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Posted on 07 June 2020

Basis for Hall Effect Technologies

 

 

 

 

 

 

 

Many technologies are based on the phenomenon known as the Hall effect, discovered in 1879 by American physicist Edwin Herbert Hall at Johns Hopkins University in Baltimore. The Hall effect is created by Lorentz forces, which act on charges moving through electric and magnetic fields. The Lorentz force acting on a charge q   traveling through an electric field and a magnetic field with velocity is given by:

where denotes the vector cross product and the arrows indicate vectors.

Consider the simplified situation shown in the diagram above, where there is no external electric field and the magnetic field and current direction are perpindicular. A thin sheet of conducting material is traversed lengthwise by a control current . The mobile charge carriers of this current are affected as the external magnetic field, , generates a Lorentz force,, perpendicular to the direction of current flow. The resulting deflection of current causes more charge carriers to be located at one edge of the sheet, creating a potential difference referred to as the Hall voltage,. For the arrangement described above, with the magnetic field, current, and sheet edges mutually perpendicular, we obtain:

where is the Hall constant of the conducting material, is the thickness of the sheet, and is the offset voltage in the absence of an external field. Such an arrangement is referred to as a Hall generator and the product is generally referred to as the Hall generator sensitivity. The sensitivity and offset voltage of Hall generators are temperature dependent. However, these effects can be greatly compensated by the biasing and amplification electronics driving and sensing the Hall generator.

 

For more information, please read:

Introduction to Closed Loop Hall Effect Current Transducers

Open Loop Hall Effect Current Transducers

Transducers - Basic Principles of Selection

Concerns When Using Transducer Measurement Devices

 

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