Design of an Energy Efficient Line-Start Two-Pole Ferrite Assisted Synchronous Reluctance Motor for Water Pumps

Electric motors used for irrigation applications contribute to a major part of worldwide energy demand. Efficiency improvement of motors used in these applications is the need of the hour. Usually, line-start (LS) induction motors are used in these applications. However, they are relatively inefficient compared to permanent magnet (PM) motors. On the other hand, PM motors have high initial cost compared to induction motors. In view of this, magnet-less machines like synchronous reluctance motors (SyRM) and PM assisted SyRM are being preferred. SyRM has poor power factor compared to induction motor and hence PM assisted SyRMs are becoming popular. In this article, a 2-pole multi-barrier LS ferrite assisted SyRM is proposed for a bore-well submersible water pump. Two-pole rotor geometry is not extensively studied for LS SyRMs. Further, the issues of ferrite magnet demagnetization for 2-pole LS applications are not explored. A separate cage is avoided by utilizing the rotor flux barriers as a cage, thereby reducing the number of ribs while housing the magnets. This improves the power factor and efficiency of proposed motor. Analytical and finite element analysis (FEA) are used for design of the proposed motor. Further, a prototype is fabricated and experimental results are presented.