capacitor C2 toward the reactor and is interrupted. As a result, a commutation current flows through the diode D2, so that the boost converter 12 performs a step-down operation from the capacitor C2 toward the battery B.

  Subsequently, in step S43, the voltage value VL output from the voltage sensor 21 and the voltage value VB output from the voltage sensor 10 are compared, and it is determined whether or not VL <VB is satisfied. If VL <VB is not established, observation is performed in step S43 until this is established.

  On the other hand, if VL <VB is satisfied in step S43, the process proceeds to step S44. In step S44, the upper arm, that is, the IGBT element Q1, is controlled to be conductive, and the lower arm, that is, the IGBT element Q2, is controlled to be nonconductive. Then, the process proceeds to step S45, and the control is returned to the main routine.

  FIG. 14 is an operation waveform diagram for illustrating the relationship between battery current IB and voltage value VL in the fourth embodiment.

  In FIG. 14, VH indicates an actual voltage, not an observation value of the voltage sensor 13. At time t1, an abnormality is detected in voltage sensor 13 that observes VH, and the motor generator is operated in a power manner so as to discharge the charge accumulated in capacitor C2 between times t1 and t2. At this time, in the first and second embodiments, the example is shown in which the upper arm of the boost converter is switched to the conductive state when the battery current IB observed by the current sensor 11 becomes a positive value.

  However, in the fourth embodiment, as in the third embodiment, it is detected that the voltage value VL observed by the voltage sensor 21 decreases for a moment.

  That is, at time t2, battery current IB changes from a negative value to a positive value. At this moment, since the current is supplemented from the capacitor C1, the voltage VL across the capacitor C1 drops for a moment. By monitoring this moment, it can be detected that the voltage across the capacitor C2 has dropped below the voltage across the capacitor C1 and the battery voltage.

  Therefore, the fourth embodiment can achieve the same effect as the second embodiment.

[Embodiment 5]
FIG. 15 is a flowchart showing a control structure of a program executed by control device 30 in the fifth embodiment.

  Referring to FIG. 15, when the process is started, it is determined in step S51 whether or not an output abnormality of voltage sensor 13 has occurred. If it is determined in step S51 that the voltage sensor is normal, the process proceeds to step S58, and control returns to the main routine.

  On the other hand, if it is detected in step S51 that an abnormality has occurred in the voltage sensor 13, the process proceeds to step S52. The abnormality of the voltage sensor is, for example, when the measured voltage value VH is always a fixed value, or when the measured value VH is out of a predetermined range.

  In step S52, control device 30 determines whether or not motor generator M1 is in a power running operation. Since the inverter 14 is controlled by the control device 30, the control device 30 itself has information in the control device 30 as to whether the motor generator M 1 is currently performing a power running operation or a regenerative operation.

  If motor generator M1 is in power running and consumes power, the process proceeds to step S53. In step S53, the upper arm and the lower arm of boost converter 12 are both controlled to be in the OFF state, and the power running operation of the motor generator currently being executed is continued in step S54. When the process of step S54 ends, the process proceeds to step S56.

  On the other hand, if it is determined in step S52 that the motor generator is not in the power running operation, the process proceeds to step S55.

  In step S55, the upper arm, ie, IGBT element Q1, of the boost converter is controlled to perform a switching operation, and the lower arm, ie, IGBT element Q2, is controlled to be nonconductive. Then, the process proceeds to step S56.

  Subsequently, in step S56, it is determined whether or not the current value IB detected by the current sensor 11 is positive. If the current value IB is not positive, step S56 is repeated until the current value IB becomes a positive value.

  On the other hand, if it is determined in step S56 that the current value IB detected by the current sensor 11 has become a positive value, the process proceeds to step S57.

  In step S57, the upper arm, that is, IGBT element Q1 in boost converter 12 is fixed to the conductive state, and the lower arm, that is, IGBT element Q2 is fixed to the non-conductive state. Then, the process proceeds to step S58, and the control is returned to the main routine.

FIG. 16 is a flowchart showing a modification of the flowchart shown in FIG.
The flowchart shown in FIG. 16 includes the process of step S56A instead of the process of step S56 in the flowchart shown in FIG. Since other processes are the same as those in FIG. 15, description thereof will not be repeated.

  In step S56A, as in the third and fourth embodiments, it is detected that the direction of the battery current has changed by observing the voltage VL between the terminals of capacitor C1. Thereby, the timing which fixes IGBT element Q1 to a conduction | electrical_connection state can be known.

  As described above, in the fifth embodiment, when the motor generator is performing the power running operation, the voltage of capacitor C1 is consumed thereby, and when the power running operation is not performed, the voltage of capacitor C1 is stepped down to flow to the battery. As a result, the capacitor C1 is discharged, so that it is possible to select a discharge method according to necessity.

[Other variations]
FIG. 17 is a diagram showing the configuration of another vehicle system to which the present invention is applied.

  17 includes motor generator MG1 instead of motor generator M1 in the configuration shown in FIG. 1, and further includes inverter 14A connected in parallel with inverter 14 and motor generator MG2 driven thereby. 1 is different from the configuration shown in FIG. Since the structure of FIG. 17 is the same as that of FIG. 1 for other portions, description thereof will not be repeated.

  The present invention can be similarly applied to a system in which two motors are mounted. For example, when a sensor observing the boost voltage VH fails, switching of the boost converter is stopped and the motor generator MG2 that rotates in synchronization with the drive wheels is stopped, and the motor generator MG1 that is a generator performs power running control. The capacitor C2 can be discharged by causing the motor generator MG1 to consume current.

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

1 is a circuit diagram showing a configuration of a vehicle 100 according to an embodiment of the present invention. 3 is a flowchart showing a control structure of a program executed by control device 30 in the first embodiment. FIG. 6 is an operation waveform diagram for illustrating control performed in the first embodiment. It is a figure for demonstrating the direction through which the electric current flows in the time t1 of FIG. FIG. 4 is a diagram for explaining that battery current IB starts to flow at time t2 in FIG. 3; It is a figure for demonstrating the state after the time t2 of FIG. 10 is a flowchart showing a control structure of a program executed by control device 30 in the second embodiment. FIG. 10 is an operation waveform diagram for illustrating a change in battery current IB in the second embodiment. It is a figure for demonstrating the direction of a battery current in the time t1 of FIG. It is a figure for demonstrating the direction through which the electric current flows after the time t2 of FIG. 10 is a flowchart showing a control structure of a program executed by control device 30 in the third embodiment. FIG. 12 is an operation waveform diagram for explaining voltage comparison in step S34 in FIG. 10 is a flowchart showing a control structure of a program executed by control device 30 in the fourth embodiment. FIG. 10 is an operation waveform diagram for illustrating the relationship between battery current IB and voltage value VL in the fourth embodiment. 10 is a flowchart showing a control structure of a program executed by control device 30 in the fifth embodiment. It is a flowchart which shows the modification of the flowchart shown in FIG. It is the figure which showed the structure of the other vehicle system to which this invention is applied.

Explanation of symbols

  10, 13, 21 Voltage sensor, 11, 24 Current sensor, 12 Boost converter, 14, 14A Inverter, 15 U-phase arm, 16 V-phase arm, 17 W-phase arm, 20 Voltage converter, 30 Control device, 35 Temperature sensor , 100 vehicle, B battery, C1, C2 capacitor, D1-D8 diode, L1 reactor, M1, MG1, MG2 motor generator, Q1-Q8 IGBT element, SR1, SR2 system main relay.

Claims (6)

DC power supply,
A DC voltage converter for performing voltage conversion of the DC power supply;
A first capacitor for smoothing the voltage at the output node of the DC voltage converter;
A drive unit that receives electric power from the DC voltage conversion unit and the first capacitor to drive the rotating electrical machine;
A first voltage detector for detecting a voltage across the terminals of the first capacitor;
A current detector for detecting a current exchanged between the DC power source and the DC voltage converter;
A controller that receives the output of the first voltage detector and controls the DC voltage converter;
The control unit is a vehicle drive device that, when an abnormality occurs in the first voltage detection unit, determines a discharge state of the first capacitor according to an output of the current detection unit. DC power supply,
A DC voltage converter for performing voltage conversion of the DC power supply;
A first capacitor for smoothing the voltage at the output node of the DC voltage converter;
A second capacitor for smoothing the voltage at the input node of the DC voltage converter;
A drive unit that receives electric power from the DC voltage conversion unit and the first capacitor to drive the rotating electrical machine;
A first voltage detector for detecting a voltage across the terminals of the first capacitor;
A second voltage detector for detecting a voltage across the terminals of the second capacitor;
A controller that receives the outputs of the first and second voltage detectors and controls the DC voltage converter;
The controller is configured to determine a discharge state of the first capacitor according to an output of the second voltage detector when an abnormality occurs in the first voltage detector.   When an abnormality occurs in the first voltage detection unit, the control unit gives an instruction to stop the operation of the DC voltage conversion unit and to cause the drive unit to perform a power running operation of the rotating electrical machine. The vehicle drive device according to claim 1, wherein the first capacitor is discharged. The DC voltage conversion unit is configured to be capable of a step-up operation from the DC power source toward the drive unit and a step-down operation from the drive unit toward the DC voltage,
3. The control unit causes the DC voltage conversion unit to perform the step-down operation to discharge the first capacitor when an abnormality occurs in the first voltage detection unit. The vehicle drive device described in 1. The DC voltage conversion unit is configured to be capable of a step-up operation from the DC power source toward the drive unit and a step-down operation from the drive unit toward the DC voltage,
The control unit stops the operation of the DC voltage conversion unit when the rotating electrical machine is performing a power running operation when an abnormality occurs in the first voltage detection unit, and causes the driving unit to operate the rotating electrical machine. Giving a command to continue the power running to discharge the first capacitor;
The controller causes the DC voltage converter to perform the step-down operation when the rotating electrical machine is not performing a power running operation when an abnormality occurs in the first voltage detector. The vehicle drive device according to claim 1, wherein the capacitor is discharged. The DC voltage converter is
A reactor having one end connected to an input node of the DC voltage converter;
A first switching element that conducts the output node and the other end of the reactor under the control of the control unit;
A second switching element that conducts the other end of the reactor and the ground node under the control of the control unit;
The controller fixes the first switching element to a conductive state and fixes the second switching element to a non-conductive state when a discharge state of the first capacitor becomes a predetermined state. The vehicle drive device according to any one of claims 1 to 5.

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