A Fractional Slot Concentrated Winding Machine with Interior PMs

Fractional slot concentrated winding (FSCW) configurations are drawing more attention in the area of brushless PM machines due to high power density, high efficiency, low copper consumption and high reliability. These characteristics make them suitable candidates in applications where high power density and efficiency are required, such as electric ship and submarine propulsion systems and electric vehicles. Detailed discussion regarding the choice of pole-slot combination is addressed form the viewpoint of winding factor, unbalanced magnetic pull, cogging torque and case-study conditions leading to narrowing down the decision choices to two candidates. A hybrid design algorithm is proposed for designing the two interior PM (IPM) FSCW machines obtaining the advantage of high processing speed and high precision simultaneously. A comprehensive comparison is made between the two IPM FSCW machines by analyzing the spatial harmonic spectrum of armature and rotor flux density distribution in air gap region. In order to validate the design and simulation results, a 2kw, 1500 rpm IPM FSCW generator is prototyped and the test results are compared with the simulation data. According to the experimental results, the measurement and simulation data have good level of consistency in which the error rate for no-load back-emf is 3.5% and for the full-load terminal voltage is 4.3%.