The partnership introduces a cascaded H-bridge AC-DC converter that eliminates bulky transformers and simplifies power conversion.
The Indian Institute of Science (IISc), in partnership with Delta Electronics India, develops a new power converter prototype for fast charging EV. The research is published in IEEE Transactions on Industrial Electronics.
The research team has come up with a cascaded H-bridge (CHB) multiport DC converter solution, that connects directly to the Medium-Voltage AC (MVAC) grid.
Current high-power EV chargers use bulky line frequency transformers (LFTs), requiring large quantities of copper and iron also relying on multiple conversion stages to step voltage up or down or switching between alternating and direct current.
These processes raise costs and lower efficiency, particularly when charging demands cross 1 MW, which can power about 1,000 homes. This 1MW scale can serve buses or multiple vehicles at once in a short time.
“Our invention simplifies the process and offers a 3-5% improvement in energy efficiency. At a megawatt scale, this translates to lower energy use, lower cost, and smaller material footprint.” Kaushik Basu, associate professor in electrical engineering at IISc.
The converter enables bidirectional charging, allowing stations to both draw from and feed power back into the grid. Local battery storage will smoothen sudden voltage spikes and provide backup in case of grid failures.
According to first author Harisyam PV, the system is also more compact than transformer-based solutions and can integrate with renewable sources such as solar.
A 1.2 kW prototype has been tested with efficiency above 95%. IISc and Delta planning to scale the system to megawatt levels. A new 2,500-square-foot laboratory at IISc, funded by the Department of Science and Technology, will demonstrate charging a 200 kW bus and a 50 kW car directly from an 11 kV grid line.
