Design, construction and evaluation of a distributed 48 V inverter for a mild hybrid vehicle

This thesis deal with the design, construction and evaluation of a prototype of an integrated inverter intended for integrated modular motor drive in a 48 V mild hybrid vehicle in order to reduce the overall volume of the inverter. The prototype is developed for a crankshaft integrated starter generator. Different semiconductor devices are evaluated theoretically with regards to performance, losses and thermal development. Moreover, different topologies for an integrated inverter are analyzed and PPB-II is selected as the platform to build the prototype of. Two prototypes are built, the first is a single phase half bridge which is used to verify and investigate different circuit designs. The second one is a three phase half bridge inverter which represents one module of eight integrated inverters. This second prototype is designed on a PCB and will have water cooling integrated. How to design and optimized a DC capacitor bank is studied. By implementing ceramic capacitors on the second prototype the size of the DC capacitor bank is reduced. Furthermore, an optimization program is used to present the optimal combination of capacitors with regards to cost, volume and losses. A switching frequency of 100 kHz is achieved.