| With the widespread use of battery in Electric Vehicle, energy storage system, communication, aerospace and other fields, the demand for large capacity battery is increasing each year. Battery formation, as the key process of battery production, has a direct impact on the quality of battery and the cost of production. The performance of battery formation equipment is regarded as a guarantee for product quality. To prolong battery life, reduce the energy consumption and production costs, the bi-directional DC/DC converters which are suitable for battery formation are mainly studied in this paper.Firstly, the characteristics of battery formation are analyzed, which is high voltage on one side and low-voltage high-current on the other side. Based on this, a two-stage converter structure is adopted. One stage is isolated bi-directional DC/DC converter, the other stage is non-isolated bi-directional DC/DC converter. By the comparison and analysis, the bi-directional half-bridge current-double converter and bi-dictional Buck-Boost converter are chosen.Secondly, the operation principle of bi-directional half-bridge current-double converter in normal working condition and starting state is analysed and verified in the Saber environment. According to the power, voltage and other requirements, the main circuit parameters are completely designed. With the state space average method, the small signal models in Buck mode and Boost mode of the bi-directional half-bridge current-double converter are established. The compensation circuit is designed in order to improve the stability and the dynamic response of system. The voltage stress on semiconductor is analysised and the suppression measures are given! The drive and protection circuits are also designed.Thirdly, the topology of bi-dictional Buck-Boost converter is analysised in this paper. The bidirectional converter stability control is realized by using the same set of PID controller parameters. And the complex logic control is simplified by using CPLD, which provides a flexible implementation. The main circuit parameters are selected. Further-more, the main circuit, control circuit and drive circuit are designed. The problem of high stress on semiconductor and high conduction losses in circuit is solved by detect inductive current when the converter start or at light load. The interleaving technique of bi-dictional Buck-Boost converters is studied in this paper. At last, the prototypes of half-bridge current-double converter and bi-dictional Buck-Boost converter are manufactured according to the design parameters. The experiments are carried out in different power flow direction and different power level state. Experimental results are presented and verify the correctness of design and theory analysis. |
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