  In this paper, Multirate Partial Differential Equations (MPDEs) are used for
the efficient simulation of problems with 2-level pulsed excitations as they
often occur in power electronics, e.g., DC-DC switch-mode converters. The
differential equations describing the problem are reformulated as MPDEs which
are solved by a Galerkin approach and time discretization. For the solution
expansion two types of basis functions are proposed, namely classical Finite
Element (FE) nodal functions and the recently introduced excitation-specific
pulse width modulation (PWM) basis functions. The new method is applied to the
example of a buck converter. Convergence, accuracy of the solution and
computational efficiency of the method are numerically analyzed.
