Researchers at the National Institute of Technology Rourkela (NIT Rourkela) have developed a hybrid energy storage system aimed at improving the efficiency and lifespan of batteries used in electric vehicles (EVs).
The technology has been developed by Prof. Monalisa Pattnaik, Associate Professor, Department of Electrical Engineering, along with her research team comprising Dr. Pradyumna Kumar Behera and Karan Gupta.
The NIT Rourkela team has secured a patent for the technology. The researchers are open to collaborations with EV original equipment manufacturers (OEMs), powertrain system integrators, fleet operators and EV retrofit startups.
Addressing battery stress in EVs
The development comes amid the rapid growth of electric mobility in India. EVs rely on battery packs comprising thousands of individual rechargeable cells. However, frequent rapid changes in power demand can expose these batteries to high current spikes and thermal stress, potentially affecting efficiency and battery life.
These challenges are particularly relevant in urban environments, where vehicles frequently undergo start-stop cycles, sudden acceleration and deceleration, and regenerative braking.
To address these limitations, battery packs can be paired with high-power-density supercapacitors to create a hybrid energy storage system (HESS).
Supercapacitors store energy electrostatically at the electrode-electrolyte interface and can charge and discharge within seconds. Their specific power can be significantly higher than that of conventional batteries, while their cycle life can exceed one million charge-discharge cycles with relatively low degradation.
During sudden acceleration, deceleration and regenerative braking, the supercapacitor can absorb or supply transient power, reducing high-rate current stress on the battery.
Simplifying hybrid architecture
Battery and supercapacitor systems are generally configured through passive, semi-active or active connections.
In a passive configuration, the battery and supercapacitor are connected directly, limiting the system’s ability to respond rapidly to changing power requirements.
Active configurations use separate electronic converters to manage the battery and supercapacitor independently. While this provides greater control, it also adds components, increasing system complexity and potentially reducing efficiency.
The NIT Rourkela researchers have developed an alternative hybrid energy storage architecture designed to protect the battery from sudden power surges, make efficient use of supercapacitor energy and reduce the number of components required.
NIT Rourkela, Associate Professor, Department of Electrical Engineering, Prof. Monalisa Pattnaik, said the architecture uses three key components, a converter connecting the battery and supercapacitor to the vehicle’s electrical system, an inductor placed in the electrical path and a single control system to manage power flow.
“The single converter for both battery and supercapacitor reduces the number of switches and control components, thereby reducing complexity. The inductor protects against sudden surges in current, thereby increasing the life of the battery. The single control system handles both speeding up and slowing down of the vehicle, thereby reducing hardware requirements,” Pattnaik said.
Tested under dynamic driving conditions
The researchers tested the hybrid system under conditions involving sudden braking, rapid acceleration and deceleration.
During the tests, the system maintained a stable 48 V voltage, enabled smoother changes in battery current and allowed the supercapacitor to efficiently handle sudden variations in power demand.
The architecture is designed specifically for low-voltage EV platforms operating in the 24 V to 60 V DC range.
NIT Rourkela, Associate Professor, Department of Electrical Engineering, Prof. Monalisa Pattnaik, said the design is optimised for a range of urban and utility electric vehicles.
“Our design is highly optimised for low-voltage EV platforms operating in the 24 V to 60 V DC range. This includes urban light electric vehicles such as electric scooters, electric motorcycles, electric rickshaws, cargo tricycles, and campus and industrial utility vehicles,” Pattnaik said.
Wider applications
Beyond electric vehicles, the hybrid energy storage technology could find applications in automated guided vehicles (AGVs), warehouse carts, DC microgrids and renewable-energy charging stations.
The researchers believe the architecture’s lower component count and ability to manage transient power demands could make it suitable for applications where battery performance, operating efficiency and system simplicity are important.
With the patent secured, the NIT Rourkela team is looking to collaborate with industry players to explore further development, integration and potential commercialisation of the technology.