Analysis of an Interleaved Three-Level ZVS Converter With Series-Connected Transformers

This paper presents a new interleaved three-level soft-switching converter with series-connected transformers to achieve zero-voltage switching for all MOSFETs, less transformer secondary windings, and partial ripple current cancellation. Two circuit modules are adopted in the proposed circuit to share the load current and reduce the ripple currents at the input and output capacitors with the interleaved pulse-width modulation (PWM). In each circuit module, two three-level PWM circuits with the same MOSFETs are operated with the phase-shift by one-half of switching period to reduce the input ripple current. The voltage stress of all switches is clamped at V_in/2. The secondary windings of two transformers are connected in series to balance the primary side currents. The current doubler rectifiers are adopted on the secondary side to partially cancel output inductor ripple current. Experiments with a 1-kW prototype, verifying the effectiveness of the proposed converter, are described.