An evolution is occurring on the highways that crisscross the globe – a transformation from century-old fossil fuel burning automobiles to clean, efficient electric vehicles (EV). With 10× growth projected in the EV market during the next decade, there is an increasing need to monitor, manage, and maintain high performance batteries to power millions of electric vehicles.
Today’s battery market continues to be driven not by cost alone but the demand for longer range vehicles, decreased charge times, and functional safety. These exacting battery management system requirements necessitate the adherence to the highest of standards with the narrowest of tolerances.
With up to 40% of the sticker price of an electric vehicle attributed to the battery, performance and battery life become major factors in an EV’s brand success. As a leader in battery management systems (BMS), Analog Devices, Inc. (ADI) collaborates with customers to find the best critical processes to monitor and manage electrical vehicle batteries and ensure their safety, productivity, and longevity.
At a Glance
Through ADI’s acquisition of Linear Technology, ADI’s portfolio includes the first integrated high voltage battery stack monitor, created in 2008. Since then, our focus has been on delivering the highest performance solution. Today, we are working on our 5th generation products.
Battery monitoring and management.
OEMs are acutely focused on battery safety, cost, efficiency, and lifetime.
The growth of EV market is increasing demands on battery manufacturers, supply chains, and automobile brands to deliver quality, reliable battery technology to keep up with the demand.
Improve the BMS to ensure safety, improve reliability, enhance performance, and increase the longevity of the EV battery.
Invest in a Better Battery Management System
The BMS closely monitors, controls, and distributes the reliable charge and discharge of the entire battery system during its lifetime. Accurate monitoring of current and voltage profiles is critical, as overcharging a battery can cause a fire or explosion, and undercharging (or a full discharge) renders a battery useless. The quality of the battery management system directly impacts the miles per charge an EV can deliver, maximizes the batteries overall lifetime, and, as a result, lowers the cost of ownership.
In this situation, price point becomes less important, and long-term value becomes the key metric. That is because you are trying to squeeze out better performance over the lifetime of a battery. “When it comes to accuracy, and accuracy over the vehicle lifetime, there are no trade-offs,” said Mike Kultgen, general manager of BMS, ADI. “The better the accuracy, the better you can understand the state of the battery cell, the more capacity you can extract out of it, the more reliable the battery pack will operate.” Considering the investment for the battery pack, the value of BMS performance is clear, and it becomes even more obvious as automotive designers consider warranty and lifetime pack costs1.
Battery Management's Stringent Requirements
Batteries put pressure on design teams, as they need to consider a range of priorities, including price, reliability, and safety. When handling EV systems delivering between 48 to 800 volts, you can’t risk anything.
A battery system expected to deliver more than a hundred kilowatts of energy with the push of a pedal must operate at hundreds of volts to be efficient. However, lithium battery cells supply only a few volts. To extract enough power, a large number of battery cells are connected together in series as one long stack. A typical electrical vehicle may employ 100 individual battery cells, delivering 350 volts at the top of the stack. And that presents some challenges.
If one cell dies in your long stack of battery cells, you effectively lose all of them. So, you need to monitor and manage ALL OF THEM—charging them, discharging them—every day for the life of the vehicle. Lithium battery cells cannot be operated to the full extent of their charge and discharge range. They must be kept in a very specific range, such as 15% to 85%, or the cells are weakened.
Monitoring and Managing the Power Source
ADI’s BMS provides accurate cell measurements from the time the pack is manufactured to its retirement. Electronics are attached directly to each cell in the stack, reporting back voltage and temperature, coordinated with cell current. The system figures out the state of charge and state of health. The current and temperature of every cell must be monitored through a complex algorithm at the central processor. ADI builds in a robust communication interface while allowing for a modular design (architecture). It is fully extensible for our varied customer base.
“The BMS is constantly monitoring the cells, delivering reliable measurement accuracy over time, temperature, and operating conditions. It knows what is going on every single moment and relies 100% on the information it receives from ADI chips.”
General Manager of BMS, ADI
Key Values: Accuracy, Reliability, and Stability
The benefits of working closely with ADI’s battery management system experts go beyond having access to a broad portfolio of components and products. They offer OEMs access to our system-level expertise, deep domain knowledge, and years of practical BMS design experience. OEMs can obtain high efficiencies in miles per charge, extend battery lifetimes, ensure safety, and increase brand confidence.
Patrick Morgan, vice president of AUTG, ADI said, “Customers tell us they need confidence when using our products. So, we stage a technical summit at their site or our factory and bring in our key designers and application engineers to meet their team. We spend a day or two going through our roadmap, issues they need to solve, and then discuss how we would approach their specific problem. We build trust by focusing on collaboration.”
Fixing Problems, Finding Solutions
“A client based in Asia asked us to design a new battery management system around an old one,” said Cuyler Latorraca, applications manager, ADI. “We looked at their assumptions, system requirements, and operating environment. We discovered that they were introducing a systematic measurement error through their grounding scheme, a common problem in the industry, and took steps to eliminate this error.”
The Rimac C_Two high-performance hypercar boasts 1,914 horsepower, accelerates 0-60 in 1.85 seconds, and top speed of 258 mph. A showcase of Rimac’s technological abilities, the all-electric hypercar features a battery pack of 6960 lithium manganese nickel cells and represents what is possible when true innovation and passion are allowed free rein.
ADI’s High Performance BMS Powering Hypercars
Founded in a garage in Croatia by a 21-year-old inventor less than 10 years ago, Rimac Automobili grew into a 600 employee technology powerhouse. Today, Rimac designs, develops and manufactures electric hypercars and high-performance electrification systems for global automotive companies.
ADI’s precision BMS integrated circuits (ICs) enable Rimac’s EVs to extract maximum energy and capacity out of its batteries by delivering highly accurate battery cell measurement. Sophisticated diagnostics enable the system to monitor cell characteristics, voltage, and temperature and to determine charge state at any given time. “Precision accuracy directly translates to maximizing battery capacity and range with fast charging time,” said Patrick Morgan, Vice President. Automotive Electrification and Infotainment, Analog Devices.
“Rimac is a technology powerhouse in the field of high-performance electric vehicles. We develop and manufacture key electrification systems for many global automotive companies and raise the bar for performance EVs with our own hypercars,” said Rimac’s CEO Mate Rimac. “Our application of battery management systems are among the most demanding in the world, requiring the highest accuracy, massive current and voltage draws over very short time scales, and rapid dynamic adjustment within the battery management control system. We have decided to adopt the Analog Devices portfolio of battery management ICs across our complete product line. We have benchmarked these ICs in the market and selected Analog Devices for superior precision measurement accuracy and product robustness over the lifetime of the vehicle.”
With an Eye Toward the Future
“High voltage battery system technology is ever-changing,” said Greg Zimmer, Marketing Manager for BMS, ADI. “We see a lot of pressure on increasing capacity and longevity. How is the industry going to achieve this? How will we get more energy out of the battery pack while making a battery last for 10 years, increase its range, support faster charging, and develop centralized and modular designs?
ADI is not only focused on our customers’ problems today but on a process of continuous improvement with an eye on tomorrow. We will continue to lead the industry with solutions that maximize range per charge, reduce total weight, and reduce total battery system cost. Our depth of system-level experience and our large family of components (3 to 18 cells with one IC supports more cell count options than any other competitor) separates us from the competition.
We’ve Not Hit a BMS Crescendo
Working with OEMs, ADI’s architectural innovations will improve the way power density, accuracy, and weight challenges are solved and communicated in the future. We continue to innovate, and our 5th generation BMS is on track for vehicle production next year.
BMS: The ADI Advantage
ADI has taken the lead in battery management systems, meeting the growing demand for safe, high quality, high performance batteries for the EV market. Customers can now leverage a partner with deep system-level experience and the largest offering of components.
- Superior industry-leading accuracy and stability
- Full ASIL D support with a single component and streamlined design
- High speed, EMI robust, electrically isolated, low cost daisy chain with redundancy for fault conditions
- A large installed base of products, with four generations of products in the field
- A family of BMS products to provide system-level solutions
1With the enormous anticipated production of battery packs comes a similarly enormous supply of used packs to be recycled. Worn down does not mean worn out, if the battery cells were well managed over their life. The potential re-use for energy storage beyond the vehicle, also known as second life, has to be considered as part of the total cost of ownership.