Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device capable of curbing generation of overvoltage and preventing a driver from having a feeling of strangeness when a vehicle performs battery-less travel.SOLUTION: An electronic control device 80 is for a hybrid vehicle 10 comprising an engine 12, a generator MG1 connected to the engine 12 and an electric motor MG2 connected to a pair of drive wheels 32 so as to allow drive force to be transmitted thereto. When detecting generation of overvoltage due to power generation through the generator MG1 during battery-less travel with the engine 12 activated, the electronic control device increases d-axis current supplied to the electric motor MG2 prior to a reduction in engine torque Te which is output torque of the engine 12. Thus, the electronic control device can curb the generation of overvoltage and prevent a driver from having a feeling of strangeness in a manner that prevents drive force for traveling unintended by the driver from being transmitted to the pair of drive wheels 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle including an engine, a generator connected to the engine, and an electric motor connected to a pair of drive wheels so as to be capable of transmitting power thereto. [Background technology]

[0002] In a hybrid vehicle having an engine, a generator driven by the engine, and an electric motor connected to a pair of drive wheels so as to be capable of transmitting power, when a battery connected to the generator and the electric motor becomes abnormal (e.g., breaks down) during driving, a control device for the hybrid vehicle is known that (a) increases the absolute value of the negative d-axis current so as to cancel out the positive field current caused by the back electromotive force generated by the rotation of the electric motor, and then (b) disconnects the battery from the generator and the electric motor to prevent overvoltage from occurring at the time of disconnection. For example, the control device for the hybrid vehicle described in Patent Document 1 is such a control device. After disconnecting the battery from the generator and the electric motor, the control device for the hybrid vehicle described in Patent Document 1 enables driving without using battery power, i.e., batteryless driving, by, for example, balancing the power generated by the generator and the power consumed by the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-233109 A Summary of the Invention [Problem to be solved by the invention]

[0004] In battery-less driving, the power generated by the generator is consumed not only by the motor but also by auxiliary devices, etc., but the power consumption by the auxiliary devices, etc. may not be constant and may change suddenly. For example, when the power consumption by the auxiliary devices, etc. suddenly decreases, it is possible to increase the power consumption by the motor in order to balance the power generated by the generator and the power consumption consuming the generated power. However, when the power consumption by the motor is increased, the driving force for driving output from the motor increases due to this, and this increased driving force for driving may be transmitted to a pair of driving wheels. Since this increase in the driving force for driving is not intended by the driver, it may cause the driver to feel uncomfortable. On the other hand, when the power consumption of the motor is not increased, the balance between the power generated by the generator and the power consumption consuming the generated power is lost, and an overvoltage may occur.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device for a hybrid vehicle that can suppress the occurrence of overvoltage during battery-less driving while suppressing the discomfort felt by the driver. [Means for solving the problem]

[0006] The gist of the first invention is as follows: (a) A control device for a hybrid vehicle including an engine, a generator connected to the engine, and an electric motor connected to a pair of drive wheels so as to be capable of transmitting power thereto, (b) When it is determined that an overvoltage occurs due to power generation by the generator during battery-less running with the engine operating, an increase in the d-axis current supplied to the electric motor is executed with priority over a decrease in the output torque of the engine. (c) the determination that an overvoltage occurs due to the power generation of the generator is made based on at least one of the following: a power difference between the power generated by the generator and the power consumed by a device that consumes the generated power exceeds a predetermined power value; and a voltage of a power line pair, which outputs the generated power after being converted to direct current by an inverter, exceeds a predetermined voltage value. (d) the generator and the electric motor are the same rotating electric machine. The point is that. Effect of the Invention

[0007] According to the control device for a hybrid vehicle of the first invention, when it is determined that an overvoltage will occur due to the power generation of the generator during batteryless running with the engine operating, the d-axis current supplied to the electric motor is increased with priority over a decrease in the output torque of the engine. As a result, during batteryless running, the power consumed by the auxiliary equipment, etc. is generated by the generator, and even if the power consumption of the auxiliary equipment, etc. suddenly decreases, the occurrence of an overvoltage can be suppressed by increasing the d-axis current supplied to the electric motor. Furthermore, the increase in the d-axis current prevents the driving force for driving that is not intended by the driver from being transmitted to a pair of drive wheels, thereby suppressing the discomfort felt by the driver. In addition, if the power difference between the power generated by the generator and the power consumption by devices such as auxiliary machinery that consume the generated power exceeds a predetermined power value, or if the voltage of a power line pair in which the power generated by the generator is converted to direct current by an inverter and output exceeds a predetermined voltage value, it can be determined that an overvoltage has occurred. Furthermore, even when a single rotating electric motor functions as both a generator and an electric motor, the occurrence of overvoltage is suppressed, and the transmission of driving force for driving unintended by the driver to a pair of drive wheels is prevented, thereby reducing the discomfort felt by the driver. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to a first embodiment of the present invention, and is also a functional block diagram showing essential parts of control functions for various controls in the hybrid vehicle. [Diagram 2] 2 is an example of a flowchart illustrating a main part of a control operation of the electronic control device shown in FIG. [Diagram 3] FIG. 11 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to a second embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. Note that in each embodiment, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of each part are not necessarily drawn accurately. EXAMPLES

[0012] FIG. 1 is a schematic configuration diagram of a hybrid vehicle 10 equipped with an electronic control device 80 according to a first embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle 10.

[0013] The hybrid vehicle 10 (hereinafter, simply referred to as "vehicle 10") includes an engine 12, a connecting shaft 22, a mechanical oil pump MOP, a power split mechanism 34, a generator MG1, an electric motor MG2, an AT input shaft 26, an automatic transmission 18, an AT output shaft 28, a differential gear 40, and a pair of axles 30. The mechanical oil pump MOP, the power split mechanism 34, the generator MG1, the electric motor MG2, and the automatic transmission 18 are housed in a case 20. The vehicle 10 also includes an electric oil pump EOP, a hydraulic control circuit 44, an inverter 60, an air conditioner 66, a main battery 70, a system main relay 72, a pair of power lines 74, an auxiliary battery 76, a DC / DC converter 78, and an electronic control device 80. The engine 12 and the electric motor MG2 are a driving force source for driving the vehicle 10, and a path for transmitting the driving force for driving from the driving force source for driving to a pair of drive wheels 32 is a power transmission path PT.

[0014] The engine 12 is a well-known internal combustion engine. An electronic control device 80 controls an engine control device 68, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, provided in the vehicle 10, to control an engine torque Te [Nm] outputted from the engine 12. In this specification, the terms torque and driving force are synonymous unless otherwise specified.

[0015] The generator MG1 and the electric motor MG2 are so-called motor generators, for example, three-phase synchronous motor generators. In battery-less running described later, the generator MG1 is used as a generator, and the electric motor MG2 is used as an electric motor.

[0016] The generator MG1, the electric motor MG2, and the electric oil pump EOP are each connected to the main battery 70 via an inverter 60. The inverter 60 is provided between the generator MG1 and the power line pair 74, between the electric motor MG2 and the power line pair 74, and between the electric oil pump EOP and the power line pair 74, and is a power supply circuit that converts DC to AC or AC to DC by being controlled by an electronic control device 80. For example, the inverter 60 converts the DC supplied from the main battery 70 to the power line pair 74 into a three-phase AC and outputs it to the generator MG1 or the electric motor MG2, or converts the three-phase AC generated by the generator MG1 or the electric motor MG2 into a DC and outputs it to the power line pair 74. The inverter 60 also converts the DC supplied from the main battery 70 to the power line pair 74 into a three-phase AC and outputs it to the electric oil pump EOP to drive it. For example, the electric oil pump EOP is a well-known oil pump that can be driven by the rotation of an EOP drive motor, such as a three-phase synchronous motor.

[0017] The inverter 60 is controlled by the electronic control device 80, thereby controlling the MG1 output torque Tmg1 [Nm] which is the torque output from the generator MG1 and the MG2 output torque Tmg2 [Nm] which is the torque output from the electric motor MG2. For example, in the case of positive rotation, the MG1 output torque Tmg1 and the MG2 output torque Tmg2 are powering torque when the positive torque is on the acceleration side, and are regenerative torque when the negative torque is on the deceleration side. When the MG2 output torque Tmg2 is powering torque, it means that a driving force for traveling is being output from the electric motor MG2.

[0018] A capacitor C is connected between the positive and negative pole lines of the power line pair 74 connected to the inverter 60, and smoothes the DC voltage VH [V] between the positive and negative pole lines. The DC voltage VH is the DC voltage of the power line pair 74. The inverter 60 functions as a power control unit (PCU) that controls the drive of the generator MG1, the electric motor MG2, and the electric oil pump EOP.

[0019] The power split mechanism 34 is provided between the engine 12 and the automatic transmission 18, and is configured, for example, with a planetary gear device. The power split mechanism 34 mechanically splits the driving force output from the engine 12 to the generator MG1 and an intermediate transmission member 36. The electric motor MG2 is connected to the intermediate transmission member 36 so as to be capable of transmitting power. The intermediate transmission member 36 is connected to the AT input shaft 26, which is the input shaft of the automatic transmission 18. The power split mechanism 34 functions as an electric continuously variable transmission in which the differential state of the planetary gear device that constitutes the power split mechanism 34 is controlled by controlling the operating state of the generator MG1.

[0020] The generator MG1 generates electricity by the driving force of the engine 12 split to the generator MG1 in the power split mechanism 34. The generated power Wg1 by the generator MG1 is stored in a capacitor C connected to a power line pair 74 via the inverter 60 and further charged to the main battery 70 via the system main relay 72, and the generated power Wg1 drives and rotates the electric motor MG2. The driving force of the engine 12 split to the intermediate transmission member 36 in the power split mechanism 34 is input to the automatic transmission 18 via the AT input shaft 26 as driving force for traveling.

[0021] The automatic transmission 18 is a well-known automatic transmission, and a desired gear ratio is formed from among different gear ratios γ by a hydraulic control circuit 44 controlled by an electronic control device 80. For example, a plurality of solenoid valves for controlling the gear shift of the automatic transmission 18 are provided in the hydraulic control circuit 44, and the on / off combinations of the drive currents of the plurality of solenoid valves are switched to switch the connected / disconnected states of hydraulic engagement devices such as clutches and brakes provided in the automatic transmission 18, so that the gear ratio γ of the automatic transmission 18 becomes the desired gear ratio. An AT output shaft 28, which is the output shaft of the automatic transmission 18, is connected to a pair of drive wheels 32 via a differential gear 40 and a pair of axles 30.

[0022] The main battery 70 is a chargeable and dischargeable secondary battery, and is mainly used to discharge (supply) power for driving the generator MG1, the electric motor MG2, and the electric oil pump EOP, and to charge the regenerative power Wg1 generated by the generator MG1 and the regenerative power Wg2 generated by the electric motor MG2. The main battery 70 is connected to a power line pair 74 via a system main relay 72. The system main relay 72 is, for example, a mechanical relay that is switched between a connected state and an open state by the electronic control device 80, and is provided on each of the positive and negative lines between the main battery 70 and the power line pair 74.

[0023] The auxiliary battery 76 is a chargeable and dischargeable secondary battery, and is mainly used to supply power to the auxiliary devices (such as the engine control device 68, various sensors, and switches). Due to differences in use, the auxiliary battery 76 has a smaller charge capacity [mAh], which is the maximum capacity of a battery that can store electricity, compared to the main battery 70. In addition, the main battery 70 has a higher battery voltage Vbat [V] compared to the auxiliary battery 76. For example, the auxiliary battery 76 has a voltage of 12 [V], whereas the main battery 70 has a higher voltage.

[0024] DC / DC converter 78 is a power supply circuit that is provided between power line pair 74 and auxiliary battery 76 and that boosts or lowers the voltage of a direct current. For example, DC / DC converter 78 lowers DC voltage VH of power line pair 74 and charges auxiliary battery 76 with a direct current having a lower voltage than DC voltage VH, or boosts the direct current supplied from auxiliary battery 76 and outputs a direct current having a higher voltage than auxiliary battery 76 to power line pair 74.

[0025] Air conditioner 66 is a device that adjusts the temperature and humidity of the air inside the vehicle cabin, and is connected to power line pair 74. For example, when air conditioner 66 is in operation, the power stored in capacitor C connected to power line pair 74 is consumed by air conditioner 66.

[0026] In the vehicle 10, for example, an engine driving mode in which the vehicle runs by operating at least the engine 12 among the driving power sources for running, and an EV driving mode in which the vehicle runs with the engine 12 stopped (stopped) can be selected. The engine driving mode is generally selected in a region where a high required driving force, i.e., a high load, is required. The EV driving mode is generally selected in a region where a low required driving force, i.e., a low load, is required.

[0027] The mechanical oil pump MOP is disposed on the connecting shaft 22. The mechanical oil pump MOP is a well-known oil pump that is rotationally driven by the engine 12. When at least one of the electric oil pump EOP and the mechanical oil pump MOP is driven, oil is pressure-fed to the hydraulic control circuit 44. This oil is, for example, ATF (Automatic Transmission Fluid) or the like.

[0028] The electronic control device 80 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 80 corresponds to the "control device" in the present invention.

[0029] The electronic control device 80 receives various signals based on detection values ​​from various sensors provided on the vehicle 10 (e.g., accelerator opening sensor 90, engine rotation speed sensor 92, output shaft rotation speed sensor 94, battery sensor 96, MG1 rotation speed sensor 98a, MG2 rotation speed sensor 98b, etc.) (e.g., accelerator opening θacc [%] as an acceleration operation amount indicating the magnitude of the acceleration operation by the driver, engine rotation speed Ne [rpm], output shaft rotation speed Nout [rpm] which is the rotation speed of the AT output shaft 28 corresponding to the vehicle speed V [km / h], battery temperature THbat [°C], battery current Ibat [A], battery voltage Vbat [V] of the main battery 70, MG1 rotation speed Nmg1 [rpm] which is the rotation speed of the generator MG1, MG2 rotation speed Nmg2 [rpm] which is the rotation speed of the electric motor MG2, etc.).

[0030] The electronic control device 80 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an MG1 control signal Smg1, an MG2 control signal Smg2, and an EOP control signal Seop for respectively controlling the rotation of the generator MG1, the rotation of the electric motor MG2, and the rotation of the electric oil pump EOP via the inverter 60, a hydraulic control signal Sp for controlling the shifting of the automatic transmission 18, a converter control signal Scon for controlling the voltage conversion of the DC / DC converter 78, and a relay control signal Ssmr for controlling the opening and closing of the system main relay 72) to each device (e.g., an engine control device 68, an inverter 60, a hydraulic control circuit 44, a DC / DC converter 78, a system main relay 72, etc.) provided in the vehicle 10.

[0031] The electronic control device 80 calculates a required driving force, which is a target value of the driving force to be output to the pair of drive wheels 32 (i.e., a target value of the driving force to be output to the AT output shaft 28), based on, for example, the accelerator opening θacc and the vehicle speed V. The engine 12, the generator MG1, the electric motor MG2, and the automatic transmission 18 are each controlled so that this required driving force is output to the AT output shaft 28.

[0032] Incidentally, when the main battery 70 is in an unusable state due to an abnormality or functional restrictions, it is desirable for the vehicle 10 to be able to run battery-less in order to run for evacuation. Evacuation running means that the vehicle 10 continues to run in order to stop at a safe place even if some kind of malfunction occurs during running, and battery-less running means running that is performed without using a battery (in this embodiment, the main battery 70).

[0033] Returning to FIG. 1, the electronic control device 80 functionally comprises a battery state determination unit 82, an SMR control unit 84, and a driving control unit 86.

[0034] The battery state determination unit 82 determines whether the main battery 70 is in an unusable state while the vehicle is traveling. For example, the battery temperature THbat, the battery current Ibat, and the battery voltage Vbat of the main battery 70 detected by the battery sensor 96 are compared with predetermined determination values ​​for them to determine whether an abnormality has occurred in the main battery 70 and the main battery 70 is in an unusable state. The predetermined determination values ​​are predetermined values ​​for determining that an abnormality has occurred in the main battery 70 that renders the main battery 70 unusable, and are, for example, values ​​that have been experimentally or design-wise determined for each of the battery temperature THbat, the battery current Ibat, and the battery voltage Vbat. For example, when the main battery 70 cannot be used due to a temporary functional restriction, the main battery 70 is determined to be in an unusable state.

[0035] When the battery state determination unit 82 determines that the main battery 70 is in an unusable state while the vehicle is running, the SMR control unit 84 opens the system main relay 72 to cut off the power supply from the main battery 70 to the generator MG1, the electric motor MG2, and the electric oil pump EOP. If the vehicle is running in the EV running mode, the engine 12 is started by cranking using the driven force input from the pair of drive wheels 32, for example, and the vehicle is run in the engine running mode (battery-less running).

[0036] When the battery state determination unit 82 determines that the main battery 70 is in an unusable state while the vehicle is running, the running control unit 86 continues running by batteryless running. In this embodiment, the MG2 output torque Tmg2 of the electric motor MG2 is set to zero during this batteryless running.

[0037] The traveling control unit 86 operates the engine 12 so that the required driving force is transmitted to the pair of drive wheels 32 via the intermediate transmission member 36, and also continues traveling by having the generator MG1 generate electricity to cover the power consumption Wc [W] of the accessories, etc., including the air conditioner 66. In this specification, the term "accessories, etc." includes accessories (such as the engine control device 68, various sensors, switches, etc.) that consume power via the auxiliary battery 76, as well as devices that consume the generated power Wg1 of the generator MG1, such as the air conditioner 66, but does not include the electric motor MG2.

[0038] During battery-less running, the power consumption Wc of the auxiliaries and the like may suddenly change. For example, when the air conditioner 66 changes from an operating state to a non-operating state, the power consumption Wc of the auxiliaries and the like suddenly decreases. If the power consumption Wc of the auxiliaries and the like suddenly decreases, the generated power Wg1 of the generator MG1 may exceed the power consumption Wc, which may cause an overvoltage in the vehicle 10 (for example, in the DC voltage VH of the power line pair 74). If the DC voltage VH of the power line pair 74 becomes an overvoltage, the durability of the capacitor C may decrease.

[0039] In order to avoid the occurrence of overvoltage within the vehicle 10, it is conceivable to charge the auxiliary battery 76, for example, via a DC / DC converter 78. However, since the charging capacity of the auxiliary battery 76 is smaller than that of the main battery 70, the effect of suppressing the occurrence of overvoltage is also limited.

[0040] The traveling control unit 86 functionally includes an engine control unit 86a, an MG control unit 86b, a hydraulic control unit 86c, and an overvoltage determination unit 86d. The MG control unit 86b functions as an overvoltage suppression control unit that suppresses overvoltage.

[0041] To continue battery-less running, the engine control unit 86a controls the engine 12 so that the required driving force is transmitted to the pair of drive wheels 32 and the generator MG1 generates power equivalent to the power consumed by the accessories, etc. The MG control unit 86b controls the MG1 output torque Tmg1 as a reaction torque against the engine torque Te so that the generator MG1 generates power equivalent to the power consumed by the accessories, etc. The hydraulic control unit 86c controls the hydraulic control circuit 44 so as to form a desired gear ratio in the automatic transmission 18. Through the control of the engine control unit 86a, the MG control unit 86b, and the hydraulic control unit 86c, the driving force of the engine 12 divided by the intermediate transmission member 36 in the power dividing mechanism 34 is transmitted to the pair of drive wheels 32 as the required driving force.

[0042] Here, in a rotating coordinate system that rotates around the axis of the rotor of the electric motor MG2, the axis along the direction of the magnetic flux created by the magnetic poles of the rotor of the electric motor MG2 (for example, the central axis of the permanent magnet in an interior magnet synchronous motor generator) is defined as the d-axis, and the axis that is electrically phase-advanced by 90° from the d-axis is defined as the q-axis. Of the supply current supplied to the coil wound on the stator of the electric motor MG2, the current component of the flux linkage created by the supply current that forms the d-axis is called the d-axis current, and the current component of the flux linkage created by the supply current that forms the q-axis is called the q-axis current. The d-axis current supplied to the electric motor MG2 creates flux linkage in the same direction as the magnetic flux created by the magnetic poles of the rotor, so the d-axis current consumes the generated power Wg1 of the generator MG1 but does not cause the electric motor MG2 to output drive torque. On the other hand, the q-axis current supplied to the motor MG2 creates a flux linkage perpendicular to the magnetic flux created by the rotor poles, causing the motor MG2 to output a driving torque. In other words, the driving torque output by the q-axis current supplied to the motor MG2 is the MG2 output torque Tmg2 of the motor MG2.

[0043] The overvoltage determination unit 86d determines whether the DC voltage VH of the power line pair 74 is within a controllable range, i.e., within a range in which an overvoltage does not occur. For example, the overvoltage determination unit 86d determines whether the DC voltage VH of the power line pair 74, which is obtained by converting the generated power Wg1 of the generator MG1 into a direct current and outputting it by the inverter 60, is equal to or lower than a predetermined voltage value VH_jdg [V]. The predetermined voltage value VH_jdg is a determination value that is determined in advance experimentally or by design in order to determine that an overvoltage does not occur due to power generation by the generator MG1, and is determined as an upper limit value of a range in which a decrease in durability is practically tolerable without applying an overload to a component (e.g., the capacitor C) electrically connected to the inverter 60. If the state in which the DC voltage VH exceeds the predetermined voltage value VH_jdg continues, the durability of the component electrically connected to the inverter 60 may decrease due to the overvoltage caused by the power generation by the generator MG1.

[0044] When the overvoltage determination unit 86d determines that the DC voltage VH of the power line pair 74 is outside the controllable range, i.e., that an overvoltage will occur, the engine control unit 86a and the MG control unit 86b cooperate to change the engine torque Te in response to a sudden change in the power consumption Wc of the accessories, etc., and to change the d-axis current supplied to the electric motor MG2.

[0045] Specifically, when the power consumption Wc of the accessories etc. suddenly decreases, the engine control unit 86a correspondingly decreases (lowers) the engine torque Te, and when the power consumption Wc of the accessories etc. suddenly increases, the engine control unit 86a correspondingly increases the engine torque Te. Also, when the power consumption Wc of the accessories etc. suddenly decreases, the MG control unit 86b correspondingly increases the d-axis current of the electric motor MG2, and when the power consumption Wc of the accessories etc. suddenly increases, the MG control unit 86b correspondingly decreases the d-axis current of the electric motor MG2.

[0046] The control of the engine torque Te by the engine control unit 86a is inferior in responsiveness to the control of the d-axis current by the electric motor MG2. Therefore, for example, when the power consumption Wc in the auxiliary equipment or the like suddenly decreases, the increase in the d-axis current of the electric motor MG2 by the MG control unit 86b is executed with priority over the decrease in the engine torque Te by the engine control unit 86a. The "priority" here means that when it is determined that an overvoltage occurs in the vehicle 10 (for example, the DC voltage VH of the power line pair 74), the d-axis current of the electric motor MG2 is increased before the decrease in the engine torque Te in order to quickly prevent the overvoltage from occurring. Therefore, when the engine torque Te decreases in response to a sudden decrease in the power consumption Wc, the increased d-axis current of the electric motor MG2 is decreased.

[0047] Fig. 2 is an example of a flowchart illustrating a main part of the control operation of the electronic control device 80 shown in Fig. 1. The flowchart in Fig. 2 is repeatedly executed while the vehicle is traveling.

[0048] First, in step S10, which corresponds to the function of the battery state determination unit 82, it is determined whether or not an abnormality has occurred in the main battery 70 while the vehicle is traveling and the main battery 70 is in an unusable state. If the determination in step S10 is positive, step S20 is executed. If the determination in step S10 is negative, the process returns.

[0049] In step S20, which corresponds to the function of the SMR control unit 84, the system main relay 72 is opened to cut off the power supply from the main battery 70 to the generator MG1 and the electric motor MG2. Then, in step S30, which corresponds to the function of the MG control unit 86b, the MG1 output torque Tmg1 is controlled so that the power consumed by the auxiliary machines including the air conditioner 66 is generated by the generator MG1. Then, in step S40, which corresponds to the function of the overvoltage determination unit 86d, it is determined whether the DC voltage VH of the power line pair 74 is within a controllable range (for example, equal to or less than a predetermined voltage value VH_jdg). If the determination in step S40 is positive, the process returns. If the determination in step S40 is negative, step S50 is executed.

[0050] In step S50, which corresponds to the functions of the engine control unit 86a and the MG control unit 86b, the engine torque Te is reduced in response to a sudden decrease in the power consumption Wc of the accessories, and the d-axis current of the electric motor MG2 is increased. Note that, in response to a sudden decrease in the power consumption Wc of the accessories, the increase in the d-axis current of the electric motor MG2 is prioritized over the decrease in the engine torque Te. Then, the process returns.

[0051] According to this embodiment, when it is determined that an overvoltage occurs due to the power generation of the generator MG1 during batteryless running with the engine 12 operating, the d-axis current supplied to the motor MG2 is increased with priority over the reduction in the engine torque Te. As a result, during batteryless running, the generator MG1 generates power for the power consumption Wc of the auxiliary devices, etc., and even if the power consumption Wc of the auxiliary devices, etc. suddenly decreases, the generation of an overvoltage can be suppressed by increasing the d-axis current supplied to the motor MG2. In addition, an increase in the d-axis current of the motor MG2 suppresses the transmission of the driving force for driving unintended by the driver to the pair of drive wheels 32, thereby suppressing the discomfort felt by the driver. In addition, by suppressing the generation of an overvoltage, the deterioration of the durability of parts (for example, the capacitor C) can be suppressed.

[0052] According to this embodiment, it is determined that an overvoltage occurs due to power generation by the generator MG1 when the DC voltage VH of the power line pair 74, which is obtained by converting the generated power Wg1 of the generator MG1 to DC and outputting it by the inverter 60, exceeds a predetermined voltage value VH_jdg. In this way, when the DC voltage VH of the power line pair 74, which is obtained by converting the generated power Wg1 of the generator MG1 to DC and outputting it by the inverter 60, exceeds the predetermined voltage value VH_jdg, it can be determined that an overvoltage occurs. EXAMPLES

[0053] Second Embodiment FIG. 3 is a schematic configuration diagram of a hybrid vehicle 110 equipped with an electronic control device 180 according to a second embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle 110.

[0054] The configuration of hybrid vehicle 110 (hereinafter simply referred to as "vehicle 110") is substantially the same as the configuration of vehicle 10 in the above-described first embodiment, but differs mainly in that a different configuration is provided between engine 12 and automatic transmission 18 in place of power split mechanism 34, and in that an electronic control device 180 is provided in place of electronic control device 80. Therefore, the following description will focus on the parts that differ from the first embodiment, and parts that are substantially the same as those in the first embodiment will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0055] The vehicle 110 includes a clutch K0, a rotating electric machine MG, a mechanical oil pump MOP, a starting clutch WSC, and the like, housed in a case 20 between the engine 12 and the automatic transmission 18. The vehicle 110 also includes an inverter 160 and an electronic control device 180, instead of the inverter 60 and the electronic control device 80. The engine 12 is a driving force source for the vehicle 110 to run. The rotating electric machine MG is a generator connected to the engine 12, and is also an electric motor connected to a pair of drive wheels 32 so as to be capable of transmitting power. That is, the rotating electric machine MG is used as both a generator and an electric motor in battery-less running, and corresponds to both the "generator" and the "electric motor" in the present invention. A path through which the driving force for running output from the engine 12 is transmitted is the power transmission path PT.

[0056] The rotating electric machine MG is a so-called motor generator, for example a three-phase synchronous motor generator.

[0057] The clutch K0 is provided between a connecting shaft 22 connected to the engine 12 and a rotor shaft 24 connected to a rotor of the rotating electric machine MG. The clutch K0 is a clutch that can connect and disconnect power transmission between the engine 12 and the rotor shaft 24, and is, for example, a wet-type multi-plate hydraulic friction engagement device.

[0058] The rotating electric machine MG is driven to rotate using electric power stored in the main battery 70 by the inverter 160 controlled by the electronic control device 180, and outputs driving force for running the vehicle 110. The rotating electric machine MG also generates electric power using driving force input from the engine 12 via the clutch K0, and generates electric power by converting the driven force input from the pair of drive wheels 32 into electric power through regeneration.

[0059] The inverter 160 is a power supply circuit provided between the rotating electric machine MG and the pair of power lines 74, and between the electric oil pump EOP and the pair of power lines 74, and is controlled by the electronic control device 180 to convert DC to AC and AC to DC.

[0060] The starting clutch WSC is provided in the power transmission path PT between the AT input shaft 26, which is the input shaft of the automatic transmission 18, and the rotor shaft 24, and is a hydraulic clutch that can connect and disconnect power transmission in the power transmission path PT, for example, a wet-type multi-plate hydraulic friction engagement device.

[0061] The mechanical oil pump MOP is provided between the rotating electric machine MG and the starting clutch WSC on the rotor shaft 24. The mechanical oil pump MOP can be rotationally driven by the rotating electric machine MG, and can also be rotationally driven by the engine 12 when the clutch K0 is engaged.

[0062] The configuration of the electronic control device 180 is substantially the same as that of the electronic control device 80 in the first embodiment described above, but differs in that the driving control device 86 is replaced with a driving control device 186 (MG control device 186b is replaced with MG control device 86b). The electronic control device 180 corresponds to the "control device" in the present invention. Instead of the MG1 rotation speed Nmg1 and the MG2 rotation speed Nmg2, the MG rotation speed Nmg [rpm], which is the rotation speed of the rotating electric machine MG, is input to the electronic control device 180 as a signal based on the detection value by the MG rotation speed sensor 98. Instead of the MG1 control signal Smg1 and the MG2 control signal Smg2, the electronic control device 180 outputs an MG control signal Smg for controlling the rotation of the rotating electric machine MG to the inverter 160. Also, the electronic control device 180 outputs a hydraulic control signal Sp for executing the clutch K0 connection / disconnection control and the starting clutch WSC connection / disconnection control in addition to the shift control of the automatic transmission 18 to the hydraulic control circuit 44.

[0063] The electronic control device 180 calculates the required driving force. The engine 12, the rotating electric machine MG, and the automatic transmission 18 are each controlled so that the required driving force is output to the AT output shaft 28.

[0064] The traveling control unit 186 functionally includes an engine control unit 86a, an MG control unit 186b, a hydraulic control unit 86c, and an overvoltage determination unit 86d. The MG control unit 186b functions as an overvoltage suppression control unit that suppresses overvoltage.

[0065] In order to continue battery-less running, the engine control unit 86a controls the engine 12 so that the required driving force is transmitted to the pair of drive wheels 32 and the rotating electric machine MG generates power equivalent to the power consumption Wc of the auxiliary machines, etc. The MG control unit 186b controls the MG output torque Tmg [Nm], which is the output torque of the rotating electric machine MG, as a reaction torque against the engine torque Te so that the rotating electric machine MG generates power equivalent to the power consumption Wc. The hydraulic control unit 86c controls the hydraulic control circuit 44 so that the clutch K0 is maintained in an engaged state, the starting clutch WSC is maintained in an engaged state, and a desired gear ratio is formed in the automatic transmission 18. By the control of the engine control unit 86a, the MG control unit 186b, and the hydraulic control unit 86c, the driving force of the engine 12 transmitted to the AT input shaft 26 is transmitted to the pair of drive wheels 32 as the required driving force.

[0066] Here, in a rotating coordinate system that rotates around the axis of the rotor of the rotating electric machine MG, the axis along the direction of the magnetic flux created by the magnetic poles of the rotor of the rotating electric machine MG is defined as the d-axis, and the axis that is electrically advanced in phase by 90° from the d-axis is defined as the q-axis.

[0067] When the overvoltage determination unit 86d determines that the DC voltage VH of the power line pair 74 is outside the controllable range, i.e., an overvoltage occurs, the engine control unit 86a and the MG control unit 186b cooperate to change the engine torque Te in response to a sudden change in the power consumption Wc of the auxiliary machines, etc., and to change the d-axis current of the rotating electric machine MG. Specifically, when the power consumption Wc of the auxiliary machines, etc. suddenly decreases, the engine control unit 86a also decreases (lowers) the engine torque Te accordingly, and the MG control unit 186b increases the d-axis current of the rotating electric machine MG accordingly. Note that the increase in the d-axis current of the rotating electric machine MG by the MG control unit 186b is executed with priority over the decrease in the engine torque Te by the engine control unit 86a.

[0068] According to this embodiment, the generator connected to the engine 12 and the electric motor connected to the pair of drive wheels 32 so as to be capable of transmitting power are realized by the same rotating electric machine MG. Even when a single rotating electric machine MG functions as a generator and an electric motor, similarly to the above-described first embodiment, the occurrence of overvoltage is suppressed, and the transmission of driving force for traveling unintended by the driver to the pair of drive wheels 32 is suppressed, thereby suppressing an uncomfortable feeling given to the driver.

[0069] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0070] In the vehicles 10, 110 in the above-described first and second embodiments, a boost converter that boosts or lowers the DC voltage was not provided on the power line pair 74 between the inverters 60, 160 and the system main relay 72 and the DC / DC converter 78, but a configuration in which a boost converter is provided may also be adopted.

[0071] In the above-described first and second embodiments, the determination that an overvoltage occurs due to the power generation of the generator MG1 or the rotating electric machine MG is performed when the DC voltage VH of the power line pair 74 exceeds the predetermined voltage value VH_jdg, but this is not limited to the above. For example, in the first embodiment, the determination that an overvoltage occurs due to the power generation of the generator MG1 may be performed when the power difference ΔW (=Wg1-Wc) between the power generation power Wg1 of the generator MG1 and the power consumption Wc of the auxiliary equipment, etc. exceeds the predetermined power value W_jdg [W]. The predetermined power value W_jdg is a determination value that is experimentally or design-wise determined in advance to determine that an overvoltage does not occur in the vehicle 10, 110, and is determined, for example, as an upper limit value of a range in which a deterioration in durability is practically acceptable without applying an overload to a component (e.g., the capacitor C) electrically connected to the inverter 60. For example, the predetermined power value W_jdg is an upper limit value of the power difference ΔW (=Wg1-Wc) that is determined in advance according to the magnitude of the capacitance [F] of the capacitor C. If the power difference ΔW continues to exceed the predetermined power value W_jdg, there is a risk that the durability of the components electrically connected to the inverters 60, 160 will decrease due to overvoltage caused by power generation by the generator MG1 and the rotating electric machine MG.

[0072] In the above-described first embodiment, the MG2 output torque Tmg2 of the electric motor MG2 is set to zero during battery-less running, but this is not limited thereto. For example, the MG2 output torque Tmg2 of the electric motor MG2 may be set to a predetermined value during battery-less running. In this embodiment, the required driving force is converted onto the AT input shaft 26 by combining the driving force of the engine 12 divided by the power split mechanism 34 to the intermediate transmission member 36 and the MG2 output torque Tmg2 of a predetermined value output from the electric motor MG2 to the intermediate transmission member 36. During battery-less running, the running control unit 86 operates the engine 12 so that the required driving force is transmitted to the pair of drive wheels 32, and continues running by causing the generator MG1 to generate the total power Wsum (=Wc+Wm2) of the power consumption Wc [W] of the auxiliary devices including the air conditioner 66 and the power supplied to the electric motor MG2 (i.e., the power consumption Wm2 of the electric motor MG2). Then, when the power consumption Wc of the auxiliary equipment, etc. suddenly decreases, similarly to the above-described first embodiment, the engine control unit 86a also decreases (lowers) the engine torque Te accordingly, and the MG control unit 86b increases the d-axis current of the electric motor MG2 accordingly.

[0073] In the above-described first and second embodiments, the engine 12, the inverters 60, 160, and the hydraulic control circuit 44 were controlled by the electronic control devices 80, 180, but the electronic control devices 80, 180 may be configured to be divided into an engine control ECU (Electronic Control Unit) that controls the engine 12 as needed, an inverter control ECU that controls the inverters 60, 160, and a power transmission control ECU that controls the hydraulic control circuit 44.

[0074] It should be noted that the above is merely an embodiment of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention. [Explanation of symbols]

[0075] 10, 110: Hybrid vehicles 12: Engine 32: A pair of drive wheels 80, 180: Electronic control device (control device) MG: Rotating electric machines (generators, electric motors) MG1: Generator MG2: Electric motor Te: Engine torque (engine output torque)

Claims

[Claim 1] A control device for a hybrid vehicle including an engine, a generator connected to the engine, and an electric motor connected to a pair of drive wheels so as to be capable of transmitting power thereto, when it is determined that an overvoltage occurs due to power generation by the generator during battery-less running with the engine operating, increasing a d-axis current supplied to the electric motor with priority over a reduction in the output torque of the engine; The determination that an overvoltage will occur due to the power generation of the generator is made based on at least one of the following: a power difference between the power generated by the generator and the power consumption of a device that consumes the generated power exceeds a predetermined power value; and a voltage of a power line pair, which outputs the generated power after being converted to direct current by an inverter, exceeds a predetermined voltage value. The generator and the motor are the same rotating electric machine. A control device for a hybrid vehicle.

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