Analysis and Flexible DV/DT Control of an Active Clamping Topology for Series-Connected SiC MOSFETs
Fan Zhang, Yuze Zheng, Xuan Zhang, Xu Yang, Wenjie Chen
Abstract
Series-connection of SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s is an attractive solution to build cost effective and high efficiency medium voltage converters, however, the unequal voltage sharing among the power devices and the induced high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> problems should be considered carefully. In this article, an active clamping topology and corresponding <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> control method for series-connected SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s are proposed. With the proposed topology, the drain-source voltage of each SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> can be clamped by discrete clamping capacitor, resulting in high robust switching. Besides, the clamping capacitor voltages can be autobalanced during the topology operation, so the peak voltages of the series-connected SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s can be easily balanced. By simply adjusting the gate drive delay time, the proposed topology could reduce the equivalent <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> of the device string with very small increase in power loss, so the high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> induced switching noise can be suppressed greatly. Finally, a 4.8 kV/10 A half-bridge prototype is established with six SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s connected in series within per bridge arm, experimental results are provided to show the effectiveness and advancement of the proposed method.