Going wireless with the next generation of battery management systems (BMS) removes heavy communications cabling from inside EVs to help improve driving range and reliability

Jan 06, 2021
 

When we create new solutions for wireless battery management systems for electric vehicles (EVs), our 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. 

Electric vehicles may boast comfortable interiors and elegant tech, but the chassis underneath is packed with as many battery cells as the manufacturer can fit. More cells mean more charge capacity, which means longer distances traveled before needing a recharge — a key consumer demand.

Every battery cell, however, must be wired to a monitor, which reports critical information to a controller to maximize battery health and performance. Since the typical EV has nearly 100 cells in a serial connection, that turns out to be several feet/meters and pounds/kilos of heavy-duty copper wire producing a bulky labyrinth of battery-management cabling that consumes precious space. The weight of all that wire is a drag on driving range, reliability and price.

Our new wireless battery management system concept -- which includes a proprietary wireless connectivity protocol, a set of electronic chips and is the first to demonstrate support for system-level functional safety compliance -- eliminates the need for this heavy, expensive and maintenance-prone wiring, creating new opportunities in EV design.

“It’s like designing with a blank canvas," said Daniel Torres, an automotive product marketing engineer at our company 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."

The BMS: A critical component behind the scenes

EV owners may not think much about the battery management system in their cars, but it’s actually a critical component, watching over the voltage and temperature in all the cells.
 
“More than anything else, it’s the BMS that maximizes the performance, reliability and longevity of electric vehicles," said Ankush Gupta, a product line manager for our 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.”

Daniel Torres quote

The engineering achievement, Ankush and Daniel say, can directly help reduce the “range anxiety," or fear of running out of power, that has held many consumers back from jumping to energy-thrifty, emission-free EVs.

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 our company. “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. 

Aging EV batteries, once they’ve served their useful life in a vehicle, can also be recycled and redeployed in battery-backup units at data centers, or energy storage attached to solar- or wind-power generating facilities — where wireless capabilities make monitoring easy. 

“You need to monitor the cell throughout its lifecycle, from the factory floor to the warehouse to the vehicle to storage after removal," Daniel said. “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 our company with expertise in battery management, connectivity and automotive systems. The requirements were daunting, noted Ram Vedantham, business line manager for 2.4-GHz connectivity at our company. “Many of the needs were conflicting," he said. “It took many hours of brainstorming and whiteboarding throughout the entire design process all while maintaining a sense of urgency."

For example, the solution needed high throughput to gather data from nearly 100 cells within milliseconds, with two-millivolt accuracy and an error rate of one in 10 million packets, in a harsh, noisy environment. And the chips needed to operate at lower power to avoid draining the batteries while monitoring thermal management in a parked car.

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,” Ram said. “This is where the reliability and performance of our new proprietary wireless protocol come into play. Our team worked hard to find innovative solutions combining state-of-the-art wireless technology features seamlessly 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, Ankush said. 

First achievement advantage for functional safety

As validation of the team’s work, our 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 – which has the highest integrity requirements for road safety and is a key consideration for EV manufacturers. The concept has also been assessed for and demonstrates compliance with SIL 3 in industrial applications. 

“Our customers care that their system is safe and reliable," Mark said, “and our system-level concept is the first to demonstrate support for functional safety compliance up to ASIL D through an independent assessment by a leading functional safety assessor." 

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," Ram 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.

Ankush Gupta quote

For consumers, wireless BMS could potentially mean lower EV costs, along with better range and reliability — for their more environmentally friendly vehicle.   

“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,” Ram said. “This means car manufacturers are able to bring this technology to the consumer faster than ever before.”  

Daniel 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."

Living our passion to create a better world

Helping our customers create wireless battery management systems (BMS) for electric vehicles that weigh less and go farther is one example of how TI innovators are living our company’s passion to create a better world by making electronics more affordable through semiconductors. As each generation of innovation builds upon the last to make technology smaller, more efficient, more reliable and more affordable, new markets open and it becomes possible for semiconductors to go into electronics everywhere. At TI, we think of this as Engineering Progress. It’s what we do and have been doing for decades.