• Power Electronics and Electric Machines

    Source: U.S. Department of Energy Vehicle Technologies Program

    Advanced electric drive vehicles (EVs) such as hybrid-electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEV), fuel cell electric vehicles (FCVs), and battery electric vehicles (BEVs) require power electronics and electrical machines (PEEM) to function. Note: In some instances on this site, the term electric vehicles (EVs) may be used which inlcudes both FCVs and BEVs. These devices allow the vehicle to use energy from the battery to assist in the propulsion of the vehicle, either on their own or in combination with an engine.

    Electric Vehicle

    Figure 1 is a simple diagram of an electric system drive, where the inverter (power electronic) takes direct current (DC) electricity from the battery and converts it to alternating current (AC) electricity and sends it to the motor. The electric motor (electric machine) uses the AC current to create torque (mechanical power) to power the wheels for propulsion. To further visualize the way an EV drivetrain works, a video is included under Figure 1.

    Figure 1:

    Hybrid Electric Vehicle

    Figure 2 is a diagram showing the increasing complexity of plug-in hybrid electric vehicles. HEVs use two electrical machines; one as a generator connected to the engine and another as a motor to drive the wheels. Each of these machines are connected to an inverter, and the two inverters run at a higher voltage than the battery. To achieve this high voltage, another power electronics device called a boost converter boosts the battery voltage before sending the DC electricity to the inverters. Key components for hybrid and electric vehicles include motors, inverters/converters, sensors, control systems, and other interface electronics. A video is included to further explain HEVs.

    Figure 2:

    power electronics diagrams
    Power Electronics in Electric and Hybrid Vehicles

    Future of Advanced Technology

    Advanced technology vehicles such as HEVs, PHEVs, fuel cell hybrid electric vehicles (FCHEVs), and BEVs can greatly reduce petroleum consumption. However, modern day PEEM technology is not sufficient to enable market-viable PHEVs, FCHEVs, and BEVs. Programs such as the Department of Energy’s Vehicle Technologies Program aims to develop these technologies by setting strategic goals for PEEM, and undertaking research projects that are carried out through collaboration among government, national laboratories, academia, and industry partners. Achieving the PEEM goals will require the development of new technologies. These new technologies must be compatible with high-volume manufacturing and must ensure high reliability, efficiency, and ruggedness. These technologies must also reduce cost, weight, and volume. Of all these challenges, cost is the greatest. PEEM project partners work together to ensure that technical attributes, vehicle-scale manufacturing, and cost sensitivities are addressed in a timely fashion and that the resulting technologies can be adopted by companies willing and able to supply products to automakers.

    CAAT Seed Funded Projects