Dual Boost Bidirectional DC-DC Converter Based On PWM Plus Phase-shift Control

Electric vehicles could be applied to Microgrid as the energe storage units in the technique of V2G(vehicle-to-grid),which may realize the win-win situation of power grid corporations and electrical vehicle users.With the advantages of large specific capacity and longer cycle using times, the lithium battery has been widely applied in V2 G fields,and the huge demand for lithium batteries promotes the formation technique.Thus,the charging and discharging system based on lithium batteries has excellent development prospect.The twostage structure comprised with bidirectional dc-dc and dc-ac elements is usually adopted to relialize bidirectional power flow,and the dc-dc element implements the voltage level transformation between battery and DC bus.Dual boost active clamping bidirectional dc-dc converter has the merits of high voltage convert ratio,low ripple current,low voltage spike of switch turning off,and easiness to realize realize Zero Voltage Switching(ZVS),which is suitable for low voltage and high current application.In this paper,the working principle and working characteristic of this converter under different control strategies is analized to improve efficiency under a wide range of input volage.Firstly the basic principle of this converter is introduced,and the power transmission characteristics under a wide range of input voltage with phase shift control is analized.With efficiency as the focus,the study of working characteristic is among with three aspects of transmission inductor current stress,the soft switching range and circulating power loss.So the disadvantages of the ZVS lost and large circulating power loss under light load under phase shift control is pointed.Therefore,the PWM with phase shift control stategy is introduced,and the advantages of realizing ZVS under full power range for all switches,enhanced power ransmission capacity,decreased tansmission inductor current stress and reduced circulating power loss are proved theoretically under the condition that the iuput voltage is less than the rating value.However,under the condition of input voltage exceeding the rating value,the ZVS lost under light load and bigger current stress under heavy load under this control strategy is explained.Finally,a optimized variable duty cycle and phase shift control statagy is proposed in this article,and the duty cycle is optimally designed under the condition that the iuput voltage is less than the rating value.Within the scope of guranting power transmission capacity and ZVS among full power range for all switches,the tansmission inductor current stress is minimed to improve convertion efficiency under heavy load with this control strategy.The working charactistics of this converter is simulated with SABER software,and a 360 W prototype based on digital control chip named DSP28335 with 8-15 V input and 380 V output voltage is built and tested in the lab.The study and analysis in this paper is verified by the results of simutation and experiments.