Standalone coreless current sensor reduces size, weight for xEV inverters
Allegro Microsystems says that the ACS37612 is the industry’s first standalone Hall-based coreless current sensor. It is available in a compact TSSOP8 package which delivers precise current measurements for applications above200A without a magnetic concentrator core or shield.
The device measures currents from 200A to 1,000A flowing through a PCB or a busbar with a typical accuracy of one per cent yet does not require a magnetic concentrator core or a shield. The differential Hall-elements used to measure the magnetic field provide great immunity to stray magnetic fields without the need of a laminated shield required by competing solutions, says Allegro, which reduces the design size and bill of materials (BoM).
The ACS37612 is designed for electric vehicle (EV) applications, such as high voltage traction inverter phase current measurement, 48V starter generators and battery disconnect.
It was created in response to trends in the xEV market, which is made up of EVs, battery EVs (BEVs) and hybrid EVs (HEVs).
Georges El Bacha, product line manager at Allegro, explained: “It is the first solution that provides a truly coreless method of accurately measuring hundreds of amps in a very small form factor, solving a key challenge for automotive engineers”.
During acceleration, hundreds of amps flow through the traction motor inverter of an EV. A precise measurement of such high currents is vital for safe performance. Engineers have traditionally relied on a low hysteresis, laminated core for such measurements using three to six cores, depending on the number of phases in the motor.
Using the ACS37612 eliminates the cores, allowing manufacturers to reduce the space and weight of the inverters, increasing the efficiency of the EV. The non-invasive, contactless current sensor is designed to improve thermal efficiency relative to shunt solutions for reducing system energy consumption in 48V e-motor platforms.
“The . . . ACS37612 . . . improves efficiency while also lowering the total system cost,” added El Bacha.
The ACS37612 can be used in either busbar or PCB designs to simplify system level design while providing mechanical flexibility. The system coupling factor is determined by the sensitivity level of the ACS37612, as well as the shape and location of the busbar. Allegro explains that this makes it easy to increase the current sensing range at any phase of the design.
The sensor is available in a very small TSSOP8 package (LU-8) that has a 3.0 x 6.4mm total PCB footprint. The coreless design enables a very small and light current sensing device, adds the company.
