Advanced Sensors Ensure Precise SOC Estimation in EVs

The automotive industry is constantly evolving to meet the demands of consumers seeking more efficient and environmentally friendly vehicles. In line with this trend, the new modular SMU family SOC estimation sensors have been introduced to cater to the needs of designers of automotive battery management systems (BMS) who are focused on extending the maximum driving range of electric vehicles. These sensors play a crucial role in continuously monitoring vehicle parameters such as battery performance and safety systems, identifying anomalies, and supporting diagnostics to enhance vehicle efficiency and ensure compliance with regulations.

The design of the high-performance sensor takes into consideration the importance of minimizing component size to reduce the weight of electric vehicles and enable them to travel further on a single charge. The compact SMU measures just 29.1 x 35.5 x 49.9 mm (LxHxW) with a busbar thickness of 2mm to 3mm, making it compatible with a range of busbar dimensions. The integrated busbar not only helps in reducing size and improving accuracy but also enhances the overall design flexibility of the sensor.

Accurate State of Charge (SOC) estimation is key to maximizing the driving range of electric vehicles by precisely determining the remaining battery capacity. This accurate estimation not only optimizes battery life and prevents unexpected power loss but also boosts user confidence and ensures efficient energy management. The SMU sensor, based on Hall effect technology and utilizing the latest LEM9 ASIC, is designed to provide intelligent monitoring at the Battery Disconnect Unit (BDU) level, enabling precise measurement of environmental factors while maintaining sensor accuracy.

The SMU sensors come equipped with various features aimed at optimizing performance, including software algorithms that enhance accuracy by correcting measurement data for distortions caused by mechanical stresses. This results in improved precision of sensor readings, achieving up to 1% accuracy up to 1300 A and less than 1.7% accuracy up to 1500 A, making it ideal for BMS applications requiring a current range of up to +/-1500 A.

Furthermore, the sensors offer digital calibration for end-to-end protection, improved offset/sensitivity calibration, and diagnostic warnings for under- or over-voltage conditions. To ensure malfunction prevention, a dedicated safe state mode is activated in case of issues such as sensitivity and offset drift, temperature measurement errors, or memory errors. The internal microcontroller of the sensor includes an algorithm to correct magnetic offset, eliminating errors caused by residual magnetism and providing more accurate and reliable readings.