Design Of Bi-Directional DC/DC Converter Based On DSP

Due to its realization of energy's two-way flow and characteristic of high power density,high efficiency,low cost and small volume in switching power supply,bidirectional DC/DC converter has been more and more widely used in many fields.This paper studies one kind of bidirectional DC/DC converter with high voltage ratio.Firstly,the paper introduces the main application field,and then studies operation principle and application direction of commonly used topologies in bidirectional DC/DC converter.Secondly,according to the requirements of bidirectional DC/DC converter with high voltage ratio,this paper uses push-pull full-bridge bi-directional DC/DC topology as the main topology of the design.Thirdly,based on this topology,to realize good dynamic and stable performance of the converter,this paper conducts overall optimization of circuit topology and analysis of control strategy.Lastly,using C2000 series controller TMS320F28035,this paper realizes the optimal control of the bidirectional converter in Buck &Boost mode.Current mode Push-pull circuit is suitable for low voltage high current situations,full-bridge circuit is very applicable in high voltage applications.Combining these two circuits,low direct voltage and high direct voltage conversion with medium or large power can be realized.This paper uses current mode push-pull voltage mode full-bridge topology as the main power converter.In buck mode,the phase-shift control strategy is adopted in full-bridge side to control switches,achieving the effect of soft switch.In boost mode,the converter uses boost circuit cascading push-pull inverter,ensuring boost to desired output voltage.A transformer is used to replace lagre inductance in the push-pull side,which can transfer the startup energy of the converter to high voltage side at the start of the converter.Average current mode control stratage is adopted to control the push-pull side switch.Aiming at the magnetic bias problem of the converter,the paper presents several solutions.At the same time,because of voltage spike generated in the push-pull side switches during shutdown,converter device can be easily damaged,a buffer circuit is used to reduce the voltage spike.After theoretical research and computing as well as realization of control strategy based on DSP,this paper makes an prototype,and then carries out experiments on the prototype,test results are given.