Rotary voice coil actuators (RVCAs) have been widely used for precision motion control applications and have drawn more and more attention in recent years. In this paper, the eddy current damping effects of RVCAs of both dual and single magnetic circuit types are studied, the electromotive forces in rotor frame arms of the RVCAs are analyzed and verified by FEM calculation, then corresponding restraining measures are proposed. Especially, influencing factors of magnetic field margin effect and influence of magnetic field structure on the margin effect are analyzed in detail, which are the unique problems in RVCAs. The research results are good references for practical engineering applications of this type of motor.