Finite-Element Analysis of Electrical Machines for Sensorless Drives With High-Frequency Signal Injection

A challenge during the design process of an electrical machine is the characterization of the various parameters in a computational time as short as possible. Frequently it is required the computation of the electrical machine parameters that are necessary for the tuning of the drive control algorithm. This paper deals with a strategy to compute the high-frequency signal injection response of a sensorless controlled electrical machine. It allows to determine the self-sensing capability of the machine directly during the design process. Such capability can be defined in any given operating point, for example, along the maximum-torque-per-amps trajectory. Then, also the high-frequency machine parameters can be computed. In addition, the strategy proposed here requires a very short computational time to get such data. After a magnetostatic field analysis, carried out so as to get the torque for a given current, the flux density distribution is stored, and the differential reluctivity tensor is evaluated in each element of the mesh. Then, a time-harmonic analysis is carried out in a linearized structure so as to compute the d - q parameters at the injection frequency. In order to validate the proposed procedure, experimental results on different machine type are included in this paper. This allows to prove the reliability of the procedure as a valued tool for the characterization of the machine.