Methods of improving efficiency in wide input range boost converters at low input voltages

Development of switching power supplies for the telecom industry has been constantly moving towards higher efficiency and more compact units, with watts per cubic inch as a key design parameter. In recent years, there has also been a growing demand for a wide input voltage range-the rectifier should be designed to operate at input voltages ranging from 90 V to 280 V while maintaining a high efficiency. A typical single-phase rectifier is composed of a power factor correction (PFC) stage and an isolated DC/DC stage. The PFC stage usually contains a full wave rectifier followed by a boost type DC/DC converter. This configuration of the PFC stage has several advantages including continuous input current and the ease of implementing power factor correction. The boost topology also yields excellent efficiency over a limited input range, but has difficulties in maintaining high efficiency at the lower end of a wide input range. The problem is of course well known and a number of papers have been published suggesting a variety of techniques to deal with it. The purpose of this paper is to present a survey covering some of the most interesting approaches the authors have come across