Battery management technology that helps strengthen the grid

With the growing popularity of electric vehicles (EVs) and the transition to more renewable energy sources, our dependence on fossil fuels that has existed for more than a century is decreasing. Electric companies are increasingly turning to solar panels and wind turbines (rather than natural gas turbines) to generate electricity to charge electric vehicles and power our homes and businesses. These trends bring us one step closer to a sustainable energy future.

These trends also pose huge challenges to the power grid. Different times of the day have different needs, and available solar and wind energy also changes with weather changes. Therefore, batteries become an important part of the electrical grid.

"Battery can fill in the gaps when it's cloudy and the winds are down," said Richard Zhang, a professor at Virginia Tech who teaches power electronics technology courses at the school and has worked in the grid and energy industry for 25 years. Charging during off-peak hours provides power during peak hours, such as charging electric vehicles, thus improving the economics of electricity.”

Making batteries safe, reliable and cost-effective to store and release large amounts of power from the grid is a complex challenge. Texas Instruments' expertise in providing advanced battery management semiconductor solutions can be put to good use.

“Batteries used in the grid are larger and have higher voltages, requiring better thermal management and more sophisticated monitoring,” said Samuel Wong, vice president and general manager of Texas Instruments’ Battery Management Solutions business unit. “To effectively manage these Batteries require an understanding of battery chemistry and the use of high-performance semiconductor devices to safely and fully utilize each battery.”

Richard says the adoption of solar and wind power, as well as electric vehicles, is good news for the planet. The problem is that the grid was not designed to take into account these new types of demands on available energy.

"It's much easier to get people to choose electric vehicles today than it was a few years ago," he said. "Now there's a growing issue of getting the electricity infrastructure to handle electric vehicles and other energy needs."

Samuel believes that the challenge lies in the instability of the grid, in other words, the fluctuations in power generation and consumption. Solar and wind power generation causes changes in energy supply, especially at night, where solar power generation is completely impossible. The charging habits of EV owners can also lead to fluctuations in supply and demand.

“If everyone went home at night and charged their electric cars overnight, the grid might not be able to handle it,” he said.

Samuel Wong (left), vice president of Texas Instruments' Battery Management Solutions business unit, discusses the impact of battery energy storage systems with Virginia Tech's Richard Zhang

Samuel and Richard, like most power experts, agree on the solution to grid instability: energy storage systems (ESS). Energy storage systems, often in the form of batteries, can capture and store excess electricity from the grid when supply is high and demand is low, and then provide power at other times. You might think of the relatively small, lightweight battery cells used in electric vehicles. But for the grid, energy storage systems are made of larger, heavier cells stacked in the shape of train cars. Each battery pack can operate at up to 4 megawatt hours (MWh), enough to power thousands of homes.

Placing energy storage systems at different locations on the grid can optimize its power distribution capabilities, that is, distributing large amounts of power to various communities anytime and anywhere. This could mean placing an energy storage system next to a solar panel farm, where it can absorb excess electricity during the day and then pump it back into the grid at night. Or placing the ESS within a community can more conveniently draw power from local rooftop solar panels and then provide additional power to charge nearby electric vehicles when needed. “Energy storage can serve as a local energy reservoir for a community,” says Samuel.

The core of the energy storage system is a high-voltage battery module, usually a lithium iron phosphate battery. If you charge or discharge too quickly, a lot of heat will be generated. The lifespan of these modules can also be shortened if completely exhausted too often.

Monitoring the temperature and charge of these batteries requires extremely sophisticated semiconductors, such as the BQ79616 industrial battery monitor, Samuel said . That's because even small fluctuations in temperature and voltage can be a sign that the battery needs attention.

"You have to have millivolt accuracy to know how much power is left in the battery," he said.

Texas Instruments’ extensive experience with ultra-precision battery monitors has proven critical in helping the energy storage industry produce systems that provide critical battery management data to the grid. Samuel noted that these results will have a significant impact on the cost-effectiveness of grid energy storage systems.

"If you can only measure the power of a 10MWh energy storage system with 5% accuracy, then you can't safely use more than 9.5MWh," he said. "TI's battery monitor can improve the measurement accuracy to 1%. , so you can use 9.9MWh of electricity.”

In addition to accurate battery monitoring, grid-scale energy storage systems, such as those integrated with solar panel farms, require efficient high-voltage power conversion technology to help reduce power losses in grid transmission and distribution. These systems also rely on sensing and isolation technology to help maintain system safety and stability, which is critical for managing power flow up to 1500V.

For the foreseeable future, innovation in battery energy storage systems will play a key role in transforming and protecting the grid amid changes brought about by solar, wind, and electric vehicle charging.

“It’s really exciting to strengthen the grid through innovation in energy storage,” said Samuel. “Texas Instruments has achieved great results today and will achieve greater success with the construction of smart grids in the future.”

For more online technical support, please visit the TI E2E™ Chinese Support Forum (e2echina.ti.com).