Electric Machines with Adaptive Surge Impedance Modeling and Hardware Development

Program: ONR BAA Announcement #N00014-22-S-B001 PI: Dr. JiangBiao He In any electric propulsion systems such as shipboard propulsion, higher efficiency, reliability, and power density are the desired features. These features can be enhanced using fast high-voltage semiconductor switches, making the powertrain of propulsion systems more electrical. However, the faster switches operating at higher voltage levels can lead to new technical challenges for designing electric motors in propulsion systems. The high voltage rate creates traveling waves in the cable between the propulsion drive and motor, and thus, generates high-frequency voltage ringing across the stator windings with high-voltage spikes. The voltage stress has negative effects on the motor insulation and ball bearings. Though the effect of high-voltage spikes is a known phenomenon, the trend toward using wide bandgap (WBG) switches, such as Silicon Carbide (SiC) power transistors, in propulsion systems requires novel solutions to mitigate the high-frequency high-voltage stress that might degrade the motor lifetime. The voltage stress on motor insolation can result in incipient faults, a propulsion system''s failure, and extra expenses associated with unexpected maintenance. Targeting at the permanent magnet synchronous machines (PMSM), we propose an adaptive surge impedance solution to enhance motor performance in WBG-based motor drives, which adaptively matches the cable and motor surge impedance. Also, the potential of using such adaptive impedance coil to mitigate the undesired common mode voltage in PMSM motor-drive system will also be investigated in this proposal.