I. Introduction
Compact high-voltage converters will be widely used in applications such as portable medical imaging, aerospace and military electronics. Pulse-width modulated (PWM) converters are not suitable for these applications because the leakage inductance and the winding capacitance of the high-turns-ratio transformer in the converter result in undesired voltage and current stresses. Therefore, resonant converters, especially the LCC-type of series-parallel resonant converter, are preferred because of their ability to effectively utilize these parasitic components [1]. A number of designs based on the full-bridge structure with LCC resonant tank have been implemented for the high-voltage applications [2]~[6]. In order to shrink the volume of passive components, thus achieving high power density, high switching frequency is desired for the converters.