A digital frequency control system for a variable speed alternator

A digital control system has been developed to control the frequency of an alternator operating at variable speeds. The power line frequency or a crystal controlled oscillator can be used as the reference frequency. The alternator output has a ±0.2 percent tolerance to the reference signal after the frequency control system was added. The frequency control of the alternator was accomplished by switching windings in the alternator field. The method is applicable to wind-powered alternators where the speed is variable and a constant 60 Hz output is desired.