Electrosurgical Generator for Driving Plasma Scalpel using Fast Frequency Tracking Technology based on a Single-Ended Resonant Inverter

In this study, an Electrosurgical Generator (ESG) for driving plasma scalpel is presented with Zero Voltage Switching (ZVS) turn-on over a wide load impedance range based on a fast frequency tracking technology. The ESG consists of a single-ended resonant inverter utilizing the frequency tracking technology and an adjustable DC voltage source. A resonant circuit for a single-ended resonant inverter is designed with an inherent frequency of 365∼403 kHz to accommodate the load range of a plasma scalpel and meet the frequency requirements for electrosurgical procedures. Near beatless fast frequency tracking and ZVS turn-on of MOSFETs are achieved by only measuring a single resonant variable. Closed-loop control of the output power is achieved by adjusting the output voltage of the DC source. An ESG prototype is built to generate constant output power from 30 to 320 W. It can perform frequency tracking and ZVS turn-on of MOSFETs within a load range of 50∼2000 Ω with a maximum efficiency reaching 93.27%. Moreover, the proposed generator is tested on porcine tissue samples to verify its effectiveness as an ESG. The total harmonic distortion (THD) of output voltage and current is below 8% under resistive loads and below 30% during the plasma discharge phase.