Feature: Electric Vehicles


Figure 1. Simplified description of the multicell battery monitor


consists of three basic devices, differentiated by the number of cells that each monitor: Te ADBMS6816 monitors six battery cells, the ADBMS6817 monitors eight battery cells in series and the ADBMS6815 monitors 12 battery cells in series. Te three different cell monitor counts can address different cell configurations for a wide range of battery pack configurations. Furthermore, these parts can be combined in a mix and match


fashion to create an ideal quantity of cell monitor channels. Because the operating environment includes extreme electrical noise, they also include adjustable low-pass filtering that reduces this noise, ensuring high fidelity measurements.


ADI BMS communication technology Te ADBMS6815 family of cell monitors are designed for daisy-chain interconnection using a 2-wire communication interface called isoSPI. Tis is a robust, EMI-insensitive and electrically isolated network that allows ADI’s BMS devices to be operated, polled and controlled synchronously from the BMS microcontroller. Tis enables all cells in the pack to be measured synchronously with pack current and pack voltage using an ADI pack monitor device. Tis daisy chain can be operated with one path to each device, or with dual paths in a loop configuration. Te loop allows for access to all of the cell monitor data in the event that a wire or connector fails. Te ADBMS6815 family also supports operation in a wireless BMS (wBMS), where the wired daisy chain is replaced with a 2.4GHz wireless BMS node at the cell monitors.


Safety Among all the goals of a BMS, ensuring that the battery pack is safe is the most important. Recognising and remedying potential failures within an IC requires built-in self-test capability and redundancy. Tese functions include redundant measurement paths, improved synchronisation between input signals, self-test


14 March 2025 www.electronicsworld.co.uk


capability and many more. Te ADBMS6815 family of parts has been designed to support the ISO 26262 ASIL-D standard. ISO 26262 is a universally adopted automotive functional


safety standard, designed to ensure safety throughout the lifecycle of automotive electrical equipment and systems. ASIL-D is a risk classification within this ISO standard that represents the highest level of automotive safety in a system. ADI’s components are designed and certified to support ASIL-D to ensure that automotive manufacturers using ADI’s components can achieve this critical milestone. Furthermore, by meeting the ISO 26262 standard, designers can


generally address other functional safety standards such as IEC 61508 to meet the standards for nonautomotive applications, as well.


Low power cell monitoring In addition to ensuring a stable, predictable and reliable source of energy to power the vehicle, the BMS must ensure that the cells themselves are always safe. While it is a rare occurrence, a battery cell defect can cause a cell to short over time and lead to thermal runaway with catastrophic results. For this reason, the BMS monitors for conditions that could indicate any potential problem. Battery cells are not inert just because they are not in use.


As electrochemical devices, they change over time even when at rest. In other words, the progression of a failing cell can continue even while a vehicle is not operated. To provide continuous monitoring of the cells within a battery pack, even while a vehicle is in a key-off state, ADI has developed low power cell monitoring (LPCM). LPCM is an advanced cell monitoring feature that periodically and autonomously checks key parameters of the battery cells. With the LPCM feature, the cell monitors alert the BMS to wake up and run appropriate checks if they detect any potential concerns. The BMS is also alerted if the cell monitors fail to provide a periodic positive confirmation.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50