Power CR1220 battery state of charge SOC is the key technology of battery management system BMS

　　The state of charge SOC of power CR1220 battery is the key technology of battery management system BMS. Accurate SOC estimation is one of the key technologies of battery management systems. The battery management system is one of the core components of electric vehicles. Its main function is to safely monitor and effectively manage the CR1220 battery pack to improve battery efficiency, extend battery life, reduce operating costs, and further improve the reliability of the battery pack.

　　Power CR1220 battery state of charge SOC is the key technology of battery management system BMS

　　The state of charge (SOC) of a CR1220 battery describes the remaining quantity of the battery and is one of the most important parameters during battery use. Accurate estimation of SOC can prevent overcharging or over-discharging of lithium batteries, effectively extend the service life of the battery, and predict the driving range of electric vehicles.

　　Since SOC state-of-charge estimation is affected by factors such as temperature, aging, charge-discharge rate, and self-discharge, batteries are highly nonlinear in practical applications, making it very difficult to accurately estimate SOC.

　　Generally speaking, the CR1220 battery management system of electric vehicles must achieve the following functions: ① Accurately estimate the state of charge of the power battery pack, that is, the remaining battery capacity; ② Ensure that the SOC is maintained within a reasonable range; ③ Prevent battery failure due to overcharging or Damage to the battery caused by over-discharge, so as to predict at any time how much energy is left in the hybrid vehicle's energy storage battery or the state of charge of the energy storage battery.

　　The SOC of the CR1220 battery pack directly reflects the remaining available capacity of the battery pack and is an important indicator for evaluating the current performance of the battery pack. It is also an important parameter for estimating the current cruising range of electric vehicles.

　　The power state reflects the maximum power that the battery pack can output in its current state. This is because at different depths of discharge, the charge and discharge current that the battery can withstand is limited while ensuring the life and safety of the battery pack. Although The size of the SOC determines the maximum charge and discharge power that the battery pack can withstand to a certain extent, but it is not comprehensive enough. In order to ensure the safe driving of electric vehicles, it is necessary to be able to evaluate the power status of the battery pack and transmit the results to the entire vehicle. control system and charging control system to optimize the charging and discharging process.

　　The SOC state of charge of a CR1220 battery reflects the safety of the CR1220 battery pack and the degree of capacity attenuation. The main description parameters include the attenuation of the total capacity, changes in the internal resistance of the battery, the insulation resistance of the system, etc. There is currently no unified definition for it. Evaluate.

　　Solutions to improve the performance of power CR1220 battery packs

　　(1) Through a large number of CR1220 battery charging and discharging experiments, and based on the analysis of existing lithium-ion battery models, an improved second-order RC equivalent circuit model is proposed. This model is convenient for automotive-grade embedded processors. Perform online calculations. It is verified that the model can better simulate the external characteristics of lithium batteries, and the good model calculation accuracy lays the foundation for subsequent CR1220 battery state estimation.

　　(2) The definition of battery state of charge was elaborated, the current relatively common CR1220 battery state of charge estimation theory was comprehensively compared, an experimental platform was built for nickel-cobalt-manganese ternary lithium-ion batteries, and the mainstream methods were elaborated The Kalman filter SOC estimation method proposes an SOC estimation algorithm based on the improved iterative central difference Kalman filter and a new algorithm that weights the fusion of this algorithm with the open circuit voltage method. Experiments have proven that the new weighted fusion algorithm has higher estimation accuracy. .

　　(3) For the safe use of power batteries, the problem of battery maximum charge and discharge power estimation is studied, and a battery maximum estimation method based on an improved dual-polarization equivalent circuit model is proposed to estimate the battery charge and discharge power in practical applications. Carrying out necessary controls can, on the one hand, maximize the performance of the battery, and on the other hand, protect the battery pack.

　　(4) Regarding the balancing problem of power CR1220 battery packs, the double-layer switched capacitor balancing method has the advantages of fast balancing speed and simple control, but conventional switched capacitors are prone to switching losses and electromagnetic interference. To address this problem, experiments were conducted Verification, simulation and experimental results all verify the effectiveness of the balance control method proposed in this article, providing effective basis and guarantee for the overall design of the power lithium-ion battery pack management system.

　　(5) On the basis of studying the state estimation and equilibrium theory of lithium-ion power battery packs, the fault diagnosis and protection strategies of power battery packs, and applying the improved analytic hierarchy process to comprehensively evaluate the battery pack status information collected by the battery management system ,Assessing the system reliability risk of the battery pack provides ,quantitative basis for the protection strategy of the fault ,diagnosis system.

　　In short, whether at home or abroad, the research on electric vehicle battery management systems is still in its infancy. How to accurately estimate the SOC value of power lithium batteries and effectively control the balance of the battery pack are two research bottlenecks of the current BMS system. .

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