Eddy current loss modelling for torque‐motors

Abstract

A torque motor is a key component that directly influences the dynamic performance of two-dimensional (2D) cartridge servo valves. Considering the effects of eddy current, a magnetic circuit model of a torque motor is proposed, and the eddy current resistance value considering the skin effect is calculated. When the eddy current effect is ignored, the natural frequency and critical damping of a torque motor are less than the calculated values under the eddy current effect, so the eddy current influence can be assumed to increase torque motor damping, as the iron loss can be equivalent to the damping energy consumption. Test rigs were set up and experiments were conducted based on a torque motor prototype. Through a finite element simulation analysis, the eddy current effect of the armature was found to be greater than that of the yokes. The magnetic leakage coefficients of the permanent magnets were calculated, and the obtained values were compared through experiments and simulations. Both the numerical simulations and experimental results showed that the eddy current model is closer to actual working conditions than the model for which the eddy current loss was ignored.