Power density improvement of three phase flux reversal machine with distributed winding

Abstract

The three phase flux reversal machine (FRM) is a doubly salient permanent magnet machine with concentrated windings. This study proposes the distributed winding for this machine. This winding (i.e. full pitch winding) offers high-power density and improves the efficiency. The permanent magnet (PM) flux linking the stator winding has effectively two or four pole flux pattern, which depends on the number of stator poles and independent of number of rotor poles. Finite element method (FEM) analysis is performed on the concentrated stator pole winding FRM (CSPFRM) and proposed full pitch winding FRM (FPFRM) to obtain induced EMF, flux linkages and inductance of the winding. The inductance of both machines is also obtained using winding function approach and compared with FEM results. The effect of armature reaction is compensated by capacitive series compensation to improve the voltage regulation. FEM analysis is also carried out on both the compensated generators to evaluate the power density. Speed of the flux pattern and that of the rotor is different in FRM. The ratio of these two speeds is termed as fictitious ‘electrical gear’. FRM and permanent magnet synchronous machine (PMSM) have sinusoidal terminal voltage and surface mounted PMs. The power density of both machines is compared using the concept of fictitious ‘electrical gear’. To verify the above analysis, a 6/14 pole FRM with distributed and concentrated winding is designed and fabricated. The experimental results are in close agreement with simulated results.