10.5120/4155-319 {bibtex}spe319t.bib{/bibtex} Abstract This paper endeavours to estimate the influence of soft switching on semi-conductor devices’ rating, when they are subjected to high frequency applications. In order to find out the extent of saving in semiconductor devices losses, soft switched circuits were studied and analyzed. An experimental set up which could be operated both in hard-switching and soft-switching modes were chosen. Specific switching devices, namely MOSFETs were selected. The ageing of the semiconductor devices was correlated with the rise in temperature of the casing of the devices. The cutoff point for the experiment was the knee region where the thermal runaway would start. This experiment was conducted on two MOSFETs at two frequencies.

A new family of zero-current-transition (ZCT) pulse-width-modulated (PWM) converters are proposed. The new family of converters implements zero-current turn-off for power transistor(s) without increasing voltage/current stresses and operates at a fixed frequency. The proposed converters are deemed most suitable for high-power applications where the minority-carrier semiconductor devices (such as IGBTs, BJTs, and MCTs) are predominantly used as the power switches. Theoretical analysis is verified on a 100-kHz, 1-kW ZCT-PWM boost converter using an IGBT.< >

The zero voltage switching single-ended-parallel multi-resonant power converter (SEP-MRC) is suitable for high frequency applications. Here, the DC and small-signal characteristics of the SEP-MRC are presented for the first time. Based on circuit analyses, guidelines for power stage optimization and compensator design are set up. The results of both DC and the small-signal analyses are verified experimentally

To provide a 48 volt DC bus for distributed power systems, AC-DC power converters with high power factor and isolation are required. Instead of using a conventional two stage scheme which has a boost front end followed by a DC-DC converter, a boost derived topology is chosen to achieve high power factor, isolation, and voltage step down. A newly proposed technology of soft switched insulated gate bipolar transistors (IGBTs) is used for this application to reduce the IGBT switching loss and achieve low conduction loss. The design considerations of the power stage and the control circuit are provided. A prototype converter is built to show the feasibility of the single stage scheme

A small-signal modeling technique based on the extended describing function concept is applied to series-resonant converters (SRCs) and parallel-resonant converters (PRCs). The models developed include both frequency control and phase-shift control. The small-signal equivalent circuit models are also derived and implemented in PSPICE. The models are in good agreement with measurement data. The high-frequency dynamics of resonant converters around the beat frequency can be accurately modeled. These simple analytical models can be employed in the control loop design of resonant converters

The dynamics of LCC resonant power converters are investigated using a small-signal model which is accurate up to the switching frequency. It is shown that the beat frequency dynamics is not only related to the operating region but also heavily dependent on the output filter design. The authors concentrate on frequency control of LCC resonant converters. Compensator designs are discussed, taking into consideration the strong impact of beat frequency dynamics. The frequency-domain analyses are verified using accurate large-signal simulations

Small-signal modeling based on the extended describing function concept is applied to LCC resonant converters. The analytical model developed includes both frequency and phase-shift control. Small-signal equivalent circuit models are also derived and implemented in PSPICE. The models ae in good agreement with the measurement data.<>