A system comprising: an independent speed variable frequency (ISVF) generator; an excitation source configured to provide an excitation signal to field windings of a rotor of the ISVF generator to produce a rotating magnetic flux that is independent of a shaft speed of the ISVF generator; a bus configured to receive an output voltage of the ISVF generator; and a generator control unit configured to: generate a first excitation voltage reference component based on a shaft frequency of the ISVF generator; generate a second excitation voltage reference component based on a difference between a reference voltage and a measured output voltage of the ISVF generator; generate an excitation voltage control signal based on a combination of the first excitation voltage reference component and the second excitation voltage reference component, the excitation voltage control signal usable to control a voltage magnitude of the excitation signal; and generate an excitation phase angle control signal based on an excitation phase angle reference, the excitation phase angle control signal usable to control a phase angle of the excitation signal, wherein the generator control unit is further configured to: determine the first excitation voltage reference component from the shaft frequency using a lookup table that maps shaft frequency values to excitation voltage reference values that, when applied to the ISVF generator, result in the output voltage at the ISVF generator having a constant magnitude for each of the shaft frequency values when the ISVF generator is in a no-load state, and is further configured to determine the second excitation voltage reference component to compensate for loaded conditions. an independent speed variable frequency (ISVF) generator; an excitation source configured to provide an excitation signal to field windings of a rotor of the ISVF generator to produce a rotating magnetic flux that is independent of a shaft speed of the ISVF generator; a bus configured to receive an output voltage of the ISVF generator; and a generator control unit configured to: generate a first excitation voltage reference component based on a shaft frequency of the ISVF generator; generate a second excitation voltage reference component based on a difference between a reference voltage and a measured output voltage of the ISVF generator; generate an excitation voltage control signal based on a combination of the first excitation voltage reference component and the second excitation voltage reference component, the excitation voltage control signal usable to control a voltage magnitude of the excitation signal; and generate an excitation phase angle control signal based on an excitation phase angle reference, the excitation phase angle control signal usable to control a phase angle of the excitation signal, wherein the generator control unit is further configured to: determine the first excitation voltage reference component from the shaft frequency using a lookup table that maps shaft frequency values to excitation voltage reference values that, when applied to the ISVF generator, result in the output voltage at the ISVF generator having a constant magnitude for each of the shaft frequency values when the ISVF generator is in a no-load state, and is further configured to determine the second excitation voltage reference component to compensate for loaded conditions. generate a first excitation voltage reference component based on a shaft frequency of the ISVF generator; generate a second excitation voltage reference component based on a difference between a reference voltage and a measured output voltage of the ISVF generator; generate an excitation voltage control signal based on a combination of the first excitation voltage reference component and the second excitation voltage reference component, the excitation voltage control signal usable to control a voltage magnitude of the excitation signal; and generate an excitation phase angle control signal based on an excitation phase angle reference, the excitation phase angle control signal usable to control a phase angle of the excitation signal, wherein the generator control unit is further configured to: determine the first excitation voltage reference component from the shaft frequency using a lookup table that maps shaft frequency values to excitation voltage reference values that, when applied to the ISVF generator, result in the output voltage at the ISVF generator having a constant magnitude for each of the shaft frequency values when the ISVF generator is in a no-load state, and is further configured to determine the second excitation voltage reference component to compensate for loaded conditions.