Koziy V. Improving the performance of gearless drives based on a synchronous motor with permanent magnets and an electronic commutator

Gearless or direct drive (DD) is a promising area of modern electromechanics, which is rapidly expanding. The advantages of DDs over traditional gear drives are in-creased reliability and energy efficiency, higher speed and accuracy of torque and ve-locity control, easier implementation, no noise. In this case, the mechanical reduction of speed and the corresponding increase of torque is replaced by electromagnetic re-duction due to the increase in the number of pairs of poles of the machine and, accord-ingly, its size. Electric machines with permanent magnets (PM) on the rotor are the most suitable for the implementation in DDs, because they provide high-energy per-formance for a relatively large air gap. Brushless implementation of the electric drive system based on such machines is achieved by means of a power semiconductor con-verter, often built by transistors, which controls the currents in the machine armature windings according to the angular position of the rotor. A number of features of a mul-tipole electric machine with PMs determine the revision of traditional methods of posi-tional electronic switching of its armature windings in order to reduce the electromag-netic torque ripple and ensure high energy performance. The thesis is directed on the decision of this actual scientific and technical problem. A theoretical study of changes in the main electrical and electromagnetic parame-ters of a synchronous machine with PMs (PMSM), as well as energy, dynamic and mass-dimension indicators of the drive with increasing number of pole pairs of the machine is conducted. Herewith, all expressions are obtained for a multipole PMSM with an arbitrary number of poles in p. u. relatively to the bipolar machine at the same values of the input electrical and output mechanical parameters of the drive. According to the obtained results, new requirements to the construction of electronic switching systems for PMSM and the formation of its electromagnetic torque in DD are formed.