The present invention provides an apparatus and methods for providing constant voltage from a permanent magnet generator at varying prime mover speeds or under varying loads. A constant voltage permanent magnet generator includes a housing, a magnetized rotor, a prime mover operationally coupled with the rotor, a stator, a main winding coupled to the stator, and an excitation winding also coupled to the stator. A controllable three-phase inverter may be coupled to the excitation winding and a control system operationally coupled to the main winding for measuring the voltage of the main winding. The control system is further operationally coupled between the power source and the controllable three phase inverter to provide a supplemental current to the excitation winding such that a combined current through the main winding and the excitation winding produces a constant voltage from the generator.