The transition to electric road transport technologies requires electric traction drive systems to offer improved performances and capabilities, such as fuel efficiency (in terms of MPGe, i.e., miles per gallon of gasoline-equivalent), extended range, and fast-charging options. The enhanced electrification and transformed mobility are translating to a demand for higher power and more efficient electric traction drive systems that lead to better fuel economy for a given battery charge. To accelerate the mass-market adoption of electrified transportation, the U.S. Department of Energy (DOE), in collaboration with the automotive industry, has announced the technical targets for light-duty electric vehicles (EVs) for 2025. This article discusses the electric drive technology trends for passenger electric and hybrid EVs with commercially available solutions in terms of materials, electric machine and inverter designs, maximum speed, component cooling, power density, and performance. The emerging materials and technologies for power electronics and electric motors are presented, identifying the challenges and opportunities for even more aggressive designs to meet the need for next-generation EVs. Some innovative drive and motor designs with the potential to meet the DOE 2025 targets are also discussed.

This paper discusses the advancements in the development of the medium voltage solid state transformer (SST) based on 15 kV SiC MOSFET and JBS diode. Designed for 7.2 kV single phase distribution grid applications, the medium voltage SST converts high voltage AC to low voltage 240/120V ac. The use of ultra-high voltage SiC devices allows the simplification of the power conversion circuit topology. This paper presents the characteristics of the high voltage SiC MOSFET devices as well as the topology innovations to achieve ultra-efficient SST design. Specifically, three different designs are discussed which utilize three-stage, two-stage and single stage power conversion topologies to achieve the AC to AC conversion.

A truly distributed and autonomous control strategy is proposed for the FREEDM System-a power electronics based distribution grid. The proposed control strategy requires no communication between and among all grid assets. By utilizing available local quantities (V, f) as a way to communicate among all connected devices, the strategy contains a novel dual droop control loops between the medium voltage feeder and dispatchable resources such as energy sources, storages. The proposed control is put forward to achieve intelligent power management of the FREEDM system under all modes of operation. This is a pre-requisite to use FREEDM system as a transformative platform for plug-and-play of energy (aka Energy Internet). Simulation results verify the autonomous nature of the proposed control.

In this paper, the operation of a single phase medium voltage Solid State Transformer (SST) is presented. With the new development of high voltage wide band gap semiconductor devices, particularly the SiC MOSFETs and JBS diodes, SSTs that are suitable for distribution grid can be developed with simpler topology and reduced device number. Features such as renewable energy integration, grid voltage restoration, load harmonic mitigation, regenerative power flow can all be implemented at the distribution node deploying SSTs. This paper explains each of these operations, accompanied by test results carried out with a laboratory prototype.