Hybrid Vehicles

Abstract

To suppress voltage of a capacitor from becoming overvoltage.SOLUTION: A second control device, when sensing a first abnormality which is an abnormality of a first control device or a second abnormality which is an abnormality of a communication with the first control device, executes first control by which an engine, an inverter and a step-up / step-down converter are controlled so that a hybrid vehicle travels together with operation of the engine and gate interception of the inverter and of the step-up / step-down converter, and when voltage of a first power line becomes predetermined voltage or higher during the execution of the first control, turns on an upper arm switching element of the step-up / step-down converter.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] Conventionally, as this type of hybrid vehicle, one that includes an engine and a motor connected to driving wheels, an inverter that drives the motor, a battery connected to the inverter via a power line, an integrated control ECU, a motor control ECU that has a controller and an arbitration circuit and controls the inverter, and an engine ECU that controls the engine (see, for example, Patent Document 1). In this hybrid vehicle, the integrated control ECU sets a torque command for the engine motor and transmits it to the controller, and the controller converts the torque command for the motor into a drive signal and outputs it to the inverter via the arbitration circuit. In addition, in the hybrid vehicle, if an abnormality occurs in the controller while the vehicle is running, the arbitration circuit cuts off the drive command from the controller to the inverter and turns the inverter on in three phases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-62930 A Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to the above hardware configuration, in a hybrid vehicle in which a step-up / step-down converter and a capacitor are provided on the power line from the battery side, when an abnormality occurs in the integrated control ECU or when an abnormality occurs in communication between the integrated control ECU and the motor control ECU, it is considered that evacuation driving is performed with the engine ECU operating the engine and the motor control ECU shutting off the gates of the inverter and step-up / step-down circuit. In this case, if the back electromotive voltage generated by the rotation of the motor is relatively high, there is a possibility that the power based on the back electromotive voltage will be supplied to the power line and the voltage of the capacitor will become relatively high.

[0005] The main object of the hybrid vehicle of the present invention is to prevent the voltage of the capacitor from reaching an overvoltage. [Means for solving the problem]

[0006] The hybrid vehicle of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The hybrid vehicle of the present invention is An engine and a motor connected to the drive wheels; an inverter connected to a first power line and configured to drive the motor by switching a plurality of switching elements; a capacitor attached to the first power line; a power storage device connected to the second power line; a buck-boost converter including an upper arm switching element connected to a positive line of the first power line, a lower arm switching element connected to the first power line and the negative line of the second power line, and a reactor connected to a connection point of the upper arm switching element and the lower arm switching element and the positive line of the second power line, the buck-boost converter being capable of exchanging power involving voltage conversion between the first power line and the second power line; A first control device that sets a driving command; A second control device that is communicatively connected to the first control device and controls the engine, the inverter, and the step-up / step-down converter based on the driving command from the first control device; A hybrid vehicle comprising: The second control device is When a first abnormality, which is an abnormality of the first control device, or a second abnormality, which is an abnormality in communication with the first control device, is detected, a first control is executed to control the engine, the inverter, and the step-up / step-down converter so as to run with operation of the engine and gate blocking of the inverter and the step-up / step-down converter; when the voltage of the first power line reaches or exceeds a predetermined voltage during execution of the first control, the upper arm switching element of the step-up / step-down converter is turned on. The gist of the present invention is as follows.

[0008] In the hybrid vehicle of the present invention, when the second control device detects a first abnormality, which is an abnormality of the first control device, or a second abnormality, which is an abnormality in communication with the first control device, the second control device executes a first control for controlling the engine, the inverter, and the buck-boost converter so as to run with the engine operating and the gates of the inverter and the buck-boost converter being cut off, and when the voltage of the first power line reaches a predetermined voltage or higher during the execution of the first control, the second control device turns on the upper arm switching element of the buck-boost converter. By executing the first control when the second control device detects the first abnormality or the second abnormality, it is possible to perform evacuation running while suppressing the supply of power from the first power line (inverter side) to the second power line (electricity storage device side). At this time, if a back electromotive voltage generated by the rotation of the motor is higher than the voltage of the first power line, power based on the back electromotive voltage is supplied to the first power line, and the voltage of the first power line increases. Therefore, by turning on the upper arm switching element of the buck-boost converter when the voltage of the first power line reaches or exceeds a predetermined voltage, current flows from the positive line of the first power line to the positive line of the second power line via the upper arm switching element of the buck-boost converter and the reactor, thereby suppressing a further increase in the voltage of the first power line and preventing this voltage from reaching an overvoltage.

[0009] In the hybrid vehicle of the present invention, the second control device may have a first processing unit that sets a control command for the inverter and the step-up / step-down converter based on the running command from the first control device, and a second processing unit that controls the inverter and the step-up / step-down converter based on the control command for the inverter and the step-up / step-down converter set by the first processing unit, and the second processing unit may perform gate cutoff for the inverter and the step-up / step-down converter when the first abnormality or the second abnormality is detected. In this case, the second processing unit may perform gate cutoff for the inverter and the step-up / step-down converter when a third abnormality, which is an abnormality of the first processing unit, is detected in addition to when the first abnormality or the second abnormality is detected. In this way, evacuation running can be performed even when a third abnormality occurs in addition to the first abnormality or the second abnormality. The first processing unit may be a microcomputer, and the second processing unit may be an ASIC. By making the second processing unit an ASIC, it is possible to reduce the component cost of the second control device having the second processing unit.

[0010] The hybrid vehicle of the present invention may further include a second motor, a planetary gear connected to three axes including the second motor, the engine, and a drive shaft connected to the drive wheels such that three rotating elements are arranged in the order of the second motor, the engine, and the drive shaft in a collinear diagram, and a second inverter connected to the first power line and driving the second motor by switching a plurality of switching elements, the motor being connected to the drive shaft, and the second control device controlling the engine, the inverter, the step-up / step-down converter, and the second inverter based on the running command from the first control device, and the second control device may control the engine to rotate at a predetermined rotation speed, perform gate cutoff for the inverter and the step-up / step-down converter, and perform three-phase ON or gate cutoff for the second inverter, where the three-phase ON of the second inverter refers to control to turn on all upper arms or all lower arms of the plurality of switching elements of the second inverter. When the second inverter is three-phase-on, drag torque is generated in the second motor, and this drag torque acts on the drive shaft as forward running torque via the planetary gear, allowing the vehicle to run in an evacuation mode.When the gate of the second inverter is cut off, the engine is operated so that the back electromotive force generated by the rotation of the second motor is higher than the voltage of the second power line, and a back electromotive force torque is generated in the second motor based on the back electromotive force, and this back electromotive force torque acts on the drive shaft as forward running torque via the planetary gear, allowing the vehicle to run in an evacuation mode. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 according to an embodiment of the present invention. [Diagram 2] 2 is a schematic diagram showing the configuration of an electric drive system including motors MG1 and MG2. FIG. [Diagram 3] 4 is a flowchart showing an example of an abnormality-time engine process executed by an engine ECU 24. [Figure 4] 10 is a flowchart showing an example of an abnormality-time motor converter process executed by an ASIC 40b of the motor ECU 40. [Diagram 5] FIG. 2 is an explanatory diagram showing an example of a collinear diagram of the planetary gear 30. [Figure 6] This is an explanatory diagram showing an example of the operation of the engine 22, inverters 41, 42, and step-up / step-down converter 46 when the engine ECU 24 and ASIC 40b detect a first abnormality or a second abnormality, the voltage VH of the high-voltage power line 45a, and the presence or absence of a voltage reduction request. [Figure 7] FIG. 13 is a diagram showing an outline of the configuration of a hybrid vehicle 120 according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, a mode for carrying out the present invention will be described using examples. EXAMPLES

[0013] Fig. 1 is a schematic diagram showing the configuration of a hybrid vehicle 20 according to an embodiment of the present invention, and Fig. 2 is a schematic diagram showing the configuration of an electric drive system including motors MG1 and MG2. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, a motor MG1 (second motor), a motor MG2 (motor), an inverter 41 (second inverter), an inverter 42 (inverter), a step-up / step-down converter 46, a main battery 50 (power storage device), an auxiliary battery 60, a DC / DC converter 62, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0014] The engine 22 is configured as an internal combustion engine that outputs power using gasoline, diesel, or the like as fuel, and a crankshaft 23 of the engine 22 is connected to a carrier of a planetary gear 30. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as the "engine ECU") 24.

[0015] The engine ECU 24 includes a microcomputer (hereinafter referred to as "microcomputer") having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors required for controlling the operation of the engine 22, such as a crank angle θcr from a crank position sensor that detects the rotational position of the crankshaft 23 of the engine 22, are input to the engine ECU 24 via an input port. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via an output port. The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor.

[0016] The planetary gear 30 is configured as a single-pinion type planetary gear mechanism. A rotor of a motor MG1 is connected to a sun gear of the planetary gear 30. A drive shaft 36 that is connected to drive wheels 39a, 39b via a differential gear 38 is connected to a ring gear of the planetary gear 30. As described above, the crankshaft 23 of the engine 22 is connected to the carrier of the planetary gear 30.

[0017] The motor MG1 is configured as a synchronous generator motor having a rotor with a permanent magnet embedded in the rotor core and a stator with a three-phase coil wound around the stator core, and as described above, the rotor is connected to the sun gear of the planetary gear 30. The motor MG2 is configured as a synchronous generator motor like the motor MG1, and the rotor is connected to the drive shaft 36.

[0018] The inverters 41 and 42 are used to drive the motors MG1 and MG2 and are connected to a high-voltage power line 45a. As shown in FIG. 2, the inverter 41 has six transistors T11-T16 as switching elements and six diodes D11-D16 connected in parallel to the six transistors T11-T16, respectively. The transistors T11-T16 are arranged in pairs, two at a time, on the source side and the other on the sink side of the positive and negative lines of the high-voltage power line 45a. The three-phase coils (U-phase, V-phase, and W-phase) of the motor MG1 are connected to the respective connection points between the paired transistors T11-T16. Therefore, when a voltage is applied to the inverter 41, a motor electronic control unit (hereinafter referred to as "motor ECU") 40 adjusts the ratio of the on-time of the paired transistors T11-T16, thereby forming a rotating magnetic field in the three-phase coils and rotating the motor MG1. The inverter 42 has six transistors T21-T26 and six diodes D21-D26, similar to the inverter 41. When a voltage is applied to the inverter 42, the motor ECU 40 adjusts the ratio of the on-time of the paired transistors T21-T26, thereby forming a rotating magnetic field in the three-phase coils and driving the motor MG2 to rotate. Hereinafter, among the transistors T11-T16 and T21-T26, the transistors T11-T13 and T21-T23 may be referred to as the "upper arm", and the transistors T14-T16 and T24-T26 may be referred to as the "lower arm".

[0019] 2, the step-up / step-down converter 46 is connected to the high-voltage power line 45a and the low-voltage power line 45b, and includes transistors T31 and T32 as two switching elements, two diodes D31 and D32 connected in parallel to the two transistors T31 and T32, respectively, and a reactor L. The transistor T31 is connected to the positive electrode side line of the high-voltage power line 45a. The transistor T32 is connected to the transistor T31 and the negative electrode side line of the high-voltage power line 45a and the low-voltage power line 45b. The reactor L is connected to the connection point of the transistors T31 and T32 and the positive electrode side line of the low-voltage power line 45b. The step-up / step-down converter 46 increases the power of the low-voltage power line 45b and supplies it to the high-voltage power line 45a or decreases the power of the high-voltage power line 45a and supplies it to the low-voltage power line 45b, with the adjustment of the voltage VH of the high-voltage power line 45a by the motor ECU 40 adjusting the ratio of the on-time of the transistors T31, T32. Hereinafter, of the transistors T31, T32, the transistor T31 may be referred to as the "upper arm" and the transistor T32 may be referred to as the "lower arm." A smoothing capacitor 47 is attached to the positive and negative lines of the high-voltage power line 45a, and a smoothing capacitor 48 is attached to the positive and negative lines of the low-voltage power line 45b.

[0020] As shown in Fig. 2, the motor ECU 40 includes a microcomputer 40a and an ASIC (Application Specific Integrated Circuit) 40b. The microcomputer 40a includes a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port, and the ASIC 40b includes a CPU and a processing unit for performing various processes, and a communication port. Signals from various sensors required for driving and controlling the motors MG1, MG2 and the step-up / step-down converter 46 are input to the microcomputer 40a via the input port. Examples of signals input to the microcomputer 40a include the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position detection sensors 43a, 44a that detect the rotational positions of the rotors of the motors MG1, MG2, and the phase currents Iv1, Iw1, Iv2, Iw2 of the V phase and W phase of the motors MG1, MG2 from the current sensors 43v, 43w, 44v, 44w that detect the phase currents flowing through the V phase and W phase of the motors MG1, MG2. Examples of the voltage VH of the high-voltage power line 45a from a voltage sensor 47a attached to the positive and negative lines of the high-voltage power line 45a, and the voltage VL of the low-voltage power line 45b from a voltage sensor 48a attached to the positive and negative lines of the low-voltage power line 45b can also be mentioned. Various control signals for driving and controlling the motors MG1, MG2 and the step-up / step-down converter 46 are output from the microcomputer 40a to the ASIC 40b via the output port. Examples of the signals output from the microcomputer 40a to the ASIC 40b include switching control commands for the transistors T11-T16, T21-T26 of the inverters 41, 42, and switching control commands for the transistors T31, T32 of the step-up / step-down converter 46. The microcomputer 40a is connected to the HVECU 70 via a communication port. The microcomputer 40a calculates the electrical angles θe1, θe2, angular velocities ωm1, ωm2, and rotation speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position detection sensors 43a, 44a.The ASIC 40b performs switching control of the transistors T11-T16, T21-T26, T31, and T32 based on switching control commands from the microcomputer 40a for the transistors T11-T16, T21-T26 of the inverters 41 and 42 and switching control commands for the transistors T31 and T32 of the step-up / step-down converter 46. The ASIC 40b is connected to the HVECU 70 via a communication port. By providing the microcomputer 40a and the ASIC 40b, it is possible to reduce the component cost of the motor ECU 40 compared to the case where two microcomputers are provided.

[0021] The main battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the low-voltage power line 45b as shown in Fig. 1. The main battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0022] The battery ECU 52 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. Signals from various sensors required for managing the main battery 50 are input to the battery ECU 52 via the input port. Examples of signals input to the battery ECU 52 include the voltage Vb of the main battery 50 from a voltage sensor attached between the terminals of the main battery 50, the current Ib of the main battery 50 from a current sensor attached to the output terminals of the main battery 50, and the temperature Tb of the main battery 50 from a temperature sensor attached to the main battery 50. The battery ECU 52 is connected to the HVECU 70 via the communication port. The battery ECU 52 calculates the power storage rate SOC of the main battery 50 based on an integrated value of the current Ib of the main battery 50 from the current sensor.

[0023] The auxiliary battery 60 is configured as, for example, a lithium ion secondary battery, a nickel hydrogen secondary battery, or a lead storage battery whose rated voltage is lower than that of the main battery 50, and is connected to the auxiliary power line 45c. In the embodiment, the engine ECU 24, the motor ECU 40, and the battery ECU 52 are connected to the auxiliary power line 45c via a power supply relay, and the HVECU 70 is connected to the auxiliary power line 45c without the power supply relay, and the power supply relay is turned on and off depending on whether the ignition switch 80 is on or off. That is, the engine ECU 24, the motor ECU 40, and the battery ECU 52 operate when the ignition switch 80 is on (when the power supply relay is on), and stop when the ignition switch 80 is off (when the power supply relay is off). The HVECU 70 operates regardless of whether the ignition switch 80 is on or off.

[0024] DC / DC converter 62 is connected to low voltage power line 45b and auxiliary power line 45c, and is controlled by HVECU 70 to step down the power of low voltage power line 45b and supply it to auxiliary power line 45c.

[0025] The HVECU 70 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. Signals from various sensors are input to the HVECU 70 via the input port. Examples of signals input to the HVECU 70 include an ignition signal from an ignition switch 80 and a shift position SP from a shift position sensor 82 that detects the operation position of a shift lever 81. Examples of signals input to the HVECU 70 include an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and a vehicle speed V from a vehicle speed sensor 87. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port.

[0026] In the hybrid vehicle 20 of the embodiment thus configured, basically, the engine 22, motors MG1, MG2, and step-up / step-down converter 46 are controlled by cooperative control between the HVECU 70, engine ECU 24, and motor ECU 40 so as to run in a hybrid driving mode (HV driving) mode in which the engine 22 is operating, or in an electric driving mode (EV driving) mode in which the engine 22 is stopped.

[0027] In the HV driving mode, the HVECU 70 first sets a driving torque Tr* required for the drive shaft 36 based on the accelerator opening Acc and the vehicle speed V, and then multiplies the driving torque Tr* by the rotation speed Nd of the drive shaft 36 (the rotation speed Nm2 of the motor MG2) to set a driving power Pr* required for the drive shaft 36. Next, the HVECU 70 subtracts a charging / discharging power requirement Pb* (a positive value when the main battery 50 is discharging) based on the power storage percentage SOC of the main battery 50 from the driving power Pr* to set a power requirement Pe* required for the engine 22. Then, the target rotation speed Ne* and target torque Te* of the engine 22 and torque commands Tm1* and Tm2* of the motors MG1 and MG2 are set so that the required power Pe* is output from the engine 22 and the running torque Tr* is output to the drive shaft 36, and the target rotation speed Ne* and target torque Te* of the engine 22 are sent to the engine ECU 24, and the torque commands Tm1* and Tm2* of the motors MG1 and MG2 are sent to the microcomputer 40a of the motor ECU 40. The engine ECU 24 performs operation control of the engine 22 (intake air amount control, fuel injection control, ignition control, etc.) so that the engine 22 is operated based on the target rotation speed Ne* and the target torque Te*. The microcomputer 40a generates switching control commands for the transistors T11-T16 and T21-T26 of the inverters 41 and 42 so that the motors MG1 and MG2 are driven by the torque commands Tm1* and Tm2*, and outputs them to the ASIC 40b. The ASIC 40b performs switching control of the transistors T11 to T16 and T21 to T26 based on the switching control command for the transistors T11 to T16 and T21 to T26.

[0028] In the EV driving mode, the HVECU 70 sets the driving torque Tr* in the same manner as in the HV driving mode, sets the torque command Tm1* of the motor MG1 to a value of 0, sets the torque command Tm2* of the motor MG2 so that the driving torque Tr* is output to the drive shaft 36, and transmits the torque commands Tm1* and Tm2* of the motors MG1 and MG2 to the microcomputer 40a of the motor ECU 40. The control of the inverters 41 and 42 by the microcomputer 40a and the ASIC 40b has been described above.

[0029] In the HV driving mode and the EV driving mode, the microcomputer 40a of the motor ECU 40 sets the target voltage VH* of the high-voltage power line 45a so that the motors MG1 and MG2 can be driven by the torque commands Tm1* and Tm2*, generates switching control commands for the transistors T31 and T32 of the step-up / step-down converter 46 so that the voltage VH of the high-voltage power line 45a becomes the target voltage VH*, and outputs the generated switching control command to the ASIC 40b. The ASIC 40b controls the switching of the transistors T31 and T32 based on the switching control commands for the transistors T31 and T32. Such control of the engine 22, the inverters 41 and 42, and the step-up / step-down converter 46 in the HV driving mode and the EV driving mode is referred to as "normal control."

[0030] Next, the operation of the hybrid vehicle 20 of the embodiment thus configured, particularly the operation when a first abnormality, which is an abnormality of the HVECU 70, or a second abnormality, which is a communication abnormality between the HVECU 70 and the microcomputer 40a of the motor ECU 40, occurs in the HV driving mode, will be described. FIG. 3 is a flowchart showing an example of an abnormality-time engine process executed by the engine ECU 24, and FIG. 4 is a flowchart showing an example of an abnormality-time motor converter process executed by the ASIC 40b of the motor ECU 40. The abnormality-time engine process of FIG. 3 is executed when the engine ECU 24 detects the first abnormality or the second abnormality. The abnormality-time motor converter process of FIG. 4 is started to be repeatedly executed when the ASIC 40b detects the first abnormality or the second abnormality. For example, when the communication interruption time with the microcomputer 40a is equal to or longer than a predetermined time T1 (for example, about several seconds), the HVECU 70 detects the second abnormality and transmits a second abnormality signal to the engine ECU 24 or the ASIC 40b, and then terminates the detection of the second abnormality and terminates the transmission of the second abnormality signal. For example, when the communication interruption time with the HVECU 70 is equal to or longer than the predetermined time T1, the microcomputer 40a detects the second abnormality and outputs a second abnormality signal to the ASIC 40b, and when the detection of the second abnormality is terminated thereafter, the output of the second abnormality signal is terminated. For example, the engine ECU 24 detects the first abnormality when the communication interruption time with the HVECU 70 is equal to or longer than the predetermined time T1, and detects the second abnormality when the second abnormality signal is received from the HVECU 70. For example, the ASIC 40b detects the first abnormality when the communication interruption time with the HVECU 70 is equal to or longer than the predetermined time T1, and detects the second abnormality when the second abnormality signal is received or input from the HVECU 70 or the microcomputer 40a.

[0031] In the abnormality engine process of Fig. 3, the engine ECU 24 starts executing the rotation speed control of the engine 22 (step S100) and ends this process. Here, in the rotation speed control, the operation of the engine 22 is controlled so that the engine 22 rotates at a target rotation speed Ne1. The target rotation speed Ne1 will be described later. This rotation speed control is performed until the first abnormality or the second abnormality is resolved or the ignition switch 80 is turned off and the engine ECU 24 stops.

[0032] In the motor converter process during an abnormality in Fig. 4, the ASIC 40b of the motor ECU 40 turns on the three phases of the inverter 41 and also cuts off the gates of the inverter 42 and the step-up / step-down converter 46 (step S200). Turning on the three phases of the inverter 41 is a control for turning on all of the upper arms (transistors T11 to T13) or all of the lower arms (transistors T14 to T16) of the transistors T11 to T16. Cutting off the gates of the inverter 42 is a control for turning off all of the transistors T21 to T26, and cutting off the gates of the step-up / step-down converter 46 is a control for turning off all of the transistors T31 and T32.

[0033] FIG. 5 is an explanatory diagram showing an example of a collinear diagram of the planetary gear 30. In the diagram, the S-axis indicates the rotation speed of the sun gear (the rotation speed Nm1 of the motor MG1), the C-axis indicates the rotation speed of the carrier (the rotation speed Ne of the engine 22), and the R-axis indicates the rotation speed of the ring gear (the rotation speed Nd of the drive shaft 36 and the rotation speed Nm2 of the motor MG2). In addition, in the diagram, "ρ" indicates the gear ratio of the planetary gear 30 (the number of teeth of the sun gear / the number of teeth of the ring gear). When the inverter 41 is turned on in three phases, a torque (so-called drag torque) Td is generated in the motor 32 in a direction that reduces the absolute value of the rotation speed Nm1. When the rotation speed Nm1 of the motor MG1 is a positive value, this drag torque Td becomes a torque in a direction that suppresses the rotation speed Ne of the engine 22 (downward in FIG. 4). Therefore, when the rotation speed control is performed for the engine 22, the drag torque Td generated by the motor MG1 acts on the drive shaft 36 as a torque (-Td / ρ) for forward travel via the planetary gear 30, and the vehicle can perform evacuation travel. The above-mentioned target rotation speed Ne1 is set so that the rotation speed Nm1 of the motor MG1 becomes a positive value even if the rotation speed Nm2 (vehicle speed V) of the motor MG2 is relatively high when the vehicle performs evacuation travel. This target rotation speed Ne1 may be set in advance, or, if communication is possible between the engine ECU 24 and the motor ECU 40, the rotation speed Nm2 of the motor MG2 may be input from the motor ECU 40 to the engine ECU 24 and set based on this rotation speed Nm2. In addition, by blocking the gate of the step-up / step-down converter 46, it is possible to suppress the supply of power from the high-voltage power line 45a (inverter 41, 42 side) to the low-voltage power line 54b (main battery 50 side) during evacuation travel. In addition, when the gate of inverter 42 is cut off, if the back electromotive voltage generated by the rotation of motor MG2 is higher than voltage VH of high-voltage power line 45a, power based on the back electromotive voltage is supplied to high-voltage power line 45a, and voltage VH of high-voltage power line 45a increases.

[0034] When a voltage reduction request is input from the microcomputer 40a while the inverter 41 is in the three-phase ON state and the inverter 42 and the step-up / step-down converter 46 are in the gate-off state, the step-up / step-down converter 46 is switched from gate-off to upper arm ON (step S220). Here, turning on the upper arm of the step-up / step-down converter 46 is a control for turning on and maintaining the upper arm (transistor T31). When the voltage VH of the high-voltage power line 45a from the voltage sensor 47a reaches or exceeds a threshold VHref1, the microcomputer 40a outputs a voltage reduction request to the ASIC 40b until the voltage VH falls below a threshold VHref2 that is equal to or lower than the threshold VHref1. The threshold VHref1 is set based on the durability of the capacitor 47 and the high-voltage power line 45a. By turning on the upper arm of the step-up / step-down converter 46, a current flows from the positive line of the high-voltage power line 45a to the positive line of the low-voltage power line 45b via the transistor T31 and the reactor of the step-up / step-down converter 46, so that a further increase in the voltage VH of the high-voltage power line 45a is suppressed, and the voltage VH can be prevented from reaching an overvoltage. After that, when the voltage reduction request is no longer input from the microcomputer 40a (step S230), the step-up / step-down converter 46 is switched from the upper arm on to the gate cutoff (step S240), and this process is terminated. This process is repeatedly executed until the first abnormality or the second abnormality is resolved or the ignition switch 80 is turned off and the motor ECU 40 is stopped.

[0035] 6 is an explanatory diagram showing an example of the operation of the engine 22, the inverters 41, 42, and the step-up / step-down converter 46, the voltage VH of the high-voltage power line 45a, and the presence or absence of a voltage reduction request when the engine ECU 24 and the ASIC 40b detect the first or second abnormality of the rotation speed Nm2 (vehicle speed V) of the motor MG2. As shown in the figure, when the engine ECU 24 and the ASIC 40b detect the first or second abnormality (time t11), the engine ECU 24 switches the engine 22 from normal control to rotation speed control, and the ASIC 40b switches the inverter 41 from normal control to three-phase on, and switches the inverter 42 and the step-up / step-down converter 46 from normal control to gate cutoff. As a result, as described above, it is possible to perform evacuation running using the drag torque Td generated by the motor MG1. When the back electromotive force generated by the rotation of motor MG2 is higher than voltage VH of high-voltage power line 45a, power based on the back electromotive force is supplied to high-voltage power line 45a, causing voltage VH of high-voltage power line 45a to rise. When voltage VH of high-voltage power line 45a reaches or exceeds threshold value VHref1 and a voltage reduction request is input from microcomputer 40a to ASIC 40b (time t12), ASIC 40b switches boost / buck converter 46 from gate-off to upper arm-on. This makes it possible to suppress a further rise in voltage VH of high-voltage power line 45a and prevent voltage VH from reaching an overvoltage.

[0036] In the hybrid vehicle 20 of the embodiment described above, the engine ECU 24 controls the rotation speed of the engine 22 when the first or second abnormality is detected. In addition, the ASIC 40b of the motor ECU 40 turns on the three phases of the inverter 41 and blocks the gates of the inverter 42 and the step-up / step-down converter 46 when the ASIC 40b of the motor ECU 40 detects the first or second abnormality. This makes it possible to perform evacuation running while suppressing the supply of power from the high-voltage power line 45a to the low-voltage power line 45b. Then, when this control is being performed, if the voltage VH of the high-voltage power line 45a reaches or exceeds the threshold value VHref1, the upper arm of the step-up / step-down converter 46 is turned on. This makes it possible to suppress a further increase in the voltage VH of the high-voltage power line 45a and to prevent the voltage VH from reaching an overvoltage.

[0037] In the hybrid vehicle 20 of the embodiment, the voltage VH of the high-voltage power line 45a is input to the microcomputer 40a of the motor ECU 40. However, the voltage VH of the high-voltage power line 45a may be input to the microcomputer 40a and the ASIC 40b of the motor ECU 40. In this case, when the engine ECU 24 controls the rotation speed of the engine 22 and the ASIC 40b of the motor ECU 40 turns on the three phases of the inverter 41 and blocks the gates of the inverter 42 and the step-up / step-down converter 46, this control may be continued even when a third abnormality, which is an abnormality of the microcomputer 40a, occurs, and when the voltage VH of the high-voltage power line 45a input to the ASIC 40b reaches or exceeds the threshold value VHref1, the ASIC 40b may turn on the upper arm of the step-up / step-down converter 46. In this way, even if a third abnormality occurs in addition to the first and second abnormalities, evacuation travel can be performed and voltage VH of high-voltage power line 45a can be prevented from reaching an overvoltage.

[0038] In the hybrid vehicle 20 of the embodiment, the ASIC 40b of the motor ECU 40 turns on the three phases of the inverter 41 when it detects the first abnormality or the second abnormality. However, it may be configured to shut off the gate of the inverter 41. In this case, the above-mentioned target rotation speed Ne1 is set so that the back electromotive voltage generated with the rotation of the motor MG1 is higher than the voltage VH of the high-voltage power line 45a, and the rotation speed of the engine 22 is controlled, whereby a back electromotive voltage torque Tbv1 is generated based on the back electromotive voltage generated in the motor MG1, and this back electromotive voltage torque Tbv1 acts on the drive shaft 36 as a torque (-Tbv1 / ρ) for forward running via the planetary gear 30, thereby enabling evacuation running. The target rotation speed Ne1 may be set in advance, or, if communication is possible between the engine ECU 24 and the motor ECU 40, the target rotation speed Ne1 may be set based on the voltage VH of the high-voltage power line 45a input from the motor ECU 40 to the engine ECU 24.

[0039] As shown in Fig. 1, the hybrid vehicle 20 of the embodiment includes the engine 22, the planetary gear 30, the motors MG1 and MG2, the inverters 41 and 42, the step-up / step-down converter 45, and the main battery 50. However, as shown in a modified hybrid vehicle 120 of Fig. 7, the hardware configuration may be such that the planetary gear 30, the motor MG1, and the inverter 41 are removed from the hybrid vehicle 20 of Fig. 1 and a clutch 128, a transmission 130, and a transmission electronic control unit (hereinafter referred to as "transmission ECU") 140 are added.

[0040] Clutch 128 is configured as, for example, a hydraulically driven friction clutch, is disposed between engine 22 and motor MG2, and is on / off controlled by transmission ECU 140 to connect and disconnect engine 22 and motor MG2. Transmission 130 has an input shaft connected to the rotating shaft of motor MG2, an output shaft connected to drive shaft 36, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches, brakes). Transmission 130 forms multiple forward and reverse gears by engaging and disengaging the multiple friction engagement elements by transmission ECU 140, and transmits power between the input shaft and the output shaft.

[0041] The gear shift ECU 140 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The rotation speed of the input shaft of the transmission 130, the rotation speed of the output shaft of the transmission 130, and the like are input to the gear shift ECU 140 via the input port. A control signal to the clutch 128, a control signal to the transmission 130, and the like are output from the gear shift ECU 140 via the output port. The gear shift ECU 140 is connected to the HVECU 70 via the communication port.

[0042] In the hybrid vehicle 120 thus configured, when the HVECU 70 detects the second abnormality, it transmits the second abnormality signal to the engine ECU 24, the ASIC 40b, and also to the transmission ECU 140, and when it subsequently ends the detection of the second abnormality, it ends the transmission of the second abnormality signal. The transmission ECU 140, like the engine ECU 24, detects the first abnormality when, for example, the communication interruption time with the HVECU 70 is equal to or longer than the predetermined time T1, and detects the second abnormality when it receives the second abnormality signal from the HVECU 70.

[0043] Next, the operation when the engine ECU 24, the ASIC 40b of the motor ECU 40, and the transmission ECU 140 detect the first or second abnormality in the HV traveling mode will be described. The engine ECU 24 performs the above-mentioned rotation speed control for the engine 22. The ASIC 40b performs gate blocking for the inverter 42 and the step-up / step-down converter 46. The transmission ECU 140 holds the clutch 128 on and controls the transmission 130 to a gear stage for evacuation traveling. This makes it possible to perform evacuation traveling while suppressing the supply of power from the high-voltage power line 45a (inverter 42 side) to the low-voltage power line 54b (main battery 50 side). At this time, when the counter electromotive voltage generated by the rotation of the motor MG2 is higher than the voltage VH of the high-voltage power line 45a, power based on the counter electromotive voltage is supplied to the high-voltage power line 45a, and the voltage VH of the high-voltage power line 45a increases. Then, when the voltage VH of the high-voltage power line 45a reaches or exceeds the threshold VHref1, a voltage reduction request is input from the microcomputer 40a to the ASIC 40b, and the ASIC 40b switches the gate of the buck-boost converter 46 from being cut off to being turned on by the upper arm. This makes it possible to suppress a further increase in the voltage VH of the high-voltage power line 45a and to prevent the voltage VH from reaching an overvoltage.

[0044] In the hybrid vehicle 20 of the embodiment, the motor ECU 40 includes the microcomputer 40a and the ASIC 40b. However, the motor ECU 40 may include a sub-microcomputer instead of the ASIC 40b. The engine ECU 24 may also include a microcomputer and an ASIC.

[0045] The hybrid vehicle 20 of the embodiment includes the engine ECU 24, the motor ECU 40, the battery ECU 52, and the HVECU 70. However, at least two of the engine ECU 24, the motor ECU 40, and the battery ECU 52 may be integrated.

[0046] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described. In the embodiment, the engine 22 corresponds to the "engine", the motor MG2 corresponds to the "motor", the inverter 42 corresponds to the "inverter", the capacitor 47 corresponds to the "capacitor", the main battery 50 corresponds to the "electricity storage device", the step-up / step-down converter 46 corresponds to the "step-up / step-down converter", the HVECU 70 corresponds to the "first control device", and the engine ECU 24, the motor ECU 40, and the battery ECU 52 correspond to the "second control device". In addition, the microcomputer 40a corresponds to the "first processing unit", and the ASIC 40b corresponds to the "second processing unit". Furthermore, the motor MG1 corresponds to the "second motor", the planetary gear 30 corresponds to the "planetary gear", and the inverter 41 corresponds to the "second inverter".

[0047] The correspondence between the main elements of the Examples and the main elements of the invention described in the Summary of the Problem column does not limit the elements of the invention described in the Summary of the Problem column, since the Examples are examples for specifically explaining the mode for implementing the invention described in the Summary of the Problem column. In other words, the interpretation of the invention described in the Summary of the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Summary of the Problem column.

[0048] Although the form for carrying out the present invention has been described above using examples, the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the gist of the present invention. [Industrial Applicability]

[0049] The present invention can be used in the hybrid vehicle manufacturing industry and the like. [Explanation of symbols]

[0050] 20,120 Hybrid vehicle, 22 Engine, 23 Crankshaft, 24 Engine ECU, 30 Planetary gear, 32 Motor, 36 Drive shaft, 38 Differential gear, 39a, 39b Drive wheel, 40a Microcomputer, 40b ASIC, 41, 42 Inverter, 43a, 44a Rotational position detection sensor, 43v, 43w, 44v, 44w Current sensor, 45a High voltage power line, 45b Low voltage power line, 45c Auxiliary power line, 46 Step-up / step-down converter, 47, 48 Capacitor, 47a, 48a Voltage sensor, 50 Main battery, 60 Auxiliary battery, 62 DC / DC converter, 70 HVECU, 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accelerator pedal, 84 Accelerator pedal position sensor, 85 Brake pedal, 86 brake pedal position sensor, 87 vehicle speed sensor, D11 to D16, D21 to D26, D31, D32 diodes, MG1 motor (second motor), MG2 motor (motor), T11 to T16, T21 to T26, T31, T32 transistors.

Claims

1. An engine and a motor connected to the drive wheels; an inverter connected to a first power line and configured to drive the motor by switching a plurality of switching elements; a capacitor attached to the first power line; a power storage device connected to the second power line; a buck-boost converter including an upper arm switching element connected to a positive line of the first power line, a lower arm switching element connected to a negative line of the first power line and the second power line, and a reactor connected to a connection point of the upper arm switching element and the lower arm switching element and the positive line of the second power line, the buck-boost converter being capable of exchanging power involving voltage conversion between the first power line and the second power line; A first control device that sets a driving command; a second control device that is communicatively connected to the first control device and that controls the engine, the inverter, and the step-up / step-down converter based on the driving command from the first control device; A hybrid vehicle comprising: The second control device is When a first abnormality, which is an abnormality of the first control device, or a second abnormality, which is an abnormality in communication with the first control device, is detected, a first control is executed to control the engine, the inverter, and the step-up / step-down converter so as to run with operation of the engine and gate blocking of the inverter and the step-up / step-down converter; when the voltage of the first power line reaches or exceeds a predetermined voltage during execution of the first control, the upper arm switching element of the step-up / step-down converter is turned on. Hybrid vehicle.

2. 2. The hybrid vehicle according to claim 1, the second control device has a first processing unit that sets control commands for the inverter and the step-up / step-down converter based on the running command from the first control device, and a second processing unit that controls the inverter and the step-up / step-down converter based on the control commands for the inverter and the step-up / step-down converter set by the first processing unit, The second processing unit performs gate cutoff for the inverter and the step-up / step-down converter when the first abnormality or the second abnormality is detected. Hybrid vehicle.

3. 3. The hybrid vehicle according to claim 2, The second processing unit performs gate cutoff for the inverter and the step-up / step-down converter when it detects a third abnormality, which is an abnormality of the first processing unit, in addition to when it detects the first abnormality or the second abnormality. Hybrid vehicle.

4. A hybrid vehicle according to any one of claims 1 to 3, A second motor; a planetary gear connected to three shafts, i.e., the second motor, the engine, and a drive shaft connected to the drive wheels, such that three rotating elements are arranged in the order of the second motor, the engine, and the drive shaft in a collinear diagram; a second inverter connected to the first power line and configured to drive the second motor by switching a plurality of switching elements; Further comprising: The motor is connected to the drive shaft, The second control device controls the engine, the inverter, the step-up / step-down converter, and the second inverter based on the running command from the first control device, The second control device, as the first control, controls the engine to rotate at a predetermined rotation speed, performs gate cutoff for the inverter and the step-up / step-down converter, and performs three-phase on or gate cutoff for the second inverter. Hybrid vehicle.

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