NIT Rourkela develops hybrid energy system to extend EV battery life

The patented system combines an EV battery with a supercapacitor to handle sudden power demand, reduce battery stress and improve operating life in low-voltage vehicles

Researchers at the National Institute of Technology (NIT) Rourkela have developed a hybrid energy storage system that will improve the efficiency and extend the lifespan of batteries used in electric vehicles (EVs).

 

The technology combines a conventional EV battery with a supercapacitor in an architecture designed to protect the battery from sudden surges in power demand while making more efficient use of the supercapacitor.

 

Battery packs used in EVs can face significant stress during sudden acceleration, rapid deceleration, regenerative braking and frequent start-stop operations. Such high-rate current fluctuations can increase thermal stress and accelerate degradation of battery cells, potentially affecting both performance and service life.

  

With the new hybrid system, the researchers have addressed this limitation by pairing the battery with a supercapacitor, which can charge and discharge within seconds and deliver substantially higher specific power than conventional batteries.

 

Monalisa Pattnaik, associate professor in the Department of Electrical Engineering, said unlike batteries, which store energy through electrochemical reactions, supercapacitors store charge electrostatically at the electrode-electrolyte interface. They can also withstand more than a million charge-discharge cycles with relatively little degradation. 

 

"In a hybrid energy storage system, the supercapacitor can absorb or supply short-duration bursts of power during events such as acceleration, deceleration and regenerative braking. This reduces the high-current burden on the battery and can potentially improve its operating life," she said.

 

According to the researchers, conventional hybrid energy storage systems generally use passive, semi-active or active configurations. In a passive configuration, the battery and supercapacitor are connected directly, limiting the ability of the supercapacitor to respond optimally to changing power requirements.

 

Active configurations provide greater control by using separate electronic converters for the battery and supercapacitor, but this increases the number of components, switches and control systems, adding to system complexity and potentially affecting efficiency.

 

The new system strikes a balance between these two approaches by reducing the number of components while retaining effective control over the flow of energy between the battery, supercapacitor and vehicle electrical system.

 

“Our hybrid system contains three main components, one converter to connect both battery and supercapacitor to the vehicle’s electrical system, an inductor that is placed in the electrical path, and a single control system to handle the power flow,” Pattnaik said.

 

The researchers have tested the system under demanding operating conditions, including sudden braking as well as rapid acceleration and deceleration. The system maintained a stable 48-volt output, enabled smoother changes in battery current and allowed the supercapacitor to respond effectively to sudden changes in power demand.

 

The technology has been designed primarily for low-voltage electric vehicles operating in the 24-60 volt DC range. This makes it relevant for electric scooters, motorcycles, e-rickshaws, cargo tricycles and campus and industrial utility vehicles, where frequent changes in speed and operating conditions can place considerable stress on battery systems.

 

“Our design is highly optimized for low-voltage EV platforms operating in the 24 V to 60 V DC range,” Pradyumna Kumar Behera, one of the researchers, said, adding that the architecture could also find applications beyond road-going EVs.

 

The development comes as India continues to expand its electric mobility ecosystem. The growing deployment of electric two- and three-wheelers in urban and commercial applications has increased the need for battery technologies that can withstand repeated high-power cycles without significant degradation.

 

While supercapacitor-battery hybrid systems are already an established area of research, the NIT Rourkela team's focus is on simplifying the power electronics architecture while retaining the ability of the supercapacitor to handle transient loads.

 

The researchers believe the reduced component count could help address some of the complexity associated with conventional active hybrid systems. They have secured a patent for the technology.

 

"We are open to collaborations with electric vehicle original equipment manufacturers (OEMs), powertrain system integrators, fleet operators and EV retrofit companies for further development and potential commercialisation of the technology," they added.