Current Source Gate Driver Integrated with Short Circuit Protection and Soft Turn-off Scheme

The state-of-the-art power electronic switches such as silicon carbide (SiC) MOSFET are capable of switching faster than its predecessor silicon (Si) IGBT. In order to turn on and off these devices an external circuits termed as gate drivers are required. The conventional voltage source gate driver (VSD) charges the gate source capacitance using the RC charging principle. However, with the increase in switching frequency the conventional VSD limits the operation due to the increases losses occurred in it due to the presence of gate resistor. On the other hand, the current source gate driver (CSD) provides a constant current during the switching transition which accelerates the switching process results in high frequency switching capability of the device. The inductor based CSD are the most suitable among all due to ability to provide a constant current of a defined magnitude by charging the inductor for the appropriate duration. However, such inductor-based CSDs are still under investigation and are not commercially available yet. One of the avenues of research in this domain is the integration of a short circuit protection system for the driven device as can be found in the commercial voltage source gate drivers. This paper presents the integration of short circuit protection and soft turn-off scheme with a current source gate driver to provide holistic protection to SiC MOSFETs. Analysis and simulation results are provided for validation of the system. A prototype is also constructed for experimental validation.

I. Introduction

Power electronic switches such as IGBTs and MOSFETs are voltage driven device which draw the gate current in accordance to charge the input capacitance [1]. Due to the limitation incurred by the microcontroller over the voltage and current requirement by the switching device, it demands an additional circuitry connected in series. These circuits are termed as gate drivers. Gate drivers serve as the intermediary between control circuitry and power switches, enabling precise and efficient control over the switching characteristics of these devices. They are responsible for providing the necessary voltage and current signals to turn the power switches on and off rapidly, allowing for precise control of power flow and facilitating the desired switching operation. With the emergence of wide bandgap semiconductor devices, such as SiC MOSFET, achieving lower switching loss and higher power density in converter has become possible due to their capability of operating at higher switching frequency [2]. The gate driver plays a decisive role in such high frequency operation. This also underlines the importance of the need for advanced gate drivers for driving these high-performance devices. Conventionally, voltage source gate drivers are utilized for driving power semiconductor switches. A general gate driver circuit is shown in Fig. 1.