Slot-less Tubular Linear Permanent Magnet Generator Using Halbach-Array Excitation

Slot-less generator attracts many researches because of high efficiency it provides. Moreover, Slot-less generator does not have cogging force that affects translator movement and create harmonics on low speed generator and removal of iron tooth in translator resulting in lower flux density than it is in conventional generator. Permanent magnet modification is done by many researcher to maximize flux density. Modification on permanent magnet array also gives satisfying result on giving high density flux. Common linear generator uses axial-array permanent magnet in them. Axial-array done by exposing two of same poles in one direction. But this array has it flaw-that is leakage flux that run through translator's core. To minimize this leakage flow, Halbach-array is proposed so that the flux focused in one direction. In this paper, length variation on axial and radial permanent magnet is done and analyzed. Flux linkage on axial and Halbach-array also analyzed and compared in different slot length. In this paper, maximum flux density is obtained by minimizing radial array length on permanent magnet. Length increase in higher ratio gives smaller rise in flux density compared to it is in lower ratio-logarithmic growth like.