Patent ID: 7764089

Claim:
A device for driving switching elements comprising: a DC power source; first and second switching elements connected in series to the DC power source to be alternately turned on and off; an electric load connected between a junction of the first and second switching elements and DC power source; and first and second control circuits connected respectively to control terminals of the first and second switching elements; the first control circuit comprising: a control DC power source; a first series circuit which includes a first resistor and a first control switching element connected in series to the control DC power source; a second series circuit which includes a second resistor and a second control switching element connected in parallel to the first series circuit and in series to the control DC power source; a drive signal generator for forwarding drive signals for each control terminal of the first and second control switching elements; a drive circuit for forwarding drive signals for a control terminal of the first switching element depending on potentials in the first and second series circuits; and a potential detector; wherein the first series circuit comprises a third resistor connected between the first resistor and first control switching element; the second series circuit comprises a fourth resistor connected between the second resistor and second control switching element; the potential detector provides drive circuit with signals in response to differences among potentials at junctions of first and third resistors, third resistor and first control switching element, second and fourth resistors and fourth resistor and second control switching element; the potential detector comprises first and second potential detectors; the first potential detector comprises a first comparator for comparing a potential at a junction of the first and second resistors with a potential at a junction of the fourth resistor and second control switching element; and the second potential detector comprises a second comparator for comparing a potential at a junction of the second and fourth resistors with a potential at a junction of the third resistor and first control switching element.