How current sensor works

FAQ | Feb 16,2023

The current sensor is based on the two basic principles of Hall magnetic balance (closed loop) and Hall direct measurement (open loop).
1. Principle of open-loop current sensor: The magnetic flux generated by the primary side current IP is gathered in the magnetic circuit by a high-quality magnetic core, and the Hall component is fixed in a small air gap for linear detection of the magnetic flux. After the Hall voltage output by the Hall component is processed by a special circuit, the secondary side output follows the output voltage consistent with the waveform of the primary side, and this voltage can accurately reflect the change of the primary side current.
2. The specific working process of the magnetic balance current sensor Is: when a current passes through the main loop, the magnetic field generated on the wire is gathered by the magnetic ring and induced to the Hall device. The generated signal output is used to drive the corresponding power tube and make it open, so as to obtain a compensating current IS. This current then generates a magnetic field through the multi-turn winding, which is opposite to the magnetic field generated by the measured current, thus compensating the original magnetic field and gradually reducing the output of Hall devices. When it Is equal to the magnetic field generated by multiplying Ip and turns, Is no longer increases, and the Hall device at this time plays the role of indicating zero flux, which can be balanced by IS. Any change in the measured current will upset this balance. Once the magnetic field is out of balance, the Hall device has a signal output. After power amplification, a corresponding current immediately flows through the secondary winding to compensate for the imbalance of the magnetic field. Theoretically, it takes less than 1μs for the magnetic field to re-balance, which is a dynamic equilibrium process.

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