Cell charging protection circuit in low-temperature environment
By designing multiple loop protection functions and heating devices in the lithium-ion battery charging protection circuit, the damage problem during battery charging in low-temperature environments is solved, and the safety of the battery is improved.
Patent Information
- Application Number
- CN202421806700.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-29
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2034-07-29
AI Technical Summary
The prior art cannot effectively protect lithium-ion batteries in low temperature environments, resulting in a degradation in battery cell performance, shortening of life during charging, and may cause irreversible damage.
A low-temperature environmental battery cell charging protection circuit is designed, adopting multiple loop protection functions, including main control unit, relay and heating device, which can prohibit charging in an environment below 0°C and prevent battery damage.
It realizes effective protection of lithium-ion batteries in low temperature environments, prevents degradation of battery performance and irreversible damage caused by charging, and improves the safety of the battery.
Smart Images
Figure CN222915698U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a battery pack charging circuit, in particular to a battery cell charging protection circuit in a low temperature environment. Background Art
[0002] With the rapid development of energy storage technology, renewable energy is gradually replacing fossil energy. Existing energy storage systems are limited by many factors such as battery cell performance. For example, the operating temperature of conventional lithium-ion batteries is -20℃~60℃, and the general optimal ambient temperature is around 0~35℃, which makes it impossible to use energy storage systems in some cold areas in the north. In order to solve this difficulty, the current common method in the industry is to use products such as PTC or heating film to heat the battery. However, during use, some circuit controls are not perfect and the circuit is not disconnected in time, which can easily cause damage to the battery cell. For example, under negative temperature (<0℃) conditions, the battery system does not allow direct charging, and it needs to be preheated with the heating system before charging. The existing electrical schematic diagram only uses single-circuit positive and negative pole control. When the temperature is below 0℃, the circuit is not disconnected in time due to faults such as adhesion of control components or signal loss. If charging continues at this time, the performance of the battery cell will be greatly reduced and the life will be shortened. At the same time, the prohibition of charging lithium batteries at low temperatures may cause irreversible damage, accelerate the deposition of metallic lithium, puncture the diaphragm, and easily lead to lithium deposition at the negative electrode, which will not only cause the battery capacity to decline rapidly, but also cause serious safety hazards. Especially when charging lithium-ion batteries under low temperature conditions, metallic lithium will be deposited on the surface of the battery anode. This process is irreversible. The permanent damage caused to the battery will significantly reduce the safety of the lithium battery. Utility Model Content
[0003] The technical problem to be solved by the utility model is to provide a battery charging protection circuit with a multi-circuit protection function of prohibiting charging in a low-temperature environment, which can avoid damaging the battery and improve the safety of lithium batteries in a low-temperature environment, in view of the deficiencies of the existing technology.
[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions.
[0005] A low temperature environment battery charging protection circuit, comprising a main control unit, a main positive relay KJ1, a total positive relay KJ2, a total negative relay KJ3, a heating relay KJ6, a heating relay KJ7 and a charging positive pole control unit, wherein the main control unit is connected to a communication end of a preset battery pack, the positive end of the battery pack is connected to one end of a normally open contact of the main positive relay KJ1, the other end of the normally open contact of the main positive relay KJ1 is used as a total output end OUT and is connected to the charging positive pole control unit, and one end of the normally open contact of the total positive relay KJ2 is connected to the The total output terminal OUT, the other end of the normally open contact of the total positive relay KJ2 is connected to the preset cold machine power supply interface and / or DC-DC power supply interface, the negative pole of the battery pack is connected to one end of the normally open contact of the total negative relay KJ3, and the other end of the normally open contact of the total negative relay KJ3 serves as the negative charging terminal, the normally open contact of the heating relay KJ6 is connected between the total output terminal OUT and the positive pole of the heating end of the battery pack, and the normally open contact of the heating relay KJ7 is connected between the negative pole of the battery pack and the negative pole of the heating end of the battery pack.
[0006] Preferably, the charging positive electrode control unit includes a fast charging positive relay KJ4, and the normally open contact of the fast charging positive relay KJ4 is connected between the total output terminal OUT and a preset fast charging positive terminal.
[0007] Preferably, the charging positive electrode control unit includes a slow charging positive relay KJ5, and the normally open contact of the slow charging positive relay KJ5 is connected between the total output terminal OUT and a preset slow charging positive terminal.
[0008] Preferably, a fire communication adapter module is included, and the fire communication adapter module is connected between the communication terminal of the battery pack and a preset debugging interface.
[0009] Preferably, the fire communication switching module is also connected to the main control unit.
[0010] Preferably, it includes a pre-charging relay KJ8 and a pre-charging resistor R1, and the pre-charging relay KJ8 and the pre-charging resistor R1 are sequentially connected in series and connected between the two ends of the normally open contact of the total positive relay KJ2.
[0011] Preferably, a heating fuse FU is included, and the heating fuse FU is connected in series between the total output terminal OUT and the normally open contact of the heating relay KJ6.
[0012] The low-temperature environment battery cell charging protection circuit disclosed by the utility model has a beneficial effect compared with the prior art in that the utility model provides a stable and reliable control circuit, especially in a low-temperature environment below 0°C, which can prohibit charging in time to achieve multiple circuit protection effects, and combined with a low-temperature environment battery cell charging protection control strategy, avoid charging of lithium-ion batteries under low temperature conditions, prevent irreversible damage to the batteries, and thus improve the safety of lithium batteries under low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 This is a block diagram of the low temperature environment battery charging protection circuit of the utility model;
[0014] Figure 2 This is the schematic diagram of the main control unit;
[0015] Figure 3 This is a control mode diagram of the low temperature environment battery charging protection circuit of the utility model;
[0016] Figure 4 This is the high voltage power-on flow chart;
[0017] Figure 5 This is the power-off flow chart;
[0018] Figure 6 This is the DC charging control flow chart. DETAILED DESCRIPTION
[0019] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments.
[0020] The utility model discloses a low temperature environment battery charging protection circuit, see Figure 1, which includes a main control unit 2, a main positive relay KJ1, a total positive relay KJ2, a total negative relay KJ3, a heating relay KJ6, a heating relay KJ7 and a charging positive pole control unit 3, wherein the main control unit 2 is connected to a communication terminal of a preset battery pack 1, the positive terminal of the battery pack 1 is connected to one end of a normally open contact of the main positive relay KJ1, the other end of the normally open contact of the main positive relay KJ1 is used as a total output terminal OUT and is connected to the charging positive pole control unit 3, and one end of the normally open contact of the total positive relay KJ2 is connected to the total output terminal O UT, the other end of the normally open contact of the total positive relay KJ2 is connected to the preset cold machine power supply interface and / or DC-DC power supply interface, the negative pole of the battery pack 1 is connected to one end of the normally open contact of the total negative relay KJ3, and the other end of the normally open contact of the total negative relay KJ3 serves as the negative charging terminal, the normally open contact of the heating relay KJ6 is connected between the total output terminal OUT and the positive pole of the heating end of the battery pack 1, and the normally open contact of the heating relay KJ7 is connected between the negative pole of the battery pack 1 and the negative pole of the heating end of the battery pack 1.
[0021] In the above-mentioned low-temperature environment battery charging protection circuit, the energy storage system operation strategy with a battery heating device is adopted. When the environment is at a negative temperature (<0°C), the battery system is not allowed to charge directly, that is, the battery temperature is below 0°C and the battery pack main positive relay KJ1 is not allowed to be closed. At this time, the main control unit 2 sends the maximum allowable charging current to the charger according to the rated operating current requirements of the heating system and the battery load. The charging pile supplies power to the heating system and the cold machine load. After the battery temperature rises above 0°C, the main positive relay of the battery pack is closed, and the state of heating and discharging is entered (the charging pile charges the battery and supplies power to the heating system and external loads at the same time).
[0022] On this basis, see Figure 1 The charging positive electrode control unit 3 includes a fast charging positive relay KJ4, and the normally open contact of the fast charging positive relay KJ4 is connected between the total output terminal OUT and the preset fast charging positive terminal. At the same time, the charging positive electrode control unit 3 includes a slow charging positive relay KJ5, and the normally open contact of the slow charging positive relay KJ5 is connected between the total output terminal OUT and the preset slow charging positive terminal.
[0023] See also Figure 2 In this embodiment, the coils of the main positive relay KJ1, the total positive relay KJ2, the total negative relay KJ3, the fast charging positive relay KJ4, the slow charging positive relay KJ5, the heating relay KJ6 and the heating relay KJ7 are respectively connected to the control ports of the main control unit 2, and the main control unit 2 is used to control the on and off states of the above relays. The specific control process and strategy are as follows Figure 3 shown.
[0024] Furthermore, the present embodiment includes a fire communication adapter module 4, which is connected between the communication terminal of the battery pack 1 and a preset debugging interface. The fire communication adapter module 4 also interacts with the main control unit 2, and specifically, the fire communication adapter module 4 is also connected to the main control unit 2.
[0025] As a parallel branch of the total positive relay KJ2, in this embodiment, see Figure 1 , and also includes a pre-charging relay KJ8 and a pre-charging resistor R1, which are sequentially connected in series and connected between the two ends of the normally open contact of the total positive relay KJ2.
[0026] Furthermore, a heating fuse FU is included, and the heating fuse FU is connected in series between the total output terminal OUT and the normally open contact of the heating relay KJ6.
[0027] In practical applications, this embodiment provides a high and low temperature operation control strategy, including:
[0028] 1. Negative temperature charging strategy: that is, under negative temperature (<0℃) conditions, the battery system is not allowed to be charged directly and needs to be preheated with the heating system, for example,
[0029] 1.1 Low temperature fast charging strategy:
[0030] Temperature range Charging / heating mode Charging rate Tmin<0℃ Heating only / 0℃≤Tmin<10℃ Heating and charging 0.2C Tmin≥10℃ Standard charging 0.5
[0031] 1.2 Low temperature discharge strategy: The battery can be discharged with a small current under negative temperature conditions:
[0032] Temperature range Discharge / heating mode Charging rate -40℃≤Tmin<-30℃ Heating and discharging 0.1C -30℃≤Tmin<0℃ Low rate discharge 0.1C Tmin≥0℃ Standard discharge 0.2C
[0033] According to the actual working conditions of the load, the maximum current of the load is about 30A (about 0.07C). The load startup phase is short. Under normal operating conditions, the load current is less than 10A, which is about 0.02C. Therefore, the low-temperature discharge performance of the battery can meet the power supply requirements under normal operating conditions of the load.
[0034] 2. High temperature charging strategy: Under the condition of 0.2C or less, the battery charging temperature rise is very small, and basically will not cause obvious temperature rise to the battery:
[0035] Temperature range Charging Mode Charging rate 45℃≤Tmax<50℃ Low rate charging 0.2C 50℃≤Tmax<55℃ Low rate charging 0.1C
[0036] 3. High temperature discharge strategy:
[0037]
[0038]
[0039] Except for the above high and low temperatures, the battery system can operate normally at a nominal rate of 0.5C in other temperature ranges (10℃~45℃).
[0040] Compared with the prior art, the utility model provides a stable and reliable control circuit, which can prohibit charging in time, especially in a low temperature environment below 0°C, to achieve multiple circuit protection, and combines the low temperature environment battery cell charging protection control strategy to avoid charging of lithium-ion batteries under low temperature conditions, prevent irreversible damage to the battery, and thus improve the safety of lithium batteries under low temperature conditions.
[0041] In actual application, the utility model can adopt a discharge control strategy: that is, the high-voltage power-on process starts from the low-voltage power-on of the vehicle (turning on the vehicle start key) to the completion of the high-voltage circuit power-on, and the main positive relay, the total positive relay, and the total negative relay are controlled by the BMS. At the same time, please refer to the high-voltage power-on process involved Figure 4 For power-off procedures, see Figure 5 , where: the high voltage power-off process starts from the disappearance of the low voltage signal or the detection of a serious fault by the BMS, and ends with the disconnection of the high voltage circuit. For DC charging control strategy, please refer to Figure 6 , follow the national standard fast charging process, and the BMS performs self-check before charging: a. The voltage and temperature acquisition lines are off; b. The master-slave communication fails; c. The battery system has a level 3 fault; d. Others.
[0042] 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 or improvements made within the technical scope of the present invention should be included in the scope of protection of the present invention.
Claims
1. A low temperature environment battery charging protection circuit, characterized in that: The invention comprises a main control unit (2), a main positive relay KJ1, a total positive relay KJ2, a total negative relay KJ3, a heating relay KJ6, a heating relay KJ7 and a charging positive electrode control unit (3), wherein the main control unit (2) is connected to a communication terminal of a preset battery pack (1), the positive terminal of the battery pack (1) is connected to one end of a normally open contact of the main positive relay KJ1, the other end of the normally open contact of the main positive relay KJ1 serves as a total output terminal OUT and is connected to the charging positive electrode control unit (3), and one end of the normally open contact of the total positive relay KJ2 is connected to the total output terminal OUT. OUT, the other end of the normally open contact of the total positive relay KJ2 is connected to a preset cooling machine power supply interface and / or a DC-DC power supply interface, the negative electrode of the battery pack (1) is connected to one end of the normally open contact of the total negative relay KJ3, and the other end of the normally open contact of the total negative relay KJ3 serves as a negative charging terminal, the normally open contact of the heating relay KJ6 is connected between the total output terminal OUT and the positive electrode of the heating end of the battery pack (1), and the normally open contact of the heating relay KJ7 is connected between the negative electrode of the battery pack (1) and the negative electrode of the heating end of the battery pack (1).
2. The low temperature environment battery cell charging protection circuit according to claim 1, characterized in that: The charging positive electrode control unit (3) comprises a fast charging positive relay KJ4, and the normally open contact of the fast charging positive relay KJ4 is connected between the total output terminal OUT and a preset fast charging positive terminal.
3. The low temperature environment battery cell charging protection circuit according to claim 1, characterized in that: The charging positive electrode control unit (3) comprises a slow charging positive relay KJ5, and the normally open contact of the slow charging positive relay KJ5 is connected between the total output terminal OUT and a preset slow charging positive terminal.
4. The low temperature environment battery cell charging protection circuit according to claim 1, characterized in that: It comprises a fire communication adapter module (4), wherein the fire communication adapter module (4) is connected between a communication terminal of the battery pack (1) and a preset debugging interface.
5. The low temperature environment battery cell charging protection circuit according to claim 4, characterized in that: The fire communication switching module (4) is also connected to the main control unit (2).
6. The low temperature environment battery cell charging protection circuit according to claim 1, characterized in that: It includes a pre-charging relay KJ8 and a pre-charging resistor R1, which are sequentially connected in series and connected between the two ends of the normally open contact of the total positive relay KJ2.
7. The low temperature environment battery cell charging protection circuit according to claim 1, characterized in that: A heating fuse FU is included, and the heating fuse FU is connected in series between the total output terminal OUT and the normally open contact of the heating relay KJ6.