This paper presents the working theory and constant average charging current characteristic from zero volts to maximum voltage of series load resonant circuit when the load is capacitive.

This paper introduces the principle of balf-bridge series-parallel resonant voltage converter and its character analysis,and gives its experiment waveform.

In order to overcome the disadvantages of high peak voltage and high peak current stresses on the switching devices of the resonant DC link inverter and the resonant DC parallel inverter and to fulfil the requirement of high voltage and little current,a series-parallel resonant dual voltage converter with zero-voltage switching is proposed in this paper.

Based on the negative impedance of the glow as the load and the particular igniting condition of the second-stage rocket motor of a surface to air missile, the high frequency series-parallel resonant DC/DC converter is proposed in the paper.

In order to overcome the disadvantages of high peak voltage and high peak current stresses on the switching devices of the resonant DC link inverter and parallel resonant DC link inverter, a three phase DC AC series parallel resonant converter with zero voltage soft switching conversion concept is proposed.