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Single-phase motors are widely used in household applications. Shaded-pole and splitphase capacitor-start single-phase induction motors are very popular for their ruggedness and their comparatively low cost. Recently, line-start single-phase motors are gaining market shares. However, their superior efficiency and torque density are counterbalanced by the higher cost of the rotor construction due to the magnets. This chapter compares the main structures of single-phase line-start motors, presenting their lumped parameter models and the finite element analysis. The equivalent circuits of the single-phase induction motor and of the line-start permanent magnet are derived. Different rotor structures for single-phase line-start permanent magnet (PM) motors are compared. The finite element method (FEM) is used to compare the characteristics of the motors. Motors with the same stator have been tested. No-load and load tests have been performed and compared to the FEM simulations and to the analytical model. Finally, the performances of line-start PM motors are compared to the shaded-pole induction motors in terms of torque density and efficiency.

This paper presents a full analysis and development of a system for vibrations reduction in a kitchen hood by using piezoelectric actuators. The control system is based on a feedback controller whose action depends on a single acceleration sensor collocated with the actuator. Two different resonant control laws have been designed: the first one operates without the information of the hood motor velocity; the second one is a more sophisticated controller which exploits also the velocity information. Overall, with the information of the motor velocity the best performances are guaranteed with a reduction of 75% of the vibrations. The resonant control system without the motor velocity information provides the best compromise in terms of performances (65% of reduction) and complexity of the implemented system. Tests held in anechoic chamber have shown the influence of the reduction of vibration upon the acoustic noise.978-1-4244-4602-5/09/$25.00 ©2009 IEEE