Electronics and Semiconductors

Innovations in EV battery management

29 August 2021
Battery management systems are engineered to prevent this fiery EV fate. Source: vladimir kondrachov/Adobe Stock

It is well known that the battery is the most expensive part of an electric vehicle (EV). In fact, the cost of the battery totals from 25% to 40% of the entire cost of a typical EV, representing a major hurdle that still must be crossed in order to bring affordable EVs to the market for even greater adoption by the general public. As battery replacements are obviously expensive, the focus for vehicle manufacturers has turned to trying to prolong the lifespan and charge as much as possible.

While manufacturers have been trialing improving battery performance and loading a higher quantity of batteries into an EV, efforts are also devoted to the improvement of higher quality Battery Management Systems (BMS). This is a device solely purposed with extracting as much energy out of battery packs as possible. They also provide other benefits, including battery safety by preventing damage to prolong battery life and stopping explosions.

A BMS is essentially the brain of the EV's batteries, which manages the charge, discharge and output during the lifespan of the batteries. They also individually monitor each battery cell along with the modules they reside in to optimize performance and prevent damage. The vehicle’s miles-per-charge is also monitored and managed by the BMS over the entire battery lifespan.

A new solution for wireless BMS has been developed, showcasing the very first concept that includes independently assessed functional safety. This is made possible by an extremely futuristic wireless protocol that features the EV industry’s highest quality network availability. This solution will allow EV designers to reduce the use of expensive, heavy and frequently maintained cables and increase the efficiency and reliability of EVs all over the world.

Reducing vehicle weight, simplifying their designs and improving reliability are all made possible by this new wireless BMS solution. These changes can result in an extended range for driving, faster production and greater flexibility in design. Texas Instruments is providing an all-encompassing solution that includes software, a wireless 2.4GHz SimpleLink CC2662R-Q1 microcontroller (MCU) evaluation module, and some safety enablers like failure mode and effects diagnostic analysis (FMEDA), failure mode and effects analysis (FMEA), functional safety manual, TÜV SÜD concept report and more. Here, the motto is “more miles, fewer wires!”

The adoption of the wireless BMS will become more and more common in the EV industry, as these upgrades give more flexibility in design with lower cost and complexity when compared to traditional alternatives. This will eventually become the new benchmark in the industry, assuming that these advantages can become compliant with Automotive Safety Integrity Level (ASIL) D.

Safety testing

In order to decrease vehicle manufacturers' development time, it was requested that TÜV SÜD, the industry’s dominant functional safety authority, analyze and evaluate the qualitative and quantitative performance of error detection. Evaluations also assessed the ability of vehicle manufacturers to satisfy ASIL-D, regarded as the highest tier of International Organization for Standardization (ISO) 26262 certification, using the wireless BMS functional safety concept.

The new wireless system features an upgraded wireless protocol designed specifically for use with the BMS. With this, it satisfies communication security and detection requirements. The bespoke protocol, through the medium of the wireless MCU (CC2662R-Q1), allows for scalable and robust exchanges of data between the new BQ79616-Q1 battery balancer and monitor and the host system’s processor.

The wireless protocol that has been put forward for the BMS gives industry-leading network availability that actually rivals wired connections. It is stated that it has a network restart speed of 300 ms maximum and a network availability of over 99.99%. The wireless MCU also gives protection against data corruption or loss due to the dedicated time slots that allow for low latency and high throughput. Furthermore, it also gives multiple battery cells the chance to send temperature data and voltage to the main MCU with an accuracy of 2 mV, and a network package error of below 10-7. Security enablers will allow vehicle manufacturers to reduce potential security issues, using debug security, key refreshment and exchange, software IP protection, unique device authentication, message integrity checks and Advanced Encryption Standard (AES).

Reliable, scalable technology

Looking forward to the long-term needs of vehicle manufacturers, this new wireless BMS technology is the most scalable of its kind in the industry. It allows for the highest amount of throughput in the market, enabling manufacturers to create battery modules using only one wireless system-on-chip as well as a few battery monitors (BQ79616-Q1) tailored for different versions like the 32, 48 and 60 cell systems. The system is stated to be able to handle up to 100 nodes, all while providing industry low latency rates (under 2 ms per node) and measurements synchronized to time across each node. Daisy chain and isolating components are no longer needed as the wireless MCU (CC2662R-Q1) ensures all individual cell monitoring units are isolated. The battery balancer and monitor (BQ79616-Q1) give various channel options in one type of package, supporting the recycling of existing software and hardware, and giving pin-to-pin compatibility.

What do you think of this new EV battery management technology? Will it be as revolutionary as its potential suggests? Engineering360 would love to hear your thoughts and opinions in the comments below.

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