Zero Current Detection Circuit based on Saturable Transformer Application in GaN based DC-DC Converter with Triple-Mode Switching

This paper analyzes application of saturable transformer for zero current detection in GaN based converter at a switching frequency above 100 kilohertz. The design of the transformer is discussed in a simplified way, development of experimental prototype of the transformer has been given. Zero current detection (ZCD) has been tested on experimental prototype of DC-DC converter. Delay times introduced by the transformer, detection circuit and digital control system have been analyzed. The efficiency of the converter by introducing triple-mode switching with ZCD circuit has been investigated. The results show that the summary delay is at least 250 nanoseconds and at such frequencies the core heats up significantly and lowers efficiency which limits the application of the circuit for switching frequencies above 250 kilohertz.