Digital integrators for condition monitoring: a DC and multitone signal analysis

The digital implementation of the integral operator is a delicate part in electrical drives. Many solutions are available in the literature, which avoid the well-known output drift of ideal digital integrators when a spurious DC offset is present at their input. Such solutions try to extend the integration accuracy toward the zero frequency as well, aiming to broaden their usability range for real applications (low-speed region of electrical machines, for example). So far, very few investigations have been performed as regards to the performances of driftfree integrators for cases where the integration is used within estimation and conditioning monitoring algorithms. This paper aims to investigate different known digital offset-free integrals, in terms of their output accuracy with respect to DC and multitone input signals, for a specific application where they could be exploited for condition monitoring. Simulation and experimental results are presented as well.