Novel high-power and high current converter technologies offering galvanic insulation and relying on conventional cooling methods are needed for developing aircraft conversion systems. The referred Power Electronics Transformer has become increasingly attractive in the aircraft electrical system and we have presented in this paper a methodology for the design of a high frequency and a high current power electronics transformer addressing specific requirements to comply with insulation safety regulations. At 50 kHz and 170kW operating conditions, GA-based optimization results indicate Litz conductors made of aluminum with a diameter of 0.1mm are enough to reduce eddy currents effects, while the Mn-Zn ferrites material is the best option for the magnetic core reaching an efficiency of 99% and a gravimetric power density of 120kW/kg.

While performances of electrical machines such as 100% available torque at standstill have enabled a direct drive from motor to wheel through a fixed mechanical gear, there is a trend toward developing electrical gearshifts which have recently gained momentum, allowing a reduction of the machine losses. In this paper, we explore the capability of the modular multilevel converter topology to incorporate an ‘electronic gearshift’. With this added functionality, we have proposed a dynamic adjustable topology based on the reconfiguration of the number of series-connected submodules per arm at low frequency operating condition of the motor. Results show an efficiency improvement of 20% for the case study of a power drive for a long-haul heavy duty truck application.

Expansion and contraction of Shockley type stacking faults (SF) due to the glide of basal plane dislocations are reported for the first time in a commercial 4H-SiC MOSFET bare die rated at 100A/1.2kV. Electroluminescence of the laboratory fabricated power MOSFET body diode is measured to detect the bipolar degradation which provides firm evidence of the presence of a 3C- like regions affected by SF. Accelerated bipolar degradation tests were performed on the device and it was found that the on-resistance which is a key indicator of the degradation level, increased by 15.6 % during the first stress while it decreased by 6.9 % in the second stress. Other related SiC material defects were as well detected. The electroluminescence spectra is an excellent tool for monitoring SiC power devices deterioration related to material defects without performing destructive tests such as SEM.

The paper aims to provide details on designing a LCL filter for a LV modular multilevel converter (MMC) with lower number of cells per arm. It is used to interface the main LV distributed grid with different local ac and dc grids in a hybrid ac/dc microgrid. Exploring the filtering capability of the equivalent arm inductance of the MMC seen from the ac grid side, a bi-objective optimization based on the Genetic Algorithm is developed which specifically finds the inductive components parameters that assure lower losses and volume under different design constraints. Results show that smaller LCL components for the MMC can be used to satisfy stringent requirement of standards such as IEEE-519. This has the benefit of reducing the overall footprint of the converter.