JP6245090B2 - Vehicle and control method thereof - Google Patents

Description

  The present invention relates to a vehicle and a control method thereof, and more particularly to a vehicle including a permanent magnet type synchronous motor and an induction motor and a control method thereof.

  When an abnormality is detected in the drive system of the vehicle, depending on the location where the abnormality has occurred, instead of immediately prohibiting the vehicle from traveling, it is required to be able to travel temporarily while suppressing the driving performance. By performing such evacuation traveling, it is possible to evacuate to a safe place or move to a repair shop.

  In a vehicle equipped with a travel motor, a configuration has been proposed in which retreat travel is performed when leakage of the motor is detected. For example, Japanese Patent Laying-Open No. 2008-154426 (Patent Document 1) discloses a detection unit that detects an insulation state of a motor, and a torque limitation unit that executes torque limitation of the motor based on the insulation state of the motor detected by the detection unit. An electric motor control device is disclosed.

JP 2008-154426 A Japanese Patent Laid-Open No. 7-15804

  2. Description of the Related Art A four-wheel drive system that drives front wheels and rear wheels with separate motors in vehicles equipped with a driving motor such as a hybrid vehicle or an electric vehicle is known. If a leak is detected at any point in this drive system, if a leak occurs at another point, a current path including the two leak points and the battery is formed, and an excessive current may flow. is there. In order to avoid such a situation, even if a leakage point is specified for one of the motors, the outputs of both motors can be suppressed in preparation for the occurrence of a second leakage. As a result, the evacuation traveling performance may be greatly reduced.

  In the four-wheel drive system in which one of the front wheels and the rear wheels is driven by a permanent magnet type synchronous motor and the other is driven by an induction motor, the inventors have specified that the leakage point is an induction motor. In such a case, it has been found that it is possible to minimize a decrease in evacuation traveling performance.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to ensure necessary evacuation traveling performance in a vehicle including a permanent magnet type synchronous motor and an induction motor.

  A vehicle according to an aspect of the present invention includes a power storage device, first and second inverters, a permanent magnet synchronous motor, an induction motor, a detection unit, and a control device. The first and second inverters convert power stored in the power storage device into AC power. The permanent magnet type synchronous motor is driven by the first inverter. The induction motor is driven by the second inverter. The detection unit detects leakage of the synchronous motor and the induction motor. The control device controls the first and second inverters. When the leakage of the induction motor is detected, the control device prohibits the driving of the second inverter, while the permanent magnet type synchronous motor does not suppress the output in response to the detection of the leakage of the induction motor.

  In the vehicle control method according to another aspect of the present invention, the vehicle includes a power storage device, first and second inverters, a permanent magnet type synchronous motor, an induction motor, and a detection unit. The first and second inverters convert power stored in the power storage device into AC power. The permanent magnet type synchronous motor is driven by the first inverter. The induction motor is driven by the second inverter. The detection unit detects leakage of the synchronous motor and the induction motor. In the above control method, the step of detecting the leakage of the induction motor and the drive of the second inverter are prohibited when the leakage of the induction motor is detected, while the leakage detection of the induction motor is detected for the permanent magnet type synchronous motor. And the step of not performing the output suppression in response to.

  If leakage of a permanent magnet type synchronous motor (hereinafter, sometimes abbreviated as a synchronous motor) is detected, the drive of the first inverter is prohibited (for example, each transistor in the inverter is controlled to be cut off). Can be cut off from the current through the first inverter to the synchronous motor.

  The rotational speeds of the synchronous motor and the induction motor can be changed by the torque transmitted from the wheels when the speed of the vehicle increases or decreases. At this time, in the synchronous motor, a relatively large counter electromotive force may be generated due to the rotation of the permanent magnet provided in the rotor. Therefore, even if the current from the power storage device is interrupted due to the prohibition of driving of the first inverter, the current due to the counter electromotive force can flow to the leakage point. Therefore, when the leakage of the synchronous motor occurs, it is necessary to limit the rotation speed of the wheels (that is, the vehicle speed) so that excessive counter electromotive force does not occur in the synchronous motor. The output is also suppressed. As a result, the evacuation traveling performance may be greatly reduced.

  On the other hand, no permanent magnet is used for the rotor of the induction motor, and in principle, no back electromotive force is generated in the induction motor if the second inverter is shut off, so there is no influence on the synchronous motor. . According to the above configuration and method, when leakage of the induction motor is detected, the current from the power storage device to the induction motor is cut off by prohibiting the driving of the second inverter. be able to. On the other hand, for synchronous motors that do not cause leakage, output suppression in response to detection of leakage from the induction motor is not performed, and the required evacuation travel is limited by limiting the motors targeted for output suppression to the minimum required induction motor. Performance can be ensured.

  Preferably, the control device suppresses the outputs of the permanent magnet type synchronous motor and the induction motor when the leakage of the permanent magnet type synchronous motor is detected as compared with the case where the leakage of the permanent magnet type synchronous motor is not detected. .

  As described above, when a leakage of the synchronous motor occurs, a current due to the counter electromotive force generated in the synchronous motor can flow to the leakage point. Therefore, according to the above configuration, when the leakage of the synchronous motor is detected, the outputs of the synchronous motor and the induction motor are suppressed (for example, prohibited). Thereby, since the vehicle speed is limited, generation of the counter electromotive force can be suppressed (for example, the magnitude of the counter electromotive force can be reduced or the generation frequency can be reduced).

  Preferably, in the prohibited state in which the driving of the second inverter is prohibited in response to the detection of the leakage of the induction motor, the control device prohibits the permanent magnet type synchronous motor or the induction motor when the leakage is further detected. As compared with the above, the output of the permanent magnet type synchronous motor is suppressed.

  When leakage occurs at two locations, a current path including the two leakage locations and the power storage device is formed, and an excessive current may flow. In order to avoid such a situation, when the second leakage is detected, it is necessary to immediately shut off the first and second inverters to suppress the outputs of both motors. Further, in the prohibited state where the leakage of the induction motor is detected and the driving of the second inverter is prohibited, if the leakage of the synchronous motor is further detected, there is a possibility that the second leakage has occurred. In addition, even when the leakage of the induction motor is detected again despite the prohibited state, the second inverter may not be properly prohibited from driving (for example, the gate is cut off properly due to damage to the transistor in the inverter, etc.) It is possible that the detector has not been executed), or that the detector may have malfunctioned. Therefore, according to the above configuration, when the leakage of the synchronous motor or the induction motor is further detected, the output of the synchronous motor is suppressed, so that it is possible to prevent an excessive current from flowing due to the leakage.

  Preferably, the permanent magnet type synchronous motor is mechanically coupled to a main drive wheel which is one of a front wheel and a rear wheel of the vehicle. The induction motor is mechanically coupled to a driven wheel that is the other of the front wheel and the rear wheel.

  According to the above configuration, since the synchronous motor is connected to the main drive wheel and the induction motor is connected to the slave drive wheel, even if leakage is detected in the induction motor, the synchronous motor is used to detect the main drive wheel. Driving can be continued. In general, since synchronous motors are more efficient than induction motors of the same size, compared to the reverse configuration (configuration in which induction motors are connected to main drive wheels and synchronous motors are connected to slave drive wheels). Thus, the evacuation traveling performance can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, in a vehicle provided with a permanent magnet type synchronous motor and an induction motor, required evacuation travel performance can be ensured.

1 is a block diagram schematically showing an overall configuration of a vehicle according to a first embodiment. It is a circuit diagram showing an example of composition of an electric system of vehicles. It is a circuit diagram which shows an example of a structure of an earth-leakage detector in detail. It is a schematic diagram for demonstrating an example of the division | segmentation of the area | region of an electric system. It is a figure for demonstrating the electric current path | route when the electric leakage of a 1st motor generator generate | occur | produces. 4 is a flowchart for explaining processing based on a measurement result of ground insulation resistance in the first embodiment. 10 is a flowchart for explaining processing based on a measurement result of ground insulation resistance in the second embodiment.

  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.

  In the embodiment described below, a hybrid vehicle will be described as one exemplary form of vehicle. However, the vehicle to which the present invention can be applied is not limited to this as long as a traveling motor is mounted, and may be an electric vehicle or a fuel cell vehicle.

[Embodiment 1]
<Overall configuration of vehicle>
FIG. 1 is a block diagram schematically showing the overall configuration of the vehicle according to the first embodiment. Referring to FIG. 1, vehicle 1 includes an engine 100, a first motor generator (hereinafter also referred to as first MG) 10, a second motor generator (hereinafter also referred to as second MG) 20, and a power split mechanism. 30, a drive shaft 40, a speed reducer 50, a PCU (Power Control Unit) 200, a battery 250, an ECU (Electronic Control Unit) 300, a front wheel 350F, and a rear wheel 350R.

  The engine 100 is an internal combustion engine such as a gasoline engine or a diesel engine. Engine 100 outputs a driving force for vehicle 1 to travel based on control signal DRV from ECU 300.

  Each of first MG 10 and second MG 20 is a three-phase AC permanent magnet type synchronous motor, and more specifically has a structure in which a permanent magnet is embedded in a rotor (both not shown). However, the configuration of first MG 10 and second MG 20 is not limited to this as long as the rotor has a permanent magnet. For example, the permanent magnet may be incorporated on the rotor surface. In the following description, the first MG 10 and the second MG 20 may be collectively referred to as “synchronous motors”.

  First MG 10 is coupled to a crankshaft (not shown) of engine 100 through power split mechanism 30. First MG 10 rotates the crankshaft of engine 100 using the electric power of battery 250 when engine 100 is started. First MG 10 can also generate power using the power of engine 100. The AC power generated by the first MG 10 is converted into DC power by the PCU 200 and charged in the battery 250. Further, the AC power generated by the first MG 10 may be supplied to the second MG 20.

  Second MG 20 rotates drive shaft 40 using at least one of the electric power from battery 250 and the electric power generated by first MG 10. The second MG 20 can also generate power by regenerative braking. The AC power generated by the second MG 20 is converted into DC power by the PCU 200 and charged in the battery 250.

  Power split device 30 is configured to include, for example, a planetary gear mechanism, and is a power transmission device that mechanically connects the three elements of the crankshaft of engine 100, the rotation shaft of first MG 10, and drive shaft 40. The power split mechanism 30 can transmit power between the other two elements by using any one of the three elements as a reaction force element.

  Reducer 50 transmits power from power split mechanism 30 and / or second MG 20 to front wheel 350F. Further, the reaction force from the road surface received by the front wheel 350F is transmitted to the second MG 20 via the speed reducer 50. As a result, the second MG 20 generates power during regenerative braking.

  PCU 200 includes a converter 240 and inverters 210 and 220 (see FIG. 2), boosts the DC power stored in battery 250, converts the boosted voltage to an AC voltage, and supplies the AC voltage to the synchronous motor. In addition, the PCU 200 converts AC power generated by the synchronous motor into DC power and supplies it to the battery 250.

  The battery 250 is a power storage device configured to be rechargeable. As the battery 250, for example, a secondary battery such as a nickel metal hydride battery or a lithium ion battery, or a capacitor such as an electric double layer capacitor can be employed.

  The vehicle 1 is configured as a four-wheel drive system, and further includes an inverter 230, a rear motor generator (hereinafter also referred to as a rear MG) 260 for driving the rear wheels 350R, and a rear differential gear 270.

  Inverter 230 converts the DC voltage stored in battery 250 into an AC voltage and supplies it to rear MG 260. Rear MG 260 is mechanically coupled to the drive shaft of rear wheel 350R via rear differential gear 270, and drives rear wheel 350R using electric power supplied from inverter 230. In the present embodiment, since an induction motor is employed for rear MG 260, hereinafter, rear MG 260 may be referred to as an “induction motor”.

  The vehicle 1 further includes an electric leakage detector (detection unit) 400 for detecting electric leakage in the electric system of the vehicle 1. Electric leakage detector 400 detects electric leakage of first MG 10, second MG 20, rear MG 260, etc., and outputs the detection result to ECU 300. The configuration of the leakage detector 400 and its detection method will be described later.

  ECU 300 includes a CPU (Central Processing Unit), a memory, and a buffer (all not shown). The ECU 300 controls the devices so that the vehicle 1 is in a desired state based on signals sent from the sensors and a map and a program stored in the memory.

<Electric system configuration>
FIG. 2 is a circuit diagram showing an example of the configuration of the electric system of the vehicle 1. Referring to FIG. 2, the electric system of vehicle 1 further includes an SMR (System Main Relay) in addition to the components described in FIG. PCU 200 includes a smoothing capacitor C1, a converter 240, a smoothing capacitor C2, a discharge resistor R1, and inverters 210 and 220.

  Relays included in SMR 280 are electrically connected between positive electrode of battery 250 and power line PL1, and between negative electrode of battery 250 and power line NL1, respectively. SMR 280 switches between power supply and interruption between battery 250 and PCU 200 based on control signal SE from ECU 300.

  Smoothing capacitor C1 is electrically connected between power line PL1 and power line NL1. Smoothing capacitor C1 smoothes the AC component of the voltage fluctuation between power line PL1 and power line NL1.

  Converter 240 boosts the DC voltage supplied from battery 250 based on control signal PWC from ECU 300, and supplies the boosted voltage to inverters 210 and 220. More specifically, converter 240 includes transistors Q1 and Q2, antiparallel diodes D1 and D2 connected in antiparallel to transistors Q1 and Q2, and a reactor L, respectively. Transistor Q1 and antiparallel diode D1 constitute the upper arm of converter 240, and transistor Q2 and antiparallel diode D2 constitute the lower arm of converter 240. Reactor L has one end connected to power line PL1, and the other end connected to a connection node between the emitter of transistor Q1 and the collector of transistor Q2.

  The collector of transistor Q1 is electrically connected to power line PL2. The emitter of transistor Q2 is electrically connected to power line NL1. Smoothing capacitor C2 and discharge resistor R1 are connected in parallel between power line PL2 and power line NL1. Smoothing capacitor C2 smoothes the AC component of the voltage fluctuation between power line PL2 and power line NL1. The discharge resistor R1 is provided to discharge the residual charges of the smoothing capacitors C1 and C2.

  Inverter 210 converts the DC voltage boosted by converter 240 into a three-phase AC voltage based on control signal PWI1 from ECU 300, and supplies the three-phase AC voltage to first MG 10. More specifically, inverter 210 includes transistors Q13 to Q18 and antiparallel diodes D13 to D18. Transistor Q13 and antiparallel diode D13 form a U-phase upper arm, and transistor Q14 and antiparallel diode D14 form a U-phase lower arm. Transistor Q15 and antiparallel diode D15 constitute a V-phase upper arm, and transistor Q16 and antiparallel diode D16 constitute a V-phase lower arm. Transistor Q17 and antiparallel diode D17 constitute a W-phase upper arm, and transistor Q18 and antiparallel diode D18 constitute a W-phase lower arm.

  Inverter 220 converts the DC voltage boosted by converter 240 into a three-phase AC voltage based on control signal PWI2 from ECU 300, and supplies the three-phase AC voltage to second MG 20.

  Inverter 230 is electrically connected to battery 250 without going through converter 240. Inverter 230 converts the DC voltage from battery 250 into a three-phase AC voltage based on control signal PWIR from ECU 300, and supplies the three-phase AC voltage to rear MG 260. Note that the configurations of inverters 220 and 230 are all the same as the configuration of inverter 210, and thus detailed description will not be repeated.

  Leakage detector 400 is electrically connected between the negative electrode of battery 250 and vehicle ground GND. For example, a vehicle frame or a vehicle body is used as the vehicle ground GND.

<Electrical leakage detection>
FIG. 3 is a circuit diagram showing in detail an example of the configuration of leakage detector 400. Referring to FIGS. 2 and 3, leakage detector 400 includes an AC signal generator 402, a voltage sensor 404, a resistor R, and a capacitor C.

  AC signal generator 402 is electrically connected between resistor R and vehicle ground GND. One end of the resistor R is electrically connected to the AC signal generator 402, and the other end of the resistor R is electrically connected to one end of the capacitor C. The other end of capacitor C is electrically connected to power line NL1. For convenience of explanation, the entire circuit connected to the leakage detector 400 in FIG. 2 is shown as an electrical system 2 in FIG.

  The AC signal generator 402 outputs an AC signal having a low voltage (for example, several V) and a low frequency (for example, several Hz). When the ground insulation resistance of the power line NL1 (resistance between the power line NL1 and the vehicle ground GND) decreases due to electric leakage of the electric system 2, the peak value (amplitude) of the AC signal decreases. Therefore, voltage sensor 404 detects the peak value Vk of the AC signal between resistor R and power line NL1, and outputs the detection result to ECU 300. When the peak value Vk from the voltage sensor 404 is less than a predetermined value, the ECU 300 determines that a leakage has occurred in the electric system 2 assuming that the ground insulation resistance of the power line NL1 is less than the predetermined value.

  The electrical system 2 is virtually divided into a plurality of regions, and when a leakage of the electrical system 2 is detected, a leakage point is specified by determining whether or not a leakage has occurred in each region. . Then, by suppressing (for example, prohibiting) driving of the circuit included in the area identified as the location of the electric leakage, the vehicle 1 can be retreated.

  FIG. 4 is a schematic diagram for explaining an example of division of a region of the electric system. Referring to FIG. 4, the electric system of vehicle 1 is divided into, for example, five regions A1 to A5.

  Regions A1, A2, and A3 are regions including first MG10, second MG20, and rear MG260, respectively. Region A4 is a region including battery 250 and leakage detector 400. Region A5 is a region including inverters 210, 220, 230 and converter 240. SMR 280 is located on the boundary between region A4 and region A5. Hereinafter, an example of a method for specifying which region is a leakage point will be described.

  In the process for specifying whether or not region A1 is a leakage point, ECU 300 shuts off inverter 210 when SMR 280 is closed and converter 240 is driven. As a result, if leakage is no longer detected, ECU 300 identifies region A1 as the leakage point.

  The process for specifying whether or not the region A2 is a leakage point and the process for specifying whether or not the region A3 is a leakage point are equivalent to the process for the region A1 described above. That is, if the leakage is not detected due to the interruption of the inverter 220, the region A2 is specified as the leakage point. Similarly, if leakage is no longer detected due to interruption of inverter 230, region A3 is identified as a leakage point.

  In the process for specifying whether or not the region A4 is a leakage point, if leakage is detected even if the SMR 280 is opened, the ECU 300 specifies the region A4 as a leakage point.

  In the process for specifying whether or not the region A5 is a leakage point, if any of the regions A1 to A3 is not a leakage point and the leakage is not detected by opening the SMR 280, the ECU 300 determines that the region A5 is a leakage point. Identify. In other words, the region A5 is specified as the leakage point when none of the regions A1 to A4 is the leakage point.

  In addition, about the specific process of area | region A1, A2, since it is necessary for the back electromotive force not to generate | occur | produce in a synchronous motor, it is an executable condition that the vehicle is in the state which does not move. In addition, regarding the identification processing of the areas A4 and A5, when the SMR 280 is opened, the vehicle system stops. Accordingly, for example, when an ignition switch (not shown) is turned off by a user, for example, the region A1 to A3 are specified in the period from when the ignition switch is turned off until the SMR 280 is released. When it is released, the specific processing of the areas A4 and A5 can be executed.

<Generation of counter electromotive force>
When the vehicle 1 having the above-described configuration travels, the reaction force from the road surface received by the front wheels 350F is transmitted to the second MG 20 via the speed reducer 50. At this time, in the second MG 20 that is a synchronous motor, a counter electromotive force can be generated by rotating a rotor (not shown) of a permanent magnet. Further, the rotational speed of engine 100 (engine rotational speed) Ne, the rotational speed of first MG 10 (first MG rotational speed) Nm1, and the rotational speed of second MG 20 (second MG rotational speed) Nm2 are aligned (not shown). ), The first MG rotation speed Nm1 can change with changes in the engine rotation speed Ne and the second MG rotation speed Nm2. As a result, a back electromotive force is generated in the first MG 10 that is a synchronous motor, and current can flow.

  FIG. 5 is a diagram for explaining a current path when a leakage of the first MG 10 occurs. Referring to FIGS. 2 and 5, when leakage in first MG 10 is detected by leakage detector 400 (when leakage in area A1 is detected), ECU 300 instructs transistors Q13 to Q18 of inverter 210 to be turned off. The control signal PWI1 to be output is output (hereinafter, outputting a signal instructing shut-off to each transistor constituting the inverter is also simply referred to as shutting off the inverter). Thereby, it is possible to prevent a current (indicated by arrow ARR1) supplied from battery 250 via power line PL2 from flowing to the leakage point.

  However, even if the inverter 210 is cut off, a current (indicated by an arrow ARR2) due to the back electromotive force is generated in the first MG 10. Even if the transistors Q13 to Q18 are cut off, there is a current path through the antiparallel diodes D13 to D18, so that the current due to the counter electromotive force leaks from the leakage point.

  As described above, when the leakage of the synchronous motor is detected, it is necessary to limit the vehicle speed so that excessive counter electromotive force is not generated in the synchronous motor. Therefore, the output is suppressed even for the induction motor in which no leakage occurs. The As a result, the evacuation traveling performance may be greatly reduced.

  On the other hand, no permanent magnet is used for the rotor of the induction motor. In principle, if the inverter for the induction motor is cut off, no back electromotive force is generated in the induction motor, so there is no influence on the synchronous motor. . Therefore, according to the present embodiment, when leakage of rear MG 260 that is an induction motor is detected (when leakage of area A3 shown in FIG. 4 is detected), drive of inverter 230 that is an induction motor inverter is driven. Ban. On the other hand, for the first MG 10 and the second MG 20 that are synchronous motors, output suppression in response to detection of leakage of the induction motor is not performed.

  When leakage of the induction motor is detected, the current from the battery 250 to the induction motor via the inverter 230 can be cut off by turning off the inverter 230. On the other hand, for synchronous motors that do not cause leakage, the required evacuation travel is performed by limiting the number of motors subject to output suppression to the minimum required induction motor without suppressing output in response to detection of leakage from the induction motor. Performance can be ensured.

  FIG. 6 is a flowchart for explaining a process based on the measurement result of the ground insulation resistance in the first embodiment. The flowchart shown in FIG. 6 and FIG. 7 described later is called from the main routine and executed when a predetermined condition is satisfied or every predetermined period. Each step of the flowchart is basically realized by software processing by the ECU 300, but may be realized by hardware (electronic circuit) manufactured in the ECU 300.

  2, 4, and 6, in step (hereinafter abbreviated as “S”) 10, ECU 300 uses earth leakage detector 400 to determine the ground insulation resistance of the entire electric system (the entire region A <b> 1 to A <b> 5). taking measurement. In S20, ECU 300 determines whether or not the ground insulation resistance has decreased to be less than a predetermined value, that is, whether or not a leakage has occurred.

  If no leakage has occurred in any region of the electrical system (NO in S20), ECU 300 returns the process to the main routine. On the other hand, if a leak has occurred in any region of the electrical system (YES in S20), ECU 300 advances the process to S30, and specifies which region of regions A1 to A5 is the leak point. .

  When the leakage location is identified as area A3 by the above-described method, that is, when the leakage location is identified as the induction motor (YES in S40), ECU 300 proceeds to S50 and controls inverter 230 that is the induction motor inverter. Prohibit driving. On the other hand, the ECU 300 does not suppress the output in response to the detection of the leakage of the induction motor for the synchronous motor in which the leakage has not occurred. That is, ECU 300 drives inverters 210 and 220 that are inverters for a synchronous motor so that a driving force equivalent to (or more than) a case where no leakage of the induction motor has occurred is output from the synchronous motor.

  On the other hand, when the leak location is specified as one of areas A1, A2, A4, and A5, that is, when the leak location is specified as not being an induction motor (NO in S40), ECU 300 proceeds to S60 and executes area A1. , A2, A4, and A5, the outputs of the synchronous motor and the induction motor are suppressed as compared with the case where no leakage is detected. Examples of output suppression include (1) prohibiting output, (2) reducing the output size compared to when no leakage is detected, and (3) equivalent to when no leakage is detected. Alternatively, a period during which more output is possible is limited to less than a predetermined time (for example, several hours). For example, it is possible to output the same (or more) as when no leakage has been detected. When the process of S50 or S60 ends, ECU 300 returns the process to the main routine.

  In this way, no permanent magnet is used in the rotor of the induction motor, and no counter electromotive force is generated in the induction motor, so the synchronous motor is not affected. Therefore, according to the first embodiment, for a synchronous motor in which no leakage occurs, output suppression in response to detection of leakage of the induction motor is not performed, and the motor targeted for output suppression is limited to the minimum necessary induction motor. By doing so, the required evacuation traveling performance can be ensured.

  Further, according to the first embodiment, the synchronous motor is mechanically connected to the drive system of the front wheel 350F that is the main drive wheel, and the induction motor is mechanically connected to the drive system of the rear wheel 350R that is the slave drive wheel. The Thereby, even if it is a case where the electric leakage of an induction motor is detected, the drive of a main drive wheel can be continued using a synchronous motor. Furthermore, since a synchronous motor is generally more efficient than an induction motor of the same size, compared to the reverse configuration (a configuration in which an induction motor is connected to a main drive wheel and a synchronous motor is connected to a slave drive wheel) The evacuation traveling performance can be improved.

  However, the configuration of the vehicle is not limited to this, and for example, in addition to rear MG10, one of first MG10 and second MG20 may be an induction motor. For example, in the configuration where the second MG 20 is an induction motor, if the drive of the inverter 220 is prohibited when the leakage of the second MG 20 is detected, the evacuation traveling performance may be significantly reduced. Therefore, when leakage of the second MG 20 is detected, it is preferable not to completely inhibit driving while limiting the time or number of times that the inverter 220 can be driven as compared to the case where leakage is not detected.

[Embodiment 2]
In the state where the drive of the induction motor inverter is prohibited due to the leakage detection of the induction motor, the leakage of the induction motor may be detected again. As a cause of such a situation, for example, when the drive prohibition of the inverter is not properly performed, or when an abnormality occurs in the leakage detector. In the second embodiment, a configuration when a leakage of the induction motor is detected again will be described.

  In the vehicle according to the second embodiment, ECU 300 uses a leakage flag (not shown) to manage whether or not leakage of rear MG 260, which is an induction motor, is detected. More specifically, the leakage flag is off in the initial state, and when leakage of the induction motor is detected, ECU 300 switches on the leakage flag. However, the configuration for managing the leakage history of the induction motor is not limited to this. For example, ECU 300 may include a counter that counts the cumulative value of the number of leakages of the induction motor. Since the other configuration of the vehicle according to the second embodiment is the same as the configuration of vehicle 1 shown in FIG. 1, detailed description will not be repeated.

FIG. 7 is a flowchart for explaining processing based on the measurement result of the ground insulation resistance in the second embodiment. The flowchart shown in FIG. 7 differs from the flowchart (see FIG. 6) of the first embodiment in that it further includes the processes of S25, S65 , and S70. Since processes other than S25, S65 , and S70 are the same as the corresponding processes in the flowchart of the first embodiment, detailed description will not be repeated.

  In an initial state where the leakage of the induction motor is not detected (for example, the state when the vehicle 1 is shipped), the leakage flag is off.

  In S25, ECU 300 determines whether or not the leakage flag is on. When the leakage flag is off, that is, when leakage is detected for the first time with no leakage history of the induction motor (NO in S25), ECU 300 advances the process to S30 and identifies the leakage point.

When the leakage point is identified as the induction motor in S40, the ECU 300 advances the process to S50 and shuts off the inverter 230 that is the induction motor inverter. In S65 , ECU 300 turns on the leakage flag. Thereafter, ECU 300 returns the process to the main routine.

  If the leakage flag is on in S25, that is, if there is a leakage history of the induction motor (YES in S25), the ECU 300 advances the process to S70, compared to the case where the leakage of the induction motor is not detected. Suppresses the output of. In other words, in the case of detecting leakage after the second time, ECU 300 suppresses the output of the synchronous motor regardless of the leakage point. When the process of S70 ends, ECU 300 returns the process to the main routine.

  Here, the reason for suppressing the output of the synchronous motor without specifying the location of the leakage in the case of the second or later leakage detection will be described.

  First, as described above, when leakage occurs at two locations, a current path including the two leakage locations and the battery is formed, and an excessive current may flow. In order to avoid such a situation, when the leakage at the second location is detected, it is desirable to shut off all inverters and suppress the outputs of both motors.

  Second, it is desirable to suppress the output of the synchronous motor when the leakage current is further detected when leakage is further detected in the state where the interruption control of the inverter 230 is performed by detecting leakage of the induction motor. It is. That is, if the leakage point is a synchronous motor, it is necessary to suppress the output of the synchronous motor. On the other hand, if the leakage point is an induction motor, there is a possibility that the inverter 230 is not properly cut off (for example, the gate may not be cut off properly due to a failure of the transistors Q23 to Q28 in the inverter 230). Therefore, it is necessary to suppress the output of the synchronous motor from the viewpoint of fail-safe. Alternatively, there is a possibility that an abnormality has occurred in the leakage detector 400 and the leakage could not be detected accurately. In this case as well, it is desirable to suppress the output of the synchronous motor.

  As described above, according to the second embodiment, when the leakage of the induction motor is detected and the leakage is further detected in the state where the driving of the inverter for the induction motor is prohibited, the leakage point is either the synchronous motor or the induction motor. However, since the output of the synchronous motor is suppressed, it is possible to prevent an excessive current from flowing due to electric leakage.

  Note that it is preferable to store information on ON / OFF of the leakage flag in a nonvolatile memory (not shown) such as an EEPROM (Electrically Erasable Programmable Read-Only Memory). Thereby, in the state where the leakage flag is on, for example, the diagnosis (history data of self-diagnosis) of the vehicle 1 is reset at the next travel, or the power supply to the ECU 300 is cut off by replacing the auxiliary battery (not shown). Even if it is done, it can be avoided that the leakage flag is turned off and the interruption of the inverter 230 is released.

  Moreover, it is preferable that the switching of the leakage flag from on to off cannot be performed by a user operation. This can be realized by requiring a specific device (service tool) installed in, for example, a dealer or a repair shop to switch the electric leakage flag.

  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 1 Vehicle, 10 1st motor generator, 20 2nd motor generator, 30 Power split mechanism, 40 Drive shaft, 50 Reducer, 100 Engine, 200 PCU, 210, 220, 230 Inverter, 240 Boost converter, 250 Battery, 260 Rear Motor generator, 270 rear differential gear, 300 ECU, 350F front wheel, 350R rear wheel, 400 leakage detector, 402 AC signal generator, 404 voltage sensor, Q1, Q2, Q13 to Q18, Q23 to Q28, Q33 to Q38 transistor, D1, D2, D13 to D18, D23 to D28, D33 to D38 Antiparallel diode, R resistor, R1 discharge resistor, C capacitor, C1, C2 smoothing capacitor, L reactor.

Claims (5)

A power storage device;
First and second inverters for converting electric power stored in the power storage device into AC power;
A permanent magnet synchronous motor driven by the first inverter;
An induction motor driven by the second inverter;
A detection unit for detecting leakage of the permanent magnet type synchronous motor and the induction motor;
A control device for controlling the first and second inverters,
The controller is
When leakage of the induction motor is detected, the second inverter is prohibited from driving, while the permanent magnet synchronous motor is not subjected to output suppression in response to detection of leakage of the induction motor ,
A vehicle that suppresses the outputs of the permanent magnet type synchronous motor and the induction motor when leakage of the permanent magnet type synchronous motor is detected, compared to a case where no leakage of the permanent magnet type synchronous motor is detected . When the leakage of the permanent magnet type synchronous motor or the induction motor is further detected in the prohibited state in which the driving of the second inverter is prohibited in response to the detection of the leakage of the induction motor, wherein compared to inhibition state, suppress the output of the permanent magnet synchronous motor, the vehicle according to claim 1. The vehicle according to claim 2, wherein the control device includes a nonvolatile memory for managing a leakage history of the induction motor. The permanent magnet type synchronous motor is mechanically coupled to a main drive wheel which is one of a front wheel and a rear wheel of the vehicle,
The vehicle according to any one of claims 1 to 3, wherein the induction motor is mechanically coupled to a driven wheel that is the other of the front wheel and the rear wheel. A vehicle control method comprising:
The vehicle is
A power storage device;
First and second inverters for converting electric power stored in the power storage device into AC power;
A permanent magnet synchronous motor driven by the first inverter;
An induction motor driven by the second inverter;
A detection unit for detecting leakage of the permanent magnet type synchronous motor and the induction motor,
The control method is:
Detecting leakage of the induction motor;
When leakage of the induction motor is detected, the drive of the second inverter is prohibited, while the permanent magnet type synchronous motor does not suppress output in response to detection of leakage of the induction motor ;
The step of suppressing the outputs of the permanent magnet type synchronous motor and the induction motor when the leakage of the permanent magnet type synchronous motor is detected as compared to the case where the leakage of the permanent magnet type synchronous motor is not detected. A vehicle control method.

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