If you drive a car, use a computer, cook with a microwave oven, talk on any type of telephone, listen to a stereo, or use a cordless drill, you use power electronics. Thanks to power electronics, the electricity that runs the things we use every day is processed, filtered, and delivered with maximum efficiency and minimum size and weight. Inside a vehicle's electronic power steering system, power electronics control motors and help move the steering rack. This translates into improved steering response and lower energy consumption.
In broad terms, power electronics control the flow of electric power via electronic power devices. In vehicles, some of these devices convert direct current (supplied by the battery) to alternating current (required by the motor). Some common applications are electronic ignitions, power semiconductor voltage regulators, audio systems, and electronic motor controllers. Hybrid electric and fuel cell vehicles rely heavily on advanced power electronics, such as electronic motor controllers, to distribute the proper amount and type of power into and out of the appropriate subsystem at the appropriate time. The power electronics determine the exact nature and timing of the current and voltage waveforms to the motor.
Advanced power electronics is a major growth area in the world—that's why NREL takes a lead in conducting research and development in this field. And key to making hybrid electric and fuel cell vehicles practical is the development of low-cost, high-power integrated power electronics devices. In these advanced vehicles the motor controller, DC to DC converters, and inverters condition the electrical signal between the power generation unit (a fuel cell or battery) and the electric motor to provide power to various components. For example, motor controllers that use insulated gate bipolar transistors (IGBTs) regulate the power to the motor. DC to DC converters typically convert high DC voltage to low DC voltage to power the vehicle's auxiliary loads, such as lighting, windshield wipers, and radios. Inverters convert DC power from a fuel cell or battery to AC power for the electric motor. (See diagram below.)
To help commercialize advanced vehicles, NREL, DOE, industry, and other national laboratories are working on the design, development, and demonstration of advanced power electronics components and systems. Specifically, NREL is looking at advanced methods to cool and control the IGBTs and capacitors that are used inside motor controllers. For more information about these projects, visit the Research & Development pages.
The diagram below shows the basic power electronic components of a hydrogen-fueled fuel cell vehicle. Roll your mouse over each component to learn more.