Voltage generation for Sawyer-Tower Coss loss measurement based on resonant converters

Output capacitance losses in modern semiconductor devices become increasingly relevant with fast switching power converters. One widely used method to measure such losses is the Sawyer-Tower circuit. A new voltage generation approach is proposed to handle the highly variable capacitive load in a Sawyer-Tower circuit. An LLC resonant converter is applied to generate the high voltage, high frequency sinusoidal excitation voltage, overcoming limitations of HF amplifiers. An external DC voltage source is introduced to prevent reverse conduction of the device under test, ensuring accurate charge-voltage (Q-V) characterization. Measurements under this voltage excitation are presented. The calculated dissipated energy is verified by thermal measurements observing the temperature rise of the DUT, showing less than 6% deviation. This article presents a scalable and practical setup for power semiconductor characterization at high voltages.