Design And Research On Permanent Magnet Generator With Circumferential Double-layer And Fractional-slot Concentrated Winding

Permanent magnet generator with circumferential double-layer andfractional-slot concentrated winding meets the need of the project for multi-poleand few-slot motor. Sometimes the engineering needs a high frequency that issupplied by a small speed, which requires that the permanent magnet generatorshould have many pole pairs. However, due to the limit of stator size, thegenerator can’t have many stator slots. Permanent magnet generator withcircumferential double-layer and fractional-slot concentrated winding solves theproblem. Each winding of the generator is wrapped around a stator tooth, so itreduces the amount of stator winding copper. Meanwhile, due to highperformance, low noise and miniaturization characteristics of the permanentmagnet generator with circumferential double-layer and fractional-slotconcentrated winding, it has been applied more and more widely. But its specialstructure leads that some common formulas in the permanent magnet generatordesign are not suitable for the special generator, which increases the difficulty ofthe generator design. Therefore, the special generator is done in-depth study inthe paper.First with the help of the electromotive force star map, the slot-polecombination of fractional-slot and concentrated winding is analysed. Thenaccording to the conclusion, slots and poles of the generator which is designed inthe paper are selected. Based on the leakage reactance formula derivation oftraditional fractional-slot winding, leakage reactance formula of fractional-slotand concentrated winding is deduced and the winding coefficient is researched indepth. Meanwhile, combined with the finite element software, no-load leakage flux coefficient of the motor is calculated. Because no-load leakage fluxcoefficient in the traditional design of the motor is estimated by experience.Therefore, in order to get more accurate no-load leakage flux coefficient, afterthe no-load leakage flux coefficient of the end and no-load leakage fluxcoefficient between the poles are calculated, the no-load leakage flux coefficientof the generator is obtained. The cogging torque is an important factor whichimpacts the performance of the motor. In order to reduce its impact on thegenerator, skew slot is adopted to weaken cogging torque. At last, on the basis ofabove results, the design of permanent magnet generator with circumferentialdouble-layer and fractional-slot winding is programmed with VB language andthe influence of motor parameters on the voltage regulation rate is analysed.