Vehicle control system

Abstract

This helps prevent situations where the vehicle becomes unable to move. [Solution] When external charging is terminated, if the temperature of the series connection resistor is lower than the first temperature and is below the second temperature (a temperature at which the temperature of the series connection resistor exceeds the first temperature when current is applied to the series connection resistor), the system main relay is turned on and the cutoff relay is turned off, and the drive circuit is controlled so that the voltage of the first capacitor changes. A fixation check is then performed to determine whether the second relay is stuck based on the change in voltage on the voltage converter side from the second relay on the connection line. When external charging is terminated, if the temperature of the series connection resistor is at or above the second temperature, the execution of the fixation check is prohibited.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a control device for this type of vehicle, there has been proposed a control device used in a vehicle including a motor, a drive circuit (inverter) for driving the motor, a power storage device (battery) connected to the drive circuit via a power line, a capacitor, a first relay (negative-side main relay) connected to the negative line of the power line, and a system main relay having a series connection resistor (precharge resistor) and a second relay (precharge relay) connected to the positive line of the power line and connected in series with each other (see, for example, Patent Document 1). In this device, when vehicle creep occurs while the charge allowable capacity of the power storage device is in a reduced state, the first relay is turned off and the second relay is turned on, and when the temperature of the series connection resistor is equal to or higher than a temperature reference value, the on / off of the first and second relays is prohibited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, a vehicle equipped with a control device has been proposed that includes a voltage converter having a second capacitor that supplies power from the charging line to the drive circuit side of the power line via the first and second relays, along with voltage conversion, and a tripping relay attached to the connection line. In this device, when external charging is performed to charge the energy storage device with external power, if the series connection resistance exceeds a first temperature, a protective control may be executed that turns off the system main relay to stop the current flowing to the series connection resistance and suppress the temperature rise of the series connection resistance in order to protect it. In this case, once the direct connection resistance exceeds the first temperature, the system main relay cannot be turned on until the series connection resistance falls below the first temperature, and the vehicle becomes unable to run.

[0005] The vehicle control device described herein is primarily intended to prevent situations in which the vehicle becomes unable to move. [Means for solving the problem]

[0006] The vehicle control device of this disclosure employs the following means to achieve the above-mentioned main objective. The vehicle control device of this disclosure is used in a vehicle comprising: a motor; a drive circuit for driving the motor; a power storage device connected to the drive circuit via a power line; a first capacitor attached to the power line; a system main relay having a first relay attached to the power storage device side of the first capacitor on one of the positive and negative lines of the power line, a series connection resistor and a second relay attached to the power storage device side of the first capacitor on the other of the positive and negative lines of the power line and connected in series with each other; a voltage converter having a second capacitor and supplying power from a charging line supplied with external power to a connecting line connected to the drive circuit side of the power line from the system main relay, along with voltage conversion; and a cutoff relay attached to the connecting line. The present invention relates to a vehicle control device that performs external charging, which charges the energy storage device with external power, and protective control, which turns off the system main relay when the series connection resistor is at or above a first temperature. When the external charging is completed, if the temperature of the series connection resistor is lower than the first temperature and is below a second temperature, which is the temperature of the series connection resistor that exceeds the first temperature when the series connection resistor is energized, the system main relay is turned on, the circuit breaker relay is turned off, and the drive circuit is controlled to change the voltage of the first capacitor. The present invention also relates to a vehicle control device that performs a fixation determination to determine whether the second relay is stuck based on the change in voltage on the voltage converter side of the connection line from the second relay. When the external charging is completed, if the temperature of the series connection resistor is at or above the second temperature, the execution of the fixation determination is prohibited. With the above configuration, the vehicle control device of this disclosure can prevent situations in which the vehicle is unable to run. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing the general configuration of an electric vehicle. [Figure 2]A flowchart showing an example of a processing routine executed by the ECU. [Figure 3] An explanatory diagram illustrating an example of the time evolution of resistance temperature Tr and the forbidden flag F. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of an electric vehicle 20 equipped with a vehicle control device according to an embodiment of this disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a driving motor 22, an inverter (drive circuit) 24, a battery (energy storage device) 30, a smoothing capacitor (first capacitor) 34, a system main relay SMR, a boost converter (voltage converter) 40, a cutoff relay (second relay) 50, a charging relay 51, and an electronic control unit (control device, hereinafter referred to as "ECU") 60.

[0009] Motor 22 is configured as a synchronous regenerative motor and comprises a rotor with embedded permanent magnets and a stator around which three-phase coils are wound. The rotor of this motor 22 is connected to a drive shaft 26 which is connected to drive wheels 28a, 28b via a differential gear 27. An inverter 24 is connected to the motor 22 and also to the power line 32. This inverter 24 is configured as a well-known inverter circuit having six transistors and six diodes. The inverter 24 is controlled by the ECU 60. Battery 30 is configured as a battery having multiple lithium-ion secondary batteries and is connected to the power line 32. A smoothing capacitor 34 is mounted on the power line 32. A system main relay SMR is mounted on the power line 32. The system main relay SMR includes a positive-side relay (first relay) SMRB provided on the positive line of the power line 32, a negative-side relay SMRG provided on the negative line of the power line 32, and a pre-charge circuit in which a pre-charge resistor R (series-connected resistor) and a pre-charge relay (second relay) SMRP are connected in series to bypass the negative-side relay SMRG. The system main relay SMR is controlled by the ECU 60. The boost converter 40 includes a capacitor (second capacitor) 40c connected to the charging line 44, and boosts the power supplied to the charging line 44 from the vehicle-side connection part 52 and supplies it to the connection line 46. The vehicle-side connection part 52 is configured to be connectable to an equipment-side connection part 92 connected to an external power supply 94 of a charging facility 90 installed at home or a charging station. The connection line 46 is connected to the inverter 24 side of the system main relay SMR on the power line 32. The boost converter 40 is controlled by the ECU 60. The disconnection relay 50 is installed on the connection line 46. The charging relay 51 is installed on the charging line 44. The disconnection relay 50 and the charging relay 51 are controlled by the ECU 60.

[0010] The ECU60 is equipped with a microcontroller that includes a CPU. Signals from various sensors are input to the ECU60 via its input ports. Examples of signals input to the ECU60 include the voltage V1 from the voltage sensor 30a that detects the voltage of the smoothing capacitor 34, the current Ir from the current sensor 31 that detects the current flowing through the pre-charge resistor R, the voltage V2 from the voltage sensor 46a that detects the voltage on the booster 40 side of the connection line 46 from the disconnection relay 50 (the voltage on the voltage converter side of the connection line from the second relay), the connection signal from the connection detection sensor 52a that detects the connection between the vehicle side connection part 52 and the equipment side connection part 92, and the start signal from the start switch 62. Various control signals are output from the ECU60 via its output ports, including control signals to multiple switching elements of the inverter 24, drive signals to the system main relay SMR, control signals to the booster 40, drive signals to the disconnection relay 50, and drive signals to the charging relay 51. When the vehicle-side connection 52 of the ECU 60 is connected to the equipment-side connection 92 of the charging equipment 90, the signal line of the equipment-side connection 92 of the charging equipment 90 is connected to the signal line of the vehicle-side connection 52, enabling the exchange of various signals with the charging equipment 90. The ECU 60 calculates the power consumption Wr of the pre-charge resistor R based on the current Ir from the current sensor 31 and the voltage V1 from the voltage sensor 30a, and calculates the temperature rise ΔTr of the pre-charge resistor R from the rated power ratio (=Wr / Wrated), which is the ratio of power consumption Wr to the rated power Wrated of the pre-charge resistor R, and the temperature rise curve. Then, the ECU 60 calculates the resistance temperature Tr of the pre-charge resistor R by adding the temperature rise ΔTr to the ambient temperature around the pre-charge resistor R detected by a temperature sensor (not shown).

[0011] In the electric vehicle 20 equipped with the vehicle control device of the embodiment configured in this way, when the start switch 62 is turned on by the user, the ECU 60 turns on the system main relay SMR to enable readiness (system on). In the connection process when turning on the system main relay SMR, the positive side relay SMRB and the pre-charge relay SMRP are turned on to pre-charge (charge) the smoothing capacitor 34, and then the negative side relay SMRG is turned on and the pre-charge relay SMRP is turned off. After that, when the start switch 62 is turned off, the system main relay SMR is turned off (the positive side relay SMRB, the negative side relay SMRG, and the pre-charge relay SMRP are turned off) to enable readiness (system off).

[0012] When the ECU 60 detects that the vehicle-side connection 52 and the equipment-side connection 92 of the charging equipment 90 are connected by the connection detection sensor 52a while the vehicle is stopped in the ready-off state, it turns on the positive side relay SMRB and negative side relay SMRG of the system main relay SMR, the cutoff relay 50, and the charging relay 51. The ECU 60 then controls the booster 40 so that the voltage V2 of the connection line 46 becomes higher than the voltage of the battery 30, and performs external charging, which is charging of the battery 30 using DC power from the charging equipment 90.

[0013] The ECU 60 performs a lock-in determination to determine if the cutoff relay 50 is locked in the ON position when external charging is terminated. The determination of ON lock-in on the positive side of the cutoff relay 50 involves controlling the cutoff relay 50 and the system main relay SMR so that the positive and negative sides of the cutoff relay 50 and the positive side relay SMRB are turned ON, and the negative side relay SMRG and the pre-charge relay SMRP are turned OFF. The ECU 60 then controls the inverter 24 so that d-axis current flows to the motor 22, discharging the smoothing capacitor 34 and the capacitor 40c of the boost converter 40, and setting the voltage V1 of the smoothing capacitor 34 and the voltage V2 on the boost converter 40 side of the cutoff relay 50 on the connecting line 46 to a value of 0. Next, the system control relay SMR and the interruption relay 50 are controlled so that the positive side of the interruption relay 50 and the negative side relay SMRG turn off, and the negative side of the interruption relay 50, the positive side relay SMRB, and the precharge relay SMRP turn on. When the voltage V2 rises in accordance with the voltage V1, it is determined that an abnormality has occurred where the positive side of the interruption relay 50 is stuck on (not turned off). The determination of the stuck on the negative side of the interruption relay 50 is performed using the same process as the determination of the stuck on the positive side.

[0014] The ECU60 performs protective control by turning off the system main relay SMR when the resistance temperature Tr is above the first temperature Trth1, thereby stopping the power supply to the pre-charge resistor R and suppressing the temperature rise of the pre-charge resistor R, thus protecting the pre-charge resistor R.

[0015] Next, we will describe the operation of the electric vehicle 20 configured in this way, in particular, the operation when the sticking determination, which determines whether the tripping relay 50 is stuck on, is prohibited. Figure 2 is a flowchart of an example of a processing routine executed by the ECU 60. This routine is repeatedly executed at predetermined intervals (for example, every few milliseconds) after external charging has ended and before the start of the aforementioned sticking determination. When the execution of this routine begins, that is, when external charging has ended, both the system main relay SMR and the tripping relay 50 are on.

[0016] When this routine is executed, the CPU of the ECU60 (not shown) inputs the calculated resistance temperature Tr and the prohibition flag F (S100). The prohibition flag F is a flag that indicates whether or not to prohibit the execution of the sticking check of the aforementioned tripping relay 50. It is set to a value of 0 when the execution of the sticking check is permitted, and to a value of 1 when the execution of the sticking check is prohibited. When the execution of this routine starts, it is set to its initial value of 0.

[0017] Next, it is determined whether the prohibition flag F is set to 0 (S110). When the prohibition flag F is set to 0, that is, when the execution of the lock-up determination of the tripping relay 50 is permitted, it is then determined whether the resistance temperature Tr is equal to or greater than the second temperature Trth2 (S120). The second temperature Trth2 is a temperature that is lower than the first temperature Trth1 and is predetermined by experimentation, analysis, machine learning, etc., as the temperature of the pre-charge resistor R exceeds the first temperature Trth1 when the pre-charge resistor R is energized. If the resistance temperature Tr is less than the second temperature Trth2 in S120, it is determined that it is acceptable to energize the pre-charge resistor R and the execution of the lock-up determination of the tripping relay 50 is permitted (S140). Then, the prohibition flag F is set to 0 (S150) and this routine ends. Since the execution of the lock-up determination of the tripping relay 50 is permitted, the ECU 60 performs a lock-up determination to determine whether the tripping relay 50 is locked on when external charging is terminated. In S120, when the resistance temperature Tr is 2 or higher than the second temperature Trth2, it is determined that energizing the pre-charge resistor R would cause its temperature to exceed the first temperature Trth1, and the execution of the sticking check for the tripping relay 50 is prohibited (S160). Then, the prohibition flag F is set to value 1 (S170), and this routine is terminated. As described above, the sticking check for the tripping relay 50 involves energizing the pre-charge resistor R. When the resistance temperature Tr is 2 or higher than the second temperature Trth2, the execution of the sticking check is prohibited, so the pre-charge resistor R is not energized, and the further rise in temperature of the pre-charge resistor R is suppressed. As a result, the system main relay SMR is prevented from being turned off when the temperature of the pre-charge resistor R exceeds the first temperature Trth1, thus preventing a situation where the vehicle cannot be driven.

[0018] In S110, if the prohibition flag F is set to value 1, it is determined that the execution of the lockout check for the tripping relay 50 is prohibited, and it is determined whether the resistance temperature Tr is less than or equal to the third temperature Trth3 (S130). The third temperature Trth3 is lower than the first and second temperatures Trth1 and Trth2, and is a temperature that has been predetermined by experiment, analysis, machine learning, etc., so that even if the pre-charge resistor R is energized, the resistance temperature Tr will not immediately exceed the first temperature Trth1. In S130, if the resistance temperature Tr exceeds the third temperature Trth, the execution of the lockout check for the tripping relay 50 is prohibited (S160), and the prohibition flag F is set to value 1 (S170). In S130, if the resistance temperature Tr is less than or equal to the third temperature Trth, the execution of the lockout check for the tripping relay 50 is permitted (S140), the prohibition flag F is set to value 0 (S150), and this routine ends.

[0019] Figure 3 is an explanatory diagram illustrating an example of the time variation of resistance temperature Tr and prohibition flag F. When external charging is completed and resistance temperature Tr is 2 or higher (time t1), the ECU 60 prohibits the lock-up determination of the shut-off relay 50 and sets the prohibition flag F to value 1 (S120, S160, S170). As a result, the energization of the pre-charge resistor R is prohibited, and resistance temperature Tr decreases. Then, when resistance temperature Tr falls to 3 or lower (time t2), the execution of the lock-up determination of the shut-off relay 50 is permitted, and the prohibition flag F is set to value 0 (S130, S140, S150). In this way, when the execution of the lock-up determination of the shut-off relay 50 is prohibited, the execution of the lock-up determination of the shut-off relay 50 is not permitted until resistance temperature Tr falls to 3 or lower, thus preventing repeated permission and prohibition of the lock-up determination of the shut-off relay 50 in a short period of time.

[0020] In the embodiment described above, if the prohibition flag F is not entered in S100, it is not necessary to execute S110, S130, S150, and S170.

[0021] As described above, embodiments for implementing the present disclosure have been explained. However, the present disclosure is not limited to such embodiments, and it is needless to say that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure.

Explanation of Signs

[0022] 20 Electric vehicle, 60 Electronic control unit (ECU).

Claims

[Claim 1] A vehicle control device used in a vehicle comprising: a motor; a drive circuit for driving the motor; a power storage device connected to the drive circuit via a power line; a first capacitor attached to the power line; a system main relay having a first relay attached to one of the positive and negative lines of the power line on the power storage device side from the first capacitor; a series connection resistor and a second relay attached to the other of the positive and negative lines of the power line on the power storage device side from the first capacitor and connected in series with each other; a voltage converter having a second capacitor and supplying power from a charging line supplied with external power to a connecting line connected to the drive circuit side from the system main relay on the power line, along with voltage conversion; and a cutoff relay attached to the connecting line, wherein the vehicle control device performs external charging to charge the power storage device with external power and protective control to turn off the system main relay when the series connection resistor is above a first temperature, When the external charging is completed, if the temperature of the series connection resistor is lower than the first temperature and is below the second temperature which would cause the temperature of the series connection resistor to exceed the first temperature when current is passed through the series connection resistor, the system main relay is turned on and the cutoff relay is turned off, and the drive circuit is controlled so that the voltage of the first capacitor changes, and a fixation determination is performed to determine whether the second relay is stuck or not based on the change in voltage on the voltage converter side from the second relay on the connection line. When the external charging is terminated, if the temperature of the series-connected resistor is equal to or higher than the second temperature, the execution of the sticking determination is prohibited. Vehicle control system.

Images