KR20200127105A - Control method of electric vehicle corresponding to BMS power disconnection - Google Patents

Abstract

The present invention relates to a control method of an electric vehicle corresponding to BMS power disconnection, and more specifically, to a control method of an electric vehicle corresponding to BMS power disconnection to safely control the vehicle in response to disconnection occurring in a circuit between a battery for providing the driving power of a motor and a battery management system (BMS) for battery management.

Description

Control method of electric vehicle corresponding to BMS power disconnection}

The present invention relates to a control method when a BMS power supply of an electric vehicle is disconnected, and in detail, a vehicle is controlled in response to a disconnection occurring in a circuit between a battery management system (BMS) for battery management and a battery supplying power to the BMS. It relates to a control method when the BMS power supply of an electric vehicle is disconnected for safe control.

An electric vehicle is equipped with an electric motor and a high voltage battery to generate driving power for driving, and the high voltage battery supplies power to the electric motor and an electric load through a battery relay.

In addition, the electric vehicle is equipped with a Battery Management System (BMS) that diagnoses the state of the high voltage battery and controls the battery relay that applies battery power to the electric motor and electric load, and a Vehicle Control Unit (VCU) for driving the vehicle. ) And a vehicle control unit such as a motor control unit (MCU) and the BMS.

Therefore, when a communication failure related to the BMS occurs while driving, it is possible to minimize the driving and prevent an accident caused by a sudden stop of the driving vehicle.

When the BMS deviates from the communication bus of the vehicle, a communication timeout phenomenon of the BMS occurs. At this time, the BMS maintains the battery relay in an operating state before the communication timeout phenomenon occurs. For example, when the battery relay is running while the battery relay is on, the battery relay is operated and maintained in the on state after a communication timeout phenomenon occurs to enable driving. At this time, the VCU regards the battery relay as maintaining the previous operating state, and continuously transmits the motor torque command to the MCU, but limits the motor output to 50% or less. In addition, the VCU induces the vehicle to wear to a repair shop by flashing a ready lamp displayed on the vehicle instrument panel to recognize to the driver that the vehicle is in an abnormal state.

Meanwhile, the BMS is supplied with power from the low-voltage battery of the vehicle, and the power of the low-voltage battery is supplied to the BMS through a battery fuse installed between the low-voltage battery and the BMS, and the BMS is a battery relay using the power of the low-voltage battery. Control the on/off operation of

When the battery fuse is disconnected, the BMS is unable to transmit a signal for communication with the vehicle control unit because power supply from the low voltage battery is interrupted, resulting in a communication timeout phenomenon, and a power supply for maintaining the closed state of the battery relay. Since this is lost, the battery relay is in an open/off state regardless of the command. At this time, the VCU attempts to maintain the vehicle driving state by continuously sending a motor torque command to the MCU as the communication timeout situation of the BMS occurs, and operates the ready lamp in the blinking mode.

When the battery relay is opened due to the disconnection of the circuit between the low voltage battery and the BMS, power for driving the motor (high voltage battery) is lost, and as the power for driving the motor is lost, the vehicle cannot be driven.

However, there is a problem in that the driver recognizes that the vehicle can continue driving by operating the ready lamp in the flashing mode in the VCU despite the situation in which vehicle operation is impossible, and accordingly, the vehicle operation is suddenly disabled on the road. Occurs.

The present invention has been devised in consideration of the above points, and diagnoses whether the battery relay is disconnected between the high voltage battery and the inverter based on the voltage transition of the inverter capacitor according to the driving condition of the vehicle while the vehicle is ready. It is an object of the present invention to provide a control method in case of disconnection of the BMS power of an electric vehicle, which ensures driving safety by inducing the vehicle to shut down by accurately recognizing the vehicle's undriving state to the driver when the disconnection of the vehicle is diagnosed.

Accordingly, in the present invention, as a control method when the BMS power is disconnected of an electric vehicle running using a motor driven by receiving power from a high voltage battery through a battery relay controlled by a battery management system (BMS),

In the ready state of the electric vehicle, when the communication timeout of the BMS occurs, an inverter that converts a current applied from the high voltage battery and supplies it to the motor and a battery relay that applies a current applied from the high voltage battery to the inverter A first step of determining whether a voltage fluctuation of the capacitor occurs by detecting a voltage of the inverter capacitor connected therebetween; A second step of dividing and determining a driving mode of the vehicle into any one of a stopping mode, an acceleration driving mode, and a regenerative braking mode when the voltage fluctuation of the capacitor occurs; A third step of determining that the battery relay is open when the voltage fluctuation value of the capacitor is greater than or equal to a reference voltage set according to a driving mode; A fourth step of shutting down the vehicle when it is determined that the battery relay is open is provided, and a control method when the BMS power of the electric vehicle is disconnected is provided.

Specifically, when the driving mode of the vehicle determined in the second step is the stop mode, in the third step, when the voltage of the capacitor falls by more than the first reference voltage, it is determined that the battery relay has changed from the closed mode to the open mode, When the driving mode of the vehicle determined in the second step is the accelerated driving mode, in the third step, when the voltage of the capacitor falls by more than the second reference voltage, it is determined that the battery relay has changed from the closed mode to the open mode. Here, the second reference voltage is set to a voltage value greater than or equal to a predetermined value than the first reference voltage. In addition, when the driving mode of the vehicle determined in the second step is the regenerative braking mode, in the third step, it is determined that the battery relay has changed from the closed mode to the open mode when the voltage of the capacitor rises above the third reference voltage. , The third reference voltage is set to a voltage value greater than or equal to a set value than the second reference voltage.

In the fourth step, the ready lamp indicating whether the vehicle can be driven is turned off to indicate that the vehicle is in a driving impossible state; When the vehicle speed becomes zero, manually shifting the shift lever of the vehicle from the driving stage (D stage) to the parking stage (P stage) and manually operating the parking brake on (ON); may be performed. .

In addition, the fourth step may be implemented as a step of automatically shifting the shift lever from the driving stage to the parking stage when the vehicle speed is reduced and falls below a predetermined vehicle speed when the electronic shift lever (SBW) is mounted.

According to the control method when the BMS power is disconnected in an electric vehicle according to the present invention, the voltage trend of the inverter capacitor is monitored to diagnose whether the battery relay is disconnected, and the vehicle status information (not allowed to run) according to the diagnosis result is accurately provided to the driver. By ensuring that appropriate follow-up (vehicle shutdown) is taken, it is possible to respond quickly and safely to the problem of a BMS power disconnection.

1 is a diagram showing a circuit configuration between a high voltage battery and a motor of an electric vehicle
2 is a diagram showing a voltage transition of an inverter capacitor in a stop mode of an electric vehicle
3 is a diagram showing a voltage transition of an inverter capacitor in an accelerated driving mode of an electric vehicle
4 is a flow chart showing a control process when the BMS power is disconnected of an electric vehicle according to the present invention

Hereinafter, the present invention will be described so that those skilled in the art can easily implement the present invention.

As shown in Fig. 1, the electric vehicle is equipped with an electric motor 7 generating driving force for driving and a high voltage battery 1 providing driving power to the electric motor 7, and the high voltage battery 1 ) Is in a state in which power can be supplied to the electric motor 7 and the electric load through the battery relay 4 when the vehicle becomes ready. Further, the power of the high voltage battery 1 may be supplied to the low voltage battery 11 through a low-voltage DC-DC converter (LDC) 9.

The low voltage battery 11 is connected to a battery management system (BMS) 8 through a battery fuse 2 to supply control power to the BMS, and the BMS 8 diagnoses the state of the high voltage battery 1 Then, the electric motor 7 and the battery relay 4 for applying high voltage power to the high voltage electric load are on/off controlled. Low voltage driving power is selectively supplied to the battery relay 4 by the BMS 8. In addition, an inverter capacitor 6 for smoothing current is connected between the inverter 5 for converting the current applied to the electric motor 7 and the battery relay 4.

When driving, the BMS 8 communicates with a vehicle control unit such as a motor control unit (MCU) for controlling the electric motor 7 and a vehicle control unit (VCU) that transmits a motor torque command to the MCU as a host controller. Will perform.

In the READY state of the electric vehicle, that is, in the state in which the driving preparation of the electric vehicle is completed, that is, in the state in which the electric vehicle can be driven, the low-voltage battery 11 and the low-voltage battery 11 and the battery fuse 2 are disconnected. The battery relay 4 is switched to an open state by the loss of the driving voltage of the battery relay due to the circuit between the BMS 8 being disconnected or the signal connector for transmitting the signal of the BMS 8 being removed.

The electric vehicle is judged to have entered a ready state when the battery relay 4 enters the closed mode and the condition for applying power to the electric motor 7 and the high voltage electric load through the battery relay 4 is satisfied. do.

Accordingly, in the present invention, in the vehicle ready state, based on the voltage transition of the inverter capacitor 6 according to the driving condition of the vehicle, it is diagnosed whether the circuit disconnection of the battery relay 4 is performed, and as a result of the diagnosis, the vehicle cannot be driven due to the circuit disconnection. When the condition is determined, the driver accurately recognizes the vehicle condition and induces the vehicle to shut down, thereby ensuring driving safety.

To this end, the control method of the electric vehicle when the BMS power is disconnected according to the present invention is a first method for determining whether a voltage fluctuation of the inverter capacitor 6 occurs when a communication timeout of the BMS 8 occurs in the vehicle ready state. Step, the second step of determining the driving mode of the vehicle when the voltage fluctuation of the inverter capacitor 6 occurs. If the voltage fluctuation value of the inverter capacitor 6 is higher than the reference voltage set according to the driving mode, the high voltage battery (1) And a third step of determining that the battery relay 4 connected between the and the inverter capacitor 6 has been switched to open, and a fourth step of shutting down the vehicle when it is determined that the battery relay 4 is open. The control process may be performed by a vehicle controller such as a VCU.

The inverter capacitor 6 converts the current applied from the high voltage battery 1 into a three-phase alternating current and supplies the inverter 5 to the electric motor 7 and the current supplied from the high voltage battery 1 to the inverter ( It is connected and arranged between the battery relays 4 applied to 5).

The VCU determines that a communication timeout of the BMS 8 has occurred if there is no signal transmitted from the BMS 8 for a certain period of time in the vehicle ready state. In the first step, when it is determined that the communication timeout of the BMS 8 has occurred when the vehicle is in a ready-to-run state, the voltage of the capacitor 6 is detected by detecting the voltage of the inverter capacitor 6 in real time. Determine whether this occurs.

In the second step, if the voltage fluctuation of the inverter capacitor 6 continuously occurs, the driving mode of the vehicle is determined by dividing the driving mode into any one of a stop mode, an acceleration driving mode, and a regenerative braking mode (or a deceleration driving mode). .

When it is determined that the driving mode of the vehicle is a stop mode in which the vehicle speed becomes 0 (zero), the battery relay 4 switches from the closed mode to the open mode when the voltage value of the inverter capacitor 6 falls by more than the first reference voltage. It is judged to be done. When the vehicle is ready to run, the battery relay 4 is maintained in the closed mode. In the stop mode, the shift lever is located at the driving end.

When the battery relay 4 is switched to the open mode, a disconnection occurs between the high voltage battery 1 and the inverter 5 by the battery relay 4, and the battery relay 4 in the closed mode The amount of charge and voltage of the inverter capacitor 6 are decreased by driving of the high-voltage electronic component that has been applied with the power of the high-voltage battery 1 through the drive. During the vehicle stop, only high-voltage electronic components such as LDC (Low-Voltage DC-DC Converter) 9 and air conditioner compressor 10 for air conditioners use the power of the inverter capacitor 6, so the inverter capacitor 6 ) Has a relatively low voltage drop rate (see FIG. 2).

If it is determined that the driving mode of the vehicle is an accelerated driving mode in which the vehicle speed increases, it is determined that the battery relay 4 has changed from the closed mode to the open mode when the voltage value of the inverter capacitor 6 falls by more than the second reference voltage. do.

When the battery relay (4) is switched to the open mode while driving in the accelerated driving mode, a disconnection occurs between the high voltage battery (1) and the inverter (5) by the battery relay (4), and the inverter is driven by the high voltage components. The charge amount and voltage of the capacitor 6 decrease. During accelerated driving, power of the inverter capacitor 6 is consumed by the driving of the electric motor 7 in addition to the high voltage electronic components such as the LDC 9 and the air conditioner compressor 10, so the voltage of the inverter capacitor 6 is instantaneously reduced. It falls sharply (refer to FIG. 3), and power of the capacitor 6 is consumed at a faster rate compared to the stop mode.

Here, the second reference voltage is set to a voltage value greater than or equal to a predetermined value than the first reference voltage. For example, the first reference voltage may be set to 30V and the second reference voltage may be set to 150V. The first and second reference voltages are set to voltage values smaller than the normal voltage value of the inverter capacitor 6 when the battery relay 4 is in the closed mode.

By setting the reference voltage value in the stop mode and the accelerated driving mode differently and setting the first reference voltage to a value smaller than the second reference voltage, it is possible to quickly diagnose whether the battery relay 4 is open in the stop mode. It is possible to increase the accuracy of diagnosis as to whether the battery relay 4 is open in the accelerated driving mode.

And if it is determined that the driving mode of the vehicle is a regenerative braking mode (or a decelerated driving mode) in which the vehicle speed decreases, the battery relay 4 is in the closed mode when the voltage value of the inverter capacitor 6 rises above the third reference voltage. It is determined that it has changed to open mode.

When the driver takes off his or her foot from the accelerator pedal and performs inertial driving (other driving) or deceleration driving (braking driving) by stepping on the brake pedal, the electric motor is driven by regenerative braking while the battery relay (4) is open (off). Back EMF is applied to (7), and the voltage and charge amount of the inverter capacitor 6 are increased. Accordingly, when the electric vehicle is running in the regenerative braking mode, when the voltage value of the inverter capacitor 6 increases by more than the third reference voltage, it can be determined that the battery relay 4 has switched to the open mode.

Here, the third reference voltage is set to a voltage value greater than or equal to a set value than the second reference voltage. For example, the third reference voltage may be set to a voltage value that is about 50V higher than the normal voltage of the inverter capacitor 6. When the battery relay 4 is in the closed mode, that is, when the power of the inverter capacitor 6 is not consumed by the high voltage electric load, the voltage value of the inverter capacitor 6 is the normal voltage value of the inverter capacitor 6.

As described above, it can be determined that the battery relay 4 is switched to the open mode based on the voltage transition of the inverter capacitor 6 according to the driving mode of the vehicle, and the battery relay 4 is opened to the electric motor 7 When it is determined that the driving power of the driver is substantially lost, the vehicle is shut down to ensure driving safety and driver safety.

The step of shutting down the vehicle (the fourth step) includes turning off a ready lamp indicating whether the vehicle is capable of driving, and when the vehicle speed becomes 0 (zero), the shift lever of the vehicle is turned off at the driving stage (D stage). It may be accomplished including the step of moving to the parking end (P end) and turning the parking brake ON.

Before shutting down the vehicle, the ready lamp displayed on the instrument panel is first turned off to make the driver aware that the vehicle is in a non-driving state. The ready lamp is controlled to be turned on when the vehicle is in a driveable state.

The driver who recognizes that the vehicle is in a state of being unable to drive, when the vehicle is stopped, shifts the vehicle's shift lever to the parking stage (P stage) for parking, and controls the parking brake to be locked so that the wheel does not rotate.

In addition, in the case of an electric vehicle equipped with an electronic shifting lever (SBW), when the vehicle speed is reduced to a certain vehicle speed (for example, 2kph) or less, the shift lever is automatically shifted to the parking level, thereby preventing the vehicle from being pushed on the slope. Can be prevented.

Here, the control process when the BMS power supply of the electric vehicle is disconnected is summarized as follows with reference to FIG. 4.

As shown in Fig. 4, when a communication timeout of the BMS 8 occurs and a voltage fluctuation of the inverter capacitor occurs in the ready state of the electric vehicle, the driving mode of the vehicle is determined. When the vehicle is stopped (vehicle speed = 0), the vehicle is shut down when the voltage drop value of the inverter capacitor becomes more than the first reference voltage, and when the vehicle is running (vehicle speed ≠ 0), the driving mode is determined according to acceleration or not. If the vehicle is running in acceleration (acceleration> 0), the vehicle is shut down when the voltage drop value of the inverter capacitor exceeds the second reference voltage. If the vehicle is under regenerative braking, the voltage rise value of the inverter capacitor will be higher than the third reference voltage. When shutting down the vehicle.

When shutting down the vehicle, the ready lamp is first turned off to make the driver aware that the vehicle is in a non-driving state. The driver, who recognizes that the vehicle is in a state of being unable to drive, shifts the vehicle's shift lever from the driving stage to the parking stage and turns on the parking brake when the vehicle speed becomes zero.

While driving in the regenerative braking mode is possible temporarily, if the back electromotive force applied to the electric motor is continuously allowed, the inverter power module may be damaged, so it is necessary to shut down the vehicle immediately to terminate the operation of the inverter.

As the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to the above-described embodiments, and various modifications and variations by those skilled in the art using the basic concept of the present invention defined in the following claims Improvements are also included in the scope of the present invention.

1: high voltage battery
2: Battery fuse
4: battery relay
5: inverter
6: inverter capacitor
7: Electric motor
8: BMS
11: Low voltage battery

Claims (6)

As a control method when the BMS power of an electric vehicle is disconnected, which runs using a motor driven by receiving power from a high voltage battery through a battery relay controlled by a BMS (Battery Management System),
In the ready state of the electric vehicle, when the communication timeout of the BMS occurs, an inverter that converts a current applied from the high voltage battery and supplies it to the motor and a battery relay that applies a current applied from the high voltage battery to the inverter A first step of determining whether a voltage fluctuation of the capacitor occurs by detecting a voltage of the inverter capacitor connected therebetween;
A second step of dividing and determining a driving mode of the vehicle into any one of a stopping mode, an acceleration driving mode, and a regenerative braking mode when the voltage fluctuation of the capacitor occurs;
A third step of determining that the battery relay is open when the voltage fluctuation value of the capacitor is greater than or equal to a reference voltage set according to a driving mode;
A fourth step of shutting down the vehicle when it is determined that the battery relay is open;
Control method when the BMS power is disconnected of the electric vehicle comprising a.
The method according to claim 1,
When the driving mode of the vehicle determined in the second step is the stop mode, in the third step, it is determined that the battery relay has changed from the closed mode to the open mode when the voltage of the capacitor falls by more than the first reference voltage. Control method when the BMS power of the electric vehicle is disconnected.
The method according to claim 2,
When the driving mode of the vehicle determined in the second step is the accelerated driving mode, in the third step, when the voltage of the capacitor falls by more than the second reference voltage, it is determined that the battery relay has changed from the closed mode to the open mode, and the The second reference voltage is set to a voltage value greater than or equal to a predetermined value than the first reference voltage.
The method of claim 3,
When the driving mode of the vehicle determined in the second step is the regenerative braking mode, in the third step, it is determined that the battery relay has changed from the closed mode to the open mode when the voltage of the capacitor rises above the third reference voltage, The third reference voltage is set to a voltage value greater than or equal to a set value than the second reference voltage.
The method according to claim 1,
The fourth step,
Indicating that the vehicle is in an undriable state by turning off a ready lamp indicating whether the vehicle is capable of driving;
When the vehicle speed becomes 0 (zero), manually shifting the shift lever of the vehicle from the driving stage (D stage) to the parking stage (P stage) and manually operating the parking brake on (ON);
Control method when the BMS power supply of an electric vehicle is disconnected, comprising a.
The method according to claim 1,
The fourth step,
Indicating that the vehicle is in an undriable state by turning off a ready lamp indicating whether the vehicle is capable of driving;
Automatically shifting the shift lever from the driving stage to the parking stage when the vehicle speed is reduced and falls below a predetermined vehicle speed when the electronic shift lever (SBW) is mounted;
Control method when the BMS power supply of an electric vehicle is disconnected, comprising a.

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