Dc-dc converter and power supplying system using same

A DC-DC converter comprising:

• a first input-output circuit;
• first and second capacitors connected in series;
• a second input-output circuit connected to the first and second capacitors;
• a switching part, responsive to switching signals comprising:
• a first diode configured to connect a positive side terminal of the first input-output circuit to a positive terminal of the first capacitor and a positive side terminal of the second input-output circuit;
• a first switch configured to connect the positive side terminal of the first input-output circuit to a negative terminal of the first capacitor and a positive terminal of the second capacitor;
• a second switch configured to connect a negative side terminal of the first input-output circuit to the negative terminal of the first capacitor and the positive terminal of the second capacitor;
• and
• a second diode configured to connect the negative side terminal of the first input-output circuit to a negative terminal of the second capacitor and the negative side terminal of the second input-output circuit;
• a voltage detector to detect voltages across the first and second capacitors and a voltage through the first and second capacitors;
• and
• a control circuit part configured to generate the switching signals control on the basis of the voltage through the first and second capacitors, calculate a difference between the voltages across first and second capacitors and controls a duty ratio of at least one of the switching signals on the basis of the difference so as to decrease the difference.

A DC-DC converter comprising:

• a first input-output circuit;
• first and second capacitors connected in series;
• a second input-output circuit connected to the first and second capacitors;
• a switching part, responsive to switching signals comprising:
• a first switch configured to connect a positive side terminal of the first input-output circuit to a positive terminal of the first capacitor and a positive side terminal of the second input-output circuit;
• a first diode configured to connect the positive side terminal of the first input-output circuit to a negative terminal of the first capacitor and a positive terminal of the second capacitor;
• a second diode configured to connect the negative terminal of the first capacitor and the positive terminal of the second capacitor to a negative side terminal of the first input-output circuit to;
• and
• a second switch configured to connect the negative side terminal of the first input-output circuit to a negative terminal of the second capacitor and the negative side terminal of the second input-output circuit;
• a voltage detector to detect voltages across the first and second capacitors and a voltage through the first and second capacitors;
• and
• a control circuit part configured to generate the switching signals control on the basis of the voltage through the first and second capacitors, calculate a difference between the voltages across first and second capacitors and controls a duty ratio of at least one of the switching signals on the basis of the difference so as to decrease the difference.