Analysis and control of photovoltaic-assisted three-phase induction machine operating as single-phase micro-wind generator

An improved control methodology for off-grid, three-phase induction machine working as a single-phase generator is presented in this study. A three-phase machine made to work as a single-phase generator has advantages of lower size and cost than their single-phase equivalent in almost all ratings except in the lower fractional kilowatt (kW) ranges. The three-phase windings are configured as isolated two equivalent phases in the proposed system for this purpose. The machine uses photovoltaic (PV)-assisted single-phase inverter to one of its two phases for variable excitation requirement to cater dynamic loads at different rotor speeds besides having a fixed capacitor to provide bulk excitation. A storage battery is used along with the PV panels to improve the reliability of the scheme during low or no insolation periods. A stator-flux-oriented control is implemented for regulating the terminal voltage within specified limit at a fixed frequency. The control strategy ensures fixed load voltage and fixed frequency even with perturbations of load or rotor speed. Different simulation results, verified by suitable experiments using a 1 kW, 415 V laboratory prototype, confirm the suitability of the proposed concept.