少开关管和低电压应力的无变压器型高增益三端口光伏储能变换器

Transformer-less High-gain Three-port Converter With Low Voltage Stress and Reduced Number of Switches Used in Photovoltaic Energy Storage System

该文提出了一种新颖的无变压器型高增益三端口变换器及其简易构造方法。其利用零电压软开关双电感高增益二端口变换器中的缓冲电容构造出第3个端口;使前、后级电感分别工作在电流连续模式和断续模式,进而采用脉冲宽度调制(pulse width modulation,PWM)+脉冲频率调制(pulse frequency modulation,PFM)混合调制策略,同时实现了光伏端的最大功率点跟踪控制与负载端的恒压控制。所提三端口变换器的所有端口均共地,可以实现蓄电池端的能量双向流动,且保留了原变换器的优点,如输入侧电流连续、开关管数量少(2个)、电压应力低、升压能力强、可实现部分功率管软开关等。该文详细分析了所提三端口变换器的工作原理、稳态特性、控制方法,给出了电感参数设计过程,并通过一台300W的样机实验验证了理论分析的正确性。实验表明,所提变换器的最大效率约为97.7%。

A novel transformer-less high-gain three-port converter(TPC)is presented in this paper.It utilizes the buffer capacitor of the zero-voltage-switching(ZVS)dual-inductor high-gain two-port converter as a third port,which makes the front-end and rear-end inductors operated in the continuous and the discontinuous conduction modes respectively.Then the PWM+PFM hybrid modulation strategy are adopted to realize the maximum power point tracking control on the photovoltaic port and the constant voltage control on the load port simultaneously.The three ports of the proposed TPC share a common ground,realizing the bidirectional flow of the energy on the battery port.Besides,the proposed TPC retains the advantages of the original converter,such as continuous input current,reduced active switches(2),low voltage stress,high voltage gain,and soft-switching ability.In this paper,the working principle,steady-state characteristics,and control methods of the proposed TPC are analyzed in detail.The design process of the inductor parameters is also presented.The correctness of the theoretical analysis is verified by a 300W experimental prototype,which shows the maximum efficiency is 97.7%.