LEM has launched a new current sensing unit for battery management in electric vehicles (EVs). The company has put together shunt and open-loop Hall effect technologies in a single part, known as a hybrid supervising unit (HSU), to meet the challenges of small footprint, low cost and highest safety level in EV battery management systems.
“The HSU represents a significant innovation in sensor technology, being the first to combine shunt and Hall effect sensing into a single component. This integration simplifies system architecture, enhances safety and allows for seamless upgrades without altering the mechanical layout. Additionally, it reduces the total bill of materials (BOM) and minimizes cycle time at the customer’s end,” said Jérémie Piro, product manager battery management systems and battery storage at LEM.
The EV’s high-voltage BMS plays three key roles: managing the battery’s state of charge and state of health, keeping the system and end user safe, and performing cell balancing as part of the battery optimization process. For higher safety levels, system engineers typically use two separate devices, a shunt to measure 2,000A and a current sensor fully isolated for measurements to 2,000A.
The company has combined the capabilities and performance of both technologies into a single unit, integrating it into the BDU. The signals from each section, the shunt and the current sensor, are then collected by the BMS.
At the BDU level, the HSU allows minimal footprint, weight and cost (BOM); minimized integration effort for faster time-to-market; and easy system upgrade without affecting the mechanical layout while improving safety. At the BMS level, the HSU enables system developers to reach the ASIL D safety level required for EVs.
The company says that the shunt’s resistance is very low at 25µΩ, and the Hall part is galvanically isolated, with accuracy of 2% at 500A and 5% at 2,000A. Signal communication lines are separated (shunt signal and analog or digital bus for the Hall part), and there is a negative temperature compensation (NTC) signal for shunt temperature compensation.
The current measuring range is up to ±2,000A at 10s for both parts, and there is a wide operating temperature range of -40°C to +125°C.
The HSU is one of the few components that combines two technologies within a standard shunt footprint. Designed as a plug-and-play unit, it enables quick and straightforward mounting.
LEM plans to expand its HSU lineup by introducing new technologies, such as integrating a shunt with a coreless Hall-effect component. The company also hopes to reduce device size and cost while enhancing performance.