Design And Research Of Electrosurgical RF-power Generator Based On Class-DE Power Amplifier

With the rapid economic development and people's awareness of health care,the medical device industry is booming all over the world.Electrosurgical RF-power generator has been widely used in various kinds of electrical surgery as a kind of high-end medical equipment products with the function of cutting,coagulation and tissue sealing.The technology of electrical surgery has become the focus of scholars.And there has been a more in-depth study in the aspects of the mechanism of electrical surgical operation,the control of radio frequency power and the expansion of the function of surgery.However,there are few studies on the high frequency switching loss and power conversion efficiency of the electrosurgical RF-power generator.In most of the traditional electrosurgical generators,class-D half bridge or full bridge power amplifier is been used to amplify RF-power.These kinds of amplifiers have a large switching loss when the operating frequency is high,so the conversion efficiency of RF-power is reduced.Therefore,it is necessary to design a high efficiency electrosurgical RF-power generator.This paper studied the the topology and performance of three kinds of RF-power amplifiers(class-D,class-E and class-DE).And it is concluded that the class-DE RF-power amplifier has the characteristics of low voltage stress and current stress like class-D RF-power amplifier,as well as very efficient RF-power conversion capability since zero voltage switching(ZVS)and zero voltage derivative switching(ZDS)condition of the class-E amplifier can be realized.So class-DE RF-power amplifier is been used to design electrosurgical RF-power generator and conduct relevant research.Different power regulation methods are studied according to the characteristics of class-DE RF-power amplifier and electrical surgery.Finally,the Buck DC chopper is selected to adjust the output power.On the basis of the theoretical analysis of class-DE RF-power amplifier,then the class-DE electrosurgical RF-power amplifier circuit is designed and studied.Simulation contrast experiments and analysis are carried out to fing out which design method is better,considering parasitic nonlinear output capacitor of MOSFET in the design process or not.It is found out that the design witch consider the influence of parasitic nonlinear output capacitor has higher output efficiency.And the hardware circuit design and experiment are carried out to verify the feasibility and correctness of this design.The design of whole system is carried out on the basis of the class-DE electrosurgical RF-power amplifier circuit.And the parameters design of Buck DC chopper circuit,the control loop design,the RF energy control system design and the design of auxiliary power supply are studied as the focus.Finally,experiments are carried out on the hardware platform,and it is verified that the design of the electrosurgical RF-power generator based on class-DE power amplifier can achieve good constant power control performance and bipolar coagulation effect.Even in a certain range of the actual load changes,this device can still maintain high RF-power conversion capability.