Influence of Parallel Paths on Current-Regulated Sine-Wave Interior-Permanent-Magnet Machines With Rotor Eccentricity

The behavior of rotor eccentricities in current-regulated interior-permanent-magnet machines is investigated. The study focuses on two typical topologies of significant industrial relevance: machines with distributed windings with two slots per pole and phase and motors with concentrated coils and three slots per pole pair. The effect of stator-winding parallel paths is examined for both cases. Coil and terminal electrical quantities and radial forces were simulated using finite-element analysis. Unbalanced operation, where the currents are not equal in parallel phase connections due to eccentricity, is also investigated. Experimental measurements of electrical quantities and forces on motors with static eccentricity are carried out using two special test setups. The experimental measurements validated the simulation results.