Self-Oscillating Control Methods for the LCC Current-Output Resonant Converter

A strategy for self-oscillating control of LCC current-output resonant converters, is presented, based on varying the phase-angle between the fundamental of the input voltage and current. Unlike other commonly employed control methodologies, the proposed technique is shown to provide a convenient, linear system input-output characteristic suitable for the design of regulators. The method is shown to have a similar effect as controlling the DC-link supply voltage, in terms of output-voltage/current control. The LCC converter variant is used as an application focus for demonstrating the presented techniques, with simulation and experimental measurements from a prototype converter being used to show the practical benefits. Third-order small and large-signal models are developed, and employed in the formulation of robust output-voltage and output-current control schemes. However, notably, the presented techniques are ultimately generic and readily applicable to other resonant converter variants.