Quantitative Evaluation of Torque Contributions of Multiple Working Harmonics on Halbach Array Consequent-Pole PM Machine

This article presents a quantitative evaluation of torque contributions of the main-order and modulated magnetic field harmonics on consequent-pole permanent magnet machine (CPPMM) with Halbach array arrangement to reveal its torque enhancement theory. Due to the field focusing effect and double slotting structure, Halbach array CPPMM exhibits an enhanced main-order and various modulated magnetic field harmonics than conventional case with radial magnetized magnets. In order to illustrate the torque enhancement theory of the Halbach array configuration, the toque contributions of the multiple air-gap magnetic field working harmonics are identified and quantified by Maxwell stress tensormethod, which shows that the main-order and modulated magnetic field working harmonics of the Halbach array design contributed higher torque components than conventional case. Besides, the modulated magnetic field harmonics on Halbach array structure shows a higher torque proportion than the conventional counterpart. Moreover, the effects of the rotor PM pole-arc and thickness on torque contributions of main-order and field modulation working harmonics are studied by finite-element method. Finally, a Halbach array CPPMM prototype is manufactured and some tested results are conducted to confirm the predictions.