Design And Implementation Of Therecovery System Of Lithium Battery Formation

In today’s society, smart hardware industry, electric car industry and aerospace industry are developing rapidly. Lithium battery has got a number of promotion and application in the related equipment because of its small volume, light weight and high capacity. The production of lithium batteries especially of the large capacity ones has been increasing year by year. As the increasing of the production of lithium batteries, the demand of lithium battery formation equipment is becoming higher and higher. However, at this stage, the energy-saving efficiency of most lithium battery formation equipment is very low because of the extensive use of energy, which doesn’t conform to the concept of energy saving and environmental protection. Committed to improve the energy-saving efficiency of lithium battery formation equipment, an energy recovery system is researched and designed in this thesis. And the realization of hardware circuits and the control strategy of the energy recovery system have been completed. The main work of this thesis is as follows:1. According to the lithium battery formation process and work requirements of the formation device, an overall energy recovery scheme is made, which is based on bus energy storage.2. According to the work requirements of the formation device, the bus energy storage capacity calculation and the selection of energy storage battery is completed. After a detailed research on the working principle of AC/DC and common topologies of it, a half bridge structure is selected according to the requirement of the step-down isolated output. Through designing the hardware circuit and completing the welding and debugging of the prototype, the constant voltage and constant current controllable output of the AC/DC is realized, when reaching an energy-saving efficiency of 85%. Then, the design and building of the energy consumption circuit is completed, which realizes the switch control and reliable work of the energy consumption in the system. The design and debugging of the STM32 control board is completed, which implements the analog control signal isolation transmission.3. According to the overall energy recovery control demand of the system, through the analyzing of the working state of the energy recovery system, an overall control scheme which taking the storage battery capacity value as the quantity of the judge is developed. After a detailed research on the estimation methods of battery capacity, the open circuit voltage measurement + Ampere-hour integral method is implemented to estimate the battery capacity. Then the method is improved through adding a Kalman filter, which improves the estimation accuracy. Then the real-time optimal current value calculation of each hardware module of the energy recovery system is completed. By adding PID closed-loop control, the optimal working current value real-time tracking of the AC/DC is achieved.4. At last, the actual running of the energy recovery system is implemented, when the test of the energy-saving effect is had. And the energy-saving efficiency is above 40 percent.