On cascading of the series loaded resonant converter

In this paper a novel method for cascading H-bridge and resonant tanks in a SLR, series loaded resonant, converter is presented. The main focus is on load sharing. Different methods are discussed. Their robustness regarding variations in operating frequency, values of the components and parasitic elements are evaluated. The results are validated both by simulations and by experiments. For the experimental part a 120 kW/70 kV system has been designed and tested. The measurements confirm the simulations, where the proposed method shows an equal sharing of the load (current) even when operating the system close to resonance with a +/- 10% worst-case variation of the resonant tank components. The method is derived for two subsystems, but can be generalised to any number of subsystems. Thus, enabling the use of compact, standardised modules connected together forming very powerful systems.