High frequency converters using resonant and nonresonant soft switching techniques

Abstract

High switching frequency can reduce the sizes of the reactive components. In the case of conventional hard switching converters, the switching loss is proportional to the switching frequency. Thus the sizes of heat sinks increase with the switching frequency which acts as a limitation factor for pushing up the switching frequcncy. Soft switching techniques offer good solutions of high switching frequency operation with low switching loss. Besides, electromagnetic interference (EMI) problem can be significantly reduced and fast system response can be obtained. Recently many soft switching techniques are reported in the literature. Zero current switching (ZCS) quantum series resonant converter (QSRC) shows the characteristic of very low switching loss and thus high switching operation is possible. The porposed ZCS QSRC scheme in the thesis is applied to an electronic transformer with a fixed voltage gain. The L, C resonant tank in ZCS QSRC can be modeled to an equivalent inductor and thus ZCS QSRC cab be modeled to aconventional PWM converter. The analytical method for mideling the proposed ZCS QSRC is also suggested. A new zero voltage switching (ZCS) pulse width modulation (PWM) module is proposed and applied to a power factor correction circuit. Since the module can replace the switch of the traditional PWM converter without changing any circuit configuration or control strategy, it has almost all the advantages of the conventional PWM converter. A ZVS series resonant converter (SRC) controlled by one chip control IC is applied to an electronic ballast. In spite of high performance of the ZVS SRC, ZCS SRC rather than ZVS SRC has been adopted to the electronic ballast so far because the control complexity increased tremendously when ZVS SRC is used. One chip control IC which is under development can solve the problem of control complexity and offers several excellent performances such as light output regulation using feedback control, soft starting operation un...