First Standalone Coreless Current Sensor for xEV Inverters
Allegro MicroSystems has launched the world’s first standalone Hall-based coreless current sensor, the ACS37612. This device measures currents from 200A to >1000A flowing through a PCB or a busbar with a typical accuracy of 1%—and without requiring 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, which reduces the design size and bill of materials (BOM).
The ACS37612 is designed for demanding electric vehicle applications, such as:
- High voltage traction inverter phase current measurement
- 48V starter generators
- Battery disconnect
“We created the ACS37612 in direct response to trends in the xEV market,” explains Georges El Bacha, Product Line Manager at Allegro. “It is the first solution that provides a truly coreless method of accurately measuring hundreds of amps in a very small formfactor, solving a key challenge for automotive engineers.”
Creating a more energy efficient—and more affordable—electric car
During acceleration, hundreds of amps flow through the traction motor inverter of an electric vehicle. 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.
Eliminating the cores with the ACS37612 allows manufactures to reduce the space and weight of the inverters, thus increasing the efficiency of the electric vehicle. This non-invasive, contactless current sensor is designed to improve thermal efficiency relative to shunt solutions and is therefore ideal for reducing system energy consumption in 48V e-motor platforms.
“The beauty of the ACS37612 is that it improves efficiency while also lowering the total system cost, which is a win-win for manufacturers and consumers,” says El Bacha.
Simplifying automotive solutions
The ability of the ACS37612 to be used in either busbar or PCB designs provides engineers with mechanical flexibility and simplifies their system level solution. The system coupling factor is determined by the sensitivity level of the ACS37612, as well as the shape and location of the busbar, making 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 3mm x 6.4mm total PCB footprint. Together with the coreless design, the ACS37612 enables a very small and light current sensing solution.