State estimation system and state estimation method for semiconductor device for power conversion

A state estimation system of a power conversion semiconductor device according to an embodiment includes an analysis processing unit and an estimation processing unit. The analyzing and processing part is used for a semiconductor device for power conversion, which is provided with a pair of main terminals. On the basis of first time history data of the voltage between the pair of main terminals detected when the pair of main terminals is biased in the forward direction and when the pair of main terminals is biased in the reverse direction, and second time history data of the detection values of both the forward current and the reverse current between the pair of main terminals, the voltage between the pair of main terminals is detected. Points representing a group of a voltage detection value in the first time history data and a current detection value in the second time history data are projected on a coordinate plane including a voltage axis and a current axis, and a distribution of the points projected on