A Resonant Current Regulator for Direct Electrical Heating of Subsea Pipelines

A single-phase LCCL resonant inverter is presented in this paper for direct electrical heating of subsea pipelines. The proposed LCCL-RI is a type of immittance converter which operates as a high-frequency, constant-amplitude alternating current source to provide superior heating performance compared to the existing line-frequency DEH system. The capacitors in the tank network provide compensation of the load inductance and mitigate the requirement of external reactive compensation. The tank network is designed to operate at the frequency of peak current gain to minimize the tank input current as well as to ensure ZVS of the inverter switches. The design procedure of the proposed LCCL-RI for constant-current operation is presented and validated through detailed simulation and experimental results on a SiC MOSFET based prototype unit.