Design and Optimization of a High Thrust Density Voice Coil Motor with Auxiliary Enhanced Magnetic Circuits

Precision instruments of aerospace equipment are often affected by low frequency and broadband vibration. Active vibration isolation system (AVIS) is usually employed to suppress vibration. Voice coil motor (VCM) is widely used in AVIS because of its compact structure, fast response speed, good linearity and high control accuracy. To ensure the normal operation of precision instruments, VCM is required to have a large stroke, a large thrust density and a low fluctuation. However, traditional VCM designs require a careful trade-off between large thrust density and low thrust fluctuations. This paper proposes a design of VCM with novel auxiliary enhanced magnetic circuits. The proposed VCM uses bipolar basic magnetic circuit to improve the utilization of permanent magnets and yokes, and further concentrate and even the magnetic flux in the airgap by adding auxiliary magnetic circuits, leading to a high thrust density and a low thrust fluctuation. Equivalent magnetic circuit method and finite element method are combined to optimize the structural parameters of the proposed VCM to obtain better comprehensive performance. Experimental results demonstrate that the average thrust of the proposed VCM is increased by 74.5% and the thrust fluctuation is reduced by 23.9% compared with the conventional VCM.