Inductive charging on Utah State University electric bus enables lighter, cheaper batteries while achieving 90 percent power transfer efficiency.

Utah State prototype is the first electric bus developed and designed by a North American entity that can be charged though Wireless Power Transfer (WPT) technology

Date Posted
One such funded project includes the WPT electric bus implementation at Utah State University (USU) and later the University of Utah. A start-up at USU named WAVE (Wireless Advanced Electric Vehicles) Inc. is commercializing Inductive Power Transfer (IPT) technology for electric buses after developing WAVE transit technology within its Electrodynamics Lab.

The WAVE electric bus operates by wirelessly charging its battery from a charging pad located under the road surface. A primary transmitter of 50kW power at 20kHz is embedded in the roadway, and an identical secondary receiver is mounted underneath the bus, allowing wireless power transfer over a large air gap of 6-10 inches.

Unveiled in 2012, the initial WAVE technology bus prototype was a USU campus shuttle, the Aggie Bus, which modified a 22-foot electric eBus to recharge its nickel cadmium battery (NiCd) for 5 minutes every 15 minutes. The Aggie Bus has achieved 90 percent power transfer efficiency for 25 kW at 20 kHz across several inch air gaps during station stops over road-embedded powered coil generating the IPT magnetic field. With FTA TIGGER-3 funding, USU and the Utah Transit Authority (UTA) later implemented the WAVE bus at the University of Utah, where it has been operational since October 2014.

Benefits of WPT technology
  • Higher energy efficiency than conventional wired alternatives.
  • Reduces vehicle cost by allowing for smaller, lighter, and lower capacity batteries.
  • Reduces noise pollution.
  • Has the potential to improve system operational safety, since road-embedded infrastructure has no exposed high voltage cables or power outlets for plug-in hybrid and electric buses.

Review and Evaluation of Wireless Power Transfer (WPT) for Electric Transit Applications

Review and Evaluation of Wireless Power Transfer (WPT) for Electric Transit Applications
Source Publication Date
Dr. Aviva Brecher, Principal Technical Advisor, and Mr. David Arthur PE, Division Chief, Energy Analysis and Sustainability Division, Energy and Environmental Systems Technical Center
U.S. Department of Transportation Federal Transit Administration
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