A Resonant Push-Pull DC-DC Converter with an Intrinsic Current Source Behavior for Radio Frequency Power Conversion

In this article, a resonant push-pull dc-dc converter suitable for switching frequencies in the MHz-range is investigated. Despite a simple design procedure with no need of multiresonant tuning, the converter topology is capable of providing a constant output current over a wide output voltage range in unregulated operation. Based on an analytical solution of steady-state operation, normalized dependencies of converter behavior are determined and used to formulate generalized design considerations. In order to verify the theoretical analysis, the design procedure of a 300-W prototype operating at a switching frequency of 6.78 MHz is described considering the impact of circuit parasitics on converter operation. The prototype provides a stable operation within the full output voltage range of 0-150 V and reaches a peak efficiency of 93% at the nominal output voltage. A rapid transient response of the converter is demonstrated by applying a closed-loop on/off-control to the prototype.