Novel soft-switching high gain transformerless DC-CD converters without auxiliary switches for renewable energy systems

This paper presents new soft-switching transformerless DC-DC converters without auxiliary switches. The soft-switching operation is achieved with the aid of simple resonant cell, which comprises of an inductor, a capacitor and a diode. In addition to the auxiliary cell, a voltage multiplier cell also included in order to ensure high voltage conversion ratio. The major advantages of the proposed converters are reduced turn on/turn off losses, high conversion ratio and very simple auxiliary circuitry. A resonant cell is incorporated in this converter which is used to turn on the main switching devices at zero current and turn them off at zero current. The zero current switching operation is achieved with a simple auxiliary cell. This paper describes the operation principles and the design simulations of proposed converters. The theoretical analysis of the proposed converters is validated by the simulation analysis on 12V/360V/1kW converter systems