| Lithium ion battery formation has to charge and discharge many times to form the battery charge and discharge performance and its capacity which is important process in the lithium-ion battery production process. The formation system of lithium ion battery is independent constant current constant voltage charging and constant discharging for a batch of batteries, and the control management of each battery formation process. Therefore, formation process is a complicated process. At present, most of domestic formation device has low power factor and efficiency etc.. During the discharging in the formation process, its electricity is consumed by resistances with resulting in waste of energy.Based on the analysis of the lithium ion battery formation equipment and its application and research status, the paper points out the existing problems of the traditional system and puts forward the control scheme with DSP as the formation system core. Main contents are controller design based on DSP processor, single-phase PWM rectifier, bi-directional DC/DC converter design and the design of the control algorithm.For the problem of formation equipment low power factor and energy waste, the paper designs a single-phase voltage source PWM rectifier so as to improve the power factor and achieve energy feedback which uses bipolar PWM modulation method and establishes its mathematical model. Then the paper proposes a new PWM control strategy of feed-forward decoupling based on rotating coordinate transformation and load current feed-forward compensation and then carries on the simulation analysis with MATLAB/Simulink. The result shows that it can work in two states of rectifier and inverter, and stable performance, strong anti-interference ability, run under nearly unit power factor, and it verifies the correctness and feasibility of the control strategy.Secondly, a bidirectional DC/DC converter circuit topology structure is presented and designed the hardware circuit and the parameters of the bidirectional DC/DC converter. Charge and discharge is analyzed with the two kinds of working state of four work modes in detail, and designs the control algorithm of charge and discharge of the converter.Finally, the DSP system control software was designed. Using the semi-physical simulation platform built experimental electric circuit and measured the relevant experiments waveform. Experimental results show that the design of hardware and software scheme can better realize the rectifier and inverter, and control its running on unit power factor, realize high charge and discharge of the lithium ion battery and energy feedback. |
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