Current sensor for EV traction inverters shrinks footprint

Designers of electric vehicle (EV) traction inverters can optimise the size, weight and efficiency ratios of products so that vehicles can travel further distances between charges, using LEM’s latest current sensor. LEM claims it is the smallest of its kind on the market.

High-power integrated traction inverters which convert DC into AC and capture energy for the vehicle need to combine performance with being as small and light as possible. Measuring just 29 x 21 x 12mm and weighing 27g, the HSTDR current sensor is more compact than a traditional C-core sensor, making it much easier to be integrated into space-limited inverter boxes.

The sensor enables traction inverters to operate at maximum efficiency by combining high accuracy with affordability and the ability to operate in demanding environments. The sensor has an operating range of -40 to +125 degrees C and is robust enough to cope with vibrations up to 10G. Using open loop Hall effect technology and an innovative magnetic core design, the HSTDR offers immunity against external field and cross talk as well as consistent behaviour over frequency with little part-to-part phase shift dispersion, ensuring more accurate torque control. 

According to LEM, the sensor is 42 per cent smaller than its predecessor (LEM’s HSNDR) but also weighs 50 per cent less and offers 50 per cent greater measuring range. It is also claimed to have best-in-class accuracy and a global error over temperature and lifetime below 3.5 per cent. This gives EV manufacturers the choice of having different current measuring ranges in the same housing, from ±300 up to ±1,500A. The sensor ensures galvanic separation between the primary circuit (high power) and the secondary circuit (electronic circuit), which is also suitable for 800V battery systems. 

According to LEM, the calibrated package of core, busbar and sensing element will enable car component designers and EV manufacturers to achieve major reductions in product development time. 

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