Allegro’s Coreless Current Sensor For Reduced Size Of EV Inverters

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  • Ultra-compact and delivers precise high-current measurements
  • Doesn’t require magnetic concentrator core or shield

During acceleration, hundreds of amps of current flow into the traction motor inverter of an electric vehicle. For a safe performance, a precise measurement is vital. Conventionally, engineers have relied on a low hysteresis, laminated cores (typically three to six) for such measurement, depending on the number of motor phases.

Now, Allegro MicroSystems, a power and sensing solutions provider for motion control and energy-efficient systems, has launched a Hall-based coreless current sensor, the ACS37612, whose current measuring range is from 200A to greater than 1000A with an accuracy of 1 per cent.

The differential Hall-elements used to measure the magnetic field provide great immunity to stray magnetic fields without needing laminated shield as compared to other competing solutions. Thanks to no requirement of a magnetic concentrator core or a shield, the design size and bill of materials (BOM) is reduced.

Improved energy efficiency

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Eliminating the cores with the ACS37612 allows manufactures to reduce the space and weight of the inverters, thus improving the thermal efficiency of electric vehicles (EVs) relative to shunt solutions. This non-invasive, contactless current sensor 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 Georges El Bacha, Product Line Manager at Allegro.

Simplifying automotive solutions

The current sensor IC can be used in either busbar or PCB designs to provide mechanical flexibility to engineers and simplify the 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 for increased current sensing range.

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Applications

The ACS37612 is ideal 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,” says El Bacha. “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.”

Availability

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.


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