Series parallel transition for power supply

In combination:

• (a) a pair of d-c load buses;
• (b) rectifying means having at least first and second legs interconnected in parallel circuit relationship between said buses, each of said legs comprising first, second, third, and fourth unilaterally conducting devices connected in series with one another and polled to conduct current in a direction from one of said buses to the other;
• (c) an a-c power supply comprising at least first and second separate windings so arranged that in-phase alternating voltages of equal amplitudes are respectively generated therein;
• (d) means for connecting said first winding between a point between the first and second devices of said first rectifier leg and a point between the corresponding devices of said second rectifier leg and for connecting said second winding between a point between the third and fourth devices of said first rectifier leg and a point between the corresponding devices of said second leg, whereby said windings are effectively connected in parallel between said buses;
• and
• (e) means for interconnecting the respective junctures of the second and third devices in all of the legs of said rectifying means, said interconnecting means having open circuit and closed circuit states between which it is selectively switchable in response to transition command signals and being effective upon switching from open to closed circuit states to short circuit said junctures, whereby the connection of said first and second windings can be changed from parallel to series.