A vehicle low-voltage power supply system and an electric vehicle

Abstract

The present application relates to the technical field of new energy vehicles, in particular to a vehicle low-voltage power supply system and an electric vehicle. The present application comprises a storage battery and a DC / DC, one end of the DC / DC is used for connecting a power battery, the other end is connected with the storage battery and a low-voltage load, and is used for charging the storage battery and supplying power to the low-voltage load. The storage battery is connected with emergency loads and 24-hour constant power equipment through a low-voltage power supply circuit. If the power battery and the DC / DC are normal, the DC / DC converts high-voltage direct current of the power battery into low-voltage direct current to supply power to the low-voltage load. If the power battery or the DC / DC fails, the storage battery supplies power to the emergency loads and the 24-hour constant power equipment. The present application not only ensures normal power supply to the emergency loads and the 24-hour constant power equipment of the vehicle, guarantees the stability and reliability of the low-voltage power supply of the vehicle, but also has low system cost and simple structure.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle technology, and in particular to a low-voltage power supply system for vehicles and electric vehicles. 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 electric vehicles being unable to start due to depletion of the lead-acid battery after being 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] Chinese invention patent application CN115051432A proposes a low-voltage power supply system for electric vehicles. This system includes a low-voltage power supply 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 its output is not controlled by a high-voltage relay. Even when the high-voltage battery pack is de-energized and the vehicle is not in operation, the high-voltage battery pack can reliably supply power to both the battery and external low-voltage circuits via the additional DC / DC converter, maintaining the battery at a healthy level, depending on the low-voltage load. This solution provides a more stable, reliable, and durable low-voltage power supply for electric vehicles; however, the additional DC / DC converter increases the cost and structural complexity of the low-voltage power supply system. Summary of the Invention

[0005] The purpose of this invention is to provide a vehicle low-voltage power supply system to solve the problems of high cost and complex structure of existing low-voltage power supply systems; and to provide an electric 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, including a battery and a DC / DC converter. One end of the DC / DC converter is connected to a power battery, and the other end is connected to the battery and a low-voltage load. The DC / DC converter is used to charge the battery and supply power to the low-voltage load. The battery is connected to emergency loads and 24-hour continuous power equipment via a low-voltage power supply circuit. If both the power battery and the DC / DC converter are functioning normally, the DC / DC converter converts the high-voltage DC power from the power battery into low-voltage DC power to supply power to the low-voltage load. If either the power battery or the DC / DC converter fails, the battery supplies power to the emergency loads and 24-hour continuous power equipment.

[0007] Beneficial effects: When the DC / DC converter is working normally, the vehicle low-voltage power supply system of the present invention converts the high-voltage DC power from the power battery into low-voltage DC power to supply power to low-voltage loads. In the event of a power battery or DC / DC converter failure, the low-voltage power supply provides power to emergency loads and 24-hour continuous electrical equipment. In this way, not only can the normal power supply to the vehicle's emergency loads and 24-hour continuous electrical equipment be ensured, guaranteeing the stability and reliability of the vehicle's low-voltage power supply, but also, compared with the existing technology that adds an additional DC / DC converter, the low-voltage power supply system of the present invention has lower cost and simpler structure.

[0008] Furthermore, a handle switch is installed on the low-voltage power supply circuit between the battery and the 24-hour continuous power equipment to control the on / off of the power supply circuit between the battery and the emergency load and the 24-hour continuous power equipment. A main switch is also installed between the handle switch and the emergency load to control the on / off of the power supply circuit for the emergency load.

[0009] Beneficial effects: By setting a main power switch, this invention can meet the power supply needs of emergency loads and 24-hour continuous power equipment; by setting an emergency switch, the low-voltage circuit connected to the emergency load can be disconnected in time, so that the limited power stored in the battery can guarantee the power supply needs of 24-hour continuous power equipment.

[0010] Furthermore, after the main ignition switch is turned off, the battery continues to supply power to the 24-hour constant electrical equipment until the time the main ignition switch is turned off exceeds the set time threshold.

[0011] Beneficial effects: When the main ignition switch is turned off, the battery continues to supply power to the 24-hour electrical equipment, ensuring the vehicle's safe and normal operation, and ensuring that monitoring data can be continuously transmitted to the backend after parking, keeping the entire vehicle in a monitorable state; when the main ignition switch is turned off for more than a set time threshold, the battery is controlled to stop supplying power to the outside, thereby preventing the battery from being depleted and avoiding damage to the battery.

[0012] Furthermore, the battery is equipped with an electronic switch, which is used to provide an activation signal to the DC / DC converter before the vehicle is started and after the handle switch is detected to be closed; at the same time, it controls the charging and discharging of the battery.

[0013] Furthermore, it also includes a temperature detection module and a heating module for detecting the battery temperature. If the detected battery temperature is lower than the set temperature threshold, the battery will not be charged or discharged.

[0014] Beneficial effects: Because the viscosity of the electrolyte in a lithium battery decreases and its conductivity drops at low temperatures, charging and discharging will terminate prematurely. This invention prevents the battery from charging and discharging when the battery temperature is detected to be below a set temperature threshold, thus avoiding irreversible damage to the battery and extending its service life. In addition, it can heat the battery in a timely manner, improving the battery's performance.

[0015] Furthermore, a storage battery is a lithium battery composed of multiple battery cells.

[0016] Beneficial effects: Compared with lead-acid batteries, lithium batteries have the advantages of being environmentally friendly, occupying less space, having high energy density, long battery life, good temperature performance, and long service life.

[0017] Furthermore, the battery is sealed with a casing made of impact-resistant metal or non-metal materials, and fire-resistant materials are installed inside the casing.

[0018] Beneficial effects: The battery is sealed with a casing made of impact-resistant metal or non-metal materials, which ensures that the battery can be used normally in the event of an impact; the fire-resistant material installed inside the casing can prevent the battery from affecting external equipment when it is at a high temperature, and at the same time, the battery can still be used normally in the event of an external fire.

[0019] Furthermore, thermally conductive adhesive is used to encapsulate the cells.

[0020] Beneficial effects: Encapsulating the battery with thermally conductive adhesive can quickly transfer heat to the adhesive through thermal conduction when a battery cell is in a localized high-temperature situation, thus preventing localized high temperatures or even fires in the battery cell.

[0021] The present invention also provides an electric 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

[0022] Figure 1 This is an electrical topology diagram of the vehicle low-voltage power supply system in an embodiment;

[0023] Figure 2 This is a schematic diagram of the vehicle low-voltage power supply system in an embodiment;

[0024] Figure 3 This is a schematic diagram of the external packaging structure of the battery module in an embodiment;

[0025] Figure 4 This is a flowchart illustrating the operation of the vehicle low-voltage power supply system in an embodiment. Detailed Implementation

[0026] 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.

[0027] Example of a vehicle low-voltage power supply system:

[0028] 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 DC / DC converter and a battery. One end of the DC / DC converter is connected to the power battery, and the other end is connected to the battery and a low-voltage load. It converts the high-voltage DC power from the power battery into low-voltage DC power to supply power to non-continuously operating loads, 24-hour continuous power equipment, and emergency loads, as well as to charge the battery. The battery is connected to the emergency load and 24-hour continuous power equipment via a low-voltage power supply circuit. A handle switch is installed on the low-voltage power supply circuit to control the connection or disconnection between the low-voltage power supply circuit and the emergency load and 24-hour continuous power equipment.

[0029] The schematic diagram of the vehicle low-voltage power supply system in this embodiment is as follows: Figure 2As shown, the system includes a DC / DC converter and a battery. The high-voltage side of the DC / DC converter is connected to the power battery, while the low-voltage side connects to the battery, electrical box 1, and electrical box 2. The DC / DC converter is used to charge the battery and supply power to the low-voltage loads connected to it via electrical box 1 and electrical box 2, respectively. Current monitoring point 1 and current monitoring point 2 are installed on the low-voltage power supply line between the DC / DC converter and electrical box 1, and on the low-voltage power supply line between the DC / DC converter and electrical box 2. Current monitoring points 1 and 2 are used to detect the magnitude of the current output from the low-voltage side of the DC / DC converter. Electrical box 1 is connected to 24-hour continuously powered equipment such as the dashcam, constant power supply, ABS, instrument cluster, door remote, vehicle control unit (VCU), bleed valve, and battery management system (BMS), as well as emergency loads such as lights and instruments, front electrical box, dual-source steering, and traditional low-voltage modules, and devices such as the player, tire pressure monitoring, electric fan, and water pump. Electrical box 2 is connected to non-continuously powered loads such as the air conditioning controller, air conditioning panel / independent unit, monitoring host, video all-in-one machine, network management system, and fire extinguishing controller. Fuse is installed between the emergency loads and electrical box 1, and between the non-continuously powered loads and electrical box 2, to provide overcurrent protection for the emergency loads and non-continuously powered loads.

[0030] The battery is equipped with an electronic manual switch, which activates the DC / DC converter and controls the battery's charging and discharging. The battery is also connected to the electrical box 1 via a handle switch, which in turn connects to 24-hour continuous electrical equipment and emergency loads. Between the handle switch and the emergency loads are a main ignition switch and a K2 switch. The main ignition switch provides power to the K2 switch and supplies power to common continuous electrical equipment such as the media player and tire pressure monitoring system. The K2 switch controls the on / off state of the emergency load power supply circuit, providing power to low-voltage loads necessary during driving. When the battery charge falls below a charging threshold (e.g., 50% of total charge), it sends a charging request signal to the DC / DC converter, which then charges the battery. The vehicle enable signal is issued by the VCU. When driving is required, the VCU is activated by the key signal, and the VCU then sends a vehicle enable signal to activate the DC / DC converter to supply power to the vehicle's low-voltage loads.

[0031] All switches appearing in this embodiment can be any type of electronic electrical control device such as relays, contactors, MOSFETs, and IGBTs.

[0032] The DC / DC power selected in this embodiment is 6kW. In other embodiments, the power of the DC / DC can be adjusted according to the actual situation.

[0033] This embodiment is equipped with a temperature detection module and a heating module for detecting the battery temperature. The battery is a 12V or 24V lithium battery module composed of multiple battery cells connected in series or parallel. The configured capacity can be less than 10Ah, and the discharge rate can reach at least 5-40C instantaneous discharge capability. Its external packaging structure diagram is shown below. Figure 3 As shown, the entire lithium battery module is sealed with a shell made of impact-resistant metal or non-metal materials, and the inner wall of the shell is lined with fire-retardant material to ensure that the battery can be used normally even under extreme conditions. Thermally conductive adhesive is used to fill the gaps between the battery cells. If a battery cell experiences localized high temperature, the heat of that battery cell can be quickly transferred to the thermally conductive adhesive through heat conduction, preventing localized high temperature of the battery cell or even fire, and improving the safety of the battery operation.

[0034] In other embodiments, the fireproof material is not limited to being placed close to the inner wall of the shell, and there may be a gap between the fireproof material and the shell; the thermally conductive adhesive is not limited to being potted between the battery cells, and thermally conductive adhesive may also be potted between the battery cells and the fireproof material.

[0035] The operation process of the vehicle low-voltage power supply system in this embodiment is as follows: Figure 4 As shown, the specific process is as follows:

[0036] Before the vehicle starts, the handle switch is closed. When the power signal of the handle switch is detected, the electronic manual switch closes. The DC / DC converter is activated by the vehicle control unit (VCU). Then the battery performs a self-check to determine if there are any abnormalities. Abnormalities include undervoltage, overvoltage, low temperature, etc. If an abnormality occurs, an alarm is issued. If the battery is normal, the temperature detection module detects the battery temperature. If the battery temperature is less than 5°C, the electronic manual switch is disconnected to stop the battery from charging and discharging, and the heating module is activated to heat the battery until the battery temperature reaches 5°C. Then the electronic manual switch is closed again. If the battery temperature is greater than or equal to 5°C, the battery charge is checked to see if it is below the charging threshold. If it is below the charging threshold, a charging request signal is sent to the DC / DC converter, which then charges the battery.

[0037] When the vehicle is charging, when the BMS receives the A+ signal, the BMS wakes up the DC / DC converter to control the charging of the entire vehicle. When the vehicle is in a stationary state, the DC / DC converter is activated by its built-in timed wake-up signal to power the BMS and other vehicle monitoring systems, ensuring that the vehicle can be woken up at regular intervals during stationary periods and to monitor the safety status of the battery and the entire vehicle periodically.

[0038] The current at monitoring points 1 and 2 is monitored in real time. If an abnormal current is detected at either monitoring point, a fault is considered in the power battery or DC / DC converter. The system then switches to the battery to power emergency loads and 24-hour continuous electrical equipment. Since the battery's stored capacity is limited, the vehicle must be pulled over promptly for inspection. During inspection, the main ignition switch must be turned off. After the main ignition switch is turned off, the battery continues to power the 24-hour continuous electrical equipment until the time since the main ignition switch was turned off exceeds a set time threshold (e.g., 1 hour). Setting the waiting time after the main ignition switch is turned off to no more than 1 hour ensures both safe and normal vehicle operation and continuous transmission of monitoring data to the backend, keeping the vehicle under monitoring control. In other embodiments, the waiting time can be adjusted as needed; a recommended range is 0.5 hours to 120 hours.

[0039] This embodiment takes the dual-source steering module as an example to illustrate the way the vehicle power supply system provides power to emergency loads. When the power battery and DC / DC converter are working normally, the DC / DC converter converts the high-voltage DC power from the power battery into low-voltage DC power to power the dual-source steering module. When the power battery or DC / DC converter is abnormal, the battery powers the dual-source steering module.

[0040] In this embodiment, a temperature threshold of 5°C is set to prevent the lithium battery from supplying power or being charged by DC / DC converters at temperatures below this threshold, thereby improving the battery's lifespan. In other embodiments, the battery's temperature threshold can be adjusted appropriately based on the battery's electrochemical system and is not limited to 5°C.

[0041] In summary, the battery in this embodiment serves three main functions: first, it activates the DC / DC converter, supplying power to the vehicle's low-voltage loads via DC-DC conversion through the vehicle's high-voltage battery system; second, it powers high-power emergency loads in the event of a failure in the power battery or DC / DC converter, such as lights, instruments, dual-source steering, and some conventional voltage devices; and third, it powers continuously operating devices 24 hours a day in the event of a failure in the power battery or DC / DC converter, such as dashcams, ABS, air release valves, and door remote controls. Under normal conditions, when both the vehicle's power battery and DC / DC converter are functioning correctly, the vehicle's low-voltage loads are powered by the vehicle's high-voltage battery system via DC-DC conversion.

[0042] Electric vehicle example:

[0043] The electric vehicle of this embodiment includes a power battery and a low-voltage load, as well as a vehicle low-voltage power supply system. The structural units included in the vehicle low-voltage power supply system and the functions that each structural unit can achieve have been described in detail in the above embodiment of the vehicle low-voltage power supply system, and will not be repeated here.

Claims

1. A vehicle low-voltage power supply system, comprising a battery and a DC / DC converter, one end of the DC / DC converter being connected to a power battery, and the other end being connected to the battery and a low-voltage load, for charging the battery and supplying power to the low-voltage load, characterized in that, The battery is equipped with an electronic switch, which is used to conduct electricity after detecting the closing of the handle switch before the vehicle starts, providing an activation signal to the DC / DC converter and controlling the charging and discharging of the battery. The battery is used to connect emergency loads and 24-hour continuous power equipment through a low-voltage power supply circuit. If both the power battery and the DC / DC converter are normal, the DC / DC converter converts the high-voltage DC power from the power battery into low-voltage DC power to supply power to the low-voltage load. If the power battery or the DC / DC converter fails, the battery supplies power to the emergency loads and 24-hour continuous power equipment. A handle switch is installed on the low-voltage power supply circuit between the battery and the 24-hour continuous power equipment. A main ignition switch is also installed between the handle switch and the emergency load. When the main ignition switch is turned off, the battery continues to supply power to the 24-hour continuous power equipment until the time the main ignition switch is off exceeds a set time threshold, at which point the battery stops supplying power.

2. The vehicle low-voltage power supply system according to claim 1, characterized in that, A K2 switch is also installed between the handle switch and the emergency load. The main ignition switch provides power to the K2 switch, which is used to control the on / off state of the emergency load power supply circuit.

3. The vehicle low-voltage power supply system according to claim 1, characterized in that, It also includes a temperature detection module for detecting the temperature of the battery. If the temperature of the battery is detected to be lower than a set temperature threshold, the battery will not be charged or discharged.

4. The vehicle low-voltage power supply system according to claim 3, characterized in that, It also includes a heating module. If the battery temperature is lower than the set temperature threshold, the heating module is activated to heat the battery until the battery temperature reaches the set temperature threshold.

5. The vehicle low-voltage power supply system according to any one of claims 1-4, characterized in that, When the vehicle is stationary, the DC / DC converter is activated by a timed wake-up signal to supply power to the BMS.

6. The vehicle low-voltage power supply system according to claim 5, characterized in that, The battery is a lithium battery composed of multiple battery cells.

7. The vehicle low-voltage power supply system according to claim 6, characterized in that, The battery is sealed by a casing made of impact-resistant metal or non-metal materials, and the casing is lined with fire-resistant materials.

8. The vehicle low-voltage power supply system according to claim 7, characterized in that, Thermally conductive adhesive is used to encapsulate the cells.

9. An electric 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 1-8.

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