基于励磁电流补偿与混合移相调制的高频DAB变换器全范围ZVS运行策略

A Full Range ZVS Operation Strategy for High-frequency DAB Converters Based on Magnetizing Current Compensation and Hybrid Phase Shift Modulation

随着宽禁带功率半导体器件的广泛使用,更高开关频率的双有源桥(dual active bridge,DAB)变换器带来了更大的开关损耗,对于软开关技术提出更高要求。为了进一步拓展零电压开通(zero-voltage switching,ZVS)范围,文中对ZVS精确模型和传统电感电流全局最优条件方法进行分析,提出一种结合励磁电流运行的移相调制策略,该策略可实现DAB变换器全功率范围内所有开关管的ZVS运行(8-ZVS运行)。在考虑开关管非线性特性和死区时间限制基础上得到更精确的ZVS模型,并推导引入励磁电流的ZVS模型。此外,所提出的控制方案具有无缝模式转换的特点,电感电流的有效值也可以达到准最佳状态。最后,搭建6kW/150kHz的高频DAB变换器样机以验证模型有效性。实验结果表明,该控制算法可以在任意模式和工况下实现8-ZVS运行,从而提升系统在轻载和中载工况下运行效率。

With the widespread utilization of wide bandgap power semiconductor devices,the dual active bridge(DAB)converter with higher switching frequency has brought about greater switching losses,putting higher demands on soft-switching technology.To expand the zero-voltage switching(ZVS)range,the ZVS model and the conventional inductor current global optimal condition(GOC)method are analyzed,and an optimal phase shift modulation scheme combined with the magnetizing current is proposed to realize the 8-ZVS operation(ZVS operation of all switches)in the full power range.In this paper,a more accurate ZVS model is obtained by considering the non-linear characteristics of the switch’s junction capacitors and the dead time limit,and the ZVS model with the introduction of the magnetizing current is derived.Furthermore,the proposed control scheme features a seamless modes transition,by which the RMS inductor current also can be quasi-optimal.Finally,a 6 kW/150 kHz DAB converter prototype is built to verify the effectiveness of the theoretical analysis.Experimental results show that the 8-ZVS operation can be realized in any mode and any working condition,and the system's operational efficiency is obviously improved,especially under light and medium loads.