| Summary: | In the past decade, there has been an increased demand to develop compact power supplies with high efficiency and high power density in order to revolutionise traditional approaches for high power radio frequency (RF) applications, such as long pulse modulators used for high energy physics acceleration experiments. Resonant technology has been considered to meet these challenges, due to its soft-switching characteristic at high operating frequency. The aim of this research project is to provide further knowledge in series resonant parallel loaded (SRPL) resonant converters for long pulse modulators, and to design advanced closed-loop control strategies for voltage pulse regulation. The proposed converter comprises three single phase SRPL resonant output stages, which guarantees a strong ability of overcoming the influence of tank unbalances and enables independent modulation procedures. A DQ modelling approach was utilized to analyse the converter. Based on it, a PI + repetitive control strategy was designed for voltage pulse regulation to obtain good dynamics and steady state performance. A combined frequency and phase shift modulation method was selected to control the converter so that soft-switching of semiconductor devices can be always achieved, even in the presence of large tank unbalances. Good correlation between simulation and experimental results has been demonstrated, which validates the converter circuit design, modelling approach, control strategy and modulation method
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