Battery Stack Monitor Maximizes Performance of Li-Ion Batteries in Hybrid and Electric Vehicles: Page 3 of 8

April 29, 2020 //By Cosimo Carriero, Analog Devices
Battery Stack Monitor Maximizes Performance of Li-Ion Batteries in Hybrid and Electric Vehicles
Lithium-ion (Li-Ion) batteries offer a high energy density, but to maximize performance, a battery monitoring system (BMS) is mandatory. A state-of-the-art BMS not only allows you to extract the highest quantity of charge from your battery pack, but also lets you manage the charge and discharge cycles in a safer way, which results in an extended life.

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.1 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 due to 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 (IoT) applications, delivers >99.999% 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.

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