TWI765084B - Electric vehicle high voltage power off method - Google Patents

Abstract

A high-voltage power-off method for an electric vehicle, comprising: a first control unit starts a high-voltage load unloading program based on not receiving any high-voltage use request, and sends an AC terminal insulation detection instruction to a motor controller; the motor controller sends an AC terminal to a power management system. terminal insulation detection request; the power management system executes the AC terminal insulation detection program; the first control unit sends an instruction to disconnect the high-voltage switch to the power management system; the power management system executes the program to disconnect the high-voltage switch; the first control unit sends an active Discharge command; the motor controller executes the active discharge program. The method is beneficial to ensure the safe power-off of the electric vehicle, and when there is a wake-up source, the electric vehicle can recover from the power-off state to the power-on state very quickly.

Description

Electric vehicle high voltage power off method

The present invention relates to the technical field of electric vehicles, and more particularly, to a high-voltage power-off method for electric vehicles.

Electric vehicles have gradually become popular. For the sake of battery life, saving electricity is one of the focuses of industry technicians.

Generally, in order to save power, in the absence of high-voltage power demand, it is expected that the electric vehicle will automatically perform the high-voltage power-off process; and when an appropriate wake-up source is found, it is expected that the electric vehicle can resume power-on from the high-voltage power-off state .

However, based on the safety considerations of pure electric vehicles, after the high-voltage function of the electric vehicle is completed, before or during the high-voltage power-off process, some tests related to the high-voltage function are carried out to ensure that the electric vehicle can be powered off safely. desired by those skilled in the art. At the same time, once the wake-up source is detected, the electric vehicle can be powered on very quickly from the power-off state, thereby improving user experience, which is also expected by those skilled in the art.

The purpose of the present invention is to provide a high-voltage power-off method for an electric vehicle, which can safely power off the electric vehicle without causing any failures.

In order to achieve the above purpose, the present invention provides a technical solution as follows: A high-voltage power-off method for an electric vehicle, comprising the following steps: a) The first control unit starts a high-voltage load unloading program based on not receiving any high-voltage use request, and sends the motor to the motor. The controller sends an AC terminal insulation detection instruction; b), the motor controller sends an AC terminal insulation detection request to the power management system based on receiving the AC terminal insulation detection instruction; wherein, the motor controller includes an IGBT unit, which is used to output the battery output. The DC current is converted into the AC current required for the operation of the motor; c), the power management system executes the AC terminal insulation detection program based on the received AC terminal insulation detection request, and feeds back the first execution result to the first control unit; d), The first control unit sends an instruction to disconnect the high-voltage switch to the power management system based on receiving the first execution result; e), the power management system executes the program of disconnecting the high-voltage switch based on receiving the instruction to disconnect the high-voltage switch, and executes the second program. The result is fed back to the first control unit; f), the first control unit sends an active discharge command to the motor controller based on receiving the second execution result; g), the motor controller executes an active discharge program based on the received active discharge command, and feeding back the third execution result to the first control unit.

Preferably, in step a), when it is determined that the first condition is satisfied, the first control unit sends an AC terminal insulation detection instruction to the motor controller, and the first condition includes: the first control unit detects that the bus current of the power management system is less than the first current threshold; or, the activation time of the high voltage load shedding routine exceeds the first time threshold.

Preferably, step a) further includes step a1): the motor controller disconnects the coupling between the IGBT unit and the output terminal of the battery based on the activation of the high-voltage load unloading program, and enters a standby mode.

Preferably, step a) further includes step a2): the voltage conversion unit disconnects the coupling with the output terminal of the battery based on the activation of the high-voltage load unloading program, and enters a standby mode, wherein the voltage conversion unit is used to output the battery high pressure is converted to low pressure.

Preferably, upon initiation of the high voltage load shedding routine by the first control unit, any one or more of the following modules enter a standby mode and issue a zero torque request to the motor controller: air conditioner; heater; and condenser.

Preferably, the high-voltage load unloading program further includes: the first control unit detects the torque output by the motor, and if the torque is less than the first torque threshold, or the motor does not respond within the second time threshold, the first control unit instructs the motor to enter the standby mode.

Preferably, step b) specifically includes: the motor controller controls the coupling between the IGBT unit and the output end of the battery based on receiving the AC terminal insulation detection instruction, and sends an AC terminal insulation detection request to the power management system.

Preferably, the AC terminal insulation detection program includes: the power management system detects the insulation of the first output terminal of the IGBT unit to the casing of the motor; the power management system detects the insulation of the second output terminal of the IGBT unit to the casing of the motor; And the power management system detects the insulation of the third output end of the IGBT unit to the casing of the motor.

Preferably, after step g), it further includes: the first control unit detects whether there is any low-voltage wake-up source; if not, the first control unit instructs the following modules to store data and enter the sleep module: power management system; motor controller; and , the voltage conversion unit.

In the high-voltage power-off method for an electric vehicle provided by each embodiment of the present invention, some detections related to the high-voltage function are performed before or during the high-voltage power-off process, so as to ensure that the electric vehicle can be powered off safely. In the case of detecting any wake-up source, the electric vehicle can recover from the power-off state to the power-on state very quickly, thereby bringing an excellent use experience to the user. The method does not need to introduce an additional detection circuit for the electric vehicle, and the implementation is simple and convenient.

Specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In the present invention, specific numerical references such as "first element", "second means" and the like may be made. However, specific numerical references should not be construed as necessarily obeying their literal order, but rather should be construed as being distinct from "a first element" and "a second element."

The specific details set forth herein are merely exemplary and may vary while remaining within the spirit and scope of the present invention. The term "coupled" is defined to mean directly connected to an element or indirectly connected to an element via another element, and may also include connection through communication means such as wireless transmission.

Preferred embodiments of methods, systems and apparatus suitable for implementing the present invention are described below with reference to the accompanying drawings. Although the various embodiments are described with respect to a single combination of elements, it is to be understood that this invention includes all possible combinations of the disclosed elements. Thus, if one embodiment includes elements A, B, and C, and a second embodiment includes elements B and D, the invention should also be considered to include other remaining combinations of A, B, C, or D, even if not explicitly stated .

It should be noted that, in an electric vehicle, there are at least the following units or modules: a vehicle control unit (VCU), a power management system (BMS), a motor controller (PEU), a motor, and a voltage conversion unit.

The Vehicle Control Unit (VCU) can communicate with the power management system and the motor controller by using the CAN bus, or other suitable communication bus, respectively. Among them, the motor controller includes an IGBT unit, which is used to convert the DC current output by the vehicle battery into the AC current required for the operation of the motor. The voltage conversion unit is used to convert the high voltage output from the battery to a low voltage to supply power to various control systems.

As shown in FIG. 1 , a first embodiment of the present invention provides a high-voltage power-off method for an electric vehicle, which includes the following steps.

Step S10, the first control unit starts a high-voltage load unloading program based on not receiving any high-voltage use request, and sends an AC terminal insulation detection instruction to the motor controller.

Here, the first control unit may be a vehicle control unit VCU, or may be any other control unit carried by the electric vehicle or coupled with the electric vehicle.

Specifically, as an example, in this step, the vehicle control unit (VCU) detects whether there is a key signal keyon and whether there is a high-voltage use request from a thermal management system. For example, if the key signal is keyoff, a high voltage use request without thermal management request, or a high voltage use request ends, the VCU will initiate a high voltage load shedding routine. On the contrary, the VCU will maintain the current state and will not perform a high voltage power-down operation but continue to provide high voltage to the thermal management system.

In the case of starting the high-voltage load unloading program, the motor controller chooses to disconnect the coupling between the IGBT unit and the DC output terminal of the battery, so that the power supply of the battery is no longer supplied to the motor, thereby ending the current work of the motor controller, and the motor controller Enter standby mode.

As shown in Figure 2, the IGBT unit can include 6 switches (VT1-VT6), the input end of the IGBT unit is coupled to the vehicle battery (represented as a pair of U/2), and the output end is coupled to the on-board battery through equivalent resistance R and inductor L. motor. Those skilled in the art can understand that by orderly controlling the on/off of these switches, the DC current output by the battery can be converted into a three-phase AC current.

Just as an example, here, disconnecting the coupling between the IGBT cell and the DC output of the battery can simply be done as follows: all 6 switches (VT1-VT6) are disconnected so that the battery no longer supplies power to the motor .

Similarly, the voltage conversion unit can also be decoupled from the output of the battery and enter a standby mode.

In addition, in response to the activation of the high voltage load shedding routine, various other modules of the electric vehicle will also enter standby mode, including, for example, the on-board air conditioner, heater, and condenser; and, these modules will report to the motor control Motors make zero torque requests to indicate that they no longer need power distribution, which will allow EVs to consume significantly less power.

Preferably, the VCU monitors the output torque of the motor. If the output torque is less than a first torque threshold (eg 5 N.M), or the motor does not respond within a set time threshold (eg 50ms), the VCU will instruct the motor to enter standby mode. In the standby mode of the motor, the motor is not turned off but can be quickly restored from the standby mode to the normal operating mode, and the motor only maintains a minimum level of power output.

As an optional implementation, once the VCU starts the high-voltage load unloading program, it sends an AC terminal insulation detection instruction to the motor controller.

As a further improvement to the above steps, the difference is that only when it is determined that the first condition is satisfied, the first control unit sends the AC terminal insulation detection instruction to the motor controller, wherein the first condition includes: the first control unit detects that the The bus current of the power management system is less than a preset current threshold (eg 4A); or, the activation time of the high voltage load shedding program exceeds a preset time threshold (eg 1s).

Step S11 , the motor controller sends an AC side insulation detection request to the power management system based on receiving the AC side insulation detection instruction.

In this step, after receiving the AC terminal insulation detection instruction, the motor controller couples the control IGBT unit with the output terminal of the battery, and simultaneously sends the AC terminal insulation detection request to the power management system.

Step S12, the power management system executes the AC side insulation detection program based on the received AC side insulation detection request.

In this step, after receiving the AC side insulation detection request, the power management system executes the following operations to implement the AC side insulation detection program: Detecting the influence of the first output terminal of the IGBT unit (shown as node A in FIG. 2 ) on the motor Insulation of the case; detection of the insulation of the second output terminal of the IGBT cell (shown as node B in FIG. 2 ) to the case of the motor; and detection of the third output terminal of the IGBT cell (shown as node B in FIG. 2 ) C) Insulation to the housing of the motor.

Specifically, in order to detect the insulation of the node A to the casing of the motor, the switch VT1 and other switches can be opened, and only the switch VT4 can be closed. In order to detect the insulation of the node B to the casing of the motor, only the switch VT3 is closed, and the other switches are opened. In order to detect the insulation of the node C to the casing of the motor, only the switch VT5 is closed, and the other switches are opened.

After executing the AC terminal insulation detection program, the power management system feeds back the first execution result obtained by executing the program to the first control unit.

In the case that any node does not have insulation to the motor housing, the electric vehicle has the risk of short circuit and leakage. At this time, for the sake of safety, the power management system will feed back a negative first execution result to the first control unit, and enter the fault power-off mode. At this time, relevant faults are recorded, and an alarm is issued to the user to remind the user to perform maintenance. In the case that each node is provided with insulation to the casing, the power management system feeds back the first execution result of the front to the first control unit.

Step S13, the first control unit sends an instruction to disconnect the high voltage switch to the power management system.

In this step, after receiving the positive execution result (first execution result) fed back by the power management system, the first control unit (as an example, the vehicle control unit is used here) sends an instruction to disconnect the high-voltage switch to the power management system.

It should be understood that the power management system can use various switching elements to control whether the high voltage is output, for example, relays, gate circuits, transistors, or physical switching elements. Here, only as an example, the power management system uses a high-voltage relay to control the high-voltage output. Correspondingly, the vehicle control unit may send an instruction to disconnect the high-voltage relay to the power management system.

Step S14, the power management system executes the program of disconnecting the high voltage switch.

In this step, after receiving the command to disconnect the high-voltage switch, the power management system will execute the program of disconnecting the high-voltage switch (corresponding to the specific implementation of step S13, which may be the program of disconnecting the high-voltage relay here), and the execution result ( The second execution result) is fed back to the VCU. Whether the second execution result is positive or negative will affect the execution of subsequent steps.

Preferably, during the power-off process, if the recovery of the high-voltage wake-up source is detected, the VCU immediately returns to the previous working state, and then resumes the work of the relevant high-voltage accessories and motors.

During the recovery process, when the high-voltage switch (such as high-voltage relay) is restored from open to closed, if a serious battery or motor failure occurs, the VCU can issue an emergency power-off request to directly enter the high-voltage unloading state and skip the insulation detection. , disconnect the high-voltage switch and perform active discharge to quickly complete the high-voltage power-off.

During the recovery process, if the DCDC, IBS and other frame loss problems occur after the high-voltage switch (such as high-voltage relay) is powered on, the VCU will start to limit the torque output and gradually reduce the vehicle speed. When the vehicle speed is lower than a set value, it will enter the active discharge. state, and skip insulation detection, make open switch request and active discharge to prevent the vehicle from suddenly losing power during driving due to minor faults, and at the same time complete the high-voltage power-off operation as quickly as possible.

Step S15, the first control unit sends an active discharge instruction to the motor controller.

In this step, the first control unit (as an example, the vehicle control unit is used here) receives feedback from the power management system about the result of executing the program of disconnecting the high-voltage switch (the second execution result). If the feedback result is positive, that is, An active discharge command is sent to the motor controller to indicate that the motor controller is no longer required to output any control commands to the motor.

Step S16, the motor controller executes an active discharge program.

In this step, after the motor controller receives the active discharge command, it will execute the active discharge program, and feed back the execution result (the third execution result) to the first control unit (such as the vehicle control unit), and the first control unit In turn, it can be used as the final execution result of the high-voltage power-down process.

When the active discharge is jumped out due to a timeout (the vehicle control unit does not receive the execution result of the active discharge program within a time threshold), the DC terminal voltage of the motor may still be higher than 60V. When there is no low-voltage wake-up source, the VCU still needs to put the motor in the wake-up state and wait until the motor enters passive discharge. When the DC terminal voltage of the motor is lower than 60V, the motor and power management system can be hibernated, and finally the VCU also enters the hibernation state. This approach can prevent the discharge device from being burned/damaged by performing active discharge by default when the DC terminal voltage is still high due to the sleep state of the motor.

As a further improvement to the above-mentioned first embodiment, after the above-mentioned step S16 is completed, the following steps are continued: the first control unit detects whether there is any low-voltage wake-up source; if not, the first control unit instructs the following modules to store data And enter the sleep module: power management system; motor controller; and, voltage conversion unit.

As an example, there are five types of low-voltage wake-up sources: LIN wake-up signal of 12V battery management system IBS, CC or CP signal of AC charging pile, CC2 or A+ signal of DC charging pile, network management frame of gateway CGW, gateway KL15 signal.

It can be understood that the wake-up source detection performed after step S16 will be able to realize: once any wake-up source is detected, the first control unit will give up the power-off operation, and can quickly perform the power-on operation, so that the user hardly feels the Significant latency to recover from a powered-down state to a powered-up state.

According to the above-mentioned first embodiment and its various improved implementations, some detections related to the high-voltage function are performed before the power-off operation is actually completed, which can ensure that the electric vehicle is powered off more safely, and at the same time, when any wake-up source is detected , the electric vehicle can also recover from the power-off state to the power-on state very quickly.

The present invention also provides a computer-readable storage medium on which a computer program is stored. When executed by the processor, the computer program will execute the high-voltage power-off method for an electric vehicle provided by the first embodiment and its various improved implementations. .

The above description is only for the preferred embodiments of the present invention, and is not intended to limit the protection scope of the present invention. Those skilled in the art may make various modification designs without departing from the spirit of the present invention and the accompanying patent application scope.

FIG. 1 shows a schematic flowchart of a method for powering down an electric vehicle under high voltage according to a first embodiment of the present invention.

FIG. 2 shows a schematic circuit diagram of an IGBT cell according to an embodiment of the present invention.

Claims (9)

A high-voltage power-off method for an electric vehicle, comprising the following steps: a), a first control unit starts a high-voltage load unloading program based on not receiving any high-voltage use request, and sends an AC terminal insulation detection instruction to a motor controller; b), all The motor controller sends an AC terminal insulation detection request to the power management system based on receiving the AC terminal insulation detection instruction; wherein, the motor controller includes an IGBT unit for converting the DC current output by the battery into the motor running. The AC current required; c), the power management system executes the AC terminal insulation detection program based on receiving the AC terminal insulation detection request, and feeds back the first execution result to the first control unit; d), the The first control unit sends a disconnection high voltage switch instruction to the power management system based on receiving the first execution result; e), the power management system performs disconnection based on receiving the disconnection high voltage switch instruction high-voltage switch program, and feed back the second execution result to the first control unit; f), the first control unit sends an active discharge command to the motor controller based on receiving the second execution result; g ), the motor controller executes an active discharge program based on receiving the active discharge command, and feeds back a third execution result to the first control unit, wherein the high-voltage load unloading program further includes: The first control unit detects the torque output by the motor, and if the torque is less than a first torque threshold, or the motor does not respond within a second time threshold, the first control unit instructs the motor to enter a standby mode. The method according to claim 1, wherein, in the step a), when it is determined that the first condition is satisfied, the first control unit sends the AC terminal insulation detection instruction to the motor controller , the first condition includes: the first control unit detects that the bus current of the power management system is less than a first current threshold; or, the startup time of the high-voltage load shedding program exceeds the first time threshold. The method according to claim 1, wherein the step a) further includes a step a1): the motor controller disconnects the output of the IGBT unit and the battery based on the activation of the high-voltage load shedding program coupling between terminals and enter standby mode. The method according to claim 1, wherein the step a) further includes a step a2): the voltage conversion unit disconnects the output terminal of the battery based on the activation of the high-voltage load shedding program coupled, and enter a standby mode, wherein the voltage conversion unit is used to convert the high voltage output by the battery to a low pressure. The method of claim 1, wherein upon activation of the high voltage load shedding routine by the first control unit, any one or more of the following modules enter a standby mode and send a message to the motor controller Zero Torque Request: Air Conditioner; Heater; and, Condenser. The method according to claim 3, wherein the step b) specifically includes: the motor controller controls the IGBT unit to couple with the output end of the battery based on receiving the AC terminal insulation detection instruction, and send the AC terminal insulation detection request to the power management system. The method according to any one of claims 1 to 6, wherein the AC terminal insulation detection program includes: the power management system detects that the first output terminal of the IGBT unit is connected to the casing of the motor. The power management system detects the insulation of the second output terminal of the IGBT unit to the casing of the motor; and the power management system detects that the third output terminal of the IGBT unit is opposite to the motor. Insulation of the motor housing. The method according to item 7 of the claimed scope, wherein in the After step g), it also includes: the first control unit detects whether there is any low-voltage wake-up source; if not, the first control unit instructs the following modules to store data and enter the sleep module: the power management system; the a motor controller; and, the voltage conversion unit. A computer-readable storage medium on which a computer program is stored, wherein, when the computer program is executed by a processor, the method as described in any one of items 1 to 8 of the scope of the patent application is performed.

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