Diode Evaluation and Series Diode Balancing for High-Voltage High-Frequency Power Converters

Abstract

Miniaturization of high voltage power converters is severely limited by the availability of fast-switching, low-loss high-voltage diodes. This paper explores techniques for using discrete low-voltage diodes in series as one high voltage diode in high-frequency applications (e.g., hundreds of kHz and above). We identify that when series connecting diodes, the parasitic capacitance from the physical diode interconnections to common can result in voltage and temperature imbalance among the diodes, along with increased loss. We quantify the imbalance and propose two related compensation techniques. To validate the approaches, a full-bridge rectifier is tested with each branch consisting of four 3.3 kV SiC diodes in series. Experimental results showcase the imbalance and demonstrate the effectiveness of the compensation techniques. Additionally, we characterize the performance of a range of diodes for use in high-frequency, highvoltage converters. The proposed technique and evaluation results will be valuable for the design of lightweight and miniaturized high voltage power converters. Index Terms-High voltage diodes, series diode balancing, high-frequency converter, high-voltage converter The paper is an extension of a conference paper, Y. He and D. J. Perreault, Series diode balancing and diode evaluation for high-voltage highfrequency power converters, in Applied Power Electronics Conference and Exposition (APEC), March 2019 [1]. Here we extend the work to include diode evaluations at higher frequencies and more accurate test results. The authors gratefully acknowledge the support of MIT Lincoln Laboratory Autonomous Systems Line and the Professor Amar G. Bose Research Grant. Y. He and D. J.