Tachometer for Low-Speed AC Generator

A generator system, comprising:

• a multi-phase stator;
• a rotor rotatably disposed within the stator, the rotor having a plurality of poles configured to electromagnetically interact with the stator and induce a phase signal in each phase while rotating relative to the stator;
• a plurality of zero-cross detectors in communication with the phase signals, the zero-cross detectors being configured to generate pulse signals responsive to zero-crossings detected in each filtered signal;
• and
• a logic circuit in communication with each zero-cross detector, the logic circuit being configured to receive the pulse signals, logically combine the pulse signals into a combined signal, and generate a tachometer signal based on the combined signal, the tachometer signal corresponding to a rotational speed of the generator.

A method of determining a rotational speed of a generator, comprising the steps of:

• receiving a phase signal from each phase of the generator;
• generating a pulse signal based on zero-crossings detected in each phase signal;
• logically combining the pulse signal from each phase into a combined signal;
• generating a tachometer signal based on the combined signal;
• and
• calculating the rotational speed of the generator based on the tachometer signal, the number of phases, and the number of poles of the generator.