A DC linear motor with a square armature

One of the advantages in using DC linear motors for low speed linear drives is that the position and speed of these motors can be precisely controlled with the help of a feedback circuit. In addition, linear motors get rid of the rotary-to-linear conversion mechanism, hence reduce the weight cost backlash and dynamic complexity which produces friction, and eventually minimizes the space required by the drive. The neodymium-iron-boron (NdFeB) permanent magnet with high energy product has been used as the field source of these motors thus reducing the size and weight of the motors further. This paper describes the analysis of flux and force in a DC linear stepping motor built with NdFeB magnets. In order to verify the experimental results obtained for determining the performance of the motor, a computational method has been employed to compute the flux distributions throughout the machine. The discrepancy between the measured and computed values of axial and radial flux at most points ranges between 8% and 16% while the discrepancy between the measured and computed values of starting thrust is in the range between 4% and 13%