提出一种新颖的零电压零电流开关PWM三电平直流变换器，它是在基本的三电平直流变换器的变压器一次侧串入一个阻断电容，使一次电流在零状态时减小到零。为了使一次电流在零状态时减小到零后不再反方向流动，在两个滞后管中分别串入一个二极管。该变换器可以实现超前管的零电压开关和滞后管的零电流开关。由于在零状态中一次电流为零，减小了通态损耗，因此可以提高变换效率。本文分析该变换器的工作原理，讨论它的参数设计，并给出实验结果。%This paper proposes a novel zero-voltage and zero-current-switching (ZVZCS) pwm three-level converter, which introduces a block capacitor in series with the primary winding of the transformer to make the primary current to reduce to zero during zero state. In order to prevent the primary current from flowing in the reverse direction during zero state, two diodes are added in series with the lagging switches respectively. The converter realizes zero-voltage-switching for the leading switches and zero-current-switching for the lagging switches. As the primary current reduces to zero, the conduction loss is eliminated during zero state, which increases the efficiency. The operation principle and parameter design are discussed in this paper, and the experimental results in also included to verify the operation of this converter.
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