Purdue ECE researchers improve EV fast charging with smarter, more efficient power control
Researchers from Purdue University’s Elmore Family School of Electrical and Computer Engineering have introduced a new way to control a key power converter used in DC fast chargers, making it more efficient and improving the quality of power it draws from the grid.
The work, recently accepted for publication in IEEE Transactions on Power Electronics, focuses on a device called a single-stage indirect matrix converter. This type of converter takes three-phase AC power from the grid and turns it into high-voltage DC power, which is what electric vehicles need for fast charging.
These converters are attractive because they are compact, provide electrical isolation at higher frequency for safety and improve power density and can support bidirectional power flow, meaning energy can move from the grid to a vehicle and potentially back again. But there has been a drawback.
Traditional modulation and control methods force the converter to follow a fixed voltage switching pattern. At certain points in the AC cycle, that rigid pattern causes short but significant distortions in the current drawn from the grid. Those distortions increase total harmonic distortion (THD), which can require larger filters, add cost, and reduce overall efficiency and power density.
The Purdue team’s solution rethinks that switching process.
“Sometimes the biggest improvements come from making a small adjustment,” said Avinash Dornala, a Purdue ECE doctoral student and lead author of the study. “By changing how the converter switches from one voltage pattern to another, we were able to smooth out the current coming from the grid and reduce the electrical stress inside the system. That means cleaner power and better efficiency without adding extra hardware.”
Instead of forcing the same voltage pattern every time, the new “translation-based modulation” method allows the pattern to alternate naturally within each switching cycle. The idea builds on well-established inverter control techniques and adapts them to this converter structure.
The results are significant. Simulations and hardware testing show that the new method reduces transformer peak current by 10%–21.1% and lowers RMS current by 18%–21%. Lower RMS current means less heat and lower conduction losses — roughly 25%–30% lower in testing — which translates to higher overall efficiency. The team measured efficiency improvements of about 4%–5% compared with conventional methods.
Just as important, grid current distortion was dramatically reduced, with total harmonic distortion improved to about 2.4%–2.8% in testing.
“In fast chargers and other high-power systems, efficiency and power quality really matter,” said Woongkul Lee, assistant professor of electrical and computer engineering and another author of the study. “If you can reduce electrical losses and clean up the current at the same time, you improve performance across the board. This work shows that smarter control strategies can make a meaningful difference.”
While the research centers on DC fast charging, the team notes that the approach could also benefit other high-power systems, including front-end rectifiers and motor drives.
As electric vehicles become more common, improvements like this help ensure that charging infrastructure is not only fast but also cleaner, more efficient and more reliable.