This paper reports a large-scale eddy-current analysis of conductive frame of large-capacity inverter. The eddy-current loss obtained by the electromagnetic field analysis is used as a heat source for the thermal analysis. Then, the suitable configuration of the frame for the suppression of temperature increase is investigated and designed. The hybrid finite-element and boundary-element (FE-BE) method is very suitable for the analysis of a complicated-shaped frame because it does not require mesh division for a free space and can easily treat eddy current. For the reduction of large computational costs, the fast multipole method (FMM) is introduced. Furthermore, in order to improve the convergence characteristic of iterative methods for system matrix, we develop the application of the IDR(s) method to the minor iterative preconditioning technique (MIP) and evaluate the performance. Finally, some numerical results that demonstrate the effectiveness of the developed method are presented.