Texas Instruments has issued a direct challenge to Analog Devices and Infineon Technologies on the next generation of wireless battery management system (BMS) technology.
Like ADI it sees a wireless BMS as key to the economics of electric vehicles, reducing the weight and complexity of wiring and allowing the battery packs to have a second life in other applications.
TI is using its 16 channel, ASIL-D compliant BQ79616-Q1 battery monitor and balancer coupled with a 2.4GHz SimpleLink CC2662R-Q1 wireless microcontroller (MCU) running a proprietary low latency, high reliability protocol. This protocol uses spread spectrum frequency hopping techniques to minimise interference and time domain modulation (TDM) to provide deterministic operation in a star-of-stars topilogy.
It is this combination that is key says TI.
“One of the unique advantage is that we believe we have the industry’s lowest power consumption, 10x lower, with the combination of frequency hopping and TDM and we can duty cycle the nodes to transmit while still maintaining the synchronous connection,” said Ram Vedantham, business line manager for 2.4 GHz Connectivity, when asked about other systems.
ADI is working with car maker GM and with electric supercar developer Rimac on a 2.4GHz mesh wireless BMS and Infineon also has plans for such a system. All three companies are major suppliers to the automotive industry with experience in the battery systems and safety requirements. Maxim Integrated, which is being acquired by ADI, has also developed a wireless BMS for electric vehicles.
“We have the ability to scale from 8 or 16 cell configurations that is the current use case all the way up to 100 nodes,” he said. “We start at the physical level with a robust and high throughput and then a MAC using a frequency hopping and adding the TDM and interframe spacing is close to zero so we can go pretty high in the [data] payload.”
Next: ASIL-D wireless BMS
“We also have security built into every stage with an AES128 accelerator, message integrity check, key authentication and key refreshment,” said Vedantham.
The wireless BMS opens up the possibility of putting batteries in other places in the vehicle he says. “This gives more flexible designs, in the hood, into other parts of the vehicle, and we are very well positioned there,” he said.
The system has been evaluated by TUV SUD to be suitable for an ASIL-D safety design. “This is designed from scratch for automotive safety from the ground up with IS26262 up to ASIL-D with a quality managed radio IC,” said Karl-Heinz Steinmetz, general manager for Powertrain in Automotive Systems at TI. “TUV SUD assessed the error detection and the common factor to achieve an ASIL-D system including the failure mode diagnostic analysis. ASIL-D is the one additional thing to complete the system with the confidence level with the assessment from TUV SUD. We are able to support customers with a full system not just pieces of the system.”
The ASIL-D capability comes from the fault management approach.
“Even in the case of a failure there is a bus restart of a max 300ms the full system is back and running again and that allows the car maker to build up a system that has the latest information in real time even in the case of a restart,” said Ivo Marocco, director of business development and functional safety for Battery Automotive products.
The wireless BMS also cuts the cost of the wiring, capacitors and opto-isolation used in traditional systems.
The CC2662R-Q1 wireless MCU is priced at US$2.79 in 1,000-unit quantities while the 16-channel BQ79616-Q1 comes in a 10-mm-by-10-mm, 64-pin thermally enhanced thin quad flat package (HTQFP), and is priced at US$6.90 in 1,000-unit quantities.
The SimpleLink wireless BMS software development kit (SDK) is available with a SimpleLink wireless BMS evaluation module (CC2662RQ1-EVM-WBMS).
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