A Multilevel Gate Driver of SiC mosfets for Mitigating Coupling Noise in Bridge-Leg Converter

Silicon carbide (SiC) devices can significantly increase power efficiency, temperature reliability, power capacity, and power density because of their outstanding characteristics. Nevertheless, in the bridge-leg configuration of a power converter, the high-speed switching capability of SiC mosfets is often restricted by the coupling noise between high-side mosfet and low-side mosfet. The coupling noise caused by high ${dv/dt}$ and ${di/dt}$ in switching transient will increase the switching loss and the risk of mosfet breakdown. In order to completely take advantage of the superior feature of SiC mosfets, a novel multilevel gate driver is proposed in this article to mitigate the coupling noise effectively. Compared to the conventional gate drivers, the proposed gate driver adds a capacitor, an auxiliary mosfet, a Zener diode, and two resistors to regulate the turn-off voltage bias felicitously. In this article, the operation principle of the proposed gate driver is first introduced, to the best of our knowledge. Moreover, to obtain the circuit parameters accurately, a series of formulas have also been derived by equivalent circuit models. A 230-V/4.6-A synchronous buck converter based on SiC mosfets is successfully experimented to verify this proposed gate driver.

I. Introduction

Wide bandgap semiconductors, e.g., SiC mosfets, draw extensive attention from the power electronics [1]–[3]. This mainly comes from their highlighted characteristics include high voltage rating, high-speed switching, and low drain–source on-state resistance. Usually, a lower drain–source on-state resistance [4] reduces the conduction losses of a power converter significantly, in comparison with that of the Si mosfets. Besides, the enhanced high-frequency performance decreases the switching losses as well. Consequently, the size and cost of the heat sink will be reduced. In the SiC devices, the increased switching frequency can lead to a reduction in the number of passive components [5]. This will be very useful to diminish the volume of the converter. Based on the superiorities of the SiC mosfets above, it is evident that the power density can be enhanced significantly [6], [7]. Moreover, the thermal reliability of electronic devices can be further improved because of the high-temperature feature of SiC mosfets. The operation voltage of power devices can also be increased by using high-voltage SiC mosfets [8].