4 MHz Electrosurgical Generator System for Wide Load Impedance Range with SiC-Based Full-Bridge Inverter

A power conversion system to drive a high-frequency electrosurgical generator (ESG) is proposed. The proposed system consists of a 4-MHz full-bridge inverter capable of ensuring power in a wide load impedance range and implementing energy control functions in accordance with the ESG characteristics. Unlike conventional inverter systems, ESG cannot deliver energy directly to the load, but through an instrument, which makes it difficult to ensure power. Thus, impedance matching is essential to ensure power in ESG. For ensuring power, impedance matching is realized using a resonance filter while considering instrument induced parasitic components that cannot be ignored at high frequencies. The inverter is composed of silicon carbide suitable for the MHz switching operation. A prototype is to validate the proposed system. Experimental test of the prototype can provide a load power of more than 100 W for a tissue model with impedance range of 5-800 Ω.