Patent ID: 7558094

Claim:
A control device for controlling a power conversion circuit including voltage-controlled type switching elements, comprising: a control unit generating conduction control signals for controlling conduction states of said switching elements in accordance with an external command; and a driver circuit applying a conduction control terminal of each of said switching elements with one of a first voltage having a value to turn on said switching elements and a second voltage having a value to turn off said switching elements in accordance with said conduction control signals; wherein said control unit includes a first function of estimating whether or not power loss of said switching elements is larger than a certain value on the basis of sensor signals received from external sensor monitoring said power conversion circuit or an electric load supplied with electric power from said power conversion circuit, and said driver circuit is configured to change at least one of said value of said first voltage and said value of said second voltage so that a voltage difference between said first and second voltages becomes large when said first function estimates that said power loss of said switching elements is larger than said certain value.