A safe power controlling method for a phase-shift migration inverter to drive a high-power ultrasonic transducer

The aim of this work is to investigate and analyze the operation mechanism and power control principle of a bolted Langevin type (BLT)-loaded phase-shifted control inverter and to find a safe power control method for a phase-shifted control inverter used to drive a high-power BLT by preventing the differential current (shock current) from occurring in the right branches of a phase-shifted full-bridge circuit. In this paper, by allowing the inverter operating frequency to operate under inductive loads that coincide with the zero points of voltage and current rather than the resonant frequency of the BLT, which results in the generation of a shock current in the right branch of the full-bridge circuit, the switches of the right-branch also enabled zero-voltage, zero-current switching on (ZVZCS turn-on). The proposed method can fundamentally eliminate the generation of shock current by realizing ZVZCS turn-on on the right-branch switch elements of the inverter. The phase-shift angle control limit for power control by this scheme is 90° and the power control range is 20%–100%.