When new solutions for wireless battery management systems for electric vehicles (EVs) are created, customers can design EVs that are lighter, go farther on a single charge and meet the highest level of functional safety standards to improve reliability.
Underneath an electric vehicle chassis is packed with as many battery cells as the manufacturer can fit. More cells mean more charge capacity, which means longer distances travelled before needing a recharge, one of the key consumer demands.
Every battery cell must be wired to a monitor, which reports critical information to a controller to maximise battery health and performance. Since the typical EV has nearly 100 cells in a serial connection, that turns out to be several metres and kilograms of heavy-duty copper wire, producing a bulky labyrinth of battery-management cabling that consumes precious space. The mass of all that wire is a drag on driving range, reliability and price.
A new wireless battery management system concept by TI eliminates the need for this heavy, expensive and maintenance-prone wiring, creating new opportunities in EV design. It includes a proprietary wireless connectivity protocol, a set of electronic chips, and is the first to demonstrate support for system-level functional safety compliance.
“It’s like designing with a blank canvas,” said Daniel Torres, an automotive product marketing engineer at TI who focuses on connectivity. “When you don’t have to worry about wires, you can figure out new ways to take advantage of the space, and even mix and match different sizes and types of batteries.”
“More than anything else, it’s the BMS that maximises the performance, reliability and longevity of electric vehicles,” said Ankush Gupta, a product line manager for the company’s battery automotive products. “Carefully managing the charge and other operating characteristics of the batteries wrings more power out of each cell when needed, while ensuring the cells don’t prematurely run low on charge or suffer damage. Also, by eliminating communication wires, the vehicle is lighter and there is more space, freedom and flexibility to design EVs with advanced battery capabilities.”
The power of wireless BMS
Going wireless also addresses a unique vulnerability of electric vehicles: potential failure in the dense wiring and the harness that keeps them in place.
“The wire harness and connectors are mechanical components exposed to vibration, humidity and other problems,” said Mark Ng, a powertrain systems engineer at TI. “They’re much more likely to need servicing than the batteries themselves.”
With a wireless BMS, that vulnerability doesn’t exist, freeing the electric-vehicle industry of one of its biggest repair costs, and making it easier and less costly to access the batteries themselves for servicing.
And the wireless advantages carry beyond a battery’s time in a car.
Ageing EV batteries, once they’ve served their useful life in a vehicle, can also be recycled and redeployed in
“You need to monitor the cell throughout its lifecycle, from the factory floor to the warehouse to the vehicle to storage after removal,” Torres says. “Instead of having to wire it up in each new situation, you can just read the data wirelessly while it sits on the shelf.”
The engineering challenge
Designing the wireless BMS solution that could do the job was an intensely collaborative project bringing together engineers across TI with expertise in battery management, connectivity and automotive systems. The requirements were daunting, noted Ram Vedantham, business line manager for 2,4 GHz connectivity. “Many of the needs were conflicting,” he said. “It took many hours of brainstorming and whiteboarding throughout the entire design process.”
For example, the solution needed high throughput to gather data from nearly 100 cells within milliseconds, with
To address these design challenges, the connectivity team created a reliable proprietary wireless protocol to facilitate communication in an environment where real-time availability of the 2,4 GHz wireless network is critical. The network must be readily available so the system can monitor and manage the battery, and communicate in real-time as soon as the driver starts the EV.
“The idea is that the network connects all of the necessary components with a push of the button, every time the car starts,” Vedantham said. “This is where the reliability and performance of TI’s new proprietary wireless protocol come into play. Our team worked hard to find innovative solutions, seamlessly combining state-of-the-art wireless technology features to ensure the features of the protocol provide optimal performance, power and functionality capable of solving the system requirements.”
The team had to push the limits of wireless connectivity, so they could push the level of performance of the batteries, without sacrificing reliability.
First achievement advantage for functional safety
As validation of the team’s work, the solution was assessed by TÜV-SÜD, a leading functional safety assessor, and became the industry’s first wireless BMS concept to demonstrate support for system-level functional safety compliance up to ASIL D. The concept has also been assessed for, and demonstrates compliance with, SIL 3 in industrial applications.
Ease of implementation
Wireless battery management systems are also easier to implement because they don’t require much wiring or reconfiguring.
“It’s very quick to add a wireless BMS in new and existing car models, and our customers get the space savings right away,” Vedantham said. As a result, automakers are planning to include wireless BMS solutions in cars going into production over the next few years, moving unusually fast to adopt this new technology in their next-generation vehicles.
“Using a new wireless connectivity protocol specifically developed for this use case, our wireless BMS solution truly leads the EV industry in terms of performance and safety,” Vedantham said. “This means car manufacturers are able to bring this technology to the consumer faster than ever before.”
Torres added, “Right now, purchasing an EV may be cost-prohibitive for most people, or they worry about running out of power. A wireless BMS could bring us a step closer to broader adoption of electric vehicles.”
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