1. 2015.03.18 A New Dual Current-Mode Controller Improves Power Regulation in Electrosurgical Generators Friedrichs, D. A., Erickson, R. W., & Gilbert, J. (2012). A New Dual Current-Mode Controller Improves Power Regulation in Electrosurgical Generators.Biomedical Circuits and Systems, IEEE Transactions on, 6(1), 39-44. Presenter ： Wei-Siang Chiou Adviser ： Dr.Yi-Chun Du 1

2. 生醫系統整合實驗室 Integrated Biomedical System Laboratory  Introduction  Materials and methods  Results  Conclusion 2 Outline

3. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 3 Introduction  Electrosurgical generators  Used to perform arc cutting and coagulation in modern surgical practice

4. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 4 Introduction  Electrosurgical generators

5. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 5 Introduction  Electrosurgical generators  Cutting  Coagulation  Blended

6. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 6 Introduction  Standard industry practice to achieve the desired output characteristic  Measure and average the ac output power over several cycles  Use a low-bandwidth control loop to adjust the duty cycle of a PWM converter

7. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 7 Introduction

8. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 8 Introduction  Disadvantages  Slow response during arcing leads to poor regulation of the ac output power  Resulting in undesirable thermal spread or tissue damage

9. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 9 Introduction  New dual current-mode control system  Produces constant power output without the need to measure output voltage or current  Providing more precise control of the desired tissue effect

10. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 10 Introduction  New dual current-mode control system

11. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 11 Materials and methods  By treating each of the three output modes separately, to achieve the desired output characteristic  Constant Power Output  Constant Voltage Output  Constant Current Output

12. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 12 Materials and methods  Constant Power Output

13. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 13 Materials and methods  Constant Voltage Output

14. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 14 Materials and methods  Constant Current Output

15. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 15 Materials and methods

16. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 16 Result  Converter Prototype  Been prototyped by using FPGA for the testing of control algorithms  Output frequency is chosen as 472 kHz

17. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 17 Result  Output voltage and current during the load step  The inverter operating in constant-power mode, delivering 50 W into a resistor

18. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 18 Result  Transition from constant voltage to constant power mode  A significant improvement is seen in the fast speed at which this inverter transitions from constant power mode into either current- or voltage- limited mode

19. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 19 Result  Measured data overlaid on a desired I/V curve  The converter output voltage and current were measured over a range of load impedances spanning all modes of operation

20. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 20 Tissue Results  Tested on porcine or chicken tissue  It's worth noting that the complete lack of any white (coagulated thermal spread) or black (charred) tissue surrounding the incision

21. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 21 Tissue Results  Tested on porcine or chicken tissue  Changing the position of the maximum voltage limit results in different tissue effects  Higher voltages will lead to charring (“black coagulation”)

22. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 22 Conclusion  Realize the desired output characteristic of an electrosurgical generator in a markedly simpler and more accurate fashion  By directing which of the two conversion stages is to be current mode controlled, can be achieved with excellent regulation and fast transitions

23. 生醫系統整合實驗室 Integrated Biomedical System Laboratory 23 Conclusion  Reduced thermal spread and charring should result in better surgical outcomes by reducing scarring and decreasing healing times  Provide near-deadbeat regulation of output power, ensuring that thermal spread is minimized by accurately supplying the specified power in each individual cycle

24. 生醫系統整合實驗室 Integrated Biomedical System Laboratory Thank you for your attention! 24 http://faculty.stust.edu.tw/~terrydu/