Elimination of Even-Order Harmonics and Unipolar Leakage Flux in Consequent-Pole PM Machines by Employing N-S-Iron–S-N-Iron Rotor

Design of a Novel Low-Cost Consequent-Pole Permanent Magnet Synchronous Machine

“…It is demonstrated that the maximum output torque of a conventional CP-PMSM can be obtained by optimizing the PM-arc ratio [23] [24]. It can be seen that the machine can obtain the maximum output torque at αp = 0.68 and the minimum torque ripple at αp = 0.5; this is due to the increase in air-gap flux density asymmetry when αp > 0.5, which is concluded based on the principle that the same flux flows through the PM and iron pole of the CP-PMSM (Φpm = Φip) [25]. From Figure 11, it can be seen that the maximum output torque and torque ripple of the conventional CP-PMSM cannot reach that of a conventional SPMSM.…”

Analysis of Consequent-Pole Flux Reversal Permanent Magnet Machine With Biased Flux Modulation Theory

“…It can be observed that the CP machine exhibits higher low-order harmonics, e.g. 1 st , 5 th and 17 th , as well as comparable 7 th harmonic than its SPM counterparts, which are the main contributor for the effective torque production, as evidenced in (19). Overall, more abundant harmonics, such as 1 st and 23 rd for "i=2" in (22) and (23), can be produced in the CP-FRM rather than the SPM structure, which is responsible for its torque improvement.…”

“…where Ns is the stator slot number, i is the order of Fourier series, Bi is the corresponding Fourier coefficient, and " s" denotes the angular degree of a particular position in the stator with respect to the phase A winding axis. For the SPM-FRM-II, the magnitude of air-gap flux density Bm1 can be represented by [19]…”

“…where Ii( ) is the three-phase armature current. As a result, by substituting (13)~ (19) into (20), the torque expression can be rewritten as…”

“…The flux leakage issue is a major concern in the above FRMs, which restricts the torque density. Meanwhile, rare-earth PM material, such as NdFeB, is very expensive, and suffers from limited resources so that the consequent-pole (CP) PM design concept [18] [19] is recently extended to FRMs [20]- [24] by replacing nearly half PMs with iron poles. In addition, PM irreversible demagnetization risk is reduced due to the existence of iron poles on the stator surface.…”