MMF harmonic reduction in permanent magnet synchronous generator using different stator flux barriers for microturbine applications

Distributed generation (DG) is playing a significant role nowadays due to the emerging emphasis of renewable energy source integration and many other inherent benefits. Microturbines are one of the most promising distributed generation units. High speed permanent magnet machines are typically used in microturbine application due to their high power density and high efficiency characteristics. To improve torque density and efficiency, fractional-slot concentrated winding (FSCW) is used. The advantages of using these windings are short and less complex end winding, high slot filling factor, low cogging torque, greater fault tolerance, and low manufacturing costs. However, the magnetic field of these windings has more space harmonics, including sub harmonics which lead to detrimental effects such as, additional losses in stator and rotor, noise and vibration. Modification of stator by using magnetic flux barriers in the stator yoke of electric machines with fractional slot concentrated winding reduces these undesirable space harmonics. Considering the machine performance this stator design has significant advantages over the conventional design. A comparison of machine with different flux barriers in stator yoke is studied using Ansoft Maxwell software. The machine with modified stator is then coupled with electrical unit of microturbine generation system using Ansoft Simplorer software.