Issue link: https://resources.mouser.com/i/1437660
16 ADI | Energy Storage Solutions transceiver, a microprocessor, and an isolator. The primary downside of a CAN bus is the added cost and board space required for these additional elements. Figure 2 shows a possible architecture based on CAN. In this case, all modules are parallel connected. An alternative to a CAN bus interface is ADI's innovative 2-wire isoSPI interface. Integrated into every LTC6811, the isoSPI interface uses a simple transformer and a single twisted pair, as opposed to the four wires required by the CAN bus. The isoSPI interface provides a noise-immune interface (for high RF signals) in which modules can be connected in a daisy-chain over long cable lengths and operated at data rates up to 1Mbps. Figure 3 shows the architecture based on isoSPI and using a CAN module as a gateway. There are pros and cons to the two architectures presented in Figure 2 and Figure 3. CAN modules are standard and can be operated with other CAN subsystems sharing the same bus; the isoSPI interface is proprietary and communication can happen only with devices of the same type. On the other hand, the isoSPI modules do not require an additional transceiver and the MCU to handle the software stack, resulting in a more compact and easy-to-use solution. Both architectures require a wired connection, which has significant disadvantages in a modern BMS, where routing wires to disparate modules can be an intractable problem, while adding significant weight and complexity. Wires are also prone to pick up noise, leading to the requirement for additional filtering. Wireless BMS The wireless BMS is a novel architecture that removes the communication wiring. In a wireless BMS, each module is interconnected via a wireless connection. The biggest advantages of a wireless connection for large multicell battery stacks are: Reduced wiring complexity Less weight Lower cost Improved safety and reliability Wireless communication is a challenge because of the harsh EMI environment, and the RF shielding metal posing as obstacles to signal propagation. ADI's SmartMesh® embedded wireless network, field-proven in Industrial Internet of Things (IIoT) applications, delivers >99.999 percent reliable connectivity in industrial, automotive, and other harsh environments by employing redundancy through path and frequency diversity. In addition to improving reliability by creating multiple points of redundant connectivity, the wireless mesh network expands BMS capability. The SmartMesh wireless network enables flexible placement of battery modules and improves battery SOC and SOH calculations. This is because additional data can be gathered from sensors installed in locations otherwise inhospitable to a wiring harness. SmartMesh also enables time-correlated measurements from each node, allowing for more precise data collection. Figure 4 shows a comparison of wired- and wireless-interconnected battery modules. ADI is demonstrating the industry's first wireless automotive BMS concept car, combining the LTC6811 battery stack monitor with ADI's SmartMesh network technology in a BMW i3. This is a significant breakthrough that has the potential to improve reliability and reduce cost, weight, and wiring complexity for large multicell battery stacks for EV/HEV. 4 3 Parallel independent CAN modules Series modules with CAN gateway Battery monitoring interconnections comparison 2