Rotor saturation impact in synchronous reluctance and PM assisted reluctance motors

The design of synchronous reluctance machines involves a lot of variables that usually lead to unpredictable machine performance. It is difficult to achieve a proper rotor barrier design that yields satisfactory results, in terms of torque ripple, average torque, etc. Geometry optimizations could be required to find optimum solutions on the basis of some objective functions. However, a good knowledge of the machine performance behavior due to rotor geometry variables is necessary to start with the machine design, as well as to know what has to be changed for obtaining the desired performance. This paper investigates the effect of a different level of saturation of the magnetic rotor path, comparing the performance of some synchronous reluctance machines. The effect of the insertion of permanent magnets is also investigated. The comparison has been carried out on the basis of finite element analysis, considering average torque, torque ripple, power factor, torque and power versus speed curves and efficiency. A prototype has been tested to compare the simulation results with the experimental measurements.