A Hall effect current sensor is a device used to measure the magnitude of an electric current by utilizing the Hall effect, which is a phenomenon observed when a conductor carrying a current is placed in a magnetic field. The Hall effect generates a voltage across the conductor perpendicular to both the direction of current flow and the magnetic field. This voltage is known as the Hall voltage.
Here's how a basic Hall effect current sensor operates:
Construction: The sensor consists of a semiconductor material through which the current to be measured passes. The semiconductor is often a thin rectangular plate or strip. The sensor also includes contacts on the sides of the semiconductor for current input and output, as well as a magnetic field source that is usually located perpendicular to the current flow.
Magnetic Field Application: When an electric current flows through the semiconductor material, a magnetic field is generated around the conductor according to Ampere's law. This magnetic field interacts with the externally applied magnetic field, causing the electrons within the semiconductor to experience a force perpendicular to both the current direction and the external magnetic field.
Hall Voltage Generation: Due to this force, an accumulation of charge carriers (either electrons or holes, depending on the type of semiconductor) builds up on one side of the semiconductor while a deficit occurs on the other side. This charge imbalance creates an electric field that opposes the further movement of charge carriers. This electric field results in a voltage difference between the two sides of the semiconductor, which is known as the Hall voltage.
Voltage Measurement: The Hall voltage is directly proportional to the product of the current passing through the sensor and the strength of the externally applied magnetic field. This relationship is described by the Hall coefficient and the dimensions of the sensor. By measuring the Hall voltage, the current magnitude can be determined using the known values of the Hall coefficient and the magnetic field strength.
Output and Calibration: The output of the Hall effect current sensor is typically a voltage signal that can be proportional to the input current. However, to obtain accurate measurements, the sensor often requires calibration to account for temperature variations, non-idealities in the semiconductor material, and other factors.
Hall effect current sensors are commonly used in various applications such as current monitoring in industrial machinery, power distribution systems, automotive electronics, and more. They offer advantages like electrical isolation between the measured current and the measurement circuit, making them suitable for high-voltage environments, and they can handle both DC and AC currents.