Technologies enabling intelligence within BMS: the MCU

At its most foundational level, the MCU has two primary roles within the BMS: connect to sensors to receive data and communicate that information back to the vehicle network. These two functions help bring functional safety and important diagnostic information, such as state-of-charge, to the BMS. Trends in MCU advancements today scale higher in both of those two main functions as more advanced sensing and computation and more advanced networking are required. Advanced MCUs, make it possible to send higher quality data from the batteries to the rest of the vehicle, helping provide a more accurate picture of what is happening within the car.

Look at advanced scenarios for MCU operation within the BMS. Computing power is increasing because of the need for complex algorithms to handle the intelligence required to maximize the usefulness of the battery. As the size of the battery increases, the number of individual cells that need measuring also increases. There are higher voltage levels and higher overall power stored within the battery. This all means that there are more signals coming in than ever before, requiring both an increase in MCU package size as well as the number of input/outputs as vehicle architectures transition from domain to zone control.

One approach to meet the requirements of these advanced algorithms and sensing needs is to increase the core computing performance. Traditional MCUs may have been able to operate in a BMS taking simple current and voltage measurements and temperature measurements with 100 MHz on a single core. Now there are multi-core devices running up to 1GHz that can compute and then act within the system. Designers could leverage digital signal processors and field-programmable gate arrays to build compute engines that are able to run at much higher speeds. TI’s Arm® Cortex®-based 32-bit MCUs portfolios include high-performance and power-efficient devices to help meet system needs.

The communication from the battery ECU to the rest of the car is also becoming more complex. Systems may need to perform diagnostics or implement dynamic changes such as predictive functions or toggling between task type depending on battery load. For example, if the car is running at a high speed, the battery will have a full load; thus it would be inefficient to perform tasks such as diagnostics or updating the cells. While the car is charging, however, there is more time and system bandwidth to perform these tasks and communicate back to the vehicle network, either wirelessly or wired over protocols like Ethernet, which provides much higher data rates than what a CAN or CAN-FD BUS could in the past. Depending on the level of modularization within the battery, there could even be communications required within the BMS itself.

The most important criteria for MCUs within the BMS is functional safety capability. Security is also becoming increasingly important, as networking levels continue to increase. MCUs need to support Automotive Safety Integrity Level (ASIL) D and have a built-in hardware security module to help meet the safety and security requirements of the system. Devices such as the AM263P4-Q1 MCU are multi-core and have much higher operating frequencies for computing with advanced peripherals for networking and the quality of the sensing and actuation IP. The MCU also needs to support open and standardized automotive software architectures such as the Automotive Open System Architecture (AUTOSAR) to help improve safety and reduce development time.