Vehicular control device

Abstract

To determine whether welding occurs on a system main relay or not, more properly.SOLUTION: When controlling an inverter so that driving of a motor is stopped after an instruction for stopping a system of a vehicle is made, and when controlling a system main relay so that the relay is turned off, a vehicular control device drives a DC / DC converter to determine whether welding occurs on the system main relay or not on the basis of voltages of a second electric power line when an abnormality due to which the DC / DC converter cannot be driven does not occur, and determines whether welding occurs on the system main relay or not, on the basis of voltages of a second electric power line at the time after a predetermined time elapses since a predetermined timing after the instruction for stopping the system is made when the abnormality due to which the DC / DC converter cannot be driven occurs.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, as this type of vehicle control device, one has been proposed that is used in a vehicle (hybrid vehicle) that includes a motor (AC motor) that can be driven by an engine, an inverter that drives the motor, a battery (DC power source) connected to a first power line that is the power line of the inverter, a system main relay attached to the first power line, and a capacitor attached to the first power line, and that controls the inverter and the system main relay (see, for example, Patent Document 1). In this device, when a system stop command is issued, the motor is driven to discharge the capacitor. During this discharge period, it is determined whether or not the system main relay is welded. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-250335 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described vehicle control device, when an abnormality occurs that makes it impossible to execute discharge, it is not possible to determine whether or not the system main relay is welded. Therefore, it is recognized as an important issue to determine more accurately whether or not the system main relay is welded when an abnormality occurs that makes it impossible to execute discharge.

[0005] A main object of the vehicle control device of the present disclosure is to more appropriately determine whether or not a system main relay is welded. [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] The vehicle control device according to the present disclosure includes: A motor connected to an output shaft of the engine; an inverter that drives the motor; a battery that exchanges power with the motor via the inverter; a system main relay attached to a first power line connecting the battery and the inverter; a DC / DC converter connected between the inverter of the first power line and the system main relay via a second power line, converting a voltage of the second power line and supplying the converted voltage to auxiliary devices; A vehicle control device for controlling the inverter, the system main relay, and the DC / DC converter, When a system stop command for the vehicle is issued to control the inverter so as to stop driving the motor and control the system main relay so as to be turned off, if no abnormality that makes it impossible to drive the DC / DC converter occurs, the DC / DC converter is driven and it is determined whether or not the system main relay has welded based on the voltage of the second power line, and if an abnormality that makes it impossible to drive the DC / DC converter occurs, it is determined whether or not the system main relay has welded based on the voltage of the second power line after a predetermined time has elapsed from a predetermined timing after the system stop command is issued. The gist of the present invention is as follows. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric drive system 20 provided in a vehicle equipped with a vehicle control device according to the present embodiment. [Diagram 2]4 is a flowchart showing an example of a determination process routine executed by an ECU 60. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of an electric drive system 20 provided in a vehicle equipped with a vehicle control device of the present embodiment. The electric drive system (circuit) 20 of the present embodiment is mounted on a vehicle having an engine that outputs power to a drive shaft connected to an axle, and includes a motor 32, an inverter 34, a high-voltage battery 36, a DC / DC converter 50, and an electronic control unit (hereinafter referred to as "ECU") 60 as shown in the figure.

[0010] The motor 32 is configured as a synchronous generator motor, and has a rotor with a permanent magnet embedded in the rotor core, and a stator with a three-phase coil wound around the stator core. The rotor of the motor 32 is connected to the output shaft of the engine.

[0011] The inverter 34 is used to drive the motor 32 and is connected to a first power line 42 that is connected to a high-voltage battery 36 via a system main relay SMR. The inverter 34 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, so as to be on the source side and the sink side of the positive and negative lines of the first power line 42, respectively. In addition, each of the three-phase coils (coils of U-phase, V-phase, and W-phase) of the motor 32 is connected to each of the connection points of two paired transistors of the transistors T11-T16. Therefore, when a voltage is applied to the inverter 34, a control microcomputer (hereinafter referred to as a "control microcomputer") 35 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 32. A smoothing capacitor 46 is attached to the positive and negative lines of the first power line 42.

[0012] The control microcomputer 35 is configured as a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. A control signal is output from the control microcomputer 35 to the inverter 34. The control microcomputer 35 operates using power supplied from the first power line 42 via a step-down circuit (not shown) that steps down the power from the first power line 42. The control microcomputer 35 exchanges various information with the ECU 60 by communication via the communication port.

[0013] The high-voltage battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-hydrogen secondary battery. The high-voltage battery 36 is connected to the first power line 42 via a system main relay SMR.

[0014] The DC / DC converter 50 is connected to a second power line 44 on the high voltage side and a third power line 52 on the low voltage side, which are connected between the system main relay SMR of the first power line 42 and a capacitor 46, i.e., the inverter 34. The DC / DC converter 50 reduces the power of the second power line 44 and supplies it to the third power line 52, or increases the power of the third power line 52 and supplies it to the second power line 44, by controlling switching elements (not shown) by the ECU 60. A smoothing capacitor 48 is attached to the positive and negative lines of the second power line 44. A low-voltage battery 54 having a rated voltage lower than that of the high-voltage battery 36 and auxiliary devices such as an air conditioner (not shown) are connected to the third power line 52.

[0015] Although not shown, the ECU 60 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. Examples of signals input to the ECU 60 include a rotational position θm from a rotational position sensor (e.g., a resolver) that detects the rotational position of the rotor of the motor 32, phase currents Iv and Iw from a current sensor that detects the phase currents of each phase of the motor 32, a voltage Vb from a voltage sensor 36a attached between the terminals of the high-voltage battery 36, a current Ib from a current sensor 36b attached to an output terminal of the high-voltage battery 36, a voltage VH of the first power line 42 (capacitor 46) from a voltage sensor (first voltage sensor) 46a attached to the first power line 42 (between the terminals of the capacitor 46), and a voltage Vdc of the second power line 44 (capacitor 48) from a voltage sensor (second voltage sensor) 48a attached to the second power line 44 (between the terminals of the capacitor 48). Various control signals are output from the ECU 60 via the output port. Examples of signals output from the ECU 60 include a control signal to the DC / DC converter 50 and a control signal to the system main relay SMR. The ECU 60 calculates the electrical angle θe and the number of rotations Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 from the rotational position detection sensor 32a, and calculates the power storage ratio SOC of the high-voltage battery 36 based on an integrated value of the current Ib of the high-voltage battery 36 from the current sensor 36b. The power storage ratio SOC is the ratio of the amount of power stored in the high-voltage battery 36 (amount of dischargeable power) to the total capacity of the high-voltage battery 36.

[0016] In the electric drive system 20 of the present embodiment thus configured, when the power that can be output from the engine is insufficient for the power required by the vehicle while the vehicle equipped with the electric drive system 20 is traveling, assist control is executed. In assist control, the ECU 60 sets a torque command Tm* for the motor 32 so that the insufficient power is output from the motor 32 to the output shaft of the engine to which the rotor is connected, and transmits the torque command Tm* to the control microcomputer 35. The control microcomputer 35, which receives the torque command Tm*, controls the inverter 34 so that the motor 32 is driven by the torque command Tm*. In addition, when braking the vehicle equipped with the electric drive system 20, charging control is executed to control the transistors T11 to T16 and the DC / DC converter 50 of the inverter 34 so that the high-voltage battery 36 and the low-voltage battery 54 are charged with the power generated by the motor 32.

[0017] Next, the operation of the electric drive system 20 of this embodiment configured as described above, particularly the operation when determining whether or not the system main relay SMR is welded, will be described. Fig. 2 is a flowchart showing an example of a determination processing routine executed by the ECU 60. This routine is executed when an ignition switch (not shown) is turned off and an instruction to stop the vehicle system is given.

[0018] When this routine is executed, the ECU 60 controls the system main relay SMR to be turned off (S100). Then, a command to stop the motor 32 is transmitted to the control microcomputer 35 (S110). The control microcomputer 35 that receives the command to stop the motor 32 executes a process to stop the motor 32. An example of the process to stop the motor 32 is a process to turn off the gates of the transistors T11 to T16 of the inverter 34.

[0019] Next, it is determined whether or not an abnormality has occurred in the DC / DC converter 50 (S120). Examples of abnormalities in the DC / DC converter 50 include an abnormality in which a switching element (not shown) included in the DC / DC converter 50 does not change from off to on or from on to off.

[0020] If DC / DC converter 50 is normal in S120, DC / DC converter 50 is driven for time tc (S130). Time tc is a time determined in advance from the capacitance of capacitors 38, 46 and the parasitic resistance and parasitic capacitance of first power line 42 and second power line 44 as the time for voltage Vdc to become sufficiently lower than the rated voltage of high-voltage battery 36 when DC / DC converter 50 is driven with system main relay SMR off.

[0021] Then, the voltage Vdc of the second power line 44 (capacitor 48) detected by the voltage sensor 48a is input (S150). Next, the voltage Vdc is used to execute the welding determination of the system main relay SMR in S160 to S180. In the welding determination, it is determined whether or not the voltage Vdc is less than the determination threshold value Vref (S160). Since the system main relay SMR is controlled to be turned off in S100, when the system main relay SMR is normal, the system main relay SMR is turned off. When the DC / DC converter 50 is driven in the off state of the system main relay SMR, the charge accumulated in the capacitors 46, 48 is discharged, and the voltage Vdc drops from the rated voltage of the high-voltage battery 36. When the system main relay SMR is welded, the system main relay SMR does not turn off even if the system main relay SMR is controlled to be turned off in S100. In this case, even if the DC / DC converter 50 is driven, the capacitors 46, 48 are charged with power from the high-voltage battery 36, so the voltage Vdc does not drop. Therefore, by checking the voltage Vdc, it can be determined whether the system main relay SMR is normal or not. The determination threshold value Vref is a threshold value for determining whether the system main relay SMR is normal or not, and is set to a voltage lower than the rated voltage of the high-voltage battery 36.

[0022] When the voltage Vdc is less than the determination threshold value Vref in S160, it is determined that the system main relay SMR is off, i.e., the system main relay SMR is normal (S170), and this routine ends. When the voltage Vdc is equal to or greater than the determination threshold value Vref in S160, it is determined that the system main relay SMR is not off, i.e., the system main relay SMR is welded (S180), and this routine ends. In this way, when the DC / DC converter 50 is normal, by driving the DC / DC converter 50 and determining whether or not welding has occurred in the system main relay SMR based on the voltage Vdc, it is possible to more appropriately determine whether or not the system main relay SMR has welded.

[0023] When an abnormality occurs in the DC / DC converter 50 in S120, the process waits until the elapsed time t from the timing (predetermined timing) when the stop command for the motor 32 was sent to the control microcomputer 35 in S110 exceeds the time tref (S140). When the stop command for the motor 32 is sent to the control microcomputer 35 in S110, the control microcomputer 35 that receives the stop command executes a process to stop the motor 32. When the system main relay SMR is normal, that is, when the system main relay SMR is off, the charge of the capacitors 46, 48 is discharged by the operation of the control microcomputer 35 and the inverter 34 even when the drive of the DC / DC converter 50 is stopped, and the voltage Vdc drops. The time tref is a time that is determined in advance based on the capacitance of the capacitors 46, 48 and the power consumption of the control microcomputer 35 and the inverter 34 for the stop command, as a time sufficient for determining such a drop in the voltage Vdc.

[0024] In this manner, after waiting until the elapsed time t exceeds the time tref, the voltage Vdc is input (S150). Then, the voltage Vdc is used to execute the welding determination of the system main relay SMR in S160 to S180, and this routine ends. When the system main relay SMR is normal, the voltage Vdc drops by waiting until the elapsed time t exceeds the time tref in S140. When the system main relay SMR is welded, the voltage Vdc does not drop even if the elapsed time t exceeds the time tref in S140. Therefore, by waiting until the elapsed time t exceeds the time tref and determining whether the system main relay SMR is welded based on the voltage Vdc, it is possible to more appropriately determine whether the system main relay SMR is welded.

[0025] According to the electric drive system 20 provided in a vehicle equipped with the vehicle control device of the present embodiment described above, in the case where a system stop instruction is given and the inverter 34 is controlled to stop driving the motor 32 and the system main relay SMR is controlled to be turned off, when no abnormality that makes it impossible to drive the DC / DC converter 50 occurs, the DC / DC converter 50 is driven and it is determined whether or not welding has occurred in the system main relay SMR based on the voltage Vdc of the second power line 44, and when an abnormality that makes it impossible to drive the DC / DC converter 50 occurs, it is determined whether or not welding has occurred in the system main relay SMR based on the voltage Vdc of the second power line 44 after a predetermined time tref has elapsed since the transmission of a stop command for the motor 32 after the system stop instruction is given, thereby making it possible to more appropriately determine whether or not the system main relay SMR has welded.

[0026] In the above embodiment, the elapsed time t is the time elapsed from the timing of transmitting a command to stop the motor 32 after a system stop instruction is given. However, the elapsed time t may be any time elapsed from a certain timing after a system stop instruction is given, and may be, for example, the time elapsed from the time the system main relay SMR is controlled to be turned off after a system stop instruction is given, or may be the time elapsed from the time this routine is started after a system stop instruction is given.

[0027] The following describes the relationship between the main elements of the embodiment and the main elements of the invention described in the Summary of the Invention section. In the embodiment, the ECU 60 corresponds to the "vehicle control device."

[0028] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

[0029] The above describes embodiments for implementing the present disclosure, but the present disclosure is not limited to these embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0030] The present disclosure can be used in the vehicle control device manufacturing industry and the like. [Explanation of symbols]

[0031] 32 Motor, 34 Inverter, 36 High voltage battery, 50 DC / DC converter, 60 Electronic control unit (ECU), SMR system main relay.

Claims

[Claim 1] A motor connected to an output shaft of the engine; an inverter that drives the motor; a battery that exchanges power with the motor via the inverter; a system main relay attached to a first power line connecting the battery and the inverter; a DC / DC converter connected between the inverter of the first power line and the system main relay via a second power line, the DC / DC converter converting a voltage of the second power line and supplying the converted voltage to auxiliary devices; A vehicle control device for controlling the inverter, the system main relay, and the DC / DC converter, When a system stop command for the vehicle is issued to control the inverter so as to stop driving the motor and control the system main relay so as to be turned off, if no abnormality that prevents the DC / DC converter from being driven occurs, the DC / DC converter is driven and it is determined whether or not the system main relay has welded based on the voltage of the second power line, and if an abnormality that prevents the DC / DC converter from being driven occurs, it is determined whether or not the system main relay has welded based on the voltage of the second power line after a predetermined time has elapsed from a predetermined timing after the system stop command is issued. Vehicle control device.

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