A Hall effect current sensor is a device used to measure the electrical current flowing through a conductor. It relies on the Hall effect, a phenomenon discovered by physicist Edwin Hall in 1879. The Hall effect occurs when a magnetic field is applied perpendicular to the flow of an electric current in a conductor, resulting in a voltage difference across the conductor.
Here's how a basic Hall effect current sensor operates:
Conductor Placement: The current-carrying conductor (usually a wire or a trace on a circuit board) is placed inside or through the core of the Hall effect sensor. The conductor serves as the primary path for the electric current being measured.
Magnetic Field Application: A magnetic field is generated either by an integrated permanent magnet or an external magnet. The magnetic field lines are oriented perpendicular to the direction of the current flow in the conductor. This magnetic field interacts with the moving charges (electrons) in the current-carrying conductor.
Hall Voltage Generation: As the electric current flows through the conductor, the moving electrons experience a force due to the magnetic field, which causes them to be deflected to one side of the conductor. This accumulation of charge creates an electric field across the conductor, perpendicular to both the current direction and the magnetic field. This phenomenon results in a voltage difference, known as the Hall voltage (VH), between the two sides of the conductor.
Hall Sensor Placement: The Hall effect sensor is positioned adjacent to the conductor in such a way that it senses the Hall voltage. The sensor contains a Hall element, which is a thin semiconductor material with a known carrier concentration. The Hall element is oriented so that its sensitive plane is perpendicular to both the current flow and the magnetic field.
Voltage Measurement: The Hall effect sensor measures the Hall voltage generated across the conductor and converts it into an output voltage that is proportional to the current flowing through the conductor. This output voltage can be analog or digital, depending on the design of the sensor and the associated circuitry.
Signal Conditioning: The output from the Hall effect sensor may need further conditioning, such as amplification or filtering, to make it suitable for measurement or processing by other electronic devices.
Current Calculation: Using the known properties of the Hall sensor (such as the sensitivity of the Hall element), the actual current passing through the conductor can be calculated based on the measured Hall voltage.
Hall effect current sensors offer advantages such as galvanic isolation between the measured current and the sensor circuitry, making them useful for applications where accurate current measurement is required without direct electrical connection. They find applications in various industries, including power monitoring, motor control, battery management, and industrial automation.