Embodiments of a ground power unit are disclosed for providing power to a grounded vehicle, such as an aircraft. In accordance with certain embodiments, the ground power unit (GPU) accepts a wide range of AC input voltages and is capable of providing a range of DC output voltages. The GPU may include a switched rectifier that converts an AC input signal to a DC link signal. The DC link signal is then converted to a switched DC signal that simulates an AC-like sine wave using a high frequency DC-to-DC switching converter. A single-phase transformer modulates and isolates the switched DC signal, which is subsequently converted to a DC output signal using diode rectifiers coupled to the secondary winding of the transformer. The disclosed GPU may be controlled using a software-based control algorithm that controls the AC input parameters independently of the DC voltage parameters.