Design and development of a low speed AC generator for wind power applications

Wind power generators operate in an uncertain environment. Recent developments have been concentrated on the excitation systems of these machines. Various designs have been developed for both stand-alone supply to the excitation system as well as the control of output voltage. Since wind velocity is uncontrolled, some means of voltage regulation is necessary for such a system. This paper describes an AC generator that is particularly designed to operate in a wide speed range suitable for wind power applications. The generator uses both permanent magnet and current as field excitation. One part of the machine output is rectified and fed into the field excitation circuit. The two-field excitation systems work together to produce a constant voltage output at all speeds in the operating range. This design is robust and reliable; cost-effective in manufacture and operation.