Control of inverter-assisted single-phase induction generators

This thesis investigates the problem of producing power using a single-phase induction machine. Single-phase induction motors are typically nonsymmetric two-phase motors, also called split-phase motors, with a main winding and an auxiliary winding. We consider the control of power delivered by the main winding through the auxiliary winding. A state-space model of an asymmetric split-phase generator has been developed. This model is used to characterize and identify a 1/3 hp induction machine. The parameters are used to predict suitable operating regions for the generator. It is found that there exists a viable operating region in a band just above the synchronous speed of the motor. Four control algorithms are presented. The first is a simple open-loop algorithm for a sinusoidal reference signal. The second is a controller based on the inverse-G adaptive algorithm. The third is an algorithm featuring an adaptive estimate of the system frequency response. Finally, a PI control method is considered for situations where the phase of the generated voltage does not need to be controlled. Simulated and experimental results are presented for each of the control algorithms. The closed-loop algorithms were able to track a desired reference. These algorithms were also able to reject a disturbance caused by a 20 percent increase in speed.