Texas Instruments today announced its new wireless battery management system (BMS) solution for electric vehicles, which includes a battery monitor and balancer and the SimpleLInk 2.4-GHz wireless MCU. In contrast to a traditional wired solution, battery modules in this case communicate battery cell information directly to the BMS MCU. The solution can gather data from nearly a hundred cells in milliseconds, with 2-millivolt accuracy and error rate of 1 in 10 million packets.
There are obvious benefits to eliminating wires in a battery management system, primarily the reduction in complexity and cost. A wireless system must also operate at the same performance levels when it comes to things like accuracy and reliability, of course, as BMS systems are the key to maximizing battery health and performance. Even more dire, the lack of accurate information could cause a battery malfunction.
But going wireless also introduces new concerns, the primary ones the ability to meet functional safety requirements, including communication error detection and cybersecurity, and availability of the 2.4-GHz wireless network.
To that end, TI said in a news release that it asked TUV SUD, the industry’s leading authority on functional safety to “Evaluate the quantitative and qualitative error-detection performance as well as the feasibility of automakers to achieve the Automotive Safety Integrity Level (ASIL) D, the highest level of International Organization for Standardization (ISO) 26262 certification, using TI’s wireless BMS functional safety concept.”
In a press conference this week, Karl-Heinz Steinmetz, General Manager, Powertrain in Automotive Systems at TI, stressed that the security is built into every layer of the solution, including device authentication and secure communications using AES-128 encryption with key refreshment and key management
Regarding network availability, TI’s Ram Vedantham, 2.4 GHz Business Line Manager, Connectivity, said that the solution “Uses a combination of time division and frequency hopping to eliminate any known interference.” He also said that TI developed a reliable proprietary wireless protocol specifically in order to meet the critical demand for real-time availability of the 2.4-GHz wireless network.
System latency has been measured at 2 msec and the TI wireless protocol has a performance of 1.2 MB/s.
TI also said in a written statement that for a 10-node network wireless, its BMS protocol “Can achieve a packet error rate of 10-7 or better, which implies that the data for any node will not be available for 100 ms out of 52.222 hours of wireless BMS operation, which translates to a wireless device uptime of >99.9999%. TI said that since each wireless device is independent, you can infer that the wireless BMS network availability is also >99.999%.”
Customers can get started developing with the solution now, with the free SimpleLink wireless BMS software development kit, and the CC2662RQ1-EVM-WBMS SimpleLink wireless BMS evaluation module for US$999. The CC266R-Q1 wireless MCU is priced at US$2.79 and the BQ79616-Q1 battery monitor and balancer is US$6.90, each in 1,000-unit quantities.
As to what production vehicles the technology might appear on first or when, Steinmetz said that while TI doesn't comment on specific customers, it is currently working with some OEMs and Tier One suppliers. In September 2020, ADI announced that its wireless battery management system would debut on General Motors’ production vehicles powered by Ultium batteries.
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