A Swiss researcher has developed a way of integrating power electronics with electric motors that could cut the costs of hybrid electric vehicles and other drive applications. Hanna Plesko, a doctoral student at ETH Zurich’s Power Electronic Systems Laboratory, has combined several electronic and electromagnetic functions to produce a compact drive which should be cheaper to manufacture than existing hybrid drives.

Hybrid drives are costly to produce, largely because of their complex combination of electric motors and energy management systems, based on inverters and DC/DC converters. In Plesko’s system, the power electronics and the motor perform several functions simultaneously.

In most conventional hybrid vehicles, a 200–500V battery DC voltage has to be converted to a three-phase AC voltage for the motor. A 12V DC supply is also needed to power items such as ventilation and lighting. Inverters convert the DC to AC, while DC/DC converters transfer the power between batteries for the two voltage levels.

These converters are conventionally located outside the motor. Plesko’s idea is to integrate the inverter, DC/DC converter and motor functionally, allowing some electronic components and the motor lamination stack to be shared. She has built a 3kW prototype (above). A 50kW system would have been more realistic, but she is convinced that her ideas will scale up.

Two patents have been applied for the technology. ETH Zurich has had initial talks with a “big car company” about collaborating on the technology. Plesko believes that it could also have applications outside the automotive sector in areas such as industrial automation, robotics and aircraft, where it could be used to actuate flight control surfaces and for onboard electrical energy management.