Design of interior permanent magnet synchronous machine for torque characteristic improvement by increasing reluctance torque and reducing leakage flux

This paper presents the design of an Interior permanent magnet (IPM) synchronous machine to improve machine performance by increasing saliency ratio and minimizing the leakage flux through the ribs and air barriers of an IPM machine. A bar-type IPM basic model is taken and two variables, variable 1 as factor-A and variable 2 as factor-B are analyzed. Factor-A is the radial distance of the rotor air barrier and factor-B is the rotor tangential rib angular distance in degrees. The two variables greatly affect the targets of the designed IPM i.e. saliency ratio and leakage flux. A 3-step design process is followed to achieve the desired targets. In step-1, the design variables, factor-A and B, are evaluated and the effect of each variable is examined on machine performance individually. In step-2, the best combinations of design variables are taken and an iterative optimization is performed for checking the combined effect of both variables on output torque and power factor. In step-3, the model is optimized using the Kriging method and Genetic algorithm (GA) for improved torque characteristics compared to the basic IPM model. All models are analyzed with the same machine size, operating conditions, and magnet volume using 2-D finite element method (FEM).