Fu Dafeng

Status and development of overcurrent protection devices for more electric aircraft applications

Development of more electric aircraft (MEA) is fostering increasing requirements for higher performance Power Distribution Units (PDU). Overcurrent protection architectures and devices in PDU require more flexibility and better performance to accommodate system components and electric loads. Traditional electromagnetic overcurrent protection devices such as CBs, AFCBs, and RCCBs are reviewed and smart power management method enabled by latest Solid State Power Controllers (SSPCs) is surveyed. Design considerations of SSPCs are addressed by advances in wide-bandgap switching devices and performance characteristics of SSPCs are verified by different modeling methods.

Characteristics of SiC MOSFET and its application in a phase-shift full-bridge converter

With the outstanding advantages of SiC MOSFET, which has lower junction capacitance, low-on-state resistor and high junction operating temperature compared to a Si devices, the converter can achieve a high-frequency and high-efficiency. This increases the power density with smaller volume of passive components and reduced cooling requirements. However, in the phase-leg configuration, high dv/dt will worsen the interference between the two devices during a switching transient (i.e., crosstalk). Unfortunately, SiC power devices are more easily affected by crosstalk than Si devices due to their intrinsic properties. To utilize the full potential of fast SiC devices, a novel and cost-effective gate assist circuit for crosstalk supression is proposed in this paper. Besides, with the increase of power density, the thermal design is increasingly becoming the key factor that affects the reliability of converters. Thus, the thermal model of the phase-shift full-bridge converter (PSFBC) is established. The simulation and experimental results are in good agreement, which testifies the accuracy of thermal model. The efficiency of 2kW PSFBC based on Si and SiC MOSFETs under different loads is also measured and compared in this paper.

Comparisons of SiC and Si devices for PMSM drives

Compared to Si IGBT, SiC MOSFET are characterized by faster switching speed and higher operating junction temperature. Potential advantages including significantly lower switching loss, lower dead time and higher switching frequency are achieved by SiC devices. For the 1kW PMSM drive prototype specification, the power losses of Si IGBTs and SiC MOSFETs are compared. Dead-time effect is analyzed and the simulation results are given. 1kW PMSM drive prototypes based on Si and SiC power devices are fabricated respectively, and experimental results including power loss, efficiency, temperature rise and dead time effect under low speed are given, which verify that the PMSM drive based on SiC MOSFET achieves higher efficiency, higher power density and better dynamic performance.