This paper investigates a new approach to face the problem of dynamic hysteresis and extra-losses in soft magnetic materials. Thanks to a spatial averaging technique and a variational principle, a dedicated formulation is derived. It takes microscopic magnetization mechanisms and domain wall motion-induced Joule losses into account. Implementation with the finite element method is discussed and first simple two dimensions and three dimensions calculations are carried out. The method is shown to be suitable within the linear dynamic approximation and far from saturation, which only requires additional non linear properties and numerical methods