Given the energy consumption of consumer appliances; building heating, ventilation and air-conditioning (HVAC) systems; and industrial drives, efforts are underway to establish system efficiency ratings through programs such as the seasonal energy efficiency ratio (SEER), minimum energy performance standards (MEPS), Energy Star and Top Runner.

Variable frequency drives (VFDs) offer the best system efficiency in heating and cooling systems, especially if they have an accurate and very wide range of speed control. VFDs use an inverter to control motor speeds, along with high-frequency pulse-width modulation (PWM) switching to obtain truly variable speed control.

Although these inverters are currently realized using insulated-gate bipolar transistors (IGBTs) and metal-oxide semiconductor field-effect transistors (MOSFETs) as the power switches, the switching frequency and power delivery are limited given high overall losses. With advancements in wide band-gap technology, however, gallium nitride (GaN)-based power switches in motor drives can help increase power density, power delivery and efficiency.