一种双向隔离三电平DC-DC变换器电流有效值最小控制方法

针对双向隔离DC-DC变换器在传统"两电平H桥结构+移相控制"模式下进行功率传输所导致的开关器件承受电压应力大、变换器传输效率低等问题,提出一种"双边三电平半桥结构+电流有效值最小控制策略"方案。该方案将H桥结构替换为三电平半桥结构并在传统移相控制的基础上增加对变压器漏感电流有效值的控制,降低了变换器损耗和开关器件承受的电压应力并提高了变换器的传输效率。根据隔离变压器漏感电流有效值表达式与零电压开关条件,对电感电流有效值最小控制方法的控制曲线进行了详细推导,并根据该控制曲线设计了基于可编程逻辑器件的控制核心。采用新型Si C MOSFET开关器件搭建了物理实验平台。实验结果表明在所提方案的作用下开关器件所承受的电压应力、变换器损耗和变换器传输效率都得到了较大的改善,验证了理论分析的正确性和所提方案的可行性。

Minimizing leakage inductor current RMS control strategy of bidirectional three-level DC-DC converter

Aiming at the large stress of switching devices and low transmission efficiency of converter when the generalized bidirectional isolated DC-DC converter with two-level H-bridge topology operates under the phase-shift control mode, a scheme with the minimizing inductor current RMS control based on the three-level half-bridge topology is proposed. The proposed scheme replaces the two-level H-bridge topology with three-level half-bridge topology, and adds the corresponding control for the leakage inductor current RMS of transformer to reduce the loss of converter and the stress of switching devices and improve the transmission efficiency of the converter. The control curve is plotted and deduced detailedly based on the expression of inductor current RMS and the condition of ZVS(Zero Voltage Switching),which is used to design the key controller based on FPGA. The experimental platform is established by using SiC MOSFET. The experimental results show that the converter can be improved in aspects of the voltage stress, switching loss and transmission efficiency, verifying the correctness and feasibility of the proposed scheme.