Explain the relationship between various state estimates of lithium batteries

The relationship between various state estimations of lithium batteries The temperature estimation of lithium batteries is the basis of other state estimations. SOC estimation is affected by SOH. SOF is determined by SOC, SOH, SOS and battery temperature. SOE is combined with SOC, SOH, The battery temperature is related to the future working conditions. The state of charge, energy state, remaining used energy, and health state of a lithium battery are all invisible states of the battery, which cannot be obtained directly by a measuring device. Temperature has a great influence on battery performance. At present, only the surface temperature of the battery can be measured, and the internal temperature of the battery should be estimated using a thermal model; the suitable working temperature of lithium batteries is 15~35℃, while the actual working temperature of electric vehicles is- 30～50℃, so the battery must be thermally managed, heating at low temperatures and cooling at high temperatures. Lithium battery SOH is one of the most important parameters in the battery management system. Accurately grasping the battery pack SOH can provide basis for its own test and diagnosis, which helps to know the health status of each battery pack in time, and replace the aging battery in time. The single battery improves the overall life of the battery pack and further improves the power performance of the electric vehicle. Lithium battery SOH characterizes the current battery's ability to store electrical energy in relation to new batteries. It represents the state of the battery from the beginning of its life to the end of its life in the form of a percentage, which is used to quantitatively describe the current battery performance status; lithium batteries have more performance indicators , There are many meanings to SOH at home and abroad, and there is no unified concept. The current meaning of SOH is mainly related to the current capacity, power, internal resistance, cycle times and peak power. Lithium battery SOC has designed a state-of-charge estimation observer for power lithium-ion batteries, using the measured current and voltage values u200bu200bas the input and observation values u200bu200bof the observer respectively, combined with double adaptive attenuation extended Kalman filter to estimate the observer Battery state of charge. The lithium battery energy state SOE represents the ratio of the energy that can be released under the current condition of the battery to the maximum available energy of the battery, and it is an important indicator that reflects the energy usage of the battery. The estimation method of battery SOE is different from SOC, which is not only affected by battery load current, but also related to battery terminal voltage. During the use of lithium batteries, when the battery temperature and battery charge-discharge rate change, the battery's discharge rate will change accordingly and affect the battery's SOE. Regarding electric vehicles, SOF can be defined as the power that a battery pack can supply to various electrical loads such as motors at a particular time. It can be simply considered that SOF is a function of SOC and temperature. In fact, for the power system of many electric vehicles, the BMS not only has to estimate the power SoF output by the battery pack at a specific time, but also supply the maximum power SoF2 that the battery pack is allowed to charge. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Which is better, lead-carbon battery or lithium battery?