Analysis and design of a higher-order T-type resonant convertor as a constant-current power supply

A higher-order resonant convertor (RC), named LCLCL-T RC, is proposed in this study. It is shown that the convertor behaves as a constant-current (CC) source under certain operating conditions. The proposed convertor additionally offers inherent dc blocking for the isolation transformer and integration of all magnetic components reducing the number of discrete passive components in the circuit. A detailed analysis of the proposed convertor is presented. Closed-form expressions for convertor gain, component stresses, condition for convertor operation as a CC power supply and component design values optimised for minimum size of resonant network are derived. An experimental 250 W prototype convertor was designed, built and tested to demonstrate its CC source behaviour, good conversion efficiency and feasibility of the use of integrated magnetic component.