A 3-kW unity-power-factor rectifier based on a two-cell boost converter using a new parallel-connection technique

This paper applies a recently introduced parallel-connection technique to a unity power-factor preregulator based on a boost converter in continuous i nductor-current mode. By means of a small extra inductance, two MOSFET puls ewidth modulation (PWM) cells are safely associated in parallel, which allo ws an increased output power being processed by two half-rated semiconducto r devices. The new technique overcomes the existent alternatives, leading t o a reliable switched converter along with simplified layout requirements, This paper also presents a theoretical analysis accompanied by digital simu lation cases. Results from a 3-kW prototype, based on the Unitrode's UC3854 strategy, sho w that the present technique is very useful in revealing a natural balance among device currents, The laboratory circuit works at a 70-kHz switching f requency and also employs a soft-commutation network. This feature points t o a high-efficiency converter and negligible device stresses, which have be en verified in the laboratory.