A cycloconverter-excited, doubly-fed machine as a wind power converter.

The thesis describes a wind-energy transducer system based on a doubly-fed, slip-ring machine and a cycloconverter operating with continuous circulating current. A theoretical analysis and experimental verification of the system have been carried out with a simulated wind turbine. Points 1 to 8 list the points covered and work carried out: The author has: 1) Surveyed existing wind energy transducers connected to the grid. 2) Developed an original theory of the doubly-fed machine operating as a generator. 3) Modified the doubly-fed generator theory to allow the generator to generate power proportional to the cube of its speed. 4) Computed a field voltage control function necessary to maintain cube-law generation at optimum power coefficient. 5) Further developed the generator theory to show that constant current excitation greatly reduces the induction power and permits the economic selection of electronic devices. 6) Designed and implemented digital and analogue electronic systems to satisfy the requirements of points (3) and (4) and to operate the system at optimum efficiency. 7) Successfully applied the cycloconverter, divided winding principle to the doubly-fed generator to provide a system able to withstand shock wind gusts over a wide-speed range. 8) Discussed the extrapolation of the system to large powers.