Low-temperature starting circuit of lithium iron phosphate battery
By setting a temperature measurement unit and an electric heating wire in the lithium iron phosphate battery, connecting it with the charging unit using the CAN bus to detect and control the battery cell temperature, the problem of the lithium iron phosphate battery being unable to start at low temperatures is solved, and normal charging and starting in a low-temperature environment is achieved.
Patent Information
- Application Number
- CN202421663329.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-15
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2034-07-15
AI Technical Summary
Lithium iron phosphate batteries cannot start charging normally within the low temperature range of -40~-20℃, resulting in unavailability in low temperature environments.
A temperature measurement unit and an electric heating wire are provided in the lithium iron phosphate battery, and connected to the charging unit through the CAN bus. The temperature measurement unit is used to detect the battery cell temperature and control the heating wire to generate thermal energy when it is lower than the preset threshold value until the battery cell temperature reaches the normal charging temperature and start charging.
The lithium iron phosphate battery is normally started and charged under an environment of -40~-20℃ to ensure that the battery can work normally under low temperature conditions.
Smart Images
Figure CN223156129U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power supplies, specifically to a low-temperature starting circuit for lithium iron phosphate batteries. Background Art
[0002] The lithium iron phosphate battery is a kind of lithium-ion battery, and its full name is lithium iron phosphate battery (Lithium Iron Phosphate Battery). This kind of battery uses lithium iron phosphate (LiFePO4) as the positive electrode material, and has the advantages of high energy density, long life, high safety, etc., so it has been widely used in the fields of electric vehicles, energy storage, etc.
[0003] As is well known, when the lithium iron phosphate battery discharges in the temperature range of -40 to 60 °C, it will still have good cycle stability and a high capacity retention rate. However, the charging temperature of the lithium iron phosphate battery is -20 to 60 °C, that is, in the temperature range of -40 to -20 °C, the lithium iron phosphate battery can only discharge and cannot start charging, resulting in the lithium iron phosphate battery being unable to start normally in the low-temperature range of -40 to -20 °C. Summary of the Utility Model
[0004] The technical problem to be solved by the utility model is to provide a low-temperature starting circuit for a lithium iron phosphate battery. By using this low-temperature starting circuit, it can be ensured that the lithium iron phosphate battery starts normally at low temperatures.
[0005] To solve the above problems, the following technical solutions are provided:
[0006] The low-temperature starting circuit of the lithium iron phosphate battery of the utility model includes a lithium iron phosphate battery and a charging unit that is adaptively connected to the lithium iron phosphate battery and used to charge the lithium iron phosphate battery. It is characterized in that the lithium iron phosphate battery is internally provided with a temperature measurement unit and an electric heating wire, and both the temperature measurement unit and the heating wire are adaptively connected to the charging unit; the temperature measurement unit is used to detect the temperature of the battery cells inside the lithium iron phosphate battery, and the heating wire is used to generate heat energy when electrified; when the charging unit is connected to an external power supply, the temperature measurement unit transmits the temperature information of the battery cells of the lithium iron phosphate battery to the charging unit. When the temperature of the battery cells of the lithium iron phosphate battery is higher than the preset threshold of the charging unit, the charging unit charges the lithium iron phosphate battery through the external power supply, and the heating wire is not electrified. When the temperature of the battery cells of the lithium iron phosphate battery is lower than the preset threshold of the charging unit, the charging unit controls the heating wire to be electrified and generate heat energy.
[0007] The lithium iron phosphate battery is connected to the charging unit through a CAN bus.
[0008] The advantage of adopting the above scheme is to use the CAN bus to realize data communication between the BMS of the lithium iron phosphate battery and the charging unit.
[0009] The lithium iron phosphate battery is internally provided with a humidity sensor, which is adaptively connected to the charging unit and used to transmit the humidity information of the battery cells of the lithium iron phosphate battery to the charging unit.
[0010] The advantage of adopting the above solution is that the humidity information of the battery cells inside the lithium iron phosphate battery can be obtained by using the humidity sensor, so as to further know the basic information of the lithium iron phosphate battery.
[0011] The temperature measurement unit contains a thermistor NTC. One end of the thermistor is connected to the power supply VDD; the other end of the thermistor NTC is respectively connected to one end of a resistor R1 and the non-inverting input terminal of an operational amplifier U1. The other end of the resistor R1 is grounded; the inverting input terminal of the operational amplifier U1 is connected to one end of a resistor R2, and the other end of the resistor R2 is connected to the reference voltage Vref; the output terminal of the operational amplifier U1 is connected to one end of a resistor R3, and the other end of the resistor R3 is connected to the inverting input terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 is connected to the charging unit.
[0012] The advantage of adopting the above solution is that the temperature measurement accuracy can be improved by using the operational amplifier, so as to realize the precise control that both the power supply VDD and the reference voltage Vref are generated by the charging unit.
[0013] There is a fuse FU between one end of the thermistor NTC connected to the resistor R1 and the non-inverting input terminal of the operational amplifier U1.
[0014] The advantage of adopting the above solution is that when the battery cells are damaged and the voltage rises, the fuse FU will break, thus avoiding the high voltage of the battery from damaging the MCU of the charging unit.
[0015] Adopting the above solution has the following advantages:
[0016] Since the lithium iron phosphate battery of the low-temperature startup circuit of the present utility model has a temperature measurement unit and an electric heating wire inside the lithium iron phosphate battery, both the temperature measurement unit and the heating wire are adaptively connected to the charging unit. The temperature measurement unit is used to detect the temperature of the battery cells inside the lithium iron phosphate battery, and the heating wire is used to generate heat energy when powered on. When the charging unit is connected to an external power source, the temperature measurement unit transmits the temperature information of the battery cells of the lithium iron phosphate battery to the charging unit. When the temperature of the battery cells of the lithium iron phosphate battery is higher than the preset threshold of the charging unit, the charging unit charges the lithium iron phosphate battery through the external power source, and the heating wire is not powered on. When the temperature of the battery cells of the lithium iron phosphate battery is lower than the preset threshold of the charging unit, the charging unit controls the heating wire to be powered on and generate heat energy. During use, the preset threshold is set at -20°C. When the lithium iron phosphate battery needs to be charged in an environment of -40°C to -20°C, after the charging unit is connected to the external power source, when the temperature measurement unit detects that the temperature of the battery cells of the lithium iron phosphate battery is lower than -20°C, the charging unit controls the heating wire to be powered on and generate heat energy until the temperature of the battery cells of the lithium iron phosphate battery is higher than -20°C, the heating wire loses power, and the charging unit starts to charge the lithium iron phosphate battery normally, realizing low-temperature startup. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 FIG. is a structural topology diagram of the low-temperature startup circuit of the lithium iron phosphate battery of the present utility model.
[0018] Figure 2 FIG. is a circuit schematic diagram of the temperature measurement unit of the low-temperature startup circuit of the lithium iron phosphate battery of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] The present utility model will be further described in detail below with reference to the drawings and embodiments.
[0020] As Figure 1 shown, the low-temperature startup circuit of the lithium iron phosphate battery of the present invention includes a lithium iron phosphate battery 1 and a charging unit 2 that is adaptively connected to the lithium iron phosphate battery 1 and used to charge the lithium iron phosphate battery 1. The lithium iron phosphate battery 1 includes a housing and a plurality of serially connected battery cells fixed inside the housing, as well as a BMS unit for managing the battery cells. The specific circuit structure belongs to the prior art and will not be described in detail here. The charging unit 2 includes a power transistor MOS and an MCU for controlling the MOS. The specific circuit structure belongs to the prior art and will not be described in detail here. During charging, the B+ port for charging the lithium iron phosphate battery 1 is connected to the C+ port of the charging unit 2, and the B- port for charging the lithium iron phosphate battery 1 is connected to the C- port of the charging unit 2.
[0021] As Figure 1 shown, there is a temperature measurement unit and an electric heating wire 3 inside the housing of the lithium iron phosphate battery 1. The humidity sensor of the temperature measurement unit and the electric heating wire 3 are both attached to the battery cells so as to accurately obtain the battery cell temperature and improve the heating efficiency.
[0022] As Figure 2 shown, one end of the thermistor NTC is connected to the power supply VDD. The other end of the thermistor NTC is respectively connected to one end of the resistor R1 and the non-inverting input terminal of the operational amplifier U1, and the other end of the resistor R1 is grounded. The inverting input terminal of the operational amplifier U1 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the reference voltage Vref. The output terminal of the operational amplifier U1 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the inverting input terminal of the operational amplifier U1. The output terminal of the operational amplifier U1 is connected to the charging unit 2. In this embodiment, both the power supply VDD and the reference voltage Vref are generated by the MCU of the charging unit 2. The specific generation circuit belongs to the prior art and will not be elaborated here.
[0023] As Figure 1 shown, one end of the heating wire 3 is connected to C+ of the charging unit 2. The other end of the heating wire 3 is connected to C+ of the charging unit 2. For the convenience of control, there is a controllable switch between the heating wire 3 and C+ of the charging unit 2, and the controllable switch is connected to the MCU of the charging unit 2 and is controlled by the MCU. In this embodiment, the heating wire 3 is a PTC heating wire 3, and the controllable switch is a MOS transistor.
[0024] In this embodiment, the preset threshold of the MCU of the charging unit 2 is -20°C.
[0025] When the charging unit 2 is connected to an external power supply, the MCU is powered on to generate the power supply VDD and the reference power supply Vref. The power supply VDD forms a sampling voltage through the thermistor NTC and enters the non-inverting input terminal of the operational amplifier U1 to form temperature information, which is transmitted to the MCU. When the core temperature of the lithium iron phosphate battery 1 is higher than the preset threshold -20°C of the charging unit 2, the charging unit 2 charges the lithium iron phosphate battery 1 through the external power supply, and the controllable switch S1 is disconnected, and the heating wire 3 is not powered on. When the core temperature of the lithium iron phosphate battery 1 is lower than the preset threshold -20°C of the charging unit 2, the controllable switch S1 is closed, the heating wire 3 is powered on and generates heat energy until the core temperature of the lithium iron phosphate battery 1 is higher than -20°C, the controllable switch S1 is disconnected, the heating wire 3 loses power, and the charging unit 2 starts to charge the lithium iron phosphate battery 1 normally, realizing low-temperature startup.
[0026] In this embodiment, the lithium iron phosphate battery 1 is connected to the charging unit 2 through the CAN bus to realize data communication between the BMS of the lithium iron phosphate battery 1 and the charging unit 2. There is a humidity sensor in the lithium iron phosphate battery 1, and the humidity sensor is adaptively connected to the charging unit 2 for transmitting the humidity information of the core of the lithium iron phosphate battery 1 to the charging unit 2. The specific circuit structure of the humidity sensor and the charging unit 2 belongs to the prior art and will not be elaborated here. The humidity information of the core in the lithium iron phosphate battery 1 can be obtained by using the humidity sensor to further know the basic information of the lithium iron phosphate battery 1.
[0027] In this embodiment, there is a fuse FU between one end of the thermistor NTC connected to the resistor R1 and the non-inverting input terminal of the operational amplifier U1. When the battery cell is damaged and the voltage rises, the fuse FU can break, thereby preventing the high voltage of the battery from damaging the MCU of the charging unit 2.
[0028] During use, when the lithium iron phosphate battery needs to be charged in an environment of -40 to -20°C, after the charging unit is connected to an external power supply, when the temperature measurement unit detects that the temperature of the battery cell of the lithium iron phosphate battery is lower than -20°C, the charging unit controls the heating wire to be energized and generate heat energy until the temperature of the battery cell of the lithium iron phosphate battery is higher than -20°C, the heating wire is de-energized, and the charging unit starts to charge the lithium iron phosphate battery normally, realizing low-temperature startup.
Claims
1. A low-temperature starting circuit for a lithium iron phosphate battery, comprising a lithium iron phosphate battery and a charging unit adapted to be connected to the lithium iron phosphate battery and used for charging the lithium iron phosphate battery; characterized in that, The lithium iron phosphate battery is internally provided with a temperature measurement unit and an electric heating wire, and both the temperature measurement unit and the heating wire are adaptively connected to the charging unit; the temperature measurement unit is used to detect the temperature of the battery cells inside the lithium iron phosphate battery, and the heating wire is used to generate heat energy when powered on; when the charging unit is connected to an external power supply, the temperature measurement unit transmits the temperature information of the battery cells of the lithium iron phosphate battery to the charging unit. When the temperature of the battery cells of the lithium iron phosphate battery is higher than the preset threshold of the charging unit, the charging unit charges the lithium iron phosphate battery through the external power supply, and the heating wire is not powered on. When the temperature of the battery cells of the lithium iron phosphate battery is lower than the preset threshold of the charging unit, the charging unit controls the heating wire to be powered on and generate heat energy.
2. The low-temperature starting circuit of the lithium iron phosphate battery according to claim 1, characterized in that, The lithium iron phosphate battery is connected to the charging unit through a CAN bus.
3. The low-temperature starting circuit of the lithium iron phosphate battery according to claim 1, wherein, The lithium iron phosphate battery is internally provided with a humidity sensor, and the humidity sensor is adaptively connected to the charging unit and is used to transmit the humidity information of the battery cells of the lithium iron phosphate battery to the charging unit.
4. The low-temperature starting circuit of the lithium iron phosphate battery according to claim 1, characterized in that, The temperature measurement unit contains a thermistor NTC, and one end of the thermistor is connected to the power supply VDD; the other end of the thermistor NTC is respectively connected to one end of a resistor R1 and the non-inverting input terminal of an operational amplifier U1, and the other end of the resistor R1 is grounded; the inverting input terminal of the operational amplifier U1 is connected to one end of a resistor R2, and the other end of the resistor R2 is connected to a reference voltage Vref; the output terminal of the operational amplifier U1 is connected to one end of a resistor R3, and the other end of the resistor R3 is connected to the inverting input terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 is connected to the charging unit.
5. The low-temperature starting circuit of the lithium iron phosphate battery according to claim 4, characterized in that, Both the power supply VDD and the reference voltage Vref are generated by the charging unit.
6. The low-temperature starting circuit of the lithium iron phosphate battery according to claim 4, characterized in that There is a fuse FU between one end of the thermistor NTC connected to the resistor R1 and the non-inverting input terminal of the operational amplifier U1.