A New Zero-Voltage Switching Three-Level Converter with Reduced Rectifier Voltage Stress

Abstract

Three-level converters are an attractive structure when the high input voltage is required. Although the voltage stress of switches in the three-level converter becomes half of the input voltage, zero-voltage switching cannot be achieved at light load conditions, which degrades the light load efficiency. This paper proposes a new three-level converter with achieving zero-voltage switching over entire load conditions. In addition, in the proposed converter, the voltage stress of rectifier diodes is low, leading to a reduction of conduction loss in the rectifier circuit. Therefore, by reducing the switching losses in primary switches, light load efficiency increases, and by decreasing the conduction loss in the rectifier circuit, heavy load efficiency is improved. The proposed converter is tested by the prototype with 540-600 VDC input and 750W (48 V/15.625 A) output.