NSF Award Powers New Technology for Electric Vehicles
Yue Zhao, assistant professor of electrical engineering, has received a $500,000 grant from the National Science Foundation’s Faculty Early Career Program to support his research on silicon carbide motor drives.
Silicon carbide devices can be used to make high-power motor drives to power electric and hybrid electric vehicles, and “more electric” aircraft and ships. Developing vehicles that use electric power along with, or instead of, fossil fuels is an important step in increasing the sustainability of the transportation industry, Zhao explained.
Motor drives convert DC power from a vehicle’s battery into the AC power that runs the traction motor. In order to do this, the power electronic devices in the motor drive need to be switched on and off quickly to create an alternating current. The power electronic devices in existing motor drives, which are made of silicon, normally have a switching frequency of less than 10 kilohertz. The silicon carbide motor drive that Zhao is working on could achieve a switching frequency between five and 10 times faster.
In addition to this higher switching frequency, silicon carbide also enables a higher power density. For example, silicon carbide motor drives that are only 20 percent the size of their silicon counterparts can deliver the same amount of electric power. Silicon carbide devices can also withstand higher temperatures.
Zhao explained that the high switching frequency and power density of these drive systems also presents challenges. The fast switching of power electronic devices creates a lot of heat in a confined space, and it generates electromagnetic interference, which can compromise the performance of the vehicle. His research will address these challenges through a new approach to controlling the motor drive, which he calls a dual-core control framework.
In Zhao’s framework, the performance of both the motor and the drive system will be monitored and a control algorithm will continuously optimize the switching sequence, making the system more efficient than traditional motor drives. This approach will minimize the amount of heat and electromagnetic interference that is produced by the drive system.
Zhao explained that there is a lack of facilities capable of testing this kind of technology at the power level necessary to run an airplane or a ship. His NSF award will also support an effort to build on the capabilities of the U of A’s National Center for Reliable Electric Power Transmission, a six megawatt power electronics testing facility. Zhao will develop a unique testbed at the center in order to test his designs and increase the U of A’s capability for future research in this area. Zhao will also integrate graduate and undergraduate research and K-12 outreach and education efforts, to provide learning opportunities for students interested in power electronics.