Analysis of current distribution and circulating currents in a permanent magnet synchronous machine with parallel coils

In this thesis the current distribution among parallel coils and the presence of circulating currents in an electric machine is investigated. Differences in induced voltage and in impedance between the parallel coils might lead to an uneven current distribution, which may cause the temperature of a single turn to become too high. To determine the flow of current in the machine it is necessary to model the machine in sufficient detail. For this research the coils in the machine have been modelled as a series connection of a voltage source, and inductance (with mutual coupling to other coils) and a resistance. This was made possible by the machine designer, who provided these parameters for every copper turn in the machine. The most important result of this research is that the difference in amplitude of the currents through parallel wires is very small, for this specific machine. The phase difference between the currents is larger, but the impact of this is still insignificant. Furthermore, the investigation on circulating currents has shown that the magnitude of these currents mainly depends on the difference in induced voltage between parallel wires and the resistance of the wires. The inductance of the coils was found to have negligible influence on the magnitude due to very good magnetic coupling between the parallel coils.Electrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc