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Objective: Technical Approach: Accomplishments: Next Steps: Potential Impact: To design Active Clamp Flyback for 20V, 5A output using GaN Systems’ GS66508 device for input voltage of 180-200V to reduce the voltage and current stress across the main switch Active Clamped Flyback Converter using GaN GS66508P device Abhay Negi, Ashish Shrivastav, Mohammad Sameer Khan, Subhashish Bhattacharya Flyback converters have wide application ranging from Cell- Phone Chargers to Solar PV inverter. High current and high voltage stress in the flyback converter requires the switch to be oversized thereby increasing the losses. GaN device GS66508P operate at high switching frequency which reduce the overall converter size but increases the overall switch stresses. Active Clamping can be used to reduce the voltage stresses due to the leakage inductance of the transformer. Reduced Voltage Stresses due to active clamping For unclamped flyback, Stress was 426V for 100V input For active clamped flyback, voltage stress was only 385V for increased voltage of 185V. Device Stress in Flyback Configuration : Ch1 – Voltage stress across switch (VDS); Ch2- Gate to Source Voltage(VGS); Ch3- Input Voltage (Vin); Ch4- Output Voltage (V0) Device Stress in Flyback Configuration with Active Clamp Circuit : Ch1 – Voltage stress across switch (VDS); Ch2-Gate to Source Voltage(VGS); Ch3- Input Voltage (Vin); Ch4- Output Voltage (V0) Active Clamp Flyback Circuit Lab Setup As GS66508P is bottom cooled device, so extracting heat from device is problematic. Top cooled devices shall be used with better thermal design Intended switching frequency to be 500 kHz and higher. Reduction in the magnetics size due to high switching frequency operation leads to smaller converter size and active clamping helps in increasing the converter efficiency.
