Low Voltage Ride Through Capability of Single-Phase Induction Machines

Stochastically occurring voltage sags as they may occur with low quality of the power supply may significantly affect the operational behavior of single-phase starting and running capacitor assisted induction machines. In contrast to three-phase machines which are still subjected to a rotating field, even during voltage sags, the single-phase machines are subjected to an alternating field that can be decomposed into two rotating fields, a positive and a negative sequence one. Thus, the behavior of these machines when submitted to voltage sags cannot be directly derived from the established understanding of the low voltage ride through capability of three-phase machines. The effects of such voltage sags on a single-phase machine’s transient behavior not only depend on the electric capacitive circuit and the machine’s electromagnetic design, but strongly on the moment the short circuit occurs, its duration, and the load of the machine. In this work, we analyze the robustness of such a system towards an extremely voltage sag, in particular a terminal short circuit. To this aim, experimentally validated transient FE computations are used.