  Despite its several qualities, the Poggio-Miller-Chang-Harrington-Wu-Tsai
(PMCHWT) formulation for simulating scattering by dielectric media suffers from
numerical instabilities and severe ill-conditioning at low frequencies. While
this drawback has been the object of numerous solution attempts in the standard
low-frequency breakdown regime for scattering problems, the eddy-current regime
requires a specific treatment. In this contribution, we present an extension of
the recently introduced quasi-Helmholtz projectors based preconditioning of the
PMCHWT to obtain an equation stable at low frequencies and specifically in
three regimes relevant for eddy currents analyses: (i) when the frequency
decreases with a constant conductivity, (ii) when the conductivity increases at
fixed frequency and (iii) when the frequency decreases while keeping the
product of the frequency and the conductivity constant. Being based on
quasi-Helmholtz projectors our new strategy does not further degrade the
conditioning of the original equation and is compatible with existing fast
solvers. The resulting full-wave formulation is capable of smoothly
transitioning from simulations at high frequencies to the different
low-frequency regimes which encompass, in particular, eddy currents
applications. Numerical results demonstrate the validity of our approach in all
the regimes with a special emphasis given to eddy currents.
