Patent ID: 7538426

Claim:
A cooling system of a power semiconductor module, comprising: a fluid flow path through which a cooling fluid to cool a power semiconductor module is circulated; a cooling fluid pressurizing unit which pressurizes the cooling fluid and supplies it to the fluid flow path; a drive unit to drive the cooling fluid pressurizing unit; a temperature detection unit provided in a semiconductor element as a heat source provided in the power semiconductor module; a control unit which estimates a change of a heat transfer coefficient from the power semiconductor module to the cooling fluid based on output information of the temperature detection unit and drive output information of the drive unit to drive the cooling fluid pressurizing unit, and controls cooling capacity of the cooling fluid according to an estimated result; a cooling fluid temperature detection unit to detect temperature of the cooling fluid; and a judgment unit which performs, based on a value of fluid temperature detected by the cooling fluid temperature detection unit, an arithmetic operation to estimate temperature of a heat transfer surface where the power semiconductor module comes in contact with the cooling fluid, and compares an estimated value of the temperature of the heat transfer surface with a value of boiling point of the cooling fluid.