Development of a square wave voltage field-oriented controller for a linear vapor compressor.

In this thesis, a novel control strategy for an inverter-driven linear compressor system is proposed in which the overall electrical losses of a coupled inverter-linear motor system are reduced through the use of a modified square wave inverter modulation scheme to minimize inverter switching losses at the expense of a modest increase in conduction losses. The controller is based on a single-phase field-oriented control strategy, and to achieve the FOC control objectives, the fundamental and dc components of the applied square wave voltage are matched to the corresponding values requested by the current controller. To validate the efficiency improvements offered by the square wave controller, the switching losses of a 4 kHz PWM control scheme were determined through empirical testing and the conduction losses of both a baseline PWM controller and the proposed square wave controller were quantified via simulation. The results showed that the square wave controller reduced the total electrical losses by 0.366 W at typical operating conditions for a household refrigerator.