Average Inductor Current Sensor for Digitally Controlled Switched-Mode Power Supplies Rodríguez, M., López, V. M., Azcondo, F. J., Sebastián, J., & Maksimović, D. (2012). Power Electronics, IEEE Transactions on, 27(8), Chairman: Dr. Shih-Chung Chen Presenter ： Ren-Yu Chen Adviser ： Dr. Yi-Chun Du

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

生醫系統整合實驗室 Integrated Biomedical System Laboratory 3 Introduction(1/6)  Electrosurgical Instrumentation origin  The real foundation for the application of electrical currents in surgical procedures by 1891

生醫系統整合實驗室 Integrated Biomedical System Laboratory 4  Disadvantages  Slow response during arcing leads to poor regulation of the ac output power  Resulting in undesirable thermal spread or tissue damage Introduction(2/2)

生醫系統整合實驗室 Integrated Biomedical System Laboratory 5 Introduction(3/3)

生醫系統整合實驗室 Integrated Biomedical System Laboratory 6 Introduction(4/4)  Digital current mode control  High costs  High Loss

生醫系統整合實驗室 Integrated Biomedical System Laboratory 7 Materials and methods(1/5)  Average Inductor Current Sensor

生醫系統整合實驗室 Integrated Biomedical System Laboratory 8 Materials and methods(2/5)  By treating each of the three output modes separately, to achieve the desired output characteristic

生醫系統整合實驗室 Integrated Biomedical System Laboratory 9 Materials and methods(3/5)  Old Current-mode control system

生醫系統整合實驗室 Integrated Biomedical System Laboratory 10 Materials and methods(4/5)  Shows a simplified diagram of the inductor current sense circuitry  Precision comparators  Low cost

生醫系統整合實驗室 Integrated Biomedical System Laboratory 11 Materials and methods(4/5)  Current-mode control system

生醫系統整合實驗室 Integrated Biomedical System Laboratory 12 Result(1/7)  Converter Prototype  Been prototyped by using FPGA for the testing of control algorithms  Output frequency is chosen as 472 kHz

生醫系統整合實驗室 Integrated Biomedical System Laboratory 13 Result(2/7)  Output voltage and current during the load step  The inverter operating in constant-power mode, delivering 50 W into a resistor

生醫系統整合實驗室 Integrated Biomedical System Laboratory 14 Result(3/7)  New current-mode control system & Old dual current- mode control system

生醫系統整合實驗室 Integrated Biomedical System Laboratory 15 Result(4/7 )  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

生醫系統整合實驗室 Integrated Biomedical System Laboratory 16 Result(5/7)

生醫系統整合實驗室 Integrated Biomedical System Laboratory 17 Tissue Results(6/7)  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”)

生醫系統整合實驗室 Integrated Biomedical System Laboratory 18 Tissue Results(7/7)  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

生醫系統整合實驗室 Integrated Biomedical System Laboratory 19 Conclusion(1/2)  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

生醫系統整合實驗室 Integrated Biomedical System Laboratory 20 Conclusion(2/2)  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

生醫系統整合實驗室 Integrated Biomedical System Laboratory Thank you for your attention! 21