Sine wave filter for stepper motor drives working with long cables

Switched mode stepper motor drives tend to have poor performance or even fail completely when the motor is fed through a long cable, as can be required in harsh environments. In this paper the design of a stepper motor output filter which solves this problem is presented. Output filters are used in induction motor applications, however their use with stepper motors and long cables has not been reported. A two stage filter, one devoted to dealing with the differential mode and the other with the common mode, is designed and validated experimentally. With this filter the drive performance is greatly improved, achieving a positioning repeatability even better than with the drive working without a long cable, the radiated emissions are reduced and the overvoltages at the motor terminals are eliminated.