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 power converter incontinuous inductor-current mode. By means of a small extra inductance, two MOSFET pulsewidth modulation (PWM) cells are safely associated in parallel, which allows an increased output power being processed by two half-rated semiconductor devices. The new technique overcomes the existent alternatives, leading to a reliable switched power converter along with simplified layout requirements. This paper also presents a theoretical analysis accompanied by digital simulation cases. Results from a 3 kW prototype, based on the Unitrdae's UC3854 strategy, show that the present technique is very useful in revealing a natural balance among device currents. The laboratory circuit works at a 70 kHz switching frequency and also employs a soft-commutation network. This feature points to a high-efficiency converter and negligible device stresses, which have been verified in the laboratory.