Investigation of permanent-magnet equivalent model for simulation of relay's static force (torque) characteristics by finite element method

Permanent-magnet (PM) is the key part of the relay. Aiming at the problem of the non-uniform magnetization for the PM with nonlinear demagnetization curve after charging magnetism and demagnetizing, a method partitioning the PM along the magnetization direction and the vertical direction of magnetization according to the condition of the specific magnetization of the PM was presented. Using this method, the demagnetization model of the PM was built, the state of the PM magnetization was simulated under one demagnetizing magnetic field intensity, and the recoil line and its initial point of each partition of the PM were obtained. Then the characteristic of the recoil line of each partition was used as its material for the equivalent model of the PM to calculate the static force (torque) characteristics under the demagnetizing magnetic field. Finally, the static torque characteristics of simulation and experiment were compared and the validity of the equivalent model presented was verified.