Abstract:The variable reluctance electromagnetic sound source has the advantages of large output force, small size and easy realization of ultra-low frequency output. Its dynamic behavior is affected by the coupling effect of mechanical recovery force and electromagnetic force. When the applied current exceeds the collapse current, the electromagnetic force will exceed the mechanical recovery force, and suction will occur, resulting in damage to the sound source. In order to accurately describe the nonlinear dynamic characteristics of the variable reluctance electromagnetic sound source and evaluate the collapse current in advance, a nonlinear dynamic model of the sound source considering the dynamic magnetic leakage coefficient is established. The magnetic leakage coefficient of the air gap where the moving iron core moves to different positions was calculated by three-dimensional finite element simulation, and the dynamic magnetic leakage coefficient was obtained by fitting. The improved electromagnetic force model of the sound source was established according to the equivalent magnetic circuit method, and then the nonlinear dynamic model of the electromagnetic sound source was established. The Runge-Kutta algorithm is used to calculate the displacement and velocity of the sound source vibration under step excitation, plot the phase plan, and study the dynamic change law of the phase trajectory under the two conditions of stability and instability, providing theoretical support for the design and control of the variable reluctance electromagnetic sound source
