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 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 is also included to verify the operation of this converter.
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