This paper introduces the design of low power consumption lithium ion battery ma
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2023/08/30 15:30:29
Abstract: The planning method of a low-temperature intelligent lithium-ion battery processing system is introduced. The system is composed of 32 20Ah4 series and 8 parallel monomers. The method has the functions of base protection, power metering, charge balance, defect recording and so on. The experiment shows that the system has perfect function and meets the requirement of planning.
Current battery handling systems are planned for applications with large capacity battery packs and short battery life. The machining system serves high-power equipment, the battery cycle is short, the power consumption of the machining system itself is not low, and it is not suitable for low-power surface applications. At the remote monitoring surface of the gas, the current of the uniform system is only a few milliamps, and it needs to work continuously at low temperatures for more than six months. In order to meet the application of this project, this paper introduces a low temperature intelligent lithium-ion battery processing system planning method. With base protection, power measurement, charge balance, defect record and other functions. The experiment shows that the system has perfect function and meets the requirement of planning.
1. Overall structure of the system
The low-temperature lithium-ion battery treatment system is mainly composed of a base protection circuit, coulometer, balance circuit and secondary protection, as shown in Figure 1.
According to the consideration of low power consumption, many low-power devices were selected in the planning, such as MSP430FG439 low-power MCU as the processor. The reference voltage is REF3325, and the power consumption is very low, only 3.9db; The operation amplifier uses LT1495, the working current is only 1.5a; The digital potentiometer uses the AD5165 with static current as low as 50nA. The power processing circuit is added to the intermittent operation circuit, the running current is large, and the energy consumption is reduced. The low-temperature battery pack has a rated voltage of 14.8v and is made up of 4 cells in series, each with 8 individual cells. Normal operating voltage is 2.5-4.2v.
Each collection cycle collects the voltage of each group of batteries, and the processor issues instructions to the protection circuit according to the voltage, and executes the corresponding protection action. The equalization circuit is realized by single chip microcomputer and transistor instead of special equalization chip. The system records abnormal information such as the maximum voltage, current, temperature, battery life, and remaining power of the storage device. The processor provides TTL communication interface, and the field computer reads the log in the storage device through TTLRS232 conversion module. In order to prevent the MCU from crashing and other abnormal situations during the charging process, there is a protection failure. A secondary protection circuit is added. If the voltage exceeds the preset value, the secondary protection circuit will be started and the three-end fuse will be blown to prevent the occurrence of failure.
2 Hardware Planning
2.1 Protection implementation circuit
The protection executive circuit is the executive mechanism of the protection action, CH is the charge control switch, DISCH is the discharge control switch, and the corresponding protection action is carried out by controlling CH and DISCH, as shown in the circuit diagram in Figure 2.
CH and DISCH are set to low during normal operation, when M1 and M2 are on at the same time. When discharge overcurrent or overdischarge occurs, set DISCH to high, disconnect Q2, and proceed to Q3. The charge sensitive discharge of the M2 gate capacitor makes M2 instantly close and the protection ends. When charging overcurrent or overcharge occurs, set CH to high and turn off M1. The MOSFET circuit is IRF4310, the on-resistance of the MOSFET is only 7k, and the flow rate is up to 140.
2.2 Balance circuit and secondary protection
Figure 3(a) shows a schematic of a battery charge balancing circuit consisting of four units in series. The ADV terminal voltage is collected by MCU to obtain the voltage of the battery. During charging, if the charging voltage exceeds 4.2v, the BLA of the MCU control pin is set to high. At this time, this group of batteries is short-circuited, and the charging current is charged to other groups of batteries through R4, thus ensuring that the electricity of each group of batteries after charging has a good consistency. Secondary protection is irreversible and can only be activated in the event of significant danger.
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