JP2012136064A - Hybrid vehicle and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle including an engine and motors connected to the engine via a power division mechanism, preventing drive power from being changed due to a reaction force at engine start when a motor fails, to enable a limp home mode using the engine.SOLUTION: When a second motor fails, the second motor is stopped to execute a limp home mode using an engine and a first motor. A control device rotates the engine by power from the first motor via the power division mechanism to start the engine when a failure of the second motor is detected. The controller turns on/off a switching element of an inverter connected to the second motor, according to a predetermined switching pattern to generate drag torque on the basis of an electromagnetic action from the stopped second motor, thereby canceling the reaction power generated in an output member at engine start.

Description

  The present invention relates to a hybrid vehicle and a control method thereof, and more particularly to a hybrid vehicle including an internal combustion engine (engine) and an electric motor (motor) connected to the engine via a power split mechanism and a control method thereof.

  As this type of hybrid vehicle, for example, Japanese Patent Laid-Open No. 2009-280036 (Patent Document 1) discloses an engine that outputs power to a drive shaft via a power split mechanism, and power generation that is connected to the power split mechanism. A hybrid vehicle is disclosed that includes a first motor, a second motor connected to a drive shaft, a generator inverter circuit that drives the first motor, and a motor inverter circuit that drives the second motor. In such a hybrid vehicle, the engine is started by rotationally driving the engine via the power split mechanism by the first motor. This eliminates the need for a starter dedicated to starting, so the number of components is reduced and the drive device mounted on the hybrid vehicle can be downsized.

  In the hybrid vehicle described in Patent Document 1, when the engine is started when some of the switching elements of the inverter circuit for the motor are off-failed, the engine is cranked by the first motor. The inverter circuit for the motor is controlled so that the second motor outputs torque (reaction force canceling torque) that cancels the reaction force acting on the drive shaft by cranking the engine by the first motor. At this time, the inverter circuit for the motor is controlled so that the second motor outputs the reaction force canceling torque within a normal electrical angle range that is a range of electrical angles in which the second motor can be normally driven. As a result, the engine can be started even when an off failure occurs in the inverter circuit for the motor.

JP 2009-280036 A JP 2008-105475 A JP 2009-195026 A

  However, in the vehicle described in Patent Document 1, when the second motor that generates the reaction force canceling torque cannot be operated normally due to a failure, the reaction force canceling torque is controlled from the second motor by the control of the inverter circuit for the motor. Cannot be generated. For this reason, the reaction force accompanying the engine start by the first motor causes a driving force fluctuation that causes driving disturbance in the vehicle, which may impair driving performance.

  In particular, when the vehicle speed is in the low vehicle speed region, the reaction force cannot be offset because the inertial force that pushes the vehicle forward is small, and the vehicle may move backward. Therefore, there has been a problem that the engine cannot be started and the retreat travel using the engine and the first motor cannot be performed.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a hybrid vehicle including an engine and a motor connected to the engine via a power split mechanism when a motor abnormality occurs. It is possible to execute retreat travel using the engine by suppressing fluctuations in driving force due to reaction force accompanying engine start.

  In one aspect of the present invention, the hybrid vehicle includes an engine that operates by fuel combustion, a first electric motor, an output member that outputs power, an output member, an output shaft of the engine, and an output of the first electric motor. A plurality of rotating elements respectively coupled to the shaft are coupled so as to be relatively rotatable with each other, and at least a part of the output from the engine is output to the output member with input and output of electric power and power by the first electric motor. A power split mechanism, a second electric motor that applies power between the output member and the drive wheel, an inverter connected to the second electric motor and configured by a plurality of switching elements, and first and second electric motors, And a control device for controlling the operation of the engine. The control device includes an abnormality detection means for detecting an abnormality of the second electric motor, and stops an operation of the second electric motor when an abnormality of the second electric motor is detected, and the engine and the first electric motor And an abnormal control means for executing an abnormal operation using the. The abnormality control means includes a starting means for starting the engine by rotating the engine through the power split mechanism by the power from the first electric motor when an abnormality of the second electric motor is detected; By causing a plurality of switching elements to be turned on and off in accordance with a predetermined switching pattern, a drag torque based on electromagnetic action is generated from the second electric motor that is not operating, resulting in the start of the engine by the starting means Reaction force canceling means for canceling the reaction force generated in the output member.

  Preferably, the second electric motor is a multiphase motor, and the inverter is connected in parallel between the power supply line and the ground line, and controls the current flowing through the multiphase coil of the multiphase motor. Includes arms. Each of the multiphase arms includes first and second switching elements connected in series between a positive bus and a negative bus via a connection point with each phase coil. The reaction force canceling means generates a drag torque from the second electric motor by executing multiphase on control for simultaneously controlling one of the first and second switching elements to the on state through the multiphase arm.

  Preferably, the reaction force canceling unit sets the rotation speed of the second electric motor when the drag torque is maximized to a determination value for determining whether or not the multi-phase on control can be executed, and the second electric motor When the rotation speed of the second electric motor becomes equal to or lower than the determination value during the operation stop, the multiphase ON control is executed.

  Preferably, the starter controls the operation of the first electric motor so that the reaction force generated in the output member due to the start of the engine does not exceed the maximum value of the drag torque.

  Preferably, the start means stops the engine start when the rotational speed of the second electric motor exceeds the determination value by the time the engine start is completed.

  Preferably, the starter stops the start of the engine when the duration of the engine start process exceeds a predetermined time.

  In another aspect of the present invention, there is provided a method for controlling a hybrid vehicle, wherein the hybrid vehicle includes an engine that operates by fuel combustion, a first electric motor, an output member for outputting power, an output member, and an engine. A plurality of rotating elements respectively coupled to the output shaft of the first motor and the output shaft of the first electric motor are coupled so as to be relatively rotatable with each other, and output from the engine is accompanied by input / output of electric power and power by the first electric motor. A power split mechanism that outputs at least a portion of the power to the output member, and a second electric motor that applies power between the output member and the drive wheels. The control method includes a step of detecting an abnormality of the second electric motor, and an abnormality using the engine and the first electric motor while stopping the operation of the second electric motor when an abnormality of the second electric motor is detected. And a step for executing hourly driving. The step of executing the abnormal operation includes a step of starting the engine by rotating the engine via the power split mechanism by the first motor when an abnormality of the second motor is detected, Generating a drag torque according to the number of rotations of the motor in the output member, thereby canceling a reaction force generated in the output member due to the start of the engine by the starting means.

  According to the present invention, in a hybrid vehicle including an engine and a motor connected to the engine via a power split mechanism, fluctuations in driving force due to reaction force accompanying engine start-up are suppressed when a motor abnormality occurs. The evacuation traveling using the engine can be executed.

1 is a schematic configuration diagram of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining details of a power train in the hybrid vehicle of FIG. 1. It is a schematic block diagram which shows the control structure of motor generator MG1, MG2. It is a collinear diagram explaining the rotational speed behavior during normal traveling. FIG. 10 is a collinear diagram illustrating a rotational speed behavior when an abnormality occurs in motor generator MG2. It is a figure explaining control of the inverter for generating drag torque. It is a figure which shows the relationship between the electric current (three-phase electric current) and torque of motor generator MG2 at the time of execution of three-phase ON control, and rotation speed. It is a block diagram which shows the control structure in ECU according to this Embodiment. It is a timing chart explaining engine start control at the time of abnormality occurrence of motor generator MG2 according to the present embodiment. Fig. 11 is a flowchart illustrating retreat travel when abnormality occurs in motor generator MG2 according to the embodiment of the present invention. Fig. 11 is a flowchart for explaining retreat travel when an abnormality occurs in motor generator MG2 according to a modification of the embodiment of the present invention.

  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.

(Configuration of hybrid vehicle)
FIG. 1 is a schematic configuration diagram of a hybrid vehicle 5 according to an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 5 includes an engine ENG, motor generators MG1 and MG2, a battery 10, a power conversion unit (PCU: Power Control Unit) 20, a power split mechanism PSD, a reduction gear RD, Front wheels 70L and 70R, rear wheels 80L and 80R, and an electronic control unit (ECU) 30 are provided. The control device according to the present embodiment is realized, for example, by a program executed by ECU 30. 1 illustrates the hybrid vehicle 5 using the front wheels 70L and 70R as drive wheels, the rear wheels 80L and 80R may be used as drive wheels instead of the front wheels 70L and 70R. Alternatively, in addition to the configuration shown in FIG. 1, a motor generator for driving the rear wheels 80L and 80R may be further provided to provide a 4WD configuration.

  The driving force generated by the engine ENG is divided into two paths by the power split mechanism PSD. One is a path for driving the front wheels 70L and 70R via the reduction gear RD. The other is a path for generating electric power by driving the motor generator MG1.

  Motor generator MG1 is typically constituted by a three-phase AC synchronous motor generator. Motor generator MG1 generates electricity as a generator by the driving force of engine ENG divided by power split mechanism PSD. Motor generator MG1 has not only a function as a generator but also a function as an actuator for controlling the rotational speed of engine ENG.

  The electric power generated by motor generator MG1 is selectively used according to the driving state of the vehicle and the state of charge (SOC) of battery 10. For example, during normal running or sudden acceleration, the electric power generated by motor generator MG1 is used as power for driving motor generator MG2 as a motor. On the other hand, when the SOC of battery 10 is lower than a predetermined value, the power generated by motor generator MG1 is converted from AC power to DC power by power conversion unit 20 and stored in battery 10.

  The motor generator MG1 is also used as a starter when starting the engine ENG. When starting engine ENG, motor generator MG1 is supplied with electric power from battery 10 and is driven as an electric motor. Then, motor generator MG1 cranks engine ENG and starts it.

  Motor generator MG2 is typically constituted by a three-phase AC synchronous motor generator. When motor generator MG2 is driven as an electric motor, it is driven by at least one of electric power stored in battery 10 and electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to front wheels 70L and 70R via reduction gear RD. Thus, motor generator MG2 assists engine ENG to travel the vehicle or causes the vehicle to travel only by the driving force of motor generator MG2.

  During regenerative braking of the vehicle, the motor generator MG2 is driven by the front wheels 70L and 70R via the reduction gear RD, and the motor generator MG2 is operated as a generator. Thus, motor generator MG2 acts as a regenerative brake that converts braking energy into electric energy. The electric power generated by motor generator MG2 is stored in battery 10 via power conversion unit 20.

  The battery 10 is constituted by a secondary battery such as nickel hydride or lithium ion, for example. In the embodiment of the present invention, battery 10 is shown as a representative example of “power storage device”. That is, another power storage device such as an electric double layer capacitor can be used in place of the battery 10. The battery 10 supplies a DC voltage to the power conversion unit 20 and is charged by the DC voltage from the power conversion unit 20.

  The power conversion unit 20 performs bidirectional power conversion between DC power supplied by the battery 10, AC power for driving and controlling the motor, and AC power generated by the generator.

  The hybrid vehicle 5 further includes a handle 40, an accelerator position sensor 44 that detects the accelerator pedal position AP, a brake pedal position sensor 46 that detects the brake pedal position BP, and a shift position sensor 48 that detects the shift position SP. Prepare.

  Motor generators MG1 and MG2 are further provided with rotation angle sensors 51 and 52 for detecting the rotor rotation angle. Rotor rotation angle θ1 of motor generator MG1 detected by rotation angle sensor 51 and rotor rotation angle θ2 of motor generator MG2 detected by rotation angle sensor 52 are transmitted to ECU 30. The rotation angle sensors 51 and 52 estimate the rotor rotation angle θ1 from the current, voltage and the like of the motor generator MG1 in the ECU 30, and estimate the rotor rotation angle θ2 from the current, voltage and the like of the motor generator MG2. The arrangement may be omitted.

  ECU 30 is electrically connected to engine ENG, power conversion unit 20 and battery 10. Based on detection signals from various sensors, ECU 30 determines the engine ENG operation state, motor generator MG1 and MG2 drive states, and battery 10 charge state so that hybrid vehicle 5 is in a desired travel state. Integrated control.

  FIG. 2 is a schematic diagram for explaining details of the power train in the hybrid vehicle 5 of FIG. 1.

  Referring to FIG. 2, the power train (hybrid system) of hybrid vehicle 5 includes motor generator MG2, reduction gear RD connected to output shaft 160 of motor generator MG2, engine ENG, motor generator MG1, A splitting mechanism PSD.

  In the example shown in FIG. 2, the power split mechanism PSD is constituted by a planetary gear mechanism, and a sun gear 151 coupled to a hollow sun gear shaft penetrating the crankshaft 150 through the center of the shaft is rotatable coaxially with the crankshaft 150. Are supported between the ring gear 152, the sun gear 151 and the ring gear 152. The pinion gear 153 revolves while rotating on the outer periphery of the sun gear 151. The rotation shaft of each pinion gear 153 is coupled to the end of the crankshaft 150. And a planetary carrier 154 for supporting the

  In power split mechanism PSD, three axes of a sun gear shaft coupled to sun gear 151, a ring gear case 155 coupled to ring gear 152, and crankshaft 150 coupled to planetary carrier 154 serve as power input / output shafts. When the power input / output to / from any two of the three axes is determined, the power input / output to the remaining one axis is determined based on the power input / output to the other two axes.

  A counter drive gear 170 for extracting power is provided outside the ring gear case 155 and rotates integrally with the ring gear 152. Counter drive gear 170 is connected to power transmission reduction gear RG. The ring gear case 155 corresponds to the “output member” in the present invention. In this way, power split device PSD operates to output at least a part of the output from engine ENG to the output member with the input and output of electric power and power by motor generator MG1.

  Further, power is transmitted between the counter drive gear 170 and the power transmission reduction gear RG. The power transmission reduction gear RG drives a differential gear DEF coupled to the front wheels 70L and 70R that are drive wheels. On the downhill or the like, the rotation of the driving wheel is transmitted to the differential gear DEF, and the power transmission reduction gear RG is driven by the differential gear DEF.

  Motor generator MG1 includes a stator 131 that forms a rotating magnetic field, and a rotor 132 that is disposed inside stator 131 and has a plurality of permanent magnets embedded therein. Stator 131 includes a stator core 133 and a three-phase coil 134 wound around stator core 133. Rotor 132 is coupled to a sun gear shaft that rotates integrally with sun gear 151 of power split device PSD. The stator core 133 is formed by laminating thin electromagnetic steel plates, and is fixed to a case (not shown).

  Motor generator MG1 operates as an electric motor that rotationally drives rotor 132 by the interaction between the magnetic field generated by the permanent magnet embedded in rotor 132 and the magnetic field formed by three-phase coil 134. Motor generator MG1 also operates as a generator that generates electromotive force at both ends of three-phase coil 134 due to the interaction between the magnetic field generated by the permanent magnet and the rotation of rotor 132.

  Motor generator MG2 includes a stator 136 that forms a rotating magnetic field, and a rotor 137 that is disposed inside stator 136 and has a plurality of permanent magnets embedded therein. Stator 136 includes a stator core 138 and a three-phase coil 139 wound around stator core 138.

  The rotor 137 is coupled to a ring gear case 155 that rotates integrally with the ring gear 152 of the power split mechanism PSD via a reduction gear RD. Stator core 138 is formed, for example, by laminating thin magnetic steel sheets, and is fixed to a case (not shown).

  Motor generator MG2 also operates as a generator that generates an electromotive force at both ends of three-phase coil 139 by the interaction between the magnetic field generated by the permanent magnet and the rotation of rotor 137. Motor generator MG2 operates as an electric motor that rotates rotor 137 by the interaction between the magnetic field generated by the permanent magnet and the magnetic field formed by three-phase coil 139.

  The speed reducer RD performs speed reduction by a structure in which a planetary carrier 166 that is one of rotating elements of a planetary gear is fixed to a case. That is, reduction device RD meshes with sun gear 162 coupled to output shaft 160 of rotor 137, ring gear 168 that rotates integrally with ring gear 152, ring gear 168 and sun gear 162, and transmits the rotation of sun gear 162 to ring gear 168. Pinion gear 164. For example, by reducing the number of teeth of the ring gear 168 to more than twice the number of teeth of the sun gear 162, the reduction ratio can be increased more than twice.

  Thus, the rotational force of motor generator MG2 is transmitted to output member (ring gear case) 155 that rotates integrally with ring gears 152 and 168 via reduction gear RD. That is, motor generator MG2 is configured to apply power between output member 155 and the drive wheel. Note that the arrangement of the reduction gear RD may be omitted, that is, the output shaft 160 of the motor generator MG2 and the output member 155 may be connected without providing a reduction ratio.

  Power conversion unit 20 includes a converter 12 and inverters 14 and 22. Converter 12 converts DC voltage Vb from battery 10 and outputs DC voltage VH between power supply line PL and ground line GL. Converter 12 is configured to be capable of voltage conversion in both directions, and converts DC voltage VH between power supply line PL and ground line GL into charging voltage Vb of battery 10.

  Inverters 14 and 22 are constituted by general three-phase inverters, convert DC voltage VH between power supply line PL and ground line GL into an AC voltage, and output the AC voltage to motor generators MG2 and MG1, respectively. Inverters 14 and 22 convert the AC voltage generated by motor generators MG2 and MG1 into DC voltage VH and output the voltage between power supply line PL and ground line GL.

FIG. 3 is a schematic block diagram showing a control configuration of motor generators MG1 and MG2.
Referring to FIG. 3, power conversion unit 20 includes capacitors C <b> 1 and C <b> 2, converter 12, inverters 14 and 22, and current sensors 24 and 28.

  ECU 30 shown in FIG. 1 and FIG. 2 follows HV-ECU 32 for generating operation commands for motor generators MG1 and MG2 and voltage command value VHref for converter 12, and output voltage VH of converter 12 follows voltage command value VHref. MG-ECU 35 that controls converter 12 and inverters 14 and 22 so that motor generators MG1 and MG2 operate according to the operation command.

  Converter 12 includes a reactor L1, IGBTs (Insulated Gate Bipolar Transistor) elements Q1, Q2, and diodes D1, D2. Reactor L1 has one end connected to the power supply line of battery 10, and the other end connected to an intermediate point between IGBT element Q1 and IGBT element Q2, that is, between the emitter of IGBT element Q1 and the collector of IGBT element Q2. The IGBT elements Q1, Q2 are connected in series between power supply line PL and ground line GL. IGBT element Q1 has a collector connected to power supply line PL, and IGBT element Q2 has an emitter connected to ground line GL. Further, diodes D1 and D2 for flowing current from the emitter to the collector side are connected between the collector and emitter of each of the IGBT elements Q1 and Q2.

  Inverter 14 includes U-phase arm 15, V-phase arm 16, and W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are provided in parallel between power supply line PL and ground line GL. U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series, V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series, and W-phase arm 17 includes IGBT elements Q7 and Q7 connected in series. Consists of Q8. Further, diodes D3 to D8 that flow current from the emitter side to the collector side are connected between the collectors and emitters of the IGBT elements Q3 to Q8, respectively.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of motor generator MG2. That is, one end of the three coils of U, V, and W phases is commonly connected to the neutral point, the other end of the U phase coil is at the middle point of the IGBT elements Q3 and Q4, and the other end of the V phase coil is the IGBT. The other end of the W-phase coil is connected to an intermediate point between the elements Q5 and Q6 and an intermediate point between the IGBT elements Q7 and Q8, respectively.

The inverter 22 has the same configuration as the inverter 14.
Voltage sensor 11 detects DC voltage Vb output from battery 10 and outputs the detected DC voltage Vb to MG-ECU 35. Capacitor C <b> 1 smoothes DC voltage Vb supplied from battery 10, and supplies the smoothed DC voltage Vb to converter 12.

  Converter 12 boosts DC voltage Vb supplied from capacitor C1 and supplies the boosted voltage to capacitor C2. Specifically, when converter 12 receives signal PWMC from MG-ECU 35, converter 12 boosts DC voltage Vb according to the period during which IGBT element Q2 is turned on by signal PWMC and supplies it to capacitor C2.

  When converter 12 receives signal PWMC from MG-ECU 35, converter 12 steps down the DC voltage supplied from inverter 14 and / or inverter 22 via capacitor C2, and charges battery 10.

  Capacitor C2 smoothes the DC voltage from converter 12, and supplies the smoothed DC voltage to inverters 14 and 22 via power supply line PL and ground line GL. The voltage sensor 13 detects the voltage across the capacitor C2, that is, the output voltage VH of the converter 12 (corresponding to the input voltage of the inverters 14 and 22. The same applies hereinafter), and the detected output voltage VH is detected by the MG-ECU 35. Output to.

  When DC voltage VH is supplied from capacitor C2, inverter 14 converts DC voltage into AC voltage based on signal PWMI2 from MG-ECU 35 to drive motor generator MG2. Thereby, motor generator MG2 is driven so as to generate torque specified by torque command value TR2.

  Inverter 14 also converts the AC voltage generated by motor generator MG2 into a DC voltage based on signal PWMI2 from MG-ECU 35 during regenerative braking of hybrid vehicle 5, and converts the converted DC voltage via capacitor C2. Supply to the converter 12. The regenerative braking here refers to braking accompanied by regenerative braking when the driver driving the hybrid vehicle 5 performs a regenerative braking, or turning off the accelerator pedal during traveling, although the foot brake is not operated. This includes decelerating the vehicle (or stopping acceleration) while generating regenerative power.

  When the DC voltage is supplied from capacitor C2, inverter 22 converts DC voltage into AC voltage based on signal PWMI1 from MG-ECU 35 to drive motor generator MG1. Thereby, motor generator MG1 is driven to generate torque specified by torque command value TR1.

  Current sensor 24 detects motor current MCRT1 flowing through motor generator MG1, and outputs the detected motor current MCRT1 to MG-ECU 35. Current sensor 28 detects motor current MCRT2 flowing through motor generator MG2, and outputs the detected motor current MCRT2 to MG-ECU 35.

  Further, rotor rotation angle θ1 of motor generator MG1 detected by rotation angle sensor 51 and rotor rotation angle θ2 of motor generator MG2 detected by rotation angle sensor 52 are transmitted to MG-ECU 35 and HV-ECU 32.

  MG-ECU 35 receives DC voltage Vb from voltage sensor 11, receives motor currents MCRT1 and MCRT2 from current sensors 24 and 28, respectively, and outputs voltage of converter 12 from voltage sensor 13 (that is, input voltage of inverters 14 and 22). VH is received, and rotor rotation angles θ1 and θ2 are received from rotation angle sensors 51 and 52, respectively. Further, MG-ECU 35 receives operation commands for motor generators MG 1 and MG 2 and voltage command value VHref for converter 12 from HV-ECU 32. The operation command sent from HV-ECU 32 includes an operation permission command / operation prohibition command (gate cutoff command), torque commands TR1, TR2, a rotation speed command, and the like of motor generators MG1, MG2.

  Then, MG-ECU 35 performs a switching control of IGBT elements Q3 to Q8 of inverter 14 when inverter 14 drives motor generator MG2 based on output voltage VH, motor current MCRT2 and torque command TR2. And the generated signal PWMI2 is output to the inverter 14. Further, MG-ECU 35 performs signal PWMI1 for switching control of IGBT elements Q3 to Q8 of inverter 22 when inverter 22 drives motor generator MG1 based on output voltage VH, motor current MCRT1 and torque command TR1. And the generated signal PWMI1 is output to the inverter 22. At these times, the signals PWMI1 and PWMI2 are generated by feedback control using sensor detection values according to, for example, a well-known PWM control method.

  On the other hand, when the gate cutoff command for motor generator MG2 is issued by HV-ECU 32, MG-ECU 35 causes each of IGBT elements Q3-Q8 constituting inverter 14 to stop (all turn off) the switching operation. In addition, the gate cutoff signal SDN is generated. When HV-ECU 32 issues a gate cutoff command for motor generator MG1, MG-ECU 35 causes each of IGBT elements Q3 to Q8 constituting inverter 22 to stop switching operation (all off). In addition, the gate cutoff signal SDN is generated.

  Further, MG-ECU 35 generates signal PWMC for switching control of IGBT elements Q1 and Q2 of converter 12 based on voltage command value VHref, DC voltage Vb and output voltage VH, and outputs the signal to converter 12. .

  Information regarding abnormality of motor generators MG1, MG2 detected by MG-ECU 35 is sent to HV-ECU 32 in the direction opposite to the operation command of motor generators MG1, MG2. The HV-ECU 32 is configured to be able to reflect such abnormality information in the operation commands of the motor generators MG1, MG2.

  In the configuration shown in FIGS. 1 to 3, motor generator MG1 corresponds to “first electric motor” in the present invention, and motor generator MG2 corresponds to “second electric motor” in the present invention. The HV-ECU 32 and the MG-ECU 35 constitute a “control device” in the present invention.

  Referring to FIG. 2 again, when an abnormality occurs in motor generator MG2, operation of motor generator MG2 is stopped, and retreat travel of hybrid vehicle 5 is performed by an abnormal operation using engine ENG and motor generator MG1. It is feasible.

  Here, in the hybrid vehicle 5 configured as described above, the rotational speed of the motor generator MG1, the rotational speed of the engine ENG, and the rotational speed of the output member (ring gear case) 155 are determined by the differential operation by the power split mechanism PSD. As shown in the collinear charts L1 and L2 of FIG. 4, the rotational speeds of the motor generator MG1 and the engine ENG with respect to the output member 155 change so that the rotational speed difference maintains a constant ratio.

FIG. 4 is a collinear diagram illustrating the rotational speed behavior during normal traveling.
Referring to FIG. 4, during normal travel, when engine ENG is started, motor generator MG1 is driven as an electric motor in accordance with torque command TR1 from ECU 30 (HV-ECU 32). Then, ring gear 152 of power split device PSD becomes a reaction force element, and torque of motor generator MG1 is transmitted to engine ENG via planetary carrier 154 and crankshaft 150, and engine ENG is cranked (rotated). Along with the cranking of engine ENG, fuel is injected and ignited in accordance with a command from HV-ECU 32, so that self-sustained operation of engine ENG is established. When self-sustained operation of engine ENG is established, torque from engine ENG is transmitted to output member 155 via crankshaft 150, planetary carrier 154, and ring gear 152. The torque of the output member 155 is transmitted to the front wheels 70L and 70R, which are drive wheels, via the counter drive gear 170, the power transmission reduction gear RG and the differential gear DEF, thereby generating a driving force.

  As described above, in the hybrid vehicle 5, by using the configuration in which the engine ENG is started by the motor generator MG1, a starter dedicated to starting is not required, the number of parts is reduced, and the power train can be downsized.

  On the other hand, when the engine ENG is rotationally driven by the motor generator MG1 via the power split mechanism PSD, a reaction force is generated in the output member 155 due to the rotational resistance (friction or the like) of the engine ENG, or the motor is started as the engine ENG starts. There is a possibility that the output torque of the generator MG1 acts on the output member 155.

Specifically, in FIG. 4, when motor generator MG1 outputs torque EN for cranking engine ENG from the state of collinear diagram L1, the state as shown in collinear diagram L2 results, and the output torque of motor generator MG1 (Cranking torque) Tg increases the rotational speed of the engine ENG. Along with this, reaction force torque Tep from engine ENG is generated in output member 155. When the direction of vehicle driving torque Tm generated by motor generator MG2 is defined as “positive”, reaction force torque Tep is generated in the “negative” direction. The reaction force torque Tep is expressed by equation (1), where ρ is the gear ratio of the power split mechanism PSD.
Tep =-(1 / ρ) × Tg × (1-Kstepng) (1)
However, Kstepng is an inertia ratio.

  Thereby, a torque obtained by subtracting reaction force torque Tep from torque Tm generated by motor generator MG2 is output from power split mechanism PSD to output member 155 as a drive torque of the vehicle. When such a phenomenon occurs, the driving torque of the vehicle substantially decreases, so that driving force fluctuations that cause driving disturbance occur in the vehicle, which may impair drivability.

  Therefore, it is known that when the engine ENG is started, torque control of the motor generator MG2 is performed in addition to the motor generator MG1 so that the driving force fluctuation that causes the driving disturbance does not occur. Specifically, engine ENG is driven to rotate by motor generator MG1, and reaction force canceling torque is generated from motor generator MG2 so as to cancel drive force fluctuations generated by the reaction force.

  However, when the motor generator MG2 cannot operate normally due to the abnormality of the motor generator MG2, the torque control of the motor generator MG2 as described above cannot be performed. Therefore, reaction force canceling torque cannot be generated from motor generator MG2.

  Here, even if the motor generator MG2 cannot operate normally, the inertial force that pushes the vehicle forward acts on the output member 155 in a state where the rotational speed of the output member 155 is high, thereby causing fluctuations in the driving force due to the reaction force torque Tep. Can be offset. Therefore, if the rotational speed of output member 155 is in the high rotational speed region, engine ENG can be started to perform retreat travel using engine ENG and motor generator MG1.

  On the other hand, as shown in the collinear diagram L3 of FIG. 5, when the output speed of the output member 155 is low, the motor generator MG1 outputs the cranking torque Tg to enter the collinear diagram L4. Since the inertial force that pushes the vehicle forward is small, the reaction force torque Tep generated in the output member 155 cannot be offset. As a result, there is a possibility that the torque transmitted to the output member 155 increases in the direction in which the rotational speed is shifted from the normal rotation region to the reverse rotation region, thereby causing the vehicle to move backward. Due to such a problem, there has been a problem that the retreat traveling using the engine ENG and the motor generator MG1 cannot be performed in the low rotation speed region of the output member 155.

  Therefore, in hybrid vehicle 5 according to the present embodiment, when abnormality occurs in motor generator MG2, drag torque Tdr based on the electromagnetic action is generated from motor generator MG2 that is rotated as output member 155 rotates. Let As shown in the collinear diagram L4 of FIG. 5, the drag torque Tdr is a torque (reaction force canceling torque) that cancels the reaction force torque Tep generated in the output member 155. As a result, fluctuations in driving force that occur when the engine ENG is started can be offset, and the vehicle can be prevented from moving backward when the engine ENG is started.

  Here, the drag torque Tdr shown in FIG. 5 is generated by an electromagnetic action from the motor generator MG2 by turning on and off the inverter 14 connected to the motor generator MG2 in a stopped state according to a predetermined switching pattern. Torque.

  FIG. 6 is a diagram for explaining control of the inverter 14 for generating drag torque. FIG. 6 shows, as an example of the occurrence of an abnormality in motor generator MG2, a case in which a short-circuit fault that remains in an on state and becomes uncontrollable occurs in IGBT element Q3 that constitutes the U-phase upper arm of inverter 14.

  As shown in FIG. 6, when motor generator MG2 rotates with rotation of output member 155, magnet PM mounted on the rotor (not shown) rotates. Thereby, an induced voltage is generated in the three-phase coil winding of motor generator MG2.

  Therefore, even if each of the IGBT elements Q3 to Q8 constituting the inverter 14 is controlled to stop (all off) by the gate cut-off signal SDN, a short-circuit path is formed via the IGBT element Q3 that is short-circuited. The Specifically, the power line PL-IGBT element Q3 (short circuit failure) -U phase coil winding-neutral point-V phase coil winding-diode D3 (or W phase coil winding-diode D5), A short circuit path (Rt1 in the figure) is formed. For this reason, an abnormal current corresponding to the induced voltage and the electrical resistance of the short-circuit path is generated.

  Since the induced voltage generated in the coil winding is proportional to the rotation speed of motor generator MG2, if the rotation speed of motor generator MG2 increases, the induced voltage generated in motor generator MG2 also increases, Abnormal current also increases. If the abnormal current becomes excessive, further element damage may occur due to the high temperature exceeding the components of the inverter.

  When a short circuit failure occurs in the IGBT element of the one-phase upper arm or the lower arm of the inverter 14 (one-phase short circuit), the corresponding arms of the other two phases are forcibly controlled to be in the on state. In the example of FIG. 6, the IGBT element Q5 of the V-phase upper arm and the IGBT element Q7 of the W-phase upper arm are simultaneously controlled to be turned on in response to the short-circuit failure of the U-phase upper arm IGBT element Q3. Hereinafter, controlling the IGBT elements of one of the upper arm and the lower arm through the multiphase arm of the inverter to be in the ON state at the same time is referred to as “polyphase on control”. Controlling simultaneously the IGBT elements of the upper arm and the lower arm through the (U-phase arm 15, V-phase arm 16, W-phase arm 17) is referred to as "three-phase on control". In addition, a state in which the IGBT elements Q3 to Q8 are turned on / off by the three-phase on control is referred to as a “three-phase on state”.

  When the magnet PM of the motor generator MG2 rotates by executing the three-phase on control of the inverter 14 as shown in FIG. 6, in addition to the short-circuit path via the IGBT element Q3, the path via the IGBT element Q5, and A path through the IGBT element Q7 is formed. As a result, motor currents Iu, Iv, and Iw showing AC waveforms having substantially the same amplitude are induced in the U-phase coil winding, V-phase coil winding, and W-phase coil winding of motor generator MG2. Then, a rotating magnetic field is formed by the induced motor current, so that drag torque (braking torque) is generated in motor generator MG2. This drag torque is transmitted to the output member 155.

  FIG. 7 is a diagram showing the relationship between the current (three-phase current) and torque of motor generator MG2 and the rotation speed when three-phase on control is executed.

  As shown in FIG. 7, at the time of three-phase on control, drag torque (negative torque) is output from motor generator MG2. This drag torque increases as the rotational speed (hereinafter also simply referred to as MG2 rotational speed) Nm2 of motor generator MG2 decreases, and becomes maximum at a predetermined rotational speed Nth in the low rotational speed range. On the other hand, the three-phase current decreases as the MG2 rotational speed Nm2 decreases.

  In the control of the inverter 14 according to the present embodiment, the predetermined rotation speed Nth is set to a determination value for determining whether or not the three-phase on control can be executed. Then, when the MG2 rotation speed Nm2 becomes equal to or less than the determination value Nth, the three-phase on control is executed.

  With this configuration, the three-phase ON control of the inverter 14 is executed in the low rotation speed region (region RGN1 in the figure) where the MG2 rotation speed Nm2 is equal to or less than the determination value Nth. As described above, when the MG2 rotational speed Nm2 is in the low rotational speed region, the reaction torque Tep due to the start of the engine ENG cannot be canceled by the inertial force of the vehicle, but the drag torque Tdr that becomes high torque in this low rotational speed region. By generating the reaction force, the reaction force torque Tep can be effectively canceled out. As a result, it is possible to suppress fluctuations in the driving force of the vehicle that accompany engine startup, and to prevent the vehicle from moving backward.

  6 shows a short-circuit failure in the inverter 14 as an example of the occurrence of an abnormality in the motor generator MG2. However, a failure in the rotation angle sensor 52 (FIG. 3) provided in the motor generator MG2, Even when the abnormality detection signal FINV is output from the self-protection circuit built in the IGBT elements Q3 to Q8, the above three-phase ON control can be performed. The abnormality detection signal FINV is a signal output from the self-protection circuit in response to the detection of an overcurrent (or overheat) in the output of the current sensor (or temperature sensor) included in the self-protection circuit. When these abnormalities occur, although switching control based on normal PWM control cannot be performed, the IGBT elements Q3 to Q8 of the inverter 14 can be turned on or off, so that the gate is cut off. By switching inverter 14 to three-phase on control, drag torque can be generated in motor generator MG2.

(Control structure)
Next, with reference to FIG. 8, a control structure for realizing the operation for switching the traveling mode of the vehicle according to the present embodiment will be described. Will be described with reference to the drawings.

  FIG. 8 is a block diagram showing a control structure in ECU 30 according to the present embodiment. Each functional block shown in FIG. 8 is typically realized by the ECU 30 executing a program stored in advance, but part or all of the function may be implemented as dedicated hardware.

  3 and 8, ECU 30 includes an HV-ECU 32, an MG-ECU 35, and an engine ECU 37 that controls the operation of engine ENG. MGECU 35 includes MG1-ECU 352 that controls the operation of motor generator MG1, and MG2-ECU 350 that controls the operation of motor generator MG2.

  MG2-ECU 350 includes a motor control phase voltage calculation unit 320, an inverter drive signal conversion unit 340, and an MG2 abnormality detection unit 360.

  Motor control phase voltage calculation unit 320 receives torque command TR as an operation command from HV-ECU 32, receives rotor rotation angle θ2 of motor generator MG2 from rotation speed sensor 52, receives motor current MCRT2 from current sensor 28, and The output voltage of converter 12 (that is, the input voltage of inverters 14 and 22) VH is received from voltage sensor 13. Based on these input signals, motor control phase voltage calculation unit 32 manipulates the voltage applied to each phase coil of motor generator MG1 (hereinafter also referred to as a voltage command) Vu *, Vv *, Vw *. And the calculation result is output to the inverter drive signal converter 340.

  The inverter drive signal conversion unit 340 actually controls switching of the IGBT elements Q3 to Q8 of the inverter 14 based on the voltage commands Vu *, Vv *, and Vw * of the respective phase coils from the motor control phase voltage calculation unit 320. Signal PWMI2 is generated, and the generated signal PWMI2 is sent to the inverter 14.

  MG2 abnormality detection unit 360 detects an abnormality that has occurred in motor generator MG2 during operation of motor generator MG2. Specifically, the MG2 abnormality detection unit 360 detects an abnormality from the rotor rotation angle θ2 from the rotation speed sensor 52, the motor current MCRT2 from the current sensor 28, and the self-protection circuit built in the IGBT elements Q3 to Q8 of the inverter 14. Based on the detection signal FINV or the like, an abnormality occurring in the motor generator MG2 is detected. For example, for the short-circuit fault in the inverter 14 as shown in FIG. 6, various known detection methods may be employed. For example, the ON / OFF control pattern of the IGBT element of each phase of the inverter 14, A one-phase short circuit or a two-phase short circuit may be detected based on the detection pattern of the current flowing in each phase. Information regarding abnormality of motor generator MG2 detected by MG2 abnormality detection unit 360 is sent to HV-ECU 32 and inverter drive signal conversion unit 340. The information regarding this abnormality includes an MG2 abnormality determination flag that is set to ON when an abnormality occurs in motor generator MG2.

  When HV-ECU 32 receives information on abnormality of motor generator MG2 from MG2 abnormality detector 360, it issues a gate cutoff command for motor generator MG2. Inverter drive signal conversion unit 340 generates gate cutoff signal SDN so that each of IGBT elements Q3 to Q8 constituting inverter 14 stops the switching operation (all off) in accordance with the gate cutoff command of motor generator MG2. .

  HV-ECU 32 further determines whether or not inverter 14 can be three-phase-on controlled based on information regarding abnormality of motor generator MG2 received from MG2 abnormality detector 36. For example, if any one of the short circuit failure in the inverter 14, the failure of the rotation speed sensor 52, and the overcurrent of the inverter 14 shown in FIG. 6 occurs, the HV-ECU 32 controls the three-phase on control of the inverter 14. Is determined to be executable.

  When it is determined that the three-phase ON control can be executed, the HV-ECU 32 detects the MG2 rotation speed Nm2 based on the rotor rotation angle θ2 detected by the rotation speed sensor 52, and detects the detected MG2 rotation. A three-phase ON control command is generated based on the number Nm2 and sent to the inverter drive signal converter 340. Specifically, the HV-ECU 32 determines that the detected MG2 rotational speed Nm2 is within the range of the low rotational speed region (corresponding to the region RGN1 in the figure) equal to or less than a predetermined determination value Nth. Sometimes a three-phase on control command is generated.

  When a three-phase on control command is issued, inverter drive signal converter 340 turns on one of the IGBT elements of the upper arm and the lower arm through the three-phase arm of inverter 14 (three-phase on state). A signal Ton for controlling is generated. Signal Ton is generated based on information relating to abnormality of motor generator MG2 detected by MG2 abnormality detection unit 360.

  Further, HV-ECU 32 issues an engine start command to MG1-ECU 352 and engine ECU 37. At this time, HV-ECU 32 generates torque command TR1 for motor generator MG1 to output a torque (cranking torque) necessary for cranking engine ENG, and provides the generated torque command TR1 to MG1-ECU 352. .

  At this time, the torque command TR1 for the motor generator MG1 is limited so that the reaction torque Tep that can be generated in the output member 155 when the engine ENG is started does not exceed the drag torque (maximum drag torque) that has the maximum absolute value. Is done. As an example, the HV-ECU 32 sets the absolute value of the drag torque Tdr when the MG2 rotational speed Nm2 becomes the determination value Nth according to the relationship shown in FIG. 7 as the maximum drag torque, and the reaction force torque Tep is the maximum drag torque. The torque command TR1 is calculated using the above equation (1) so as not to exceed the torque.

  MG1-ECU 352 receives torque command TR1 output from HV-ECU 32, rotor rotation angle θ1 from rotation angle sensor 51, and motor current MCRT1 from current sensor 24. MG1-ECU 352 performs switching control of IGBT elements Q3-Q8 of inverter 22 so that motor generator MG1 operates in accordance with torque command TR1 by feedback control based on detection values from rotation angle sensor 51 and current sensor 24. Signal PWMI1 is generated.

  When the start of the engine ENG is started by the rotational drive of the motor generator MG1, the HV-ECU 32 monitors the engine speed of the engine ENG (hereinafter also referred to as engine speed) Ne detected by the engine ECU 37, whereby the engine It is determined whether the start is completed. Specifically, the HV-ECU 32 generates a control signal so that the fuel injection control and the ignition control are started when the engine rotational speed Ne reaches a predetermined rotational speed Nref or more. It is sent to the ECU 37. When it is determined that the engine ENG has reached the complete explosion state based on the change in the engine speed Ne, the HV-ECU 32 determines that the start of the engine ENG has been completed and ends the start process.

  When the start of the engine ENG is completed, the HV-ECU 32 turns off (invalidates) the three-phase on control command and turns on (validates) the gate cutoff command. As a result, inverter drive signal converter 340 stops generating signal Ton for controlling inverter 14 to the three-phase on state, generates gate cutoff signal SDN, and outputs the signal to inverter 14. That is, when the start of engine ENG is completed, the switching operations of IGBT elements Q3 to Q8 constituting inverter 14 are again stopped (all turned off). This is because it is not necessary to cancel the reaction torque generated at the start of the engine ENG upon completion of the start. As a result, the retreat travel using engine ENG and motor generator MG1 can be executed without generating a drag torque accompanying the rotation of motor generator MG2.

  FIG. 9 is a timing chart illustrating engine start control when abnormality occurs in motor generator MG2 according to the present embodiment.

  Referring to FIG. 9, when occurrence of abnormality in motor generator MG2 is detected at time t1, MG2 abnormality detection unit 360 in MG2-ECU 350 sets the MG2 abnormality determination flag to ON. Upon receiving information relating to the abnormality of motor generator MG2 including this MG2 abnormality determination flag, HV-ECU 32 validates (turns on) the gate cutoff command of motor generator MG2. Inverter drive signal converter 340 in MG2-ECU 350 generates a gate cutoff signal SDN in accordance with the gate cutoff command, thereby stopping (all off) each switching operation of IGBT elements Q3-Q8 of inverter 14. To control.

  By stopping the operation of motor generator MG2 in accordance with the gate cutoff command, MG2 rotation speed Nm2 gradually decreases. The HV-ECU 32 turns on (validates) the three-phase on control command when the MG2 rotational speed Nm2 becomes equal to or less than a predetermined determination value Nth at time t2. When the inverter drive signal converter 340 in the MG1-ECU 350 controls the IGBT elements Q3 to Q8 of the inverter 14 to the three-phase ON state according to the signal Ton according to the three-phase ON control command, the HV-ECU 32 turns on the engine start command. (Enable).

  MG1-ECU 352 rotates motor generator MG1 according to the engine start command, and starts engine ENG. After the start of cranking in engine ENG, reaction torque Tep is generated in output member 155 in the “negative” direction as the engine speed is increased by motor generator MG1. At the same time, drag torque Tdr corresponding to the rotational speed of motor generator MG2 is generated in output member 155 in the “positive” direction by three-phase ON control of inverter 14. The drag torque acts as a reaction force canceling torque, thereby suppressing fluctuations in the driving force of the vehicle.

  When it is determined at time t3 that the engine ENG has been started, HV-ECU 32 turns off (invalidates) the engine start command and the three-phase on control command, and issues a gate cutoff command for motor generator MG2. Turn on (enable). Thus, when the start of engine ENG is completed, operation of motor generator MG2 is stopped, and retreat travel of hybrid vehicle 5 using engine ENG and motor generator MG1 is executed. At this time, since the switching operation of each of the IGBT elements Q3 to Q8 of the inverter 14 is controlled by the gate cutoff signal SDN, the drag torque from the motor generator MG2 accompanying the rotation of the motor generator MG2 during the evacuation travel. Will not occur.

The above processing can be summarized in a processing flow as shown in FIG.
(Processing flow)
FIG. 10 is a flowchart illustrating retreat travel when abnormality occurs in motor generator MG2 according to the embodiment of the present invention. The flowchart shown in FIG. 10 is realized by the ECU 30 shown in FIGS. 1 and 2 functioning as each control block shown in FIG.

  Referring to FIG. 10, HV-ECU 32 determines whether or not an abnormality has occurred in motor generator MG2 based on information (for example, MG2 abnormality determination flag) relating to abnormality in motor generator MG2 sent from MG2-ECU 350. Determination is made (step S01).

  If no abnormality has occurred in motor generator MG2 (NO determination in step S01), HV-ECU 32 ends the control process related to the retreat travel without instructing the operation at the time of abnormality (retreat travel).

  On the other hand, when abnormality has occurred in motor generator MG2 (when YES is determined in step S01), HV-ECU 32 instructs retreat travel. At this time, HV-ECU 32 issues a gate cutoff command for motor generator MG2 to MG2-ECU 350 (step S02). In response to this, the gate cutoff signal SDN is output from the MG2-ECU 350, whereby the IGBT elements Q3 to Q8 of the inverter 14 are all turned off.

  Next, the HV-ECU 32 determines whether or not the vehicle speed of the hybrid vehicle 5 is within the range of the low vehicle speed region (step S03). Specifically, the HV-ECU 32 determines whether or not the rotational speed of the output member 155 determined corresponding to the vehicle speed is within a predetermined low rotational speed range. In this predetermined low rotational speed region, in consideration of the inertial force in the traveling direction of the vehicle acting on the output member 155, the inertial force of the vehicle cannot cancel the reaction force generated in the output member 155 when the engine ENG starts. It is set assuming

  When the hybrid vehicle 5 is not within the low vehicle speed range (when NO is determined in step S03), that is, when the vehicle inertial force that can cancel the reaction force is acting on the output member 155, the HV The ECU 32 generates a start command for the engine ENG without instructing the three-phase on control of the inverter 14. In response to this, MG1-ECU 352 cranks engine ENG by rotational driving of motor generator MG1 (step S07).

  On the other hand, when the hybrid vehicle 5 is in the range of the low vehicle speed region (when YES is determined in step S03), that is, the inertia force of the vehicle that can cancel the reaction force does not act on the output member 155. In this case, HV-ECU 32 determines whether or not the three-phase ON control of inverter 14 can be executed based on information regarding abnormality of motor generator MG2 detected by MG2-ECU 350 (step S04). As an example, when the abnormality of the motor generator MG2 corresponds to any one of the short-circuit fault of the inverter 14, the fault of the rotation speed sensor 52, and the overcurrent of the inverter 14, the HV-ECU 32 It is determined that control can be executed.

  When the inverter 14 cannot execute the three-phase on control (NO determination at step S04), the HV-ECU 32 does not instruct the three-phase on control of the inverter 14 and the start of the engine ENG. The control process related to the retreat travel is ended.

  On the other hand, when inverter 14 can execute the three-phase ON control (when YES is determined in step S04), HV-ECU 32 determines whether or not MG2 rotation speed Nm2 is equal to or smaller than predetermined determination value Nth. Is determined (step S05). When MG2 rotational speed Nm2 is equal to or smaller than predetermined determination value Nth (when YES is determined in step S05), that is, in a low rotational speed region (region RGN1 in FIG. 7) where MG2 rotational speed Nm2 is equal to or smaller than predetermined determination value Nth. When within the range, HV-ECU 32 turns off (invalidates) the gate cutoff command of motor generator MG2, and issues a three-phase on control command to MG2-ECU 350. In response to this, MG2-ECU 350 generates signal Ton to control IGBT elements Q3-Q8 of inverter 14 to the three-phase on state (step S06).

  Next, HV-ECU 32 issues an engine start command to MG1-ECU 352 and engine ECU 37. In response to this, MG1-ECU 352 cranks engine ENG by rotational driving of motor generator MG1 (step S07).

  The HV-ECU 32 determines whether or not the engine ENG has been started by monitoring the engine speed Ne (step S08). If the engine ENG has not been started (NO in step S08), the process returns to step S07.

  On the other hand, when engine ENG has been started (when YES is determined in step S08), HV-ECU 32 turns off the three-phase on control command and the engine start command, and again issues a gate cutoff command for motor generator MG2. Turns on (step S09). In response to this, the gate cutoff signal SDN is output from the MG2-ECU 352, whereby the IGBT elements Q3 to Q8 of the inverter 14 are all turned off. Therefore, in hybrid vehicle 5, operation of motor generator MG2 is stopped, and retreat travel using engine ENG and motor generator MG1 is performed.

(Example of change)
In the above-described embodiment, when starting engine ENG, motor generator MG1 does not exceed the maximum drag torque generated by execution of three-phase ON control so that reaction force torque Tep generated at output member 155 at the time of engine startup does not exceed. Although the configuration for limiting the cranking torque Tg to be output has been described, there may be a problem that the engine ENG cannot be started by limiting the cranking torque Tg in this way.

  In the modified example of the embodiment of the present invention, control when the engine ENG cannot be started even if the engine start process according to the above-described embodiment is performed in accordance with the limitation of the cranking torque will be described.

  FIG. 11 is a flowchart for explaining retreat travel when an abnormality occurs in motor generator MG2 according to the modification of the embodiment of the present invention. The flowchart shown in FIG. 10 is realized by the ECU 30 shown in FIGS. 1 and 2 functioning as each control block shown in FIG.

  Referring to FIG. 11, ECU 30 (HV-ECU 32) performs the same three-phase on control as in the above-described embodiment in steps S01 to S05 in FIG. 10 (step S06).

  Further, HV-ECU 32 issues an engine start command to MG1-ECU 352 and engine ECU 37. In response to this, MG1-ECU 352 cranks engine ENG by rotational driving of motor generator MG1 (step S07).

  The HV-ECU 32 determines whether or not the engine ENG has been started by monitoring the engine speed Ne (step S08). If the engine ENG has not been started (NO determination in step S08), the HV-ECU 32 determines that the MG2 rotational speed Nm2 is a predetermined determination value based on the rotor rotational angle θ2 from the rotational speed sensor 52. It is determined whether or not Nth is exceeded (step S11).

  When MG2 rotation speed Nm2 exceeds predetermined determination value Nth (when YES is determined in step S11), HV-ECU 32 determines that the drag torque cannot cancel the reaction force accompanying engine start. Then, the engine ENG start process is stopped (step S13). This is because when the MG2 rotational speed Nm2 increases beyond the low rotational speed region (RGN1 in the figure), the drag torque decreases, and the vehicle may move backward when the engine is started.

  On the other hand, when MG2 rotational speed Nm2 is equal to or smaller than predetermined determination value Nth (NO determination in step S11), HV-ECU 32 starts the start processing time that is an elapsed time from the start of the engine start processing in step S07. It is determined whether or not the predetermined time has been exceeded (step S12). When the start processing time does not exceed the predetermined time (when NO is determined in step S12), the processing in step S07 is repeatedly executed. On the other hand, when the start processing time exceeds the predetermined time (when YES is determined in step S12), HV-ECU 32 stops the start processing of engine ENG (step S13).

  When engine ENG start is completed (when YES is determined in step S08) or engine ENG start processing is stopped (step S13), HV-ECU 32 issues a three-phase on control command and an engine start command. While turning off, the gate cutoff command of motor generator MG2 is turned on again (step S09). In response to this, the gate cutoff signal SDN is output from the MG2-ECU 352, whereby the IGBT elements Q3 to Q8 of the inverter 14 are all turned off. When engine ENG start processing is stopped, retreat travel using engine ENG and motor generator MG1 is prohibited.

  In the above description, by setting IGBT elements Q3 to Q8 of inverter 14 connected to motor generator MG2 to one of the upper arm and the lower arm being simultaneously on (three-phase on) through three phases, The configuration in which drag torque based on electromagnetic action is generated from the motor generator MG2 during operation stop is illustrated, but the control of the inverter 14 is not limited to this three-phase on control, and the output member 155 is rotated. As long as a rotating magnetic field can be formed in the three-phase coil from the induced voltage generated in the motor generator MG2, a switching pattern other than this can be applied.

  As described above, according to the embodiment of the present invention, when engine ENG is started when abnormality occurs in motor generator MG2, IGBT elements Q3-Q8 of inverter 14 connected to motor generator MG2 are set in a predetermined manner. The drag torque generated by the electromagnetic action is generated from the motor generator MG2 by turning on and off according to the switching pattern. Thereby, since the reaction force accompanying engine starting can be canceled, the fluctuation | variation of the driving force at the time of engine starting can be suppressed. As a result, when abnormality occurs in motor generator MG2, retreat travel using engine ENG and motor generator MG1 is executed.

  Further, according to the embodiment of the present invention, when the output member 155 enters the low rotation speed region, the output member 155 is susceptible to the reaction force accompanying the start of the engine ENG, and increases in the low rotation speed region. Since the drag torque can be generated as described above, fluctuations in the driving force when starting the engine can be effectively suppressed. Thereby, even when the vehicle speed is low, the vehicle can be prevented from retreating as the engine starts, so that the retreat travel using engine ENG and motor generator MG1 can be performed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  5 Hybrid vehicle, 10 Battery, 11, 13 Voltage sensor, 12 Converter, 14, 22 Inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm, 20 Power conversion unit, 24, 28 Current sensor, 30 ECU, 32 HV-ECU, 35 MG-ECU, 37 engine ECU, 40 steering wheel, 44 accelerator position sensor, 46 brake pedal position sensor, 48 shift position sensor, 51, 52 rotation angle sensor, 70L, 70R front wheel, 80L, 80R rear wheel , 131, 136 Stator, 132, 137 Rotor, 133, 138 Stator core, 134, 139 Three-phase coil, 150 Crankshaft, 151, 162 Sun gear, 152, 168 Ring gear, 153, 164 Pinion gear, 154,166 Planetary carrier, 155 Ring gear case (output member), 160 Output shaft, 170 Counter drive gear, C1, C2 capacitor, D1-D8 diode, DEF differential gear, L1 reactor, MG1, MG2 Motor generator, PSD Power split mechanism , Q1-Q8 IGBT element, RD reduction gear, RG power transmission reduction gear.

Claims (7)

An engine that operates by burning fuel,
A first electric motor;
An output member for outputting power;
A plurality of rotating elements respectively coupled to the output member, the output shaft of the engine, and the output shaft of the first electric motor are coupled so as to be relatively rotatable with each other, and input / output of electric power and power by the first electric motor A power split mechanism that outputs at least a part of the output from the engine to the output member,
A second electric motor for applying power between the output member and the drive wheel;
An inverter connected to the second electric motor and configured by a plurality of switching elements;
The first and second electric motors, and a control device for controlling the operation of the engine,
The controller is
An abnormality detection means for detecting an abnormality of the second electric motor;
An abnormality control means for stopping the operation of the second electric motor and executing the abnormal operation using the engine and the first electric motor when an abnormality of the second electric motor is detected; Including
The abnormality control means includes
A starting means for starting the engine by rotating the engine via the power split mechanism by power from the first motor when an abnormality of the second motor is detected;
The engine is started by the starting means by generating a drag torque based on electromagnetic action from the second electric motor that is stopped by turning on and off the plurality of switching elements according to a predetermined switching pattern. And a reaction force canceling means for canceling a reaction force generated in the output member due to the vehicle. The second electric motor is a multi-phase motor;
The inverter includes a multi-phase arm connected in parallel to each other between a power line and a ground line, each for controlling a current flowing in a multi-phase coil of the multi-phase motor,
Each of the polyphase arms includes first and second switching elements connected in series between the positive bus and the negative bus via a connection point with each phase coil,
The reaction force canceling means executes the multiphase on control for simultaneously controlling one of the first and second switching elements through the multiphase arm to turn on the drag torque from the second electric motor. The hybrid vehicle according to claim 1, which is generated.   The reaction force canceling means sets the rotation speed of the second electric motor when the drag torque becomes maximum to a determination value for determining whether or not to execute the multi-phase on control, and the second The hybrid vehicle according to claim 2, wherein the multi-phase on control is executed when the rotation speed of the second motor becomes equal to or less than the determination value while the operation of the motor is stopped.   The said starting means controls the driving | operation of a said 1st electric motor so that the reaction force which arises in the said output member resulting from starting of the said engine may not exceed the maximum value of the said drag torque. The hybrid vehicle of any one of Claims.   5. The hybrid vehicle according to claim 4, wherein the start unit stops the start of the engine when the number of revolutions of the second electric motor exceeds the determination value before the start of the engine is completed.   5. The hybrid vehicle according to claim 4, wherein the start unit stops the start of the engine when a duration of a start process of the engine exceeds a predetermined time. 6. A control method for a hybrid vehicle,
The hybrid vehicle
An engine that operates by burning fuel,
A first electric motor;
An output member for outputting power;
A plurality of rotating elements respectively coupled to the output member, the output shaft of the engine, and the output shaft of the first electric motor are coupled so as to be relatively rotatable with each other, and input / output of electric power and power by the first electric motor A power split mechanism that outputs at least a part of the output from the engine to the output member,
A second electric motor for applying power between the output member and the drive wheel,
The control method is:
Detecting an abnormality of the second electric motor;
When an abnormality of the second electric motor is detected, the operation of the second electric motor is stopped, and an abnormal operation using the engine and the first electric motor is executed.
The step of executing the abnormal operation is as follows:
Starting the engine by rotating the engine via the power split mechanism by the first electric motor when an abnormality of the second electric motor is detected;
Canceling the reaction force generated in the output member due to the start of the engine by the starting means by generating a drag torque according to the rotation speed of the second electric motor in the output member. Control method of hybrid vehicle.

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