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Powerful, Efficient Electric Vehicle Chargers

Arkansas Power Electronics International (APEI)
ARPA-E Award: 
Fayetteville, AR
Project Term: 
09/14/2010 to 03/31/2014
Project Status: 
Technical Categories: 
Image of APEI's technology
Critical Need: 

All electric devices are built to operate with a certain type and amount of electrical energy, but this is often not the same type or amount of electrical energy that comes out of the outlet in your wall. Power converters modify electrical energy from the outlet to a usable current, voltage, and frequency for an electronic device. Power stations also use power converters on a larger scale to modify electrical energy so it can be efficiently transmitted. Today's power converters are inefficient because they are based on decades-old technologies and rely on expensive, bulky, and failure-prone components. Within the next 20 years, 80% of the electricity used in the U.S. will flow through these devices, so there is a critical need to improve their efficiency.

Project Innovation + Advantages: 

Currently, charging the battery of an electric vehicle (EV) is a time-consuming process because chargers can only draw about as much power from the grid as a hair dryer. APEI is developing an EV charger that can draw as much power as a clothes dryer, which would drastically speed up charging time. APEI's charger uses silicon carbide (SiC)-based power transistors. These transistors control the electrical energy flowing through the charger's circuits more effectively and efficiently than traditional transistors made of straight silicon. The SiC-based transistors also require less cooling, enabling APEI to create EV chargers that are 10 times smaller than existing chargers.

Potential Impact: 

If successful, APEI would make it faster and easier to charge EVs, helping to facilitate their widespread use.


Widespread use of EVs would reduce fossil fuel consumption and reliance on foreign sources of fuel.


Increased use of EVs could reduce the number of gas-powered vehicles and their harmful emissions.


Making it cheaper and easier to charge EVs would save consumers time and money.

Innovation Update: 
(As of May 2016) 
APEI, now named Wolfspeed, has developed a Silicon Carbide (SiC)-based power module that converts energy more efficiently than current converters. The SiC module developed by the team is currently being used in their active product line, the HT-4000 series of power modules and an associated evaluation gate driver board. R&D 100 recognized Wolfspeed’s plug-in vehicle technology as one of the top technological breakthrough products released in 2013. This recognition resulted in follow-on funding from the Department of Energy’s Vehicle Technology Office (VTO). The team’s technology significantly reduces the amount of energy lost when charging a battery. By continuing to seek improvement in energy loss and developing more effective power conversion systems, it is possible to drive down the costs associated with clean energy applications, making them more marketable and viable for consumer and industry adoption.
To develop their improved high-performance power module, Wolfspeed incorporated an advanced SiC multichip power module power packaging concept with a tightly integrated, high-temperature gate driver board. The new module was developed by coupling Wolfspeed’s existing SiC transistor (MOSFET) design with packaging technology specifically optimized to maximize the performance of the SiC chip for low inductance, higher temperature capability, and a small gate loop through high-level gate driver integration. The SiC-based charger has been integrated into a Toyota 2010 Hybrid Electric Vehicle platform. The platform demonstrated reductions in system losses by nearly half, increases in operation efficiency by greater than 96%, and significant reductions in the time needed to charge an electric vehicle battery.
For a detailed assessment of the APEI team's project and impact, please click here.

ARPA-E Program Director: 
Dr. Timothy Heidel
Project Contact: 
Dr. Ty McNutt
Cree, Inc.
Oak Ridge National Laboratory
Toyota Motor Engineering & Manufacturing North America
University of Arkansas
Release Date: