A power-on / off control circuit and control method for an electric vehicle power supply system

Abstract

The application discloses a power-on / off control circuit and a control method of an electric vehicle power supply system. The electric vehicle power supply system comprises a motor controller, a high-voltage power battery and a low-voltage storage battery. The motor controller comprises a control unit and the power-on / off control circuit. The power-on / off control circuit comprises a low-voltage power supply circuit and a high-voltage power supply circuit. The low-voltage storage battery is connected with a low-voltage load and the control unit through the low-voltage power supply circuit respectively. The high-voltage power battery is connected with a motor through the high-voltage power supply circuit. The low-voltage power supply circuit and the high-voltage power supply circuit are selectively turned on or turned off according to the control instruction of the control unit to control the power-on / off of the electric vehicle power supply system. The power-on / off process of the power supply system is realized under the control of the control unit. Compared with the existing battery management system (BMS) and motor controller cooperative control mode, the power-on / off process is simpler, and the system complexity and cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle technology, and in particular to a power-on / off control circuit and control method for an electric vehicle power supply system. Background Technology

[0002] Existing electric vehicle power systems consist of multiple control subsystems, including high-voltage power batteries, battery management systems (BMS), and chargers. The power-on and power-off control is achieved through a collaborative approach between the battery management system (BMS) and the motor controller, which makes the power-on and power-off process quite complex and increases the system's complexity, significantly raising the integration cost of the power system. Summary of the Invention

[0003] In view of the problems existing in the prior art, the purpose of this invention is to provide a power-on / off control circuit and control method that simplifies the power-on / off process and reduces system complexity and cost.

[0004] To achieve the above objectives, the present invention provides a power-on / off control circuit for an electric vehicle power system. The electric vehicle power system includes a motor controller, a high-voltage power battery, and a low-voltage storage battery. The motor controller includes a control unit and the power-on / off control circuit. The power-on / off control circuit includes a low-voltage power supply circuit and a high-voltage power supply circuit. The low-voltage storage battery is connected to a low-voltage load and the control unit via the low-voltage power supply circuit, and the high-voltage power battery is connected to the motor via the high-voltage power supply circuit. The circuit selectively connects or disconnects the low-voltage power supply circuit and the high-voltage power supply circuit according to control commands from the control unit to power on / off the electric vehicle power system.

[0005] Furthermore, the low-voltage power supply circuit includes a first power supply branch and a second power supply branch. The low-voltage battery is connected to the control unit through the first power supply branch, and the low-voltage battery is connected to the low-voltage load through the second power supply branch.

[0006] Furthermore, the first power supply branch includes an ON switch and a power control chip, and the low-voltage battery is connected to the control unit in sequence via the switch and the power control chip.

[0007] Furthermore, the second power supply branch includes a power chipset, and the low-voltage battery is connected to the low-voltage load in sequence through the power chipset.

[0008] Furthermore, the high-voltage power supply circuit includes a pre-charge contactor K4, a pre-charge resistor R1, a main positive contactor K5, a main negative contactor K6, a bus capacitor C1, a discharge contactor K3, and a discharge resistor R2. The high-voltage power battery is connected to the high-voltage load via the main positive contactor K5 and the main negative contactor K6. The high-voltage power battery is connected to the bus capacitor C1 via the pre-charge contactor K4, the pre-charge resistor R1, and the main positive contactor K5 in parallel. The bus capacitor C1 is connected in parallel to the positive and negative sides of the power supply downstream of the pre-charge resistor. The output side of the bus capacitor C1 is connected to the discharge contactor K3 and the discharge resistor R2.

[0009] Furthermore, when the electric vehicle power system is powered on, the low-voltage power supply circuit is turned on, supplying power to the control unit through the low-voltage battery. The control unit issues a control command to turn on the high-voltage power supply circuit, pre-charging the bus capacitor C1 through the high-voltage power battery. After the bus capacitor C1 is pre-charged, the high-voltage part is powered on. When the power system is powered off, the low-voltage power supply circuit is turned off, disconnecting the low-voltage battery from the control unit and the low-voltage load. The high-voltage power supply circuit is also turned off, disconnecting the high-voltage power battery from the motor. The bus capacitor C1 is discharged through the discharge contactor K3 and the discharge resistor R2.

[0010] Furthermore, it also includes a charging circuit, which includes a DC-DC module, relays K2 and K1. The high-voltage power battery is connected to the low-voltage storage battery via the DC-DC module, relays K2 and K1. When the electric vehicle power system is powered on, if the low-voltage storage battery needs to be charged, the control unit issues a control command to control relays K2 and K1 to conduct so that the high-voltage power battery can charge the low-voltage storage battery.

[0011] A second aspect of the present invention provides a power-on / off control method for an electric vehicle power supply system, utilizing the power-on / off control circuit described above, the power-on / off control method comprising the following steps:

[0012] When the electric vehicle power system is powered on, the low-voltage power supply circuit controls the low-voltage battery to connect with the control unit and supplies power to it.

[0013] According to the control instructions of the control unit, the high-voltage control circuit is selectively switched on to perform bus capacitor pre-charging, high-voltage load power-on, low-voltage load power-on, and low-voltage battery charging.

[0014] When the electric vehicle power system is powered off, the low-voltage battery is disconnected from the control unit by the ON switch, and the battery is actively discharged through the hardware circuit.

[0015] The power failure of the control unit causes the high-voltage power supply circuit to selectively disconnect, thereby powering off the high-voltage load, powering off the low-voltage load, and discharging the bus capacitor.

[0016] Furthermore, according to the control instructions of the control unit, the high-voltage power supply circuit is selectively switched on to perform bus capacitor pre-charging, high-voltage load power-on, low-voltage load power-on, and low-voltage battery charging, including:

[0017] The control unit issues control commands to control the pre-charge contactor K4 and the main negative contactor K6 of the high-voltage power supply circuit to conduct through the charging circuit to pre-charge the bus capacitor.

[0018] The control unit issues a control command to turn on relay K2, thereby powering on the low-voltage load through the low-voltage power-on circuit;

[0019] After the bus capacitor C1 is pre-charged, the pre-charge contactor K4 and discharge contactor K3 of the high-voltage power supply circuit are turned off, and the main positive contactor K5 and main negative contactor K6 are turned on to power the high-voltage load through the high-voltage power-on circuit.

[0020] When the system detects that the low-voltage battery needs to be charged, the control unit issues a control command to control the relays K2 and K1 in the charging circuit to conduct, so that the high-voltage power battery can charge the low-voltage battery.

[0021] Furthermore, the selective disconnection of the high-voltage power supply circuit caused by the power failure of the control unit to power off the high-voltage load, power off the low-voltage load, and discharge the bus capacitor includes:

[0022] When the control unit is powered off, the pre-charge contactor K4, the main positive contactor K5, the main negative contactor K6, the relay K2, and the relay K1 are all turned off, thereby energizing the high-voltage load and the low-voltage load.

[0023] When the control unit is powered off, the pre-charge contactor K4, the main positive contactor K5, the main negative contactor K6, the relay K2, and the relay K1 are all turned off, and the discharge contactor K3 is turned on to discharge the bus capacitor C1.

[0024] This invention realizes the power-on and power-off process of the power system under the control of the motor controller. Compared with the existing battery management system (BMS) and motor controller coordinated control method, the power-on and power-off process is simpler, reducing system complexity and cost. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a schematic diagram of the power-on / off control circuit of an electric vehicle power supply system according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the power-on control process of an electric vehicle power system according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the power-down control process of an electric vehicle power system according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the electric vehicle power system of the present invention includes a power-on / off control circuit. The electric vehicle power system includes a motor controller, a high-voltage power battery, and a low-voltage storage battery. The motor controller includes a control unit 1 and the power-on / off control circuit. The power-on / off control circuit includes a low-voltage power supply circuit 2 and a high-voltage power supply circuit 3. The low-voltage storage battery is connected to a low-voltage load and the control unit 1 through the low-voltage power supply circuit. The high-voltage power battery is connected to the motor through the high-voltage power supply circuit 3. According to the control command of the control unit 1, the low-voltage power supply circuit 2 and the high-voltage power supply circuit 3 are selectively turned on or off to power on or off the electric vehicle power system.

[0031] In one embodiment of the present invention, the low-voltage power supply circuit 2 includes a first power supply branch 21 and a second power supply branch 22. The low-voltage battery is connected to the control unit 1 through the first power supply branch 21, and the low-voltage battery is connected to the low-voltage load through the second power supply branch 22.

[0032] The first power supply branch 21 includes an ON switch and a power control chip. The low-voltage battery is connected to the control unit 1 via the ON switch and the power control chip. In practical applications, the first power supply branch 21 supplies power to the power control chip, the MCU, and their peripheral circuits. The control unit 1 processes the overall input signals, makes decisions, and outputs control signals for the motor controller, and is powered by the low-voltage battery. When the driver presses the vehicle start button, the ON switch is activated, and the low-voltage battery outputs 3.3V through the power control chip LM2596-3.3, providing power to the MCU.

[0033] The second power supply branch 22 includes a power chipset, through which the low-voltage battery is connected to the low-voltage load. In practical applications, the second power supply branch 22 supplies power to the voltage sensor, current sensor, inverter circuit power devices, resolver excitation, resolver input signal processing, controller communication circuit, and other components. ±15V is output from the URA-15 chip, ±12V from the LM2596-12, ±5V from the LM2596-5, and ±3.3V from the AS1117-3.3. When the control unit MCU is powered on, the MCU controls relay K2 to conduct, powering on the low-voltage integrated circuit power supply section, thus completing the low-voltage power-on process.

[0034] The high-voltage power supply circuit 3 includes a pre-charge contactor K4, a pre-charge resistor R1, a main positive contactor K5, a main negative contactor K6, a bus capacitor C1, a discharge contactor K3, and a discharge resistor R2. The high-voltage power battery is connected to the high-voltage load via the main positive contactor K5 and the main negative contactor K6. The high-voltage power battery is connected to the bus capacitor C1 via the pre-charge contactor K4, the pre-charge resistor R1, and the main positive contactor K5 connected in parallel. The bus capacitor C1 is connected in parallel to the positive and negative sides of the power supply downstream of the pre-charge resistor. The output side of the bus capacitor C1 is connected to the discharge contactor K3 and the discharge resistor R2. In practical applications, the high-voltage control circuit 3 controls the output of the high-voltage power battery and consists of an on-board charger, a pre-charge contactor K4, a main positive contactor K5, a main negative contactor K6, a pre-charge resistor R1, a bus capacitor C1, a discharge contactor K3, and a discharge resistor R2. When the vehicle is charging, the on-board charger charges the high-voltage power battery. Pre-charging is achieved by the pre-charge contactor K4 and the pre-charge resistor R1. Discharge contactor K3 and the discharge resistor R2 enable the active discharge of the bus capacitor after the high-voltage part of the motor controller and the high-voltage power battery are disconnected. The three-phase bridge inverter circuit supplies power to the drive motor under the control of the MCU, realizing the control of the motor.

[0035] When the electric vehicle power system is powered on, the low-voltage power supply circuit 2 is turned on, supplying power to the control unit 1 through the low-voltage battery. The control unit 1 issues a control command to turn on the high-voltage power supply circuit 3, pre-charging the bus capacitor C1 through the high-voltage power battery. After the bus capacitor C1 is pre-charged, the high-voltage part is powered on. When the power system is powered off, the low-voltage power supply circuit 2 is turned off, disconnecting the low-voltage battery from the control unit 1 and the low-voltage load. The high-voltage power supply circuit 3 is turned off, disconnecting the high-voltage power battery from the motor. The bus capacitor C1 is discharged through the discharge contactor K3 and the discharge resistor R2.

[0036] In one embodiment of the present invention, the power-on / off control circuit further includes a charging circuit 4, which includes a DC-DC module, relays K2 and K1. The high-voltage power battery is connected to the low-voltage storage battery via the DC-DC module and relays K2 and K1. When the electric vehicle power system is powered on, if the low-voltage storage battery needs to be charged, the control unit 1 issues a control command to control relays K2 and K1 to conduct so that the high-voltage power battery can charge the low-voltage storage battery.

[0037] This invention integrates the power supply system of the electric vehicle motor controller, simplifies the high and low voltage power-on and power-off process of the system, and enables the motor controller to control the high and low voltage power supply. The overall system structure is more compact, reducing hardware costs and system size.

[0038] like Figure 2 As shown, the power-on of the electric vehicle's power system is controlled by the control unit MCU, and the power-on process includes the following steps:

[0039] 1) When the electric vehicle power system is powered on, the ON switch of the first power supply branch is turned on, which connects the low-voltage battery to the control unit and supplies it with power.

[0040] 2) The control unit sends a control command to turn on the low-voltage relay K2, and the integrated circuit inside the motor controller is powered on.

[0041] 3) The control unit controls the pre-charge contactor K4 and the main negative contactor K6 to conduct, and controls the normally closed discharge contactor K3 to close. The high-voltage power battery is connected to the controller bus capacitor C1, and pre-charging begins.

[0042] 4) Detect the voltage across bus capacitor C1. When the voltage reaches 90% of the rated voltage, the MCU controls the pre-charge contactor K4 to turn off and simultaneously controls the main positive contactor K5 to turn on. Pre-charging is complete, and the high-voltage power battery is connected to bus capacitor C1 through the main positive contactor K5 and the main negative contactor K6.

[0043] 5) Detect whether the low-voltage battery needs to be charged. If it needs to be charged, control relay K1 to close and conduct; otherwise, it will not conduct.

[0044] 6) Power-on complete.

[0045] like Figure 3 As shown, the power-off of the electric vehicle's power system is automatically achieved by hardware, and the power-off process includes the following steps:

[0046] 1) When the electric vehicle power system is powered down, the ON switch of the first power supply branch is turned off, and the control unit is powered down.

[0047] 2) The control signals of each relay and contactor become low level, normally open contactors K4, K5 and K6 are disconnected, and the high-voltage power supply circuit is disconnected from the high-voltage power battery.

[0048] 3) When normally open relays K1 and K2 are disconnected, the low-voltage power supply circuit is powered off, and the low-voltage battery stops charging.

[0049] 4) When the normally closed discharge contactor K3 is turned on, the electrical energy stored in the bus capacitor begins to discharge through the discharge resistor, and the voltage gradually drops to a safe voltage.

[0050] 5) Power off complete.

[0051] In this invention, the discharge contactor K3 is a normally closed contactor, which is in the ON state when there is no control signal. K4 (pre-charge contactor), K5 (total positive contactor), and K6 (total negative contactor) are normally open contactors, which remain in the OFF state when there is no control signal. By utilizing the characteristic of relays and contactors to maintain normally open and normally closed states when there is no control signal, the high and low voltages can automatically complete the power-off and discharge process after the ON position is turned off, simplifying the power-off procedure.

[0052] In summary, this invention realizes the power-on and power-off process of the power system under the control of the motor controller. Compared with the existing battery management system (BMS) and motor controller collaborative control method, the power-on and power-off process is simpler, reducing system complexity and cost.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A power-on / off control circuit for an electric vehicle power supply system, characterized in that, The electric vehicle power system includes a motor controller, a high-voltage power battery, and a low-voltage storage battery. The motor controller includes a control unit and a power-on / off control circuit. The power-on / off control circuit includes a low-voltage power supply circuit and a high-voltage power supply circuit. The low-voltage storage battery is connected to a low-voltage load and the control unit through the low-voltage power supply circuit, and the high-voltage power battery is connected to the motor through the high-voltage power supply circuit. According to the control command of the control unit, the low-voltage power supply circuit and the high-voltage power supply circuit are selectively turned on or off to power on and off the electric vehicle power system. The high-voltage power supply circuit includes a pre-charge contactor K4, a pre-charge resistor R1, a main positive contactor K5, a main negative contactor K6, a bus capacitor C1, a discharge contactor K3, and a discharge resistor R2. The high-voltage power battery is connected to the high-voltage load via the main positive contactor K5 and the main negative contactor K6. The high-voltage power battery is connected to the bus capacitor C1 via the pre-charge contactor K4, the pre-charge resistor R1, and the main positive contactor K5 in parallel. The bus capacitor C1 is connected in parallel to the positive and negative sides of the power supply downstream of the pre-charge resistor. The output side of the bus capacitor C1 is connected to the discharge contactor K3 and the discharge resistor R2. The power-on / off control circuit also includes a charging circuit, which includes a DC-DC module, relays K2 and K1. The high-voltage power battery is connected to the low-voltage storage battery via the DC-DC module and relays K2 and K1. When the electric vehicle power system is powered on, if the low-voltage storage battery needs to be charged, the control unit issues a control command to control relays K2 and K1 to conduct so that the high-voltage power battery can charge the low-voltage storage battery. When the electric vehicle power system is powered on, the low-voltage power supply circuit is turned on, supplying power to the control unit through the low-voltage battery. The control unit issues a control command to turn on the high-voltage power supply circuit, pre-charging the bus capacitor C1 through the high-voltage power battery. After the bus capacitor C1 is pre-charged, the high-voltage part is powered on. When the power system is powered off, the low-voltage power supply circuit is turned off, disconnecting the low-voltage battery from the control unit and the low-voltage load. The high-voltage power supply circuit is also turned off, disconnecting the high-voltage power battery from the motor. The bus capacitor C1 is discharged through the discharge contactor K3 and the discharge resistor R2.

2. The power-on / off control circuit as described in claim 1, characterized in that, The low-voltage power supply circuit includes a first power supply branch and a second power supply branch. The low-voltage battery is connected to the control unit through the first power supply branch, and the low-voltage battery is connected to the low-voltage load through the second power supply branch.

3. The power-on / off control circuit as described in claim 2, characterized in that, The first power supply branch includes an ON switch and a power control chip, and the low-voltage battery is connected to the control unit in sequence via the switch and the power control chip.

4. The power-on / off control circuit as described in claim 2, characterized in that, The second power supply branch includes a power chipset, and the low-voltage battery is connected to the low-voltage load in sequence through the power chipset.

5. A power-on / off control method for an electric vehicle power supply system, characterized in that, The power-on / off control method, utilizing the power-on / off control circuit as described in any one of claims 1-4, comprises the following steps: When the electric vehicle power system is powered on, the low-voltage power supply circuit controls the low-voltage battery to connect with the control unit and supplies power to it. According to the control instructions of the control unit, the high-voltage power supply circuit is selectively switched on to perform bus capacitor pre-charging, high-voltage load power-on, low-voltage load power-on, and low-voltage battery charging. When the electric vehicle power system is powered off, the low-voltage battery is disconnected from the control unit by the ON switch, and the battery is actively discharged through the hardware circuit. The power failure of the control unit causes the high-voltage power supply circuit to be selectively disconnected to power off the high-voltage load, power off the low-voltage load, and discharge the bus capacitor. The high-voltage power supply circuit is selectively switched on according to the control instructions of the control unit to perform bus capacitor pre-charging, high-voltage load power-on, low-voltage load power-on, and low-voltage battery charging, including: The control unit issues control commands to control the pre-charge contactor K4 and the main negative contactor K6 of the high-voltage power supply circuit to conduct through the charging circuit to pre-charge the bus capacitor. The control unit issues a control command to turn on relay K2, thereby powering on the low-voltage load through the low-voltage power-on circuit; After the bus capacitor C1 is pre-charged, the pre-charge contactor K4 and discharge contactor K3 of the high-voltage power supply circuit are turned off, and the main positive contactor K5 and main negative contactor K6 are turned on to power the high-voltage load through the high-voltage power-on circuit. When the system detects that the low-voltage battery needs to be charged, the control unit issues a control command to control the relays K2 and K1 in the charging circuit to conduct, so that the high-voltage power battery can charge the low-voltage battery.

6. The power-on / off control method as described in claim 5, characterized in that, The power failure of the control unit selectively disconnects the high-voltage power supply circuit to power off the high-voltage load, power off the low-voltage load, and discharge the bus capacitor, including: The control unit is powered off, causing the pre-charge contactor K4, the main positive contactor K5, the main negative contactor K6, the relay K2, and the relay K1 to all turn off, thereby powering off the high-voltage load and the low-voltage load. When the control unit is powered off, the pre-charge contactor K4, the main positive contactor K5, the main negative contactor K6, the relay K2, and the relay K1 are all turned off, and the discharge contactor K3 is turned on to discharge the bus capacitor C1.

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