Finite-element (FE) analysis of winding losses in electrical machines can be computationally uneconomical. Computationally lighter methods often place restrictions on the winding configuration or have been used for time-harmonic problems only. This paper proposes a domain decomposition-type approach for solving this problem. The slots of the machine are modeled by their impulse response functions and coupled together with the rest of the problem. The method places no restrictions on the winding and naturally includes all resistive ac loss components. The method is then evaluated on a 500-kW induction motor. According to the simulations, the method yields precise results 70-100 faster compared with the established FE approach.