1200 V SiC MOSFET is a suitable replacement for Si IGBTs due to its improved switching behavior. However, high di/dt and dv/dt of SiC MOSFET cause very high voltage overshoot and oscillations due to the presence of parasitic inductance in the converter layout and parasitic capacitance of the load. These undesired switching responses increase switching loss and give rise to EMI related issues. Therefore, it is important to minimize these adverse effects in order to extract maximum benefits from SiC MOSFET. This paper proposes an active gate driving technique for SiC MOSFET to improve its overall switching performance in the presence of moderately higher amount of parasitic inductance in the converter layout. It is achieved by controlling the device di/dt and dv/dt independently in four stages with appropriate values of gate resistances for both turn-on and turn-off switching transient. The developed active gate driver is tested in a double pulse test bed and in a two-level voltage source inverter driving an induction motor load.

An isolated multilevel bidirectional dc-dc converter is presented in this paper to interface the low voltage (LV) battery and the high voltage (HV) propulsion inverter in electric vehicles. The proposed topology achieves a high voltage step-up ratio in the motoring mode by reconfiguring two split capacitor half-bridge circuits in series/parallel through the symmetrical modulation of a voltage bidirectional, two quadrant switch. This reconfiguration generates a high-frequency multilevel voltage output at the dc bus side of the inverter, which reduces the output filter volume. The dc bus voltage is regulated by the duty cycle modulation of the intermediary switch in the motoring mode, simplifying the sensing and control. During regenerative braking, the converter is operated with phase shift modulation between the HV half bridges and the LV full bridge to regulate the battery voltage. The presented modulation strategies achieve ZVS for the full bridge devices over a wide load range. A comprehensive analysis of the proposed multilevel converter in motoring and braking modes along with the design constraints and soft switching boundary conditions is presented in this paper. Detailed experimental results on a 1.5 kW laboratory prototype are presented to verify the design approach and illustrate the converter performance.

SiC MOSFET can operate at a junction temperature of 200-250 °C due to its improved material properties and thermal stability. However, successful realization of SiC MOSFET based high-temperature (HT) converter requires HT gate drivers. This paper presents a low-cost HT gate driver developed with discrete transistors and signal diodes rated at 180-200 °C. The gate driver has a robust overcurrent and undervoltage lock out protection circuit. The propagation delay of the protection circuit and gate driving circuit is greatly reduced compared to commercial HT gate drivers. A comparative analysis of the developed HT gate driver using discrete components and the commercially available silicon-on-insulator technology based HT gate driver is presented. The performance of the HT gate driver is evaluated for both hard switched fault and fault under load condition at an ambient temperature of 180 °C.

This paper proposes a single-stage isolated PWM rectifier topology to interlink utility grid and renewable energy sources in a 380V dc distribution system for residential applications. The proposed topology provides both power factor correction (PFC) and output dc voltage regulation within a single power conversion stage. Furthermore, it includes an integrated flyback based active lossless clamp (ALC) circuit to mitigate the device overvoltage issues generally noticed in the isolated single-stage PWM rectifiers. Thus, low voltage rating devices can be selected. The regenerative feature of the flyback ALC circuit along with soft-switching of the main converter structure helps in realizing higher efficiency. A dual-duty hybrid control algorithm is also reported to improve the converter performance. A SiC MOSFET based 1.5 kW hardware prototype is developed. The converter performance is evaluated from the experimental results obtained during both steady state and dynamic operation. Comprehensive performance analysis and comparison study have also been presented in this article.

This letter proposes a novel soft-switched single-stage isolated dc-ac converter topology from the industry point of view. The proposed converter requires a lesser number of MOSFETs compared to widely studied cycloconverter type (CCT) isolated dc-ac converter topology. This converter provides lower duty cycle loss, better efficiency, and EMI performance compared to CCT dc-ac converter. Also, it is thermally more stable, thus requires a smaller heat sink. The converter operation is demonstrated in a 1kW prototype developed with SiC MOSFETs.