Reimagining EV Charging at Megawatt Scale
As electric vehicle adoption accelerates, fast charging stations are pushing beyond 1 MW of power delivery. That level of output is comparable to powering hundreds of homes and demands high efficiency, compact hardware, and robust grid integration. A team from the Indian Institute of Science (IISc) in Bengaluru, in collaboration with Delta Electronics India, has broken new ground with a cascaded H-bridge (CHB) multiport DC converter that connects directly to a medium-voltage grid. This approach eliminates the need for bulky, copper- and iron-heavy line-frequency transformers (LFTs) and the cascade of conventional AC–DC stages that typically accompany mega-scale charging.
How the CHB Innovation Works
Traditional high-power EV chargers rely on stepping 11 kV or higher grid voltages down through transformers, followed by several power-conversion stages to reach the car’s battery. This architecture introduces energy losses, material overhead, and a large physical footprint. The IISc-Delta solution is a solid-state alternative: a CHB-based multiport DC converter that taps directly into the medium-voltage grid, operating at higher frequencies to stay compact while delivering several isolated output ports for parallel charging of multiple vehicles.
Prof. Kaushik Basu of IISc explains that this approach addresses two core bottlenecks of fast charging: transformer size and conversion losses. By removing the bulky transformers and employing high-frequency power electronics, the system becomes lighter, cheaper in material costs, and better suited for scalable charging networks. The design enables charging multiple EVs concurrently and offers potential for direct energy exchange with the grid (bidirectional flow), which can support demand response or backup power for critical facilities like hospitals.
Prototype Progress and Efficiency Milestones
In a first milestone, the IISc team built a 1.2 kW lab prototype achieving DC charging efficiency above 95%. While the goal is megawatt-scale operation, this proof-of-concept demonstrates the viability of a direct 11 kV-to-DC conversion with multiple, independent output ports. The researchers are optimistic about scaling challenges and view the prototype as the first step toward a high-power, multiport system.
“The concept is essentially a solid-state transformer,” notes Prof. Basu. “Transformers at high voltage are efficient, but adding high-frequency power electronics can increase the number of semiconductor devices and introduce new losses. Our results show it is possible to meet or even beat the losses of traditional systems, and we can significantly cut copper and iron use in the process.”
From Lab to Field: Testing, Partnerships, and Policy Alignment
To translate this concept into a practical megawatt facility, IISc has launched a dedicated lab project with funding from the Department of Science and Technology (DST) and a collaboration with Delta Electronics. The planned facility, spanning around 2,500–3,000 square feet, will host a 250–500 kW (half-megawatt) system and car-emulator tests. The aim is to demonstrate a megawatt-level converter capable of charging a 200 kW bus and a 50 kW car directly from an 11 kV grid line, signaling a path to commercial pilots within a year of field trials.
Beyond EV charging, officials suggest the technology could power data centers, wind energy systems, and railway traction, delivering high-efficiency conversion directly at medium voltages. The system’s potential for integrating renewables—such as solar—and for reducing the need for transformer rooms aligns with India’s broader EV and infrastructure goals. The developers have filed multiple patents and anticipate licensing opportunities, with international extensions under consideration.
What This Means for the Future of EV Infrastructure
Experts anticipate that, within the next 5–10 years, ultra-fast charging could reach under-10-minute fill times as power electronics become more widespread and efficient. Direct high-voltage-to-low-voltage DC conversion inside buildings or charging hubs could dramatically reduce energy losses, footprint, and operational costs while enabling robust, renewables-friendly charging networks. As Prof. Basu remarks, the ultimate payoff is a resilient, low-carbon energy system that uses indigenous innovations to scale rapidly.
Looking Ahead
The IISc-Delta collaboration marks a significant step toward compact, transformer-free megawatt charging. If scaling hurdles are met, field deployments could redefine fast charging, decarbonize critical infrastructure, and set a new standard for high-power, multiport EV charging using medium-voltage grids.
