Simulation of current control for 3-D motion of a permanent magnet spherical stepper motor

In view of the permanent magnet spherical stepper motor designed by Stein et al,a current control strategy was designed based on the dynamic model in rotor-fixed coordinates frame expressed with Cardan angle rotation.The rotor was expected to track the point-to-point motion or the continuous path motion.The desired torque for the motion of the rotor was derived when the control parameter was adjusted.Meanwhile the stability of the kinematic control was analyzed by using the Lyapunov method,and the currents in sixteen stator coils to accomplish the desired motion task were calculated using the generalized inverse matrix based on the acquired torque model.Finally the simulation experiments were presented.