Low-frequency electromagnetic compatibility and interference (EMC/EMI) circuit simulations are often based on quasi-static, eddy-current approximations of Maxwell's system and require ad-hoc solvers to be employed. The need for relying on approximate physics stems from the instability of standard full-wave Maxwell solvers when the frequency decreases. The focus of this thesis has been to work on and extend a formulation capable of overcoming this limitation and performing exact modelling of circuits with a full-wave Maxwell solver. Based on the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) equation, this full-wave formulation is well-conditioned, stable and accurate over a broad frequency range. This result is obtained by exploiting primal and dual quasi-Helmholtz projectors that allow for an adequate frequency rescaling of the solenoidal and quasi-irrotational components of the system.