Dual-Frequency Ultra-Wide-Load Resonant Inverter for Electrosurgical Generator System

This paper presents a dual-frequency electrosurgical generator (ESG) based on a Class EF inverter, designed to ac commodate ultra-wide impedance variations encountered during surgical procedures. The inherent load-insensitive characteristics of the Class EF inverter at a single frequency are further enhanced through the adoption of a dual-frequency operation strategy. To explore the design potential, inequality constraints and an impedance-based analysis method are employed. High operational efficiency is established as the primary design goal, and a simple dual-frequency and current control scheme is implemented to maintain stable output power. In the experimental validation, a 3/4 MHz ESG system is developed, achieving an efficiency above 63% and delivering 20 W of output power across a wide load range of 50 to 1500 Ω.