Analysis and modelling of single-phase induction motor with external rotor for domestic applications

Many domestic appliances require low-power motors operating at essentially constant speed to drive compressors, pumps, air conditioners, and other equipment that must start under load. Well known for its reliability and robustness in operation the single-phase induction motor is one of the most widely used types of AC machines. Constant speed at different load can be easily achieved by increasing the motor inertia, by using an external rotor. The paper presents an external rotor squirrel-cage single-phase induction motors, where the short-circuiting rings can be shunted by a conducting shell joining the two rings, which improves cooling and operating characteristics. This ring-shunting effect is emphasised and new equivalent circuits of the rotor with conducting shell between the rings and the lumped parameters are established. The new equivalent circuit can be used in vector control drives with such an induction machine. The special features of the single-phase induction motor with external rotor are determined by reverse magnetic field. Some tests and results are presented to highlight the parameters of the single phase induction motor.