The working principle of the zero flux current sensor is based on magnetic-electric conversion, relying on the strong non-linearity of magnetic materials. The static magnetic field generated by direct current does not produce measurable electrical effects. In a linear system, there is no relationship between the system's output and the input current, meaning a linear system cannot measure direct current through flux induction. A non-linear system can establish a connection between the input direct current and the output.
In zero flux current sensors, the Hall element output is connected to an error amplification circuit. When the sensor is in an ideal balanced state, the magnetic flux through the Hall element is zero, resulting in a zero Hall potential output. Thus, the Hall element is essentially used to detect zero magnetic flux, or in other words, to detect the presence of magnetic flux.
In zero flux current sensors, the Hall element's output Hall potential is linearly related to the flux in the core, and the flux in the core is linearly related to the primary current, which is almost independent of the secondary output, having little impact on measurement accuracy. This is a significant advantage of zero flux Hall current sensors over open-loop Hall current sensors.
Zero-flux current sensors are widely used in variable frequency speed control systems, inverters, UPS power supplies, photovoltaic power generation, communication rooms, CNC machine tools, microcomputer monitoring systems, grid monitoring systems, and various fields requiring isolated current detection.
