Research on the Method of AC Current Zero-crossing Detection Based on Hall Switches

A method of ac current zero-crossing detection based on Hall switches is proposed in this paper. The periodic magnetic field generated by core with ac current can make the output signal of Hall switch where was put in the air gap change. The current zero-crossing time will be detected while the output signal changing from high to low. On the one hand, the zero-crossing point can be detected accurately by increasing the number of windings of the measured current or the current amplitude. On the other hand, the measurement accuracy also can be improved by adding a magnetic bias compensation in the core without changing the number of windings or the current amplitude. This magnetic bias compensation method can be used in AC contactor to achieve its zero-crossing breaking. The magnetic circuit calculation and finite element calculation were used to verify the feasibility of the method. The method was simulated by Matlab-Simulink and Ansoft-Maxwell, the accuracy of measurement was verified through the simulation.