Flux Linkage Determination for Correct Modeling of Switched Reluctance Machines - Dynamic Measurement versus Static Computation

This paper presents a study on the determination of flux-linkage characteristics of switched reluctance machines. These characteristics are used to describe the behavior of individual machines for modeling as well as control purposes. Typically, the flux-linkage characteristics are either obtained by static FEM-calculations or by measurements. With the example of a 55 kW switched reluctance machine (SRM) it is shown that these two characterization methods do not inherently yield the same results but that they can differ more than 10%. FEM simulations are performed to analyze the dynamic processes occurring during flux-linkage measurements. It was found that current displacements due to winding eddy currents are responsible for a transient reduction of phase inductance and flux-linkage. Finally, it is investigated whether the results of static or dynamic flux- linkage determination are more accurate for look-up table based torque control.