First-of-its-kind high-voltage battery sensor that combines shunt and Hall effect technologies

LEM has released a new current sensing unit for battery management in EVs. For the first time on the market, it has combined shunt and open-loop Hall effect technologies in a single part, called the Hybrid Supervising Unit (HSU), to meet the challenges of a small footprint, low cost, and the 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 minimises cycle time at the customer's end," said Jérémie Piro, product manager of Battery Management Systems and Battery Storage at LEM.

The EV's high-voltage BMS plays three key roles: it manages the battery's state of charge and state of health, keeps the system and end-user safe, and performs cell balancing as part of the battery optimisation process. For higher safety levels, system engineers commonly use two separate devices: a shunt to measure 2000A and a current sensor, fully isolated for measurements up to 2000A.

Now, the company has combined the capabilities and performance of both technologies into a single unit, incorporating it into the BDU. The signals from each section – the shunt and the current sensor – are then collected by the BMS.

At BDU level, the HSU enables:

• Minimal footprint, weight and cost (BOM).
• Minimised integration effort for faster time to market
• Easy system upgrade without impacting 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 easily.

The shunt's resistance is very low at 25µΩ, and the Hall part is galvanically isolated, with an accuracy of 2% at 500A and 5% at 2000A. Signal communication lines are separated (a shunt signal and an analogue or digital bus for the Hall part), and there is an NTC (Negative Temperature Compensation) signal for shunt temperature compensation.

The current measuring range is up to ±2000A at 10s for both parts, as is the wide operating temperature range of −40C to +125C.

The HSU is the only component on the market that combines two technologies into a standard shunt footprint. It is a plug-and-play unit, allowing easy mounting. The company initially offers the HSU00 part, with HSU01 to follow in June. The two are suited to the most common BDU busbar sizes: 84mm x 36mm x 3mm (HSU00) and 84mm x 20mm x 3mm (HSU01).