High efficiency DC/DC current source converter

A converter accepting DC current from a DC current source to supply power to a load, comprising:

• (a) a transformer having a highly coupled primary and secondary;
• (b) a first controllable switch connected in series with the primary;
• (c) a second controllable switch connected in parallel with the series combination of the first switch and the primary and connectable to the current source to bypass the current from the current source therethrough when the second switch is closed;
• (d) resistance connected in parallel with the first and second switches;
• (e) rectifying means connected to the secondary for rectifying the output of the secondary to provide unidirectional current;
• (f) an energy storage capacitor connected across the rectifying means, the voltage across the capacitor comprising the output voltage of the converter for supply to the load;
• and
• (g) control means for controlling the switching of the first and second switches to alternately open and close to maintain a controlled voltage across the energy storage capacitor.

A method of controlling a DC current to DC voltage converter of the type receiving current from a current source and having a transformer with a closely coupled primary and secondary, a first switch connected in series with the primary, a second switch connected in parallel with the series connected first switch and the primary, a rectifying device for rectifying the output of the secondary, and an energy storage capacitor connected to receive the unidirectional current from the rectifying device, with the output voltage of the converter being taken across the energy storage capacitor, comprising the steps of:

• (a) initially closing the second switch to cause the current from the current source to bypass the primary;
• (b) closing the first switch and opening the second switch to cause the current from the current source to pass into the primary and to provide an output from the secondary which charges up the voltage across the energy storage capacitor;
• (c) when the voltage across the capacitor reaches a selected minimum voltage level, closing the second switch and opening the first switch to bypass the current from the current source through the second switch;
• (d) when the voltage across the capacitor reaches the selected minimum voltage level, closing the first switch and opening the second switch to provide the current from the current source through the primary;
• (e) then repeating steps (c) and (d) in a repetitive cycle for as long as power is to be provided from the converter to the load.