Measurement Results Based Approximation of the Nonlinear Flux-Current Characteristic of an Electromechanical Actuator

A Hamiltonian model of an electromechanical actuator requires approximation of its flux-current characteristic. It can be made using a simplicial approximation, which requires the sets of corresponding points in the spaces of currents and fluxes. These points can be chosen from the trajectories that describe the behaviour of the electromechanical system in these spaces. In the paper, a method of obtaining these trajectories by measurements is shown and four original methods of choosing points lying on them to construct the required points sets are presented. The sets are constructed so that they contain a possibly small number of points, but the approximation which is based on them is precise. The presented methods are used to approximate a flux-current characteristic of the prototype synchronous reluctance machine. The simulation results, computed using the models based on these approximations, are also presented and discussed. The best results are obtained by methods using the computed value of the magnetic field coenergy in the modelled machine.