A method for controlling a switching power converter which includes a
central capacitor exchanges charge between the capacitor and plural nodes
of a first terminal, and then transfers the charge between the capacitor
and plural nodes of a second terminal. The charge interchanged between
the capacitor and the nodes establishes the amount of power transferred
during each cycle. The charge which is interchanged is controlled by
selecting the electrical phase between the currents drawn from the nodes
and the voltages at the nodes.