Patent ID: 8582335

Claim:
An inverter apparatus comprising: a direct-current power supply; high-potential side switching elements and freewheel diodes and low-potential side switching elements and freewheel diodes which are connected to the direct-current power supply; a unit which converts a direct current voltage into a predetermined alternating current voltage of a predetermined current and a predetermined frequency, depending on switching on/off of the high-potential side and low-potential side switching elements; a temperature sensor provided near at least one of the low-potential side switching elements; and a temperature estimation unit, wherein the temperature estimation unit estimates temperatures of the high-potential side switching elements by subtracting a temperature increase estimation value of said at least one of the low-potential side switching elements for which the temperature sensor is provided from a detected temperature of said at least one of the low-potential side switching elements, and then adding to a result of the subtraction a temperature increase estimation value of one of the high-potential side switching elements for which the temperature sensor is not provided, based on a loss model of the high-potential side and low-potential side switching elements and freewheel diodes, and a thermal resistance model of a module which fixes the high-potential side and low-potential side switching elements and freewheel diodes.