Analysis of the Internal Stability of Two Different Control Implementations of the Phase-Shifted Full-Bridge Resonant Converter

The phase-shifted series-parallel resonant converter has shown to be a good candidate for high-voltage and high power applications. In some of those applications, the converter has to work under heavy and light load conditions that affect both its efficiency and operation conditions. This paper is focused on the analysis of two control strategies, commonly used to achieve ZCS in one branch, which provides the same steady-state driving for the switches but, depending on the load and frequency, their dynamic behavior is different and may also produce instability.