The introduction of wide band gap devices such as silicon carbide (SiC) MOSFETs has brought a revolutionary in the field of power electronic converters especially for Medium Voltage (MV) applications. The fast electron mobility and lower capacitance provides benefits for fast switching with reduced losses. The increase in switching frequency operation allows the reductions in size of the passive elements that directly reduces the overall converter size and cost and hence improves the power density. However, these devices suffer from various challenges – higher slew rate (dv/dt and di/dt) and higher cost. Also, the conventional existing gate drivers based on voltage source are not capable of utilizing the benefits of these devices.
To overcome the challenges associated to SiC MOSFETs, we at IIT Bombay work on the development of new gate driver topologies based on current source which improves the switching performance, and also contributes for the further reduction in switching losses. Furthermore, to reduce the slew rates with lower switching time we have come with new gate driver family of active current source which controls the slew rate and reduces the EMI, oscillations and overshoots in the current and voltage. Further, to solve the problem of cost, we are working on developing the mixed device based converter which comprises of both Si IGBTs and SiC MOSFETs. Also, new modulations techniques are developed which ensure to allocate all the high frequency switching functions to the SiC MOSFETs and the Si IGBT being switched at relatively lower frequency. Such solutions allows the better performance with reduced converter cost and losses.
