A vehicle and a low-voltage power supply system thereof

Abstract

The present application relates to the technical field of new energy vehicles, in particular to a vehicle and a low-voltage power supply system thereof. The scheme comprises a low-voltage storage battery and a DC / DC. The low-voltage storage battery is used to supply power to part of the low-voltage load through a low-voltage power supply circuit when the DC / DC is not activated. The DC / DC is used to charge the low-voltage storage battery and supply power to all low-voltage loads after being activated. The low-voltage load comprises a VCU connected to the low-voltage storage battery through a first switch, and the working state of the VCU is controlled by controlling the on-off of the first switch, thereby controlling the working state of the DC / DC. On the one hand, the low-voltage storage battery and the DC / DC supply power to the low-voltage load under different working conditions, respectively. On the other hand, since the VCU does not have a low-power mode, a first switch is arranged between the VCU and the low-voltage storage battery, which can further reduce the consumption of the VCU on the power of the low-voltage storage battery, thereby prolonging the endurance mileage of the low-voltage storage battery, and can also flexibly control the working state of the VCU, thereby improving the safety of vehicle operation.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a vehicle and its low-voltage power supply system. Background Technology

[0002] Currently, lead-acid batteries are the main low-voltage power source for electric vehicles. However, lead-acid batteries have problems such as environmental pollution, high cost, large space occupation in the vehicle, and the inability to start the electric vehicle due to low-voltage lead-acid batteries running out of power after the vehicle has been parked for a long time. Therefore, some manufacturers have chosen to use lithium batteries as the low-voltage power source to avoid these problems.

[0003] Chinese invention patent application CN109624714A proposes a power supply system for electric vehicles. This battery system uses multiple power supply units connected in series to form a battery box. When the vehicle requires low-voltage power, power is drawn from a local power supply unit to supply the low-voltage load. Chinese invention patent application CN109050257A proposes a novel low-voltage power supply system for new energy vehicles. The high-voltage battery pack consists of multiple battery cells connected in series and parallel. Low-voltage power interfaces are led out from both ends of some of the series-connected battery cells, and power is supplied to low-voltage loads through these interfaces. Both solutions draw power from a localized portion of the battery system to supply the vehicle's low-voltage system. While this approach is theoretically feasible and can reduce costs and weight, in practical use, drawing power from the battery pack series can easily lead to poor consistency in the battery system, affecting its cycle life. Furthermore, since low-voltage and high-voltage systems share a single power supply system, a failure in the high-voltage system can cause a simultaneous failure in the low-voltage system, potentially leading to abnormal situations such as steering failure and doors that cannot be opened, significantly reducing the overall safety performance of the vehicle.

[0004] To address the shortcomings of the two solutions mentioned above, Chinese invention patent application CN115051432A proposes a low-voltage power supply system for electric vehicles. This system includes a low-voltage battery and at least one additional DC / DC converter. The additional DC / DC converter is located in the normally closed circuit of the high-voltage battery pack, ensuring that its output is not controlled by a high-voltage relay. Even when the high-voltage battery pack is de-energized and the vehicle is no longer running, the high-voltage battery pack can still charge the low-voltage battery and supply power to the low-voltage circuit via the additional DC / DC converter, depending on the low-voltage load. Furthermore, the low-voltage battery can supply power to the low-voltage load even when the DC / DC converter is not activated or is faulty. When the DC / DC converter is activated and operating normally, it prioritizes powering the low-voltage load, and there is no power supply priority for the low-voltage load. However, due to the large number of low-voltage loads, the cost of using large-capacity low-voltage batteries would be very high; if small-capacity low-voltage batteries are used, it cannot be guaranteed that the low-voltage batteries can simultaneously power various low-voltage loads of the vehicle, especially some low-voltage loads that affect the normal operation of the vehicle, thus leading to safety hazards in the operation of the vehicle. Summary of the Invention

[0005] The purpose of this invention is to provide a vehicle low-voltage power supply system to solve the problems in the prior art where large-capacity low-voltage batteries are expensive and small-capacity low-voltage batteries cannot ensure power supply to low-voltage equipment that plays a critical role in driving safety; and to provide a vehicle for installing the above-mentioned vehicle low-voltage power supply system and realizing the functions of the above-mentioned system.

[0006] To address the aforementioned technical problems, this invention provides a vehicle low-voltage power supply system, comprising a low-voltage battery and a DC / DC converter. The low-voltage battery supplies power to a first type of low-voltage load and a second type of low-voltage load via a low-voltage power supply circuit when the DC / DC converter is not activated. The DC / DC converter, when activated, charges the low-voltage battery and supplies power to the first type of low-voltage load, the second type of low-voltage load, the third type of low-voltage load, and the fourth type of low-voltage load.

[0007] The first type of low-voltage load is a continuously powered load, which refers to low-voltage equipment that can work in driving, charging and stationary states, including at least BCM, BMS and VCU; a first switch is set on the power supply circuit between VCU and low-voltage battery, and the power supply to VCU is controlled by controlling the first switch to be open; the power supply to VCU is controlled by controlling the first switch to be open, thereby activating DC / DC by the low-voltage battery;

[0008] The second type of low-voltage load is constant electrical equipment, which refers to low-voltage equipment that can work when the vehicle is in motion or starting.

[0009] Category III and Category IV low-voltage loads are all low-voltage loads other than Category I and Category II low-voltage loads.

[0010] Beneficial effects: The vehicle low-voltage power supply system of the present invention uses a low-voltage battery and a DC / DC converter to supply power to low-voltage loads. When the DC / DC converter is activated, it prioritizes supplying power to low-voltage loads to ensure that all low-voltage loads of the vehicle can operate normally. When the DC / DC converter is not activated, the low-voltage battery supplies power to continuously powered loads and constantly powered equipment, so that the low-voltage battery can use its limited power to supply power to low-voltage equipment that plays a critical role in driving safety, thereby ensuring the safe operation of the vehicle. Since the VCU does not have a low-power mode, a first switch is set between the VCU and the low-voltage battery. This not only reduces the VCU's power consumption on the low-voltage battery and extends the low-voltage battery's driving range, but also allows for flexible and convenient control of the VCU's operating state by controlling the on / off state of the first switch.

[0011] Furthermore, when the DC / DC converter or the power battery fails, the system switches to supply power to the first and second type low-voltage loads via the low-voltage battery, and stops supplying power to the remaining low-voltage loads.

[0012] Beneficial effects: In the event of a DC / DC failure, the low-voltage battery supplies power to a portion of the low-voltage load, allowing the low-voltage battery to utilize its limited capacity to power low-voltage equipment that plays a critical role in driving safety, thereby ensuring the safe operation of the vehicle.

[0013] Furthermore, the methods for driving the first switch to close include:

[0014] When the vehicle is in driving mode, if the BCM is started, the BCM will drive the first switch to close; or, if the ON switch is closed, the BMS will be activated by the Key on activation signal, and then the BMS will drive the first switch to close.

[0015] In charging mode, if the charging pile outputs an A+ signal, the A+ signal will wake up the BMS, and the BMS will then drive the first switch to close.

[0016] In BMS self-wake-up / 24H monitoring mode, if the BMS enters the working state from the sleep state through RTC self-wake-up, the BMS drives the first switch to close.

[0017] Beneficial effects: When the VCU does not have a low-power mode, a switching device is set between the low-voltage battery and the VCU to prevent the VCU from consuming too much power while always being energized; and the switching device is driven by the BCM, BMS or ON switch so that the low-voltage power supply circuit between the low-voltage battery and the VCU can be turned on in time when the VCU needs to activate the DC / DC. In this way, power consumption can be reduced and the normal operation of low-voltage load can be ensured.

[0018] Furthermore, if the A+ signal changes from valid to invalid in charging mode or the BMS self-wake-up working time meets the standard in BMS self-wake-up / 24H monitoring mode, the reverse wake-up VCU signal before BMS power-down is set to invalid. After the VCU detects that all activation signals are invalid and the vehicle meets the power-down conditions, it unlocks the low-voltage power supply self-locking circuit, and the low-voltage battery supplies power only to the first type of low-voltage load.

[0019] Beneficial effects: Through the reverse wake-up mode, it is possible to shut down the power supply to all low-voltage loads except for the first type of equipment, preventing the low-voltage battery standby time from being shortened or over-discharged due to other low-voltage equipment not being turned off.

[0020] Furthermore, the low-voltage battery is equipped with a charge / discharge protection module, which is located between the DC / DC converter and the low-voltage power supply circuit of the low-voltage battery, and is used to protect the low-voltage battery from over-temperature, under-temperature, over-voltage, and under-voltage.

[0021] Beneficial effects: The charge / discharge protection module can protect the low-voltage battery from over-temperature, under-temperature, over-voltage, and under-voltage during the DC / DC charging process. This not only helps ensure the safety of the charging process but also helps maintain the performance of the low-voltage battery and extend its service life.

[0022] Furthermore, the low-voltage battery is equipped with a charging module, which is located between the DC / DC converter and the low-voltage power supply circuit of the low-voltage battery. This module is used to convert the voltage output by the DC / DC converter and then charge the low-voltage battery pack with constant current and constant voltage.

[0023] Beneficial effects: The charging module is located in the middle of the DC / DC charging circuit for low-voltage batteries. The voltage output by the DC / DC is boosted by the charging module to provide constant current and constant voltage charging for the low-voltage battery pack, ensuring that the low-voltage battery can be fully charged and preventing a large voltage difference between the DC / DC output voltage and the low-voltage battery pack, which could damage the charge / discharge protection module and the low-voltage battery.

[0024] The present invention also provides a vehicle, including a power battery and a low-voltage load, and further including the vehicle low-voltage power supply system described in any of the preceding claims. Attached Figure Description

[0025] Figure 1This is an electrical topology diagram of the vehicle low-voltage power supply system of the present invention;

[0026] Figure 2 This is a schematic diagram of the vehicle low-voltage power supply system of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical principles and practical applications of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Example of a vehicle low-voltage power supply system:

[0029] The electrical topology diagram of the vehicle low-voltage power supply system in this embodiment is as follows: Figure 1 As shown, it includes a low-voltage battery and a DC / DC converter. One end of the DC / DC converter is used to connect to the power battery system via a multi-function controller, and the other end is connected to the low-voltage battery via a charging module, as well as to a continuously powered load via switch K1, and to ON-fire equipment via switch K1 and ON-fire switch. It is also connected to general equipment via switch K1, ON-fire switch, and switch K2. After being activated, it converts the high voltage of the power battery system to a low voltage to charge the low-voltage battery and to supply power to the low-voltage equipment.

[0030] The low-voltage battery is connected to the continuously powered load via the low-voltage power supply circuit, to the normally powered equipment via switch K1, to the normally powered equipment via the ON fire switch, and to general equipment via the ON fire switch and switch K2. It is used to supply power to the continuously powered load and the normally powered equipment when the DC / DC is not activated, and the ON fire equipment and general equipment are disconnected by the VCU control.

[0031] The schematic diagram of the vehicle low-voltage power supply system in this embodiment is as follows: Figure 2 As shown, a low-voltage battery and a DC / DC converter are connected. One end of the DC / DC converter is used to connect to the power battery system via a multi-function controller, and the other end is connected to the low-voltage battery and low-voltage equipment via a charging module. After being activated, the DC / DC converter converts the high voltage of the power battery system to a low voltage, thereby supplying power to the low-voltage equipment and charging the low-voltage battery when its charge level is below a set threshold (e.g., 50%).

[0032] The low-voltage battery is connected to the low-voltage power supply circuit and the continuously powered load and the constantly powered equipment to supply power to the continuously powered load and the constantly powered equipment; it is also connected to the VCU through switch K1, the VCU and the DC / DC converter, the ON fire switch and the ON fire equipment, and the ON fire switch and switch K2 and the general equipment.

[0033] Among them, continuously powered loads refer to low-voltage equipment that can operate in driving, charging, and stationary states, mainly including the Body Control Module (BCM), Battery Management System (BMS), Vehicle Control Unit (VCU), and handle switches, K1 and ON ignition switches, etc.; constantly powered equipment refers to low-voltage equipment that can operate in driving and vehicle-start states, mainly including the Vehicle Monitoring System (ICARD) and low-voltage equipment that needs to operate before the vehicle is started, such as power windows and radios; ON ignition equipment refers to low-voltage equipment that can operate when the vehicle key is turned ON, mainly including the air conditioning panel, refrigeration panel, 360-degree panoramic camera, and reversing radar, etc.; general equipment refers to low-voltage equipment that can operate during vehicle operation, mainly including reversing radar, collision warning, lane departure warning, etc.

[0034] In this embodiment, the VCU does not have a low-power mode. Therefore, to prevent the VCU from consuming too much power while powered, a switch K1 is installed between the VCU and the low-voltage battery. Disconnecting K1 controls the VCU to be powered off. Only when the BCM, BMS, or ON fire switch drives switch K1 can the VCU and low-voltage battery be connected, allowing the low-voltage battery to power the VCU, and the VCU to activate the DC / DC converter to power the low-voltage load. Here, the BCM, BMS, and ON fire switch employ different driving strategies to drive switch K1 according to different operating conditions. The specific driving strategies are as follows:

[0035] When the vehicle is in driving mode (including when the vehicle is stationary and powered on), there are two ways to drive the low-voltage battery to supply power to the VCU. One way is that after the BCM is started, the BCM can drive switch K1 to close, so that the low-voltage battery can provide a constant 24V voltage to the VCU. After the VCU is powered on, the DC / DC converter is activated to supply power to the low-voltage load. The other way is that after the ON ignition switch is closed, the ON ignition switch can directly activate the BMS using the Key on activation signal, and then the BMS can drive K1 to close, so that the low-voltage battery can supply power to the VCU, and the VCU can then activate the DC / DC converter to supply power to the low-voltage load.

[0036] In charging mode, if the charging pile outputs an A+ signal after swiping the card, and the A+ signal wakes up the BMS, the BMS can drive switch K1 to close, thereby providing a constant 24V voltage to the VCU from the low-voltage battery. After the VCU is powered on, it activates the DC / DC converter to supply power to the low-voltage load. If the charging pile no longer outputs an A+ signal or the output A+ signal fails, the BMS will invalidate the reverse wake-up signal to the VCU before powering on from the working state, and the low-voltage equipment will enter a sleep state. Then, after the VCU checks that all activation signals are invalid and the vehicle meets the power-off conditions, it unlocks the low-voltage power supply self-locking circuit to supply power to the low-voltage load.

[0037] In BMS self-wake-up / 24H monitoring mode, if the BMS enters the working state from the sleep state through RTC self-wake-up when the self-wake-up conditions are met, the BMS can drive switch K1 to close, so that the low-voltage battery provides a constant 24V voltage to the VCU. After the VCU is powered on, the DC / DC converter is activated to supply power to the low-voltage load. When the BMS self-wake-up working time reaches the target, the BMS will invalidate the reverse wake-up VCU signal before powering on from the working state, and the low-voltage equipment will enter the sleep state. Then, after the VCU checks that all activation signals are invalid and the whole vehicle meets the power-down conditions, it unlocks the low-voltage power supply self-locking circuit to supply power to the low-voltage load.

[0038] The low-voltage battery in this embodiment is equipped with a charge and discharge protection module, which mainly includes diodes, control circuits, etc., to realize over-temperature, low-temperature, over-voltage, and under-voltage protection of the low-voltage battery pack.

[0039] For example, during battery charging, if the temperature of the low-voltage battery is too low, it will be heated; if the temperature of the low-voltage battery is too high, charging will stop, and when the temperature returns to the normal range, it will be determined whether the charge of the low-voltage battery is lower than a set threshold (e.g., 50%). If so, a charging command will be sent to the DC / DC converter to continue charging the low-voltage battery; if the charging voltage is too low or too high, charging will stop, and charging voltage information will be sent to the charging module to adjust the output voltage until the output voltage is detected to be normal before charging will resume.

[0040] In this embodiment, the low-voltage battery is also equipped with a charging module, which mainly includes resistors, capacitors, inductors, diodes, switching transistors and other devices. The charging module uses the voltage output from the power battery system after DC / DC step-down to boost the voltage of the low-voltage battery through the charging module's boost circuit, so as to perform constant current and constant voltage charging for the low-voltage battery, ensuring that the low-voltage battery can be fully charged, and preventing the voltage difference between the DC / DC output voltage and the low-voltage battery pack from being too large, which could damage the charge and discharge protection module and the low-voltage battery.

[0041] In this embodiment, the output terminal of the low-voltage battery is equipped with an anti-backflow diode to prevent the low-voltage battery from being charged by the voltage output by the power battery system after DC / DC step-down without management and control.

[0042] In this embodiment, the switching device can be any type of switching device such as a relay, contactor, MOSFET, IGBT, key switch, or push button switch.

[0043] In this embodiment, low-voltage loads are divided into four categories. In other embodiments, the classification of low-voltage loads can be adjusted according to the actual needs of the customer for power supply allocation.

[0044] Vehicle Example:

[0045] The vehicle in this embodiment includes a power battery and a low-voltage load, as well as the vehicle low-voltage power supply system in the above embodiments. The structural units included in the system and the functions that each structural unit can achieve have been described in detail in the above embodiments, and will not be repeated here.

Claims

1. A vehicle low-voltage power supply system, comprising a low-voltage battery and a DC / DC converter, characterized in that, The low-voltage battery is used to power continuously powered loads and constantly powered equipment through the low-voltage power supply circuit when the DC / DC is not activated; the DC / DC is used to charge the low-voltage battery and power continuously powered loads, constantly powered equipment, and other low-voltage loads other than continuously powered loads and constantly powered equipment after it is activated. A continuously powered load refers to a low-voltage device that can operate while the vehicle is in motion, charging, or stationary states, including at least a BCM, BMS, and VCU; a first switch is installed on the power supply circuit between the VCU and the low-voltage battery, and the power to the VCU is cut off by controlling the opening of the first switch; The methods for driving the first switch to close include: in driving mode, after the BCM is started, the BCM drives the first switch to close; or after the ON ignition switch is closed, the ON ignition switch activates the BMS, and the BMS drives the first switch to close. After the VCU is powered on, it activates the DC / DC converter to supply power to the low-voltage load. In charging mode, if the charging pile outputs an A+ signal, the A+ signal wakes up the BMS, and then the BMS drives the first switch to close. In BMS self-wake-up / 24H monitoring mode, if the BMS enters the working state from the sleep state through RTC self-wake-up, the BMS drives the first switch to close. If the A+ signal changes from valid to invalid or the BMS self-wake-up working time reaches the standard, the reverse wake-up signal of the VCU before the BMS is powered off is set to invalid. After the VCU detects that all activation signals are invalid and the vehicle meets the power-off conditions, it unlocks the low-voltage power supply self-locking circuit, and the low-voltage battery supplies power to the continuous load only. Constant voltage equipment refers to low-voltage equipment that can operate while the vehicle is in motion or running.

2. The vehicle low-voltage power supply system according to claim 1, characterized in that, When the DC / DC converter or power battery fails, the system switches to use the low-voltage battery to continuously power the loads and constant-voltage equipment, and stops powering the remaining low-voltage loads.

3. The vehicle low-voltage power supply system according to claim 1 or 2, characterized in that, The output terminal of the low-voltage battery is also equipped with an anti-backflow diode.

4. The vehicle low-voltage power supply system according to claim 1 or 2, characterized in that, Other low-voltage loads include ON-fired equipment and general equipment. ON-fired equipment refers to low-voltage equipment that can operate when the vehicle key is turned ON, while general equipment refers to low-voltage equipment that can operate while the vehicle is running.

5. The vehicle low-voltage power supply system according to claim 1 or 2, characterized in that, The low-voltage battery is equipped with a charge / discharge protection module, which is located between the DC / DC converter and the low-voltage power supply circuit of the low-voltage battery, and is used to protect the low-voltage battery from over-temperature, low-temperature, over-voltage, and under-voltage.

6. The vehicle low-voltage power supply system according to claim 1 or 2, characterized in that, The low-voltage battery is equipped with a charging module, which is located between the DC / DC converter and the low-voltage power supply circuit. The module is used to convert the voltage output by the DC / DC converter and then charge the low-voltage battery pack with constant current and constant voltage.

7. A vehicle comprising a power battery and a low-voltage load, characterized in that, It also includes the vehicle low-voltage power supply system as described in any one of claims 1-6.

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