Based on the commutation characters of the T-type neutral-pointclamped(T-NPC)three level inverter,a novel zero-current-transition softswitching topology is proposed.The topology employs only two auxiliary switches and one LC resonant tank for each phase arm.The commutation process and operation principle of the soft-switching technique are analyzed in detail,all switching device on main bridge arm and Auxiliary arm can achieve soft-switching condition without changing the traditional PWM control strategy.The dual relationship between the shift of the resonant center and the soft-switching topology is introduced by using the simplified topology and the state plane diagram.Then,the theoretical analysis and mathematical derivation about the design of the resonant tank parameters and the timing schemes are given in this paper.At last,a half bridge prototype of the T-NPC three level inverter is built,and the effectiveness and advantages of the proposed topology are verified.%依据T型中点钳位(T-NPC)三电平逆变器的换流特点,提出了一种零电流软开关拓扑,每相桥臂仅需要额外使用两个辅助谐振开关器件和一条LC谐振支路.详细介绍了该软开关技术的换流过程和工作原理,在不改变传统PWM控制策略的前提下就能够保证主桥臂和辅助桥臂的开关器件实现零电流开关.通过对拓扑电路的简化并结合相平面分析图的方法,指出了所提出软开关拓扑具有谐振圆心偏移的对偶关系,并对该软开关拓扑的谐振参数选择和辅助桥臂的控制时序进行了理论分析和推导.最后通过半桥样机实验,对所提出软开关拓扑的可行性和优点进行了验证.
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