High frequency ZVS for high power rectifiers

This paper describes a family of rectifiers with power outputs from 1.5 kW to 7 kW, based on high frequency (200 kHz) converters using power MOSFETs. The circuit uses full-bridge converters in the quasi-resonant mode (zero-voltage switching), which results in very low switching losses. Both single-phase and three-phase designs are available. The single-phase 230 V versions are equipped with a power factor controller to comply with IEC 555-2. Two bridges are mounted in series for operation from a three-phase 400 V supply. An innovative construction of the power transformer, protected by a patent, guarantees perfect equilibrium between the two bridges without any additional control circuit. The principle is also extended to transformers mounted in parallel for higher power levels. >