JP2013066326A - Vehicle, and vehicle control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle and a vehicle control method which allow the vehicle to move while suppressing a secondary failure of equipment in the vehicle, when the vehicle is towed in case that a switching element included in an inverter causes short-circuit fault, in the vehicle which can travel by driving a motor generator by the inverter.SOLUTION: The vehicle 100 includes the motor generator 140, the inverter 130, and an ECU 300. The inverter 130 includes three-phase drive arms 131, 132, 133 each having two switching elements which respectively constitute an upper arm and a lower arm, converts DC power from an electricity storage device 110 to AC power, and drives the motor generator 140. The ECU 300 changes a switching state of the inverter 130 in response to a vehicle speed when the inverter 130 causes one-phase short-circuit fault in case that the vehicle 100 is not self-propelled by drive force from the motor generator 140.

Description

  The present invention relates to a vehicle and a vehicle control method, and more particularly, to an inverter control when a vehicle is transported when a failure occurs in a vehicle capable of running by driving a motor generator with an inverter.

  2. Description of the Related Art In recent years, attention has been paid to a vehicle that is mounted with a power storage device (for example, a secondary battery or a capacitor) and travels using driving force generated from electric power stored in the power storage device as an environment-friendly vehicle. Examples of the vehicle include an electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

  In these vehicles, generally, an inverter is used to convert DC power from a power storage device into AC power for driving a rotating electrical machine such as a motor generator. And while driving a vehicle using the driving force which generate | occur | produced with the rotary electric machine, at the time of regenerative braking etc., the rotational force from a driving wheel, an engine, etc. is converted into an electrical energy, and an electrical storage apparatus is charged.

  In such a vehicle, when an abnormality occurs in the inverter, it is necessary to take an appropriate measure in order to prevent the influence on other devices.

  Japanese Patent Laying-Open No. 2006-087175 (Patent Document 1) discloses that in a vehicle that can run using electric power, when a short circuit failure of a switching element included in an inverter occurs, the vehicle is pulled by the driver. A configuration for instructing prohibition and operating the brake to physically stop the rotation of the wheel is disclosed.

JP 2006-087175 A JP 2009-195026 A JP 2007-245966 A JP-A-10-257604 JP 2007-028733 A

  In a vehicle that can run by driving a motor generator with an inverter, if a short-circuit failure occurs in a switching element included in the inverter, in general, further failure of the inverter and its peripheral devices is prevented by the short-circuit current. Therefore, driving of the motor generator by the inverter is prohibited. After that, the failed vehicle will be transported by traction by other vehicles, but if the motor generator is a permanent magnet type rotating electrical machine with a permanent magnet embedded in the rotor, If the motor generator also rotates with the rotation of the wheel, a counter electromotive force is generated in the motor generator.

  Then, even if the motor generator is not actively driven by the inverter using the electric power from the power storage device, a large short-circuit current can flow through the circuit including the inverter and the motor generator due to a short-circuit failure of the switching element. As a result, the inverter, the current transmission path, and the motor generator constituting the circuit generate heat, which may cause damage and deterioration of these devices and peripheral devices.

  According to the configuration disclosed in the above Japanese Patent Laid-Open No. 2006-087175 (Patent Document 1), in order to solve such a problem, when a short-circuit failure occurs in the inverter, traction of the vehicle is prohibited. And the wheel is locked by the brake. As a result, generation of counter electromotive force of the motor generator can be prevented.

  However, if this happens, it will no longer be possible to tow or move by other vehicles, and it will not be possible to easily evacuate the damaged vehicle to a safe place or to transport the damaged vehicle. Problems such as the need for special devices may occur.

  Therefore, in order to further enhance the fail-safe function for ensuring the safety of the vehicle in the event of a failure, it is necessary to protect the equipment in the vehicle and to move the vehicle even in a failure state. Is required.

  The present invention has been made to solve such a problem, and an object of the present invention is to cause a short-circuit failure in a switching element included in an inverter in a vehicle capable of running by driving a motor generator by the inverter. When the vehicle is transported, it is possible to move the vehicle while suppressing secondary failure of the equipment in the vehicle.

  A vehicle according to the present invention is a vehicle capable of traveling using electric power from a power storage device, and controls a three-phase AC rotating electric machine for generating a driving force for driving, an inverter for driving the rotating electric machine, and the inverter. And a control device. The inverter includes a three-phase drive arm having two switching elements each constituting an upper and lower arm, and drives the rotating electrical machine by converting DC power from the power storage device into AC power. The control device controls the vehicle speed when a short circuit failure occurs in one of the switching elements in one phase of the drive arm when the vehicle is moving even though the rotating electrical machine does not generate a drive force. Change the drive status of the inverter accordingly.

  Preferably, when the vehicle speed exceeds the reference speed, the control device sets the arm on the same side as the switching element in which the short circuit failure has occurred among the upper and lower arms of the phase in which the short circuit failure has not occurred.

  Preferably, when the vehicle speed is lower than the reference speed, the control device sets all the switching elements of the drive arms to a non-conduction state.

  Preferably, the control device detects a short circuit failure based on at least one of a failure signal output from the inverter, a temperature of a power transmission path connecting the inverter and the rotating electrical machine, a temperature of the rotating electrical machine, and a current flowing through the rotating electrical machine. Determine if it has occurred.

  Preferably, the vehicle further includes an alarm device for notifying the user when a short circuit failure has occurred.

  A vehicle control method according to the present invention is a control method for a vehicle that can travel using electric power from a power storage device. The vehicle has a three-phase AC rotating electric machine for generating a driving force for driving and a three-phase driving arm having two switching elements each constituting an upper and lower arm, and converts DC power from the power storage device into AC power. And an inverter that drives the rotating electrical machine. The control method includes a step of determining whether or not the vehicle is moving even though no driving force is generated from the rotating electrical machine, and a short-circuit failure occurs in one switching element in one phase of the driving arm. An inverter according to the vehicle speed when the vehicle is moving without generating a driving force from the rotating electrical machine and a short circuit failure has occurred in one of the driving arms. A step of changing the driving state.

  According to the present invention, in a vehicle capable of running by driving a motor generator with an inverter, secondary failure of equipment in the vehicle is suppressed during transportation of the vehicle when a short circuit failure occurs in a switching element included in the inverter. In addition, the vehicle can be moved.

1 is an overall block diagram of a vehicle according to an embodiment. It is a figure for demonstrating a problem when a short circuit failure occurs in an inverter. It is a figure for demonstrating the outline | summary of the inverter drive control by this Embodiment. It is a figure for demonstrating an example of the relationship between the drag torque which generate | occur | produces in a motor generator, and the vehicle speed (rotation speed of a motor generator) in the case of a one-phase short circuit state, and the case of three-phase ON control. In this Embodiment, it is a functional block diagram for demonstrating the inverter drive control performed by ECU. In this Embodiment, it is a flowchart for demonstrating the detail of the inverter drive control process performed by ECU. It is a flowchart for demonstrating the detail of the self-running determination process in S100 of FIG. It is a flowchart for demonstrating the detail of the one phase short circuit determination process in S120 of FIG. It is a flowchart which shows the other example of execution of a warning output process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, about the same or equivalent part in a figure, the same code | symbol is attached | subjected and the description is not repeated.

[Basic configuration of vehicle]
FIG. 1 is an overall block diagram of a vehicle 100 according to an embodiment of the present invention. In the present embodiment, a configuration in which vehicle 100 is an electric vehicle will be described as an example. However, the configuration of vehicle 100 is not limited to this, and any vehicle that can run with electric power from a power storage device is applicable. Is possible. Vehicle 100 includes, for example, a hybrid vehicle and a fuel cell vehicle in addition to an electric vehicle.

  Referring to FIG. 1, vehicle 100 includes a power storage device 110, a system main relay (SMR) 115, a converter 120, an inverter 130, a motor generator 140, a power transmission gear 150, and driving wheels. 160, alarm device 200, and ECU (Electronic Control Unit) 300 which is a control device.

  The power storage device 110 is a power storage element configured to be chargeable / dischargeable. The power storage device 110 includes, for example, a secondary battery such as a lithium ion battery, a nickel metal hydride battery, or a lead storage battery, and a power storage element such as an electric double layer capacitor.

  Power storage device 110 is connected to converter 120 of converter 120 through power lines PL1 and NL1. Power storage device 110 supplies electric power for driving motor generator 140 to converter 120. Power storage device 110 stores the electric power generated by motor generator 140. The output of power storage device 110 is, for example, about 200V.

  Relays included in SMR 115 are connected to power storage device 110 and power lines PL1, NL1, respectively. SMR 115 is controlled by control signal SE <b> 1 from ECU 300, and switches between power supply and cutoff between power storage device 110 and converter 120.

  Capacitor C1 is connected between power line PL1 and power line NL1. Capacitor C1 reduces voltage fluctuation between power line PL1 and power line NL1.

  Converter 120 includes switching elements Q1, Q2, diodes D1, D2, and a reactor L1.

  Switching elements Q1 and Q2 are connected in series between power lines PL2 and NL1, with the direction from power line PL2 toward power line NL1 as the forward direction. In this embodiment, an IGBT (Insulated Gate Bipolar Transistor) is described as an example of the switching element, but a power MOS (Metal Oxide Semiconductor) transistor or a power bipolar transistor is used instead of the IGBT. Also good.

  Antiparallel diodes D1 and D2 are connected to switching elements Q1 and Q2, respectively. Reactor L1 is provided between a connection node of switching elements Q1 and Q2 and power line PL1. That is, converter 120 forms a chopper circuit.

  Switching elements Q1, Q2 are controlled based on control signal PWC from ECU 300, and perform voltage conversion operation between power lines PL1, NL1 and power lines PL2, NL1.

  Converter 120 is basically controlled such that switching elements Q1 and Q2 are turned on and off in a complementary manner in each switching period. Converter 120 boosts the DC voltage from power storage device 110 during the boosting operation. This boosting operation is performed by supplying the electromagnetic energy accumulated in reactor L1 during the ON period of switching element Q2 to power line PL2 via switching element Q1 and antiparallel diode D1.

  Converter 120 steps down the DC voltage from inverter 130 during the step-down operation. This step-down operation is performed by supplying the electromagnetic energy stored in reactor L1 during the ON period of switching element Q1 to power line NL1 via switching element Q2 and antiparallel diode D2.

  The voltage conversion ratio in these step-up and step-down operations is controlled by the on-period ratio (duty ratio) of the switching elements Q1 and Q2 in the switching period. When the step-up operation and the step-down operation are not required, the voltage conversion ratio = 1.0 (duty ratio = 100) is set by setting the control signal PWC to fix the switching elements Q1 and Q2 to ON and OFF, respectively. %).

  In the present invention, converter 120 is not essential, and the output voltage from power storage device 110 may be directly supplied to inverter 130.

  Capacitor C2 is connected between power lines PL2 and NL1 connecting converter 120 and inverter 130. Capacitor C2 reduces voltage fluctuation between power line PL2 and power line NL1. Voltage sensor 170 detects the voltage applied to capacitor C2 and outputs the detected value VH to ECU 300.

  Inverter 130 is connected to converter 120 via power lines PL2 and NL1. Inverter 130 is controlled by control command PWI from ECU 300, and converts DC power output from converter 120 into AC power for driving motor generator 140.

  Inverter 130 includes a U-phase arm 131, a V-phase arm 132, and a W-phase arm 133, which form a three-phase bridge circuit. U-phase arm 131, V-phase arm 132, and W-phase arm 133 are connected in parallel between power line PL2 and power line NL1.

  U-phase arm 131 includes switching elements Q3 and Q4 connected in series between power line PL2 and power line NL1, and diodes D3 and D4 connected in parallel to switching elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of switching element Q3, and the anode of diode D3 is connected to the emitter of switching element Q3. The cathode of diode D4 is connected to the collector of switching element Q4, and the anode of diode D4 is connected to the emitter of switching element Q4.

  V-phase arm 132 includes switching elements Q5 and Q6 connected in series between power line PL2 and power line NL1, and diodes D5 and D6 connected in parallel to switching elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of switching element Q5, and the anode of diode D5 is connected to the emitter of switching element Q5. The cathode of diode D6 is connected to the collector of switching element Q6, and the anode of diode D6 is connected to the emitter of switching element Q6.

  W-phase arm 133 includes switching elements Q7 and Q8 connected in series between power line PL2 and power line NL1, and diodes D7 and D8 connected in parallel to switching elements Q7 and Q8, respectively. The cathode of diode D7 is connected to the collector of switching element Q7, and the anode of diode D7 is connected to the emitter of switching element Q7. The cathode of diode D8 is connected to the collector of switching element Q8, and the anode of diode D8 is connected to the emitter of switching element Q8.

  The motor generator 140 is, for example, a three-phase AC motor generator including a rotor in which a permanent magnet is embedded and a stator having a three-phase coil Y-connected at a neutral point, and includes U-phase, V-phase, and W-phase. Each of the three coils has one end connected together to a neutral point. The other end of the U-phase coil is connected to the connection node of switching elements Q3 and Q4. The other end of the V-phase coil is connected to a connection node of switching elements Q5 and Q6. The other end of the W-phase coil is connected to the connection node of switching elements Q7 and Q8.

  The output torque of motor generator 140 is transmitted to drive wheels 160 via power transmission gear 150 constituted by a speed reducer and a power split mechanism, and causes vehicle 100 to travel. The motor generator 140 can generate power by the rotational force of the drive wheels 160 during the regenerative braking operation of the vehicle 100. Then, the generated power is converted into charging power for power storage device 110 by inverter 130.

  Further, in a hybrid vehicle equipped with an engine (not shown) in addition to motor generator 140, necessary engine driving force is generated by operating this engine and motor generator 140 in a coordinated manner. In this case, it is also possible to charge the power storage device 110 using the power generated by the rotation of the engine.

  Although FIG. 1 shows a configuration in which one motor generator is provided, the number of motor generators is not limited to this, and a configuration in which a plurality of motor generators are provided may be employed. For example, in the case of a hybrid vehicle including two motor generators, one motor generator is used exclusively as an electric motor for driving the drive wheels 160, and the other motor generator is used exclusively as a generator driven by an engine. May be.

  Temperature sensor 180 is provided in a power transmission path between inverter 130 and motor generator 140, and detects the temperature of these power transmission paths. Temperature sensor 180 outputs detected value TW to ECU 300.

  Temperature sensor 185 is provided in the vicinity of motor generator 140 or in motor generator 140. Temperature sensor 185 detects the temperature of motor generator 140 and outputs the detected value TM to ECU 300. The temperature of motor generator 140 may be the temperature of the housing of motor generator 140 or the temperature of a coil included in the stator.

  Current sensor 190 is provided in a power transmission path between inverter 130 and motor generator 140. Since the sum of the currents flowing through the phases of motor generator 140 is basically zero, current sensor 190 may be provided in at least any two phases of the power transmission path. In FIG. 1, for example, current sensor 190 is provided in the U-phase and V-phase power transmission paths, and detected currents Iu and Iv are sent to ECU 300. The current detected by the current sensor 190 is collectively referred to as “MCRT”.

  The speed sensor 195 is provided in the vicinity of the drive wheel 160. Speed sensor 195 detects the vehicle speed based on the rotational speed of drive wheel 160 and outputs detected value SPD to ECU 300. For detection of the vehicle speed SPD, a rotation angle sensor (not shown) for detecting the rotation angle of the motor generator 140 may be used instead of the speed sensor 195. In that case, the detected rotation angle and deceleration are detected. From the ratio or the like, the ECU 300 calculates the vehicle speed SPD.

  The alarm device 200 is a device for notifying the driver of the occurrence of an abnormality based on a control signal ALM from the ECU 300 when an abnormality occurs. The alarm device 200 includes, for example, an audible notification such as a buzzer or a chime, and a visual notification such as a lamp or a liquid crystal display.

  ECU 300 includes a CPU (Central Processing Unit), a storage device, and an input / output buffer, all of which are not shown in FIG. 1, and inputs signals from each sensor and the like, and outputs control signals to each device. 100 and each device are controlled. Control in ECU 300 is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

  In addition, in FIG. 1, although demonstrated as an example the structure provided with one ECU300 as a control apparatus, the structure of a control apparatus is not limited to this. For example, ECU 300 may have a configuration in which a control device is provided for each device or function.

  ECU 300 receives voltage VB and current IB from power storage device 110. ECU 300 calculates a state of charge (SOC) of the power storage device based on voltage VB and current IB. ECU 300 receives an ignition signal IG by a user operation.

  ECU 300 receives a failure signal FLT indicating a failure of inverter 130 from inverter 130. Fault signal FLT includes, for example, information on whether an abnormality has occurred in any of the U, V, and W phases, and whether an abnormality has occurred in any of switching elements Q3-Q8.

[Problems when an inverter short-circuit failure occurs]
In such a vehicle 100, for example, when a short circuit failure occurs in which the switching element Q3 of the U-phase arm 131 of the inverter 130 remains in a conductive state during traveling, the switching operation is continued as it is. When the switching element Q4 of the lower arm of the U phase is turned on, the power lines PL2 and NL1 are short-circuited, and a large short-circuit current flows in the direction from the power line PL2 to NL1. If the short-circuit current flows continuously, the switching element Q4 that has not failed may be damaged, or the power path such as the power lines PL2 and NL1 may be heated.

  Therefore, it is desirable to stop the inverter 130 promptly when the abnormality of the inverter 130 as described above occurs.

  However, when the inverter 130 is stopped, the vehicle 100 cannot move the vehicle to a safe place by itself, and therefore, for example, it is necessary to move the vehicle by traction or human power by another vehicle.

  However, in the vehicle 100 configured as shown in FIG. 1, unless the output shaft of the motor generator 140 is physically separated by a clutch or the like, when the driving wheel 160 is rotated by the movement of the vehicle 100, the motor generator is accordingly accompanied. 140 can also rotate. At this time, when the motor generator 140 is a permanent magnet type rotating electrical machine having a permanent magnet on the rotor as described above, an induction voltage is generated in each phase coil by the rotation of the rotor.

  Then, for example, as shown in FIG. 2, switching element Q3 of the U-phase upper arm is short-circuited, and the potentials generated in U, V, and W phases of motor generator 140 are Vu, Vv, and Vw (Vv> Vw, respectively). > Vu), a short-circuit current as indicated by a solid line arrow AR10 is present on the path from the V-phase terminal of the motor generator 140 to the U-phase terminal via the diode D5 and the short-circuited switching element Q3. Flowing. When the potential Vw of the W-phase terminal is higher than the potential Vv of the V-phase terminal (Vw> Vv> Vu), the U-phase terminal is connected from the W-phase terminal via the diode D7 and the short-circuited switching element Q3. A short-circuit current as indicated by a broken-line arrow AR20 flows in the path leading to.

  Since the induced voltage generated by the counter electromotive force of the motor generator 140 is proportional to the rotational speed of the motor generator 140, if the rotational speed of the motor generator 140 increases due to traction by another vehicle, the induced voltage of the motor generator 140 also increases. It becomes high and the short circuit current which flows into a circuit also increases. When the short-circuit current becomes excessive, for example, the components and the power transmission path of the inverter 130 exceed the heat-resistant temperature, or the permanent magnet is demagnetized due to heat generation of the coil of the motor generator 140, thereby functioning as a rotating electric machine. May be damaged.

  Therefore, in the present embodiment, in a vehicle that can be driven by driving a motor generator with an inverter, the inverter drive state according to the vehicle speed when the vehicle is transported when a short circuit failure occurs in the switching element included in the inverter. Inverter drive control is executed.

[Description of inverter drive control]
FIG. 3 is a diagram for explaining an overview of inverter drive control according to the present embodiment. Referring to FIG. 3, as in FIG. 2, it is assumed that a short circuit failure has occurred in switching element Q <b> 3 of the upper arm of U phase in inverter 130.

  When the vehicle 100 is moved in this state, a short-circuit current such as a solid arrow AR30 may flow as described with reference to FIG.

  At this time, when the speed of the vehicle 100 (that is, the rotational speed of the motor generator 140) is low, the induced voltage generated in the motor generator 140 is low, so the current flowing through the short-circuit path is small and the degree of heat generation is small. Therefore, even if the short-circuit current continues to flow through the short-circuit path indicated by the arrow AR30, there is little possibility of causing damage to the device. Therefore, when the vehicle speed is low, inverter 130 is shut down, and all switching elements Q3 to Q8 of inverter 130 are set to non-conduction (however, switching element Q3 becomes conductive due to a short-circuit failure).

  On the other hand, when the speed of the vehicle 100 is high, the current flowing through the short circuit path also increases, which increases the possibility of damage to the equipment. Therefore, the same arm as the switching element in which the failure occurs (in the case of FIG. The switching elements Q3, Q5, Q7 of each phase of the arm) are switched to a conductive state (hereinafter also referred to as “three-phase ON control”). As a result, a part of the current flowing as indicated by solid line arrow AR30 is branched to a path reaching the V phase terminal of motor generator 140 via W phase switching element Q7 as indicated by broken line arrow AR40.

  Although not shown in FIG. 3, when the potential Vw of the W-phase terminal is larger than the potential Vv of the V-phase terminal, the diode D7 and the switching element Q3 from the V-phase terminal as indicated by the arrow AR20 in FIG. A part of the short-circuit current flowing through the path leading to the U-phase terminal via is branched to the path reaching the V-phase terminal via the V-phase switching element Q5.

  Thus, when the vehicle speed is high and the short circuit current is large, the generation of excessive heat is suppressed by distributing the short circuit current to a plurality of paths, so that the heat generation of the components of the inverter 130 and the power transmission path is suppressed. It can be prevented from becoming excessive.

  On the other hand, in motor generator 140, torque is generated by a short-circuit current flowing. Since this torque acts as a braking torque that resists the force that moves the vehicle, this braking torque will also be referred to as “drag torque” below. A relationship as shown in FIG. 4 is established between the drag torque and the vehicle speed (or the rotational speed of the motor generator 140).

  FIG. 4 is a diagram for explaining an example of the relationship between the drag torque generated in the motor generator and the vehicle speed (rotation speed of the motor generator) in the case of the one-phase short-circuit state and the case of the three-phase on control. The relationship shown in FIG. 4 is, for example, when the switching element Q3 of the U-phase upper arm as shown in FIG. 3 is short-circuited and the switching elements Q3 to Q8 are all set to non-conducting, and the switching elements Q3 and Q5 , Q7 shows the drag torque generated when the short-circuit current shown in FIG. The drag torque is represented by a negative value in order to distinguish it from torque generated during power running control of motor generator 140.

  In FIG. 4, a solid curve W10 indicates the drag torque in the case of the one-phase short-circuit state, and a broken curve W20 indicates the drag torque in the case of the three-phase on control.

  As shown in FIG. 4, in the case of the one-phase short circuit state, it can be seen that the absolute value of the drag torque increases as the vehicle speed SPD and the rotation speed MRN of the motor generator increase. On the other hand, when the three-phase on control is executed, the drag torque has an extreme value at a predetermined speed in the low speed range, and tends to become smaller as the speed increases from the predetermined speed. ing.

  That is, in the case of the one-phase short-circuit state and the case of the three-phase on control, the drag torque has different characteristics, and the magnitude relationship between the reference speed Vth (reference rotation speed Nth) in FIG. Inverted. As a result, the drag torque can be lowered by setting the one-phase short-circuit state in the speed region lower than the reference speed Vth and the three-phase on control in the speed region higher than the reference speed Vth, and the driving force required for vehicle transportation can be reduced. be able to. In particular, when the vehicle is moved manually, there is an advantage that the vehicle can be easily moved by reducing the drag torque.

  FIG. 5 is a functional block diagram for illustrating inverter drive control executed by ECU 300 in the present embodiment. Each functional block described in the block diagram illustrated in FIG. 5 is realized by hardware or software processing by ECU 300.

  Referring to FIGS. 1 and 5, ECU 300 includes a short circuit determination unit 310, a self-running determination unit 320, an alarm output unit 330, and an inverter control unit 340.

  Short circuit determination unit 310 includes failure signal FLT from inverter 130, temperature TW of the power transmission path from temperature sensor 180, temperature TM of motor generator 140 from temperature sensor 185, and current flowing from motor sensor 140 to current generator 190. Take MCRT.

  The short circuit determination unit 310 determines the presence or absence of a short circuit failure based on any of these pieces of information or an arbitrary combination, and determines the switching element in which the short circuit failure has occurred. Short circuit determination unit 310 then outputs a short circuit occurrence signal SHT as a determination result to alarm output unit 330 and inverter control unit 340.

  Self-running determination unit 320 receives torque command value TRQ for motor generator 140 set by the host ECU and vehicle speed SPD from speed sensor 195. Based on these pieces of information, self-running determination unit 320 determines whether or not vehicle 100 is running with a driving force other than that from motor generator 140. Specifically, self-running determination unit 320 travels with a power other than the driving force from motor generator 140 when vehicle speed SPD is generated even though there is no torque command value TRQ to motor generator 140. It is determined that Such cases include, for example, being pulled by another vehicle, being moved by human power, or descending downhill by gravity. In the case of a hybrid vehicle, the case where the vehicle is running only with the driving force of the engine is also applicable. Then, self-running determination unit 320 outputs determination result RUN to inverter control unit 340.

  Alarm output unit 330 receives short circuit occurrence signal SHT from short circuit determination unit 310 and determination result RUN from self-running determination unit 320.

  The alarm output unit 330 outputs a control signal ALM to the alarm device 200 when it is determined that the vehicle is not self-running based on the determination result RUN and a short-circuit failure occurs due to the short-circuit occurrence signal SHT. Notifying the driver of the occurrence of Alternatively, regardless of the determination result RUN from the self-running determination unit 320, an abnormality may be notified when a short-circuit failure has occurred.

  Inverter control unit 340 receives short circuit occurrence signal SHT from short circuit determination unit 310, determination result RUN from self-running determination unit 320, and vehicle speed SPD from speed sensor 195.

  The inverter control unit 340 changes the switching state of the inverter 130 according to the vehicle speed SPD when the vehicle 100 is towed or the like and a short circuit failure has occurred in the inverter 130. Specifically, when the vehicle speed SPD is lower than the reference speed, the inverter 130 is shut off and all the switching elements are set in a non-conductive state, while when the vehicle speed SPD exceeds the reference speed, each phase Only the switching element of the arm in which the short-circuit failure has occurred is set to the conductive state.

  Based on the above, inverter control unit 340 generates control signal PWI and changes the switching state of inverter 130.

  FIG. 6 is a flowchart for illustrating details of the inverter drive control process executed by ECU 300 in the present embodiment. Each step in the flowcharts shown in FIG. 6 and FIGS. 7 to 9 to be described later is realized by a program stored in advance in the ECU 300 being called from the main routine and executed at a predetermined cycle. Alternatively, for some steps, it is also possible to construct dedicated hardware (electronic circuit) and realize processing.

  Referring to FIGS. 1 and 6, ECU 300 determines in step (hereinafter, step is abbreviated as “S”) 100 whether vehicle 100 is self-propelled.

  Here, the details of the self-running determination process of S100 are shown in FIG. 7, but the ECU 300 has zero torque command value TRQ of the vehicle 100 in S102, that is, no driving force is generated by the motor generator 140. In addition, it is determined whether the condition that the vehicle speed SPD is not zero and the vehicle 100 is moving is satisfied.

  If the above condition is satisfied (YES in S102), ECU 300 determines that it is not self-propelled in S104, that is, towing by another vehicle, movement by human power, or the like is being performed. . Then, the process proceeds to S110 in FIG.

  On the other hand, when the above condition is not satisfied (NO in S102), ECU 300 causes the process to be performed because driving force is generated from motor generator 140 or vehicle 100 is stopped. Proceed to S110 in FIG.

  Referring to FIG. 6 again, in S110, ECU 300 determines whether or not vehicle 100 is currently traveling from the result of the self-running determination process in S100.

  If vehicle 100 is not self-propelled (NO in S110), the process proceeds to S120, and ECU 300 next determines whether or not a single-phase short-circuit failure has occurred in inverter 130.

  Details of the one-phase short-circuit state determination process in S120 are shown in FIG. In S122, ECU 300 determines whether or not a one-phase short-circuit failure has occurred by failure signal FLT from inverter 130, and temperature TW of the power cable that is the power transmission path exceeds predetermined threshold value α. It is determined whether the motor generator 140 is overheated or whether the motor generator 140 is heated so that the temperature TM of the motor generator 140 exceeds a predetermined threshold value β. Although not shown in FIG. 8, whether or not a large current (short-circuit current) is flowing in any phase may be further determined based on current MCRT flowing to motor generator 140.

  If at least one of the above conditions is satisfied (YES in S122), the process proceeds to S124, and ECU 300 determines that a one-phase short-circuit fault has occurred in inverter 130 and performs the process. Proceed to S130 of 6.

  On the other hand, if none of the above conditions is satisfied (NO in S124), ECU 300 determines that a one-phase short-circuit failure has not occurred and advances the process to S130 in FIG.

  Referring to FIG. 6 again, in S130, ECU 300 determines whether or not a single-phase short-circuit fault has occurred in inverter 130 from the result of the determination process for a single-phase short-circuit fault in S120.

  If a one-phase short-circuit failure has not occurred (NO in S130), ECU 300 ends the process because a short-circuit current does not flow in inverter 130 even if traction or the like is performed.

  If a one-phase short-circuit failure has occurred (YES in S130), the process proceeds to S140, and it is determined whether vehicle speed SPD is greater than a predetermined reference speed Vth. Instead of vehicle speed SPD, it may be determined whether or not rotational speed MRN of motor generator 140 is greater than reference speed Nth.

  If vehicle speed SPD is greater than reference speed Vth (YES in S140), ECU 300 determines that the short-circuit current is large and there is a risk of damage to the components of inverter 130, and that drag torque increases, and the process is performed in S150. Then, the switching state of the inverter 130 is switched so as to execute the three-phase on control in which all the switching elements on the same side as the switching element in which the short-circuit failure has occurred are brought into conduction. Then, ECU 300 advances the process to S160.

  If vehicle speed SPD is equal to or lower than reference speed Vth (NO in S140), the process proceeds to S170, and ECU 300 shuts off inverter 130 and switches all switching elements to the non-conductive state, and proceeds to S160. . Note that when all the switching elements are already non-conductive, the state is maintained.

  In S160, ECU 300 outputs an alarm from alarm device 200 to notify the driver that a one-phase short circuit has occurred. In addition, it may be notified whether or not the three-phase ON control is selected, or the power transmission path, the temperature of the motor generator 140, and the like.

  If it is determined in S110 that vehicle 100 is traveling (YES in S110), the processes from S120 to S160 are skipped, and ECU 300 ends the process.

  In the flowchart of FIG. 6, an alarm is output when a one-phase short-circuit failure occurs when the vehicle is not running, but whether or not it is running as shown in FIG. 9. Regardless of this determination, an alarm may be output in response to the occurrence of a one-phase short-circuit fault. The processes in steps S200, S210, and S220 in FIG. 9 correspond to the processes in S120, S130, and S160 in FIG. 6, respectively, and therefore description thereof will not be repeated.

  By performing control according to the above-described process, in a vehicle capable of running by driving the motor generator with an inverter, the induced voltage of the motor generator when the vehicle is transported when a short circuit failure occurs in the switching element included in the inverter. It is possible to move the vehicle to a safe place while protecting the equipment in the vehicle due to the short-circuit current generated by. As a result, the fail-safe function for ensuring the safety of the vehicle when an abnormality occurs can be made more reliable.

  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.

  DESCRIPTION OF SYMBOLS 100 Vehicle, 110 Power storage device, 115 SMR, 120 Converter, 130 Inverter, 131 U-phase arm, 132 V-phase arm, 133 W-phase arm, 140 Motor generator, 150 Power transmission gear, 160 Drive wheel, 170 Voltage sensor, 180, 185 Temperature sensor, 190 Current sensor, 195 Speed sensor, 200 Alarm device, 300 ECU, 310 Short circuit determination unit, 320 Self-running determination unit, 330 Alarm output unit, 340 Inverter control unit, C1, C2 capacitor, D1-D8 diode, L1 reactor, NL1, PL1, PL2 power line, Q1-Q8 switching element.

Claims (6)

A vehicle capable of traveling using electric power from the power storage device,
A three-phase AC rotating electric machine for generating travel driving force;
An inverter for driving the rotating electrical machine by converting a DC power from the power storage device into an AC power, including a three-phase drive arm having two switching elements each constituting an upper and lower arm;
A control device for controlling the inverter;
In the control device, when the vehicle is moving even though the rotating electrical machine does not generate driving force, a short circuit failure has occurred in one switching element in one phase of the driving arm. Sometimes, the vehicle changes the driving state of the inverter according to the vehicle speed.   When the vehicle speed exceeds a reference speed, the control device sets the arm on the same side as the switching element in which the short-circuit failure has occurred among the upper and lower arms of the phase in which the short-circuit failure has not occurred. The vehicle according to claim 1.   The vehicle according to claim 2, wherein the control device sets the switching elements of all the drive arms to a non-conductive state when the vehicle speed is lower than a reference speed.   The control device is based on at least one of a failure signal output from the inverter, a temperature of a power transmission path connecting the inverter and the rotating electrical machine, a temperature of the rotating electrical machine, and a current flowing through the rotating electrical machine. The vehicle according to claim 1, wherein it is determined whether or not the short-circuit failure has occurred.   The vehicle according to claim 1, further comprising an alarm device for notifying a user when the short-circuit failure has occurred. A method for controlling a vehicle capable of traveling using electric power from a power storage device,
The vehicle is
A three-phase AC rotating electric machine for generating travel driving force;
Each having a three-phase drive arm having two switching elements constituting upper and lower arms, and including an inverter that converts the DC power from the power storage device into AC power and drives the rotating electrical machine,
The control method is:
Determining whether the vehicle is moving even though no driving force is generated from the rotating electrical machine;
Determining whether a short circuit fault has occurred in one of the switching elements in one of the drive arms;
When the vehicle is moving without generating a driving force from the rotating electrical machine and a short-circuit failure has occurred in one phase of the driving arm, the driving state of the inverter is changed according to the vehicle speed. And a step of changing the vehicle.

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