New zero-voltage and zero-current mized mode switching partial resonant converters

Abstract

The resonant operation of inductor and capacitor provides zero crossing points of capacitor voltage or inductor current. When the switching devices in a converter are switched on or off in synchronization with the voltage or current zero crossing points, the switching loss and electro magnetic interference can be significantly reduced. In case of conventional bard switching converters, the switching loss increases proportional to the switching frequency and thus the volume of the heat sink to protect the switching devices from thermal runaway should be increased. Recently, many active research works on high frequency resonant mode operating converters have made it possible to achieve high efficiency small size and light weight converter in a variety of industrial particularly aerospace applications. High switching frequency is the key to reduce the size and weight of the reactiove elements and isolation transformer in the construction of the converters. Besides the reduced size and weight, fater response time and lower acoustic noise are obtained as a result of the high switching frequency. Although the main role of the inductor and the capacitor in the resonant converters in the reduction of switching loss, however, high VAr raings of the reactive components are required and the switching frequency should be varied to regulate the oupput power because the power is transferred form source to load through inductor-capacitor resonant tank. Thus the design of magnetic componets becomes difficult. This paper proposes several types of new partial resonant converters to obtain constant operating frequency with simple control and low VAr ratings of reactive elements as well as low switching loss, low acoustic and EMI noise, high power density and fast response time. The power of the proposed converters is transferred thorugh the inductor as for the chopper and inductor-capacitor resonant operation occurs partially only during a short period starting at the instants of...