Innovative Hybrid Energy-Storage System Patented by NIT Rourkela Researchers
Breakthrough in Electric Vehicle Battery Technology
New Delhi/Raurkela: Researchers from the National Institute of Technology (NIT) in Rourkela have been granted a patent for a cutting-edge hybrid energy-storage system aimed at enhancing the efficiency and longevity of batteries utilized in electric vehicles, as confirmed by officials.
As one of the largest automobile markets globally, India is witnessing a surge in electric vehicle adoption, driven by dwindling petroleum resources and government initiatives like the National Electric Mobility Mission Plan and the Faster Adoption and Manufacturing of Hybrid and Electric Vehicles in India (FAME) schemes.
Monalisa Pattnaik, an Associate Professor in the Department of Electrical Engineering at NIT-Rourkela, explained that electric vehicles rely on a battery pack, which is a substantial, rechargeable energy-storage system composed of numerous interconnected cells. These battery packs often face challenges such as low power density, limited cycle life, and high thermal stress due to rapid current fluctuations.
These issues are particularly pronounced in urban environments where vehicles frequently start and stop, leading to sudden speed changes that can harm battery cells. To address these challenges, battery packs are commonly paired with high-power-density supercapacitors, forming a hybrid energy-storage system (HESS), according to Pattnaik.
Supercapacitors store energy electrostatically at the interface of electrodes and electrolytes, allowing for rapid charge and discharge cycles, and delivering power levels significantly higher than traditional batteries. They also boast an impressive cycle life, often exceeding one million charge-discharge cycles with minimal degradation. This capability allows supercapacitors to manage sudden demands for power during acceleration, deceleration, and regenerative braking, thus alleviating stress on the battery and extending its lifespan.
Pattnaik noted that battery packs and supercapacitors can be connected in three configurations: passive, semi-active, and active. In a passive setup, the two components are directly linked, which limits the supercapacitor's responsiveness to power demand changes. Active connections involve separate electronic converters for managing the battery and supercapacitor, but this adds complexity and reduces efficiency. To tackle these issues, the NIT-R researchers have created a hybrid energy-storage architecture designed to shield the battery from sudden power surges, optimize supercapacitor energy use, and minimize component count, thereby simplifying the system.
The architecture comprises three key components: a single converter that connects both the battery and supercapacitor to the vehicle's electrical system, an inductor positioned in the electrical pathway, and a unified control system to regulate power flow. Each component serves a distinct purpose. The single converter reduces the number of switches and control elements, simplifying the design. The inductor safeguards against abrupt current surges, enhancing battery longevity. The unified control system manages both acceleration and deceleration, reducing hardware needs, according to Pattnaik.
The researchers have conducted tests on this hybrid system under conditions involving sudden braking, rapid acceleration, and deceleration. The system maintained a stable 48 V voltage, facilitated smooth battery current transitions, and enabled the supercapacitor to efficiently manage sudden power fluctuations. "Our design is highly optimized for low-voltage electric vehicle platforms operating within the 24 V to 60 V DC range, including urban light electric vehicles such as electric scooters, motorcycles, e-rickshaws, cargo tricycles, and utility vehicles for campuses or industries," Pattnaik added.