Analog Devices’ inspiration for the development of the wBMS technology was an analysis of the drawbacks of the communications wiring in conventional EV battery packs. This analysis drew on the company’s expertise: it supplies the market’s most accurate conventional BMS, and in the wireless communications field it is a leader in 5G radio technology. It also developed the world’s most robust mesh networking technology for industrial environments.
In a conventional EV battery, wiring supports communication between each cell in the battery pack and an electronic control unit (ECU), which regulates its operation to ensure that it provides power to the vehicle.
This requirement for communications inside the battery reflects the complex architecture of a large battery pack: it is made up of modules, each of which contains multiple cells. Natural production variations mean that each cell has individual characteristics that vary within a specified tolerance range. To maximize battery capacity, lifetime, and performance, the key parameters of battery operation—voltage, charge/discharge current, and temperature—need to be monitored and logged individually for each module. This is the job of the cell monitoring units in the BMS.
But the data from each cell only become useful when they reach the BMS’s ECU, which controls the way power is supplied to and drawn from the battery, module by module, and maintains the battery’s safety functions.
And this is why an EV’s battery requires a means to transfer data from each module—where voltage, current, and temperature are measured—to the ECU’s processor
(see Figure 1). Traditionally these connections have been made with wires: wired connections have the advantage of being familiar and well understood.