DC-DC converters

Modern electronic systems require high quality, small, lightweight, reliable, and efficient power supplies. Linear power regulators, whose principle of operation is based on a voltage or current divider, are inefficient. The dc-dc converters can be divided into hard-switching pulse width modulated (PWM) converters and resonant and soft-switching converters. This chapter deals with the former type of dc-dc converters. The step-down dc-dc converter is commonly known as a buck converter. The state of the converter in which the inductor current is never zero for any period of time is called the continuous conduction mode (CCM). The CCM is preferred for high efficiency and good utilization of semiconductor switches and passive components. The DCM may be used in applications with special control requirements, since the dynamic order of the converter is reduced. It is uncommon to mix these two operating modes because of different control algorithms. An economical mean of achieving such isolation is to employ a transformer version of a dc-dc converter. High-frequency transformers are of a small size and weight and provide high efficiency.