An electrical power supply system can include: at least one virtual air gap transformer; a heterodyning component configured to generate a corresponding heterodyned signal having frequency components corresponding to a sum and a difference of the first fundamental frequency and a reference frequency; a filtering component configured to filter a heterodyned signal to remove one of the sum and the difference frequency components therefrom and provide a corresponding filtered signal; an input port; and a control component configured: (i) to receive a signal and to generate a corresponding frequency control signal to determine a reference frequency of the heterodyning component such that the filtered signal has a target output frequency; and (ii) to receive a signal representing the first input voltage, and to generate a corresponding virtual air gap control signal to determine the electrical current in the control windings of the at least one virtual air gap transformer.