Apparatus for power conversion are provided. One apparatus includes a power converter including an input circuit and an output circuit. The power converter is configured to receive power from a source for providing power at a DC source voltage VS. The power converter is adapted to convert power from the input circuit to the output circuit at a substantially fixed voltage transformation ratio KDC=VOUT/VIN at an output current, wherein VIN is an input voltage and VOUT is an output voltage. The input circuit and at least a portion of the output circuit are connected in series across the source, such that an absolute value of the input voltage VIN applied to the input circuit is approximately equal to the absolute value of the DC source voltage VS minus a number N times the absolute value of the output voltage VOUT, where N is at least 1.