Rohde & Schwartz, ADI Cutting the Cord on EV Battery Management Systems
Rohde & Schwarz uses wireless battery management system technology from Analog Devices to develop an automated test equipment solution for wireless systems in electric vehicles.
Leveraging the latest technologies from Analog Devices, Inc. (ADI), Rohde & Schwarz is seeking to “cut the cord” for electric vehicle (EV) battery management systems (BMS) with automated test equipment (ATE) designed specifically for wireless battery management systems (wBMS).
EV battery pack. Image used courtesy of Adobe Stock
Working with ADI, Rohde & Schwarz has developed a highly compact production testing solution capable of quickly testing wBMS module calibration, receiver and transmitter, and DC testing. The platform is suited to both laboratory and production environments.
Wireless technology eliminates the complex wiring within an EV BMS, simplifying assembly and maintenance while saving space and weight for extended EV ranges.
Wired vs. Wireless Battery Management Systems
The BMS is an essential system with an EV, managing the charge and discharge cycles of the battery pack, monitoring battery health, and ensuring safe operation. Cell data from the battery needs to be relayed to a centralized controller that monitors and coordinates the battery system operation. Connectivity within the BMS has traditionally been through cables, wired connections, and harnesses. But, this wiring can be complex, consume significant amounts of space, and add weight to the vehicle. Wired connections can also degrade over time and become subject to failure.
Traditional wired BMS platform. Image used courtesy of Analog Devices
As an alternative, wBMS eliminates mechanical wiring and replaces it with wireless data communications. ADI’s wBMS can eliminate up to 24 harnesses, 48 connector pairs, and 12 cell monitoring controllers (CMC) in a typical 12-module battery system. Along with reduced weight and more space for battery cells (leading to longer ranges), the simpler architecture of a wBMS also eases assembly requirements and reduces production costs.
Within ADI’s wBMS system, each battery module has a wireless cell monitoring controller (wCMC) unit that communicates with a centralized wireless manager. The wireless manager, in turn, communicates with the vehicle ECU (engine control unit). Wireless protocols within the wBMS are more robust than those used in consumer Bluetooth or Wi-Fi. They run on low-power 2.4 GHz ISM (industrial, scientific, and medical) band radios designed to meet the reliability and communication security requirements of automotive applications.
Wireless BMS platform. Image used courtesy of Analog Devices
Developed through a collaboration with General Motors, ADI’s wBMS technology is deployed in multiple production EVs, including GM’s Hummer EV.
Wireless Battery Management System Automated Test Platform
The Rohde & Schwarz wBMS ATE platform comprises the company’s CMW100 radio communication tester, WMT wireless automated testing software framework, and the recently released ExpressTSVP universal test and measurement platform. For testing accuracy, the device under test is placed in a shielded box to eliminate external interfering signals.
Wireless BMS production testing. Image used courtesy of Rohde & Schwarz
A key function of the test platform is to simulate the challenging radio frequency (RF) environments in which wBMS needs to operate. To help create these test environments, Rohde & Schwarz, and ADI collaborated on recording real-world RF spectrum (signals) that could then be re-played in the test platform.
Subsequent testing demonstrated both the capabilities of the Rohde & Schwarz wBMS ATE system and the ability of ADI’s wBMS to communicate battery data accurately and reliably, even in the most challenging RF environments.