Vehicle control device

Abstract

To more appropriately determine whether or not a DC / DC converter is normal.SOLUTION: When there is an abnormality in a DC / DC converter at system startup, a system main relay, a starter motor and an engine are controlled so that engine travel in which the engine is started along with cranking of the engine by the starter motor while the system main relay is off and a vehicle travels with power from the engine. During the engine travel, driving of an alternator is stopped and a pressure stepdown operation of stepping down the voltage of a first power line via the DC / DC converter and supplying the voltage to a second power line is executed. It is determined whether or not the DC / DC converter is normal on the basis of an inter-terminal voltage on a high-voltage side of the DC / DC converter and a state of charge of the second battery.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle control device. [Background technology]

[0002] Conventionally, a vehicle control device of this type has been proposed for use in a vehicle that includes an engine and a motor, a first battery, a second battery having a lower rated voltage than the first battery, an inverter that drives the motor, an alternator that is coupled to the output shaft of the engine and connected to a second power line from the second battery, and a DC / DC converter that is connected to the first power line and the second power line from the first battery (see, for example, Patent Document 1).In this device, while the vehicle is running on power from the engine while operating with the engine at low load and low rotation speed, the DC / DC converter is stopped and electric power generated by the alternator is supplied to the second power line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-217757 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, in a vehicle control device used in a vehicle that adds a starter motor capable of cranking the engine and a system relay attached to the first power line to the above configuration, if an abnormality occurs in the DC / DC converter during system startup, the system main relay is turned off, and the engine is started by cranking the engine using the starter motor, and engine running begins, where the vehicle runs on power from the engine. Because some DC / DC converter abnormalities can be recovered to a normal state, it is recognized as an important issue to properly determine whether the DC / DC converter is normal even after an abnormality occurs in the DC / DC converter.

[0005] A main object of the vehicle control device of the present disclosure is to more appropriately determine whether or not a DC / DC converter is normal. [Means for solving the problem]

[0006] The vehicle control device of the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] A vehicle control device according to the present disclosure is provided for a vehicle including an engine that outputs power for driving, a motor capable of outputting power for driving, a first battery, a second battery having a lower rated voltage than the first battery, an inverter that drives the motor and is connected to a first power line from the first battery, a system main relay attached to the first power line, an alternator that is coupled to an output shaft of the engine and connected to a second power line from the second battery, a starter motor that is connected to the second power line and is capable of cranking the engine, and a DC / DC converter that is connected to the first power line and the second power line, and controls the engine, the inverter, the system main relay, the starter motor, and the DC / DC converter. The gist of the vehicle control device is that, when an abnormality occurs in the DC / DC converter at system startup, the system main relay, the starter motor, and the engine are controlled so that the engine is started with the starter motor cranking the engine while the system main relay is turned off, and engine running is initiated in which the vehicle runs on power from the engine, and while the engine is running, driving of the alternator is stopped and a step-down operation is performed in which the DC / DC converter steps down the voltage of the first power line and supplies it to the second power line, and whether the DC / DC converter is normal or not is determined based on the voltage between the high-voltage side terminals of the DC / DC converter and the state of charge of the second battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the outline of the configuration of a hybrid vehicle 20. [Figure 2] 4 is a flowchart showing an example of a post-startup control routine. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 equipped with a vehicle control device of the embodiment. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, a starter motor 25, an alternator 26, a motor 30, an inverter 32, a clutch K0, an automatic transmission 40, a high-voltage battery (first battery) 60, a system main relay SMR, a low-voltage battery (second battery) 62, a DC / DC converter 64, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0010] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel fuel from a fuel tank. A crankshaft (output shaft) 23 of the engine 22 is connected to a rotating shaft 31 (rotor) of a motor 30 via a clutch K0. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24. Although not shown, the engine ECU 24 includes a 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 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. A starter motor 25 for cranking the engine 22 and an alternator 26 for generating electricity using power from the engine 22 are connected to the crankshaft 23 of the engine 22. The starter motor 25 and the alternator 26, together with the low-voltage battery 62, are connected to a low-voltage power line (second power line) 63 and are controlled by the HVECU 70. When the field current is flowing, the alternator 26 generates electricity through rotation to charge the low-voltage battery 62, and when the field current is interrupted, the power output is lost and the alternator enters an idle state. In this embodiment, the act of flowing the field current in response to a drive signal from the HVECU 70 is referred to as "driving the alternator 26," and the act of interrupting the field current in response to a drive signal from the HVECU 70 is referred to as "stopping driving the alternator 26."

[0011] The motor 30 is configured as a synchronous generator motor. A rotating shaft 31 to which a rotor of the motor 30 is fixed is connected to the crankshaft 23 of the engine 22 via a clutch K0 and to an input shaft 41 of an automatic transmission 45. The inverter 32 is used to drive the motor 30 and is connected to a high-voltage power line (first power line) 61. The motor 30 is driven and rotated by a motor electronic control unit (hereinafter referred to as the "motor ECU") 34 controlling the switching of multiple switching elements of the inverter 32. The motor ECU 34 includes a microcomputer (not shown) having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the motor ECU 34 via input ports. Control signals and the like to the inverter 32 are output from the motor ECU 34 via output ports. The motor ECU 34 is connected to the HVECU 70 via a communication port.

[0012] The clutch K0 is configured as, for example, a hydraulically driven friction clutch and is controlled by the HVECU 70 to connect and disconnect the crankshaft 23 of the engine 22 and the rotating shaft 31 of the motor 30. The automatic transmission 40 has a torque converter 43 and an automatic transmission 45 with multiple speeds, such as four or six. The torque converter 43 amplifies the torque of the power of an input shaft 41 connected to the rotating shaft 31 of the motor 30 and transmits it to a transmission input shaft 44, which is the input shaft of the automatic transmission 45, or transmits the torque directly without amplifying it. The automatic transmission 45 is controlled by the HVECU 70.

[0013] High-voltage battery 60 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery with a rated voltage of several hundred volts, and is connected to high-voltage power line 61 together with inverter 32. A system main relay SMR is connected to high-voltage power line 61, and connects and disconnects high-voltage battery 60 to DC / DC converter 64 and inverter 32. Low-voltage battery 62 is configured as a secondary battery with a lower rated voltage than high-voltage battery 60, for example, a lead-acid battery with a rated voltage of approximately 12 V or 14 V, and is connected to low-voltage power line 63 together with starter motor 25 and alternator 26. DC / DC converter 64 is connected to high-voltage power line 61 and low-voltage power line 63. DC / DC converter 64 supplies power from high-voltage power line 61 to low-voltage power line 63 with the voltage being stepped down.

[0014] The HVECU 70 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports (not shown). Signals from various sensors are input to the HVECU 70 via the input ports. Examples of signals input to the HVECU 70 include the inter-terminal voltage Vbl from a voltage sensor attached between the terminals of the low-voltage battery 62, the voltage VH from a voltage sensor 64a attached between the high-voltage terminals of the DC / DC converter 64, and an ignition signal from the ignition switch 80. Various control signals are output from the HVECU 70 via output ports. Examples of signals output from the HVECU 70 include a control signal to the starter motor 25, a control signal to the alternator 26, a control signal to the clutch K0 and the automatic transmission 40 (hydraulic control device), and a control signal to the DC / DC converter 64. The control signal to the DC / DC converter 64 is output via a command line 64b. The HVECU 70 is connected to the engine ECU 24 and the motor ECU 34 via the communication ports.

[0015] In the hybrid vehicle 20 of this embodiment configured as described above, the engine 22, the clutch K0, the motor 30, and the automatic transmission 40 are controlled by cooperative control between the HVECU 70, the engine ECU 24, and the motor ECU 34 to travel in a hybrid driving mode (HV driving mode) or an electric driving mode (EV driving mode). The HV driving mode is a mode in which the clutch K0 is engaged and the vehicle travels using power from the engine 22, while the EV driving mode is a mode in which the clutch K0 is disengaged and the vehicle travels without using power from the engine 22. In the HV driving mode and the EV driving mode, the system main relay SMR is turned on. Furthermore, the starter motor 25 and the alternator 26 are controlled as necessary to drive them. In this embodiment, traveling in the HV driving mode or the EV driving mode with the system main relay SMR turned on may be referred to as "normal driving."

[0016] Next, the operation of the hybrid vehicle 20 of this embodiment, particularly the operation when an abnormality occurs in the DC / DC converter 64, will be described. Figure 2 is a flowchart showing an example of a post-start control routine executed by the HVECU 70. This routine is executed when the ignition switch 80 is turned on. When execution of this routine begins, the system main relay SMR is off.

[0017] When this routine is executed, the CPU of the HVECU 70 determines whether an abnormality has occurred in the DC / DC converter 64 (S100). Here, if the voltage VH detected by the voltage sensor 64a is within a predetermined normal range and the inter-terminal voltage Vbl of the low-voltage battery 62 is also within the predetermined normal range, it is determined that the DC / DC converter 64 is normal, and if the voltage VH is outside the predetermined normal range, it is determined that an abnormality has occurred in the DC / DC converter 64 due to a break in the command line 64b. If the DC / DC converter 64 is normal, the CPU of the HVECU 70 turns on the system main relay SMR and executes a predetermined system startup process (S110). Thereafter, the CPU of the HVECU 70 controls the engine 22, inverter 32, clutch K0, automatic transmission 40, system main relay SMR, and DC / DC converter 64 in cooperation with the engine ECU 24 and motor ECU 34 to drive normally (S170), and then ends this routine.

[0018] If an abnormality occurs in the DC / DC converter 64 in S100, the system main relay SMR is turned off and the drive of the DC / DC converter 64 is stopped (S110). Next, with the system main relay SMR turned off, the engine 22, the system main relay SMR, and the starter motor 25 are controlled so that the engine 22 starts with cranking of the engine 22 by the starter motor 25 (S120). Then, when the accelerator pedal (not shown) is depressed, the engine ECU 24 and the motor ECU 34 cooperatively control the engine 22, the inverter 32, the clutch K0, the automatic transmission 40, and the system main relay SMR so that the vehicle runs on engine power from the engine 22 with the clutch K0 in an engaged state and the motor 30 stopped (S130). This control initiates evacuation running using engine running. At this time, the motor 30 is rotated by the rotation of the crankshaft 23 of the engine 22, and a back electromotive force of the motor 30 is generated in the high-voltage power line 61.

[0019] When engine running is started in this manner, a control signal is sent to command line 64b to drive DC / DC converter 64 during engine running, thereby driving DC / DC converter 64 and stopping the drive of alternator 26 (S140). At this time, DC / DC converter 64 sends a control signal to command line 64b to perform a voltage step-down operation to step down the voltage of high-voltage power line 61 and supply it to low-voltage power line 63. Then, it is determined whether DC / DC converter 64 is normal (S150). If DC / DC converter 64 is normal, DC / DC converter 64 is driven in S140, and voltage VH, which is the voltage between the terminals of DC / DC converter 64, increases due to the back electromotive force of motor 30, and low-voltage battery 62 is charged. Therefore, in S150, it is determined that the DC / DC converter 64 is normal when the voltage VH is equal to or higher than the threshold Vref and the terminal voltage of the low-voltage battery 62 is higher than before S140 was executed or when the amount of charge stored in the low-voltage battery 62 has increased compared to before S140 was executed. The threshold Vref is a voltage determined in advance through experiments, analysis, machine learning, etc. as the lower limit of the back electromotive force of the motor 30. If the DC / DC converter 64 is not normal, the engine running described above continues (S180) and this routine ends.

[0020] If DC / DC converter 64 is normal in S150, then since DC / DC converter 64 was previously determined to be abnormal in S100 and then determined to be normal, it is determined that DC / DC converter 64 has returned to normal (S160). Then, system main relay SMR is turned on to start normal running (S170), and this routine ends. In this way, by controlling DC / DC converter 64 to perform voltage step-down operation and stopping the alternator 26 during engine running, and determining whether DC / DC converter 64 is normal based on the voltage between the terminals of DC / DC converter 64 detected by voltage sensor 64a and the state of charge of the second battery, it is possible to more accurately determine whether DC / DC converter 64 is normal.

[0021] In hybrid vehicle 20 equipped with the vehicle control device of the embodiment described above, if an abnormality occurs in DC / DC converter 64 at system startup, engine 22 is started with starter motor 25 cranking engine 22 with system main relay SMR turned off, and engine running is initiated. During engine running, driving of alternator 26 is stopped and DC / DC converter 64 performs a voltage step-down operation, and it is determined whether DC / DC converter 64 is normal or not based on the voltage between the high-voltage side terminals of DC / DC converter 64 and the state of charge of low-voltage battery 62, thereby making it possible to more accurately determine whether DC / DC converter 64 is normal or not.

[0022] Note that the correspondence between the main elements of the embodiments and the main elements of the invention described in the "Summary" section does not limit the elements of the invention described in the "Summary" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Summary" section. In other words, the interpretation of the invention described in the "Summary" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Summary" section. While the modes for implementing the present disclosure have been described above using the embodiments, the present disclosure is not limited to these embodiments and may, of course, be embodied in various forms within the scope of the present disclosure. [Explanation of symbols]

[0023] 22 engines, 26 alternators, 64 DC / DC converters.

Claims

[Claim 1] a first battery; a second battery having a lower rated voltage than the first battery; an inverter that drives the motor and is connected to a first power line from the first battery; a system main relay attached to the first power line; an alternator that is coupled to an output shaft of the engine and is connected to a second power line from the second battery; a starter motor that is connected to the second power line and is capable of cranking the engine; and a DC / DC converter that is connected to the first power line and the second power line, and If an abnormality occurs in the DC / DC converter at the time of system startup, the system main relay, the starter motor, and the engine are controlled so that the engine is started with the starter motor cranking the engine while the system main relay is turned off, and engine running is initiated in which the vehicle runs on power from the engine. During engine running, the alternator is stopped from being driven, and a step-down operation is performed in which the DC / DC converter steps down the voltage of the first power line and supplies the voltage to the second power line. Whether the DC / DC converter is normal or not is determined based on the voltage between the high-voltage side terminals of the DC / DC converter and the state of charge of the second battery. Vehicle control device.

Images