A new robust closed-loop control system for electrosurgical generators

Commercially available electrosurgical generator (ESG) depends on circuit topologies that are responsive to changes in resistance of the tissue. This change in resistance varies the amount of power delivered, especially amid arcing. Changes in resistance along the body make it even harder to keep the power delivery and voltage in limits. An important property of ESG is to be able to keep the output power constant in the constant power region. In this work, a closed-loop control system is designed and tested for ESG to improve its performance in the nonlinear constant power region. A quantitative study of a buck converter and boost inverter is presented along with the closed-loop response for the ESG unit. A comparative analysis of two control methods, i.e., proportional integral derivative (PID) and proportional integral derivative sliding mode control (PIDSMC), is presented for the ESG unit. Results confirm that the presented closed-loop system can highly improve the performance of the ESG system and PIDSMC is found to be a more suitable choice.