High Dynamic Power Control Combining Duty Cycle Predictive Feedforward and Power Feedback for Electrosurgical Inverter

An electrosurgical generator (ESG) is a surgical instrument that generates high-frequency ac voltage and requires constant power control under wide-range tissue load impedance to achieve a specific therapeutic effect. This article presents a power control method that combines duty cycle predictive feedforward and power feedback (DCPF-PF), which achieves high dynamic performance when load impedance changes suddenly. An improved DCPF-PF control method based on an inductor current lookup table (DCPF-PF-LUT) is proposed to further suppress the power overshoot and undershoot caused by the time delay of duty cycle calculation and update. Besides, a voltage and current limiting control is proposed to avoid excessive voltage and current and ensure safety. A 50∼200 W prototype was built in the laboratory, and the experimental results verified the feasibility of the proposed control methods.