Single-Phase and Asymmetrical Three-Phase Induction Motors: A Comparative Steady-State Analysis Under Single-Phase Feeding.

In Brazilian rural areas single-phase power supply is very common. Single-phase induction motors with reasonable power are used to run farming activities which often, depending of their size, is not an inexpensive option. The aim of this work is to provide to farmers a simple, inexpensive and reliable option by running a modified three-phase induction motor [3] with as little structural modification as possible in order to run it with the available single-phase power supply. The asymmetrical three-phase induction machine fed by a single phase source, already discussed in previous work [1], has nothing more than an ordinary squirrel cage rotor and a stator where three-phase windings are located. These windings have the ordinary spatial design with a displacement of 1200 between them, but with a different number of turns in each phase. With a proper relation of number of turns in each phase and with the help of a capacitor (Cap) connected between phases B and C, as in Figure 1, can be possible to make the asymmetrical induction motor to produce nominal power at nominal speed.