IIT Guwahati researchers developed an advanced technique which can boost overall performace of Lithium-ion batteries used in electric vehicles.
The advanced techique brought out by IIT Guwahati researchers can precisely estimate one of the most important battery internal states known as State-of-Charge (SOC).
IIT Guwahati researchers comprised Mr. Gautam Sethia, Research Scholar, Dr. Sisir Kumar Nayak, Associate Professor and Professor Somanath Majhi, Professor.
All of them are associated with the Department of Electronics and Electrical Engineering, IIT Guwahati.
The research findings are recently published in IEEE Transactions on Circuit and System I: Regular Papers, a highly reputed international scientific journal IIT Guwahati research team is currently also working on various other important battery issues such as cell balancing, monitoring state of health, state of power, etc.
SOC reflects the remaining capacity of the battery, i.e., how much more charge can be withdrawn from the battery before it gets fully discharged, say IIT Guwahati researchers.
The knowledge of remaining capacity helps to optimize battery’s capacity utilization, prevent overcharging and undercharging of the battery, increases its lifespan, reduces cost and ensures safety of the battery and its surroundings.
Unfortunately, such a vital parameter cannot be directly measured by any sensor, say the researchers from IIT Guwahati.
‘We can only infer SOC by using the available measured quantities such as battery terminal voltage and current,’ say the researchers from IIT Guwahati.
However, the highly non-linear characteristic of the lithium-ion battery makes it difficult to estimate the SOC accurately.
Hence, a well-developed estimation algorithm is crucial, which can ensure precise, reliable, and cost-effective SOC estimation.
In recent years, lithium ion batteries are widely recognized in various applications due to their low carbon emission, high energy density, low self-discharge rate, and low maintenance cost.
Apart from the various day-today small devices such as cell phones, laptops, etc, they have been also widely used in various other important applications such as electric vehicles, Renewable Energy Sources (RES) integrated smart grids, micro grids and others.
The emission of greenhouse gases in burning fossil fuel in the combustion engine has made the transportation sector the highest contributor in increasing air pollution, say IIT Guwahati researchers.
The greenhouse gases are known to be heat-trapping and thus cause global warming.
The electric vehicles (EVs) are becoming the most suitable alternatives to the conventional fossil fuel-based vehicles.
The battery acts as the prime energy source of electric vehicles.
In RES integrated smart grid, the availability of solar and wind energy is intermittent in nature.
Hence, an energy storage system such as a battery is required to store the energy when available and use it later when needed.
In smart-grid, batteries can be used for the purpose of peak shaving, voltage regulation and frequency regulation by storing or feeding energy.
In micro-grids, intermittent RES are integrated with the battery so that it can store energy in off-peak hours and supply energy in peak hours or during the unavailability of renewable energy, says, the research team from IIT Guwahati.
Speaking about their work, IIT Guwahati research team members said they split their work into two parts.
First was to derive the mathematical model of the lithium-ion battery, which can closely exhibit its dynamic characteristics.
Then, using few advanced system control and mathematical concepts such as sliding mode theory, we have tried to estimate the battery internal states precisely, said researchers of IIT Guwahati.
The proposed technique shows the highly robust characteristics and works accurately even in the presence of various external disturbances such as sensor inaccuracy, temperature variation, etc.
Compared to the existing techniques, the proposed technique not only increases the accuracy but also reduces the computational time, and hence needs a cost-effective microcontroller chip for its implementation, say the researchers from IIT Guwahati.