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WIEGAND SENSORS: BATTERYLESS AND AUTONOMOUS SENSORS

Wiegand Sensor
WIEGAND SENSORS: BATTERYLESS AND AUTONOMOUS SENSORS

The Wiegand effect: what is it?

Wiegand sensors are used as pulse generators in a variety of applications. The sensor does not need any external power source and has no moving parts. Everything works thanks to a very small diameter wire with special properties, invented by John Wiegand.

When the magnetic field passes certain headings (every 180 °), this impacts the magnetic state of the Wiegand wire, creating at the same time an impulse. This pulse can be recovered at the output and is sufficient to be used as an energy source for a revolution counter. The system then becomes energetically autonomous.

POSITAL Wiegand sensors are the result of the expertise and knowledge acquired over more than ten years of manufacturing Wiegand effect revolution counters. These high performance sensors are assembled using the SMD mounting method. They can be used as revolution counters both in absolute rotary encoders and for other applications such as flow meters.

Benefits

  • No need for a battery anymore!
  • Longer life
  • Able to operate in aggressive environments
  • Works without contact with the moving part

The POSITAL Product Range

POSITAL provides you with a whole range of products based on the Wiegand effect, suitable for many applications:

  • Wiegand Wire Sensor intended for multi-turn encoders without batteries, enabling the energy produced by the rotation of a magnetic field to be collected.
  • Optimization of operations thanks to the iC-PMZ and iC-PMX revolution counting modules from iC-Haus
  • Surface mounted technology compatible with burn-in process, RoHS 2 compatible
  • Versions 2.5 mm or 5 mm away from the seat surface
  • High intensity energy pulse typically 170 nJ (on average)
  • Increased traceability: machine readable serial numbers

Important: Harvesting energy via the Wiegand effect within rotary encoders may fall under the protection of a worldwide patent for certain applications and therefore requires the acquisition of a license.

POSITAL and Wiegand Technology:

  • 2004: First design of Wiegand sensor
  • 2006: Serial production of rotary encoders based on Wiegand technology. Partial assembly of Wiegand sensors (part of the production is then subcontracted)
  • 2012: Stop of wire production at HID
  • 2013: Acquisition of two production lines for Wiegand yarns from HID, technical documentation included. Knowledge transfer ensured via a consulting contract with the experts concerned.
  • 2014: Opening of a Wiegand technology center in Aix-la-Chapelle (Aachen, Germany), Start of yarn production in Aachen.
  • 2015: 100% of the assembly is carried out in-house.
  • 2016: Production volume reaching 120,000 Wiegand Sensors.
    Creation of a second production line for the United States.
    Creation of a second production line in Asia.

POSITAL multiturn encoders have been using Wiegand sensors successfully since 2006. This energy harvesting system generates very short but nonetheless powerful pulses sufficient to power the electronic revolution counting circuit, even when the rotation speed is low. This solution allows precise and reliable measurement of the absolute position in multiturns without the need for an external energy source.

The Wiegand effect

Wiegand effect technology uses the unique magnetic properties of extremely fine, specially treated ferromagnetic wires. John Wiegand discovered a way to make the magnetic field within this special wire change polarization instantly. When this happens, an extremely precise and uniform pulse is then generated. It is called the Wiegand Pulse.

Wiegand Effect Explanations
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 →  Applying an opposing field reverses the polarity of the core, producing a voltage peak.

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 →  As the opposing field continues to grow, the outer part of the wire changes polarity as well, generating a second, somewhat weaker pulse in the same direction.

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 →  After saturation of the Wiegand wire, the opposite field is removed.

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 →  By applying a magnetic field with the initial polarization of the wire, the polarization of the core is changed again, again creating a large voltage peak in the opposite direction.

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 →  Increasing the internal field will again change the polarity of the outer part of the wire. The wire is back to its original state. This represents a complete cycle.

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