Current detection device and power conversion device for power device

Abstract

The present invention improves a problem associated with the acquisition of loss data and accurately estimates, from a sense current, main current flowing through a power device. This power device current detection device is characterized in that a circuit for detecting the current of a power device mounted with a power semiconductor having a main element, a current detection sense element, and a temperature detection temperature-sensitive element comprises: a sense element temperature estimation unit for estimating, on the basis of the output of the temperature-sensitive element, a sense element temperature that is the temperature of the sense element; a reference temperature acquiring unit for acquiring the reference temperature of the power device; a main element temperature estimation unit for estimating, on the basis of the sense element temperature and the reference temperature, a main element temperature that is the temperature of the main element; and a main current estimation unit for estimating, on the basis of a sense current value detected by the sense element, the sense element temperature, and the main element temperature, a main current value flowing through the main element. The main element temperature estimation unit uses a thermal impedance ratio that is the ratio between the mutual thermal impedance of the sense element with respect to the heat generation of the main element and the self-thermal impedance of the main element to estimate the main element temperature.