Authors: Marco Liserre, Giampaolo Buticchi, Jose Ignacio Leon, Abraham M. Alcaide, Vivek Raveendran, Youngjong Ko, Markus Andresen, Vito G. Monopoli, Leopoldo Franquelo
Currently, the necessity of efficient and reliable power systems is increasing because of the strict requirements that standards and regulations impose, but still costs have to remain low. The monitoring and control of the components lifetime can lead to reduce the maintenance costs. However, overcoming the related challenges is not a straightforward task, as it involves knowledge of power device physics, smart management of electrical quantities, and optimal maintenance planning and scheduling. It represents a multidisciplinary issue being faced in the last decade.
In this work, a new paradigm is proposed: the power routing for the maintenance scheduling. Power routing is the control technique for which each module building up a modular power converter processes a different amount of power or faces a different voltage/current stress combination. In this way, it is possible to relieve the stress from some parts of the power converter and shift it to other parts. Coupled with state-of-health detection algorithms for the power modules and the capacitor, the power routing is the tool that allows having the time of failure as the controlled variable. This opens up limitless possibilities in terms of maintenance scheduling: the power can be routed away from the modules which will not be substituted at the next planned maintenance even in order to “use up” the remaining lifetime of the modules that will be substituted anyways. The failure of some clusters of power cells can be “grouped” together in order for them to be replaced at the same time, reducing the overall number of maintenance events, and so on.
In order to leave the performance of the converter unchanged in terms of harmonic distortion when the power routing is performed, a series of control techniques should be implemented. Among them, discontinuous modulation or the variable carrier phase-shift pulse width modulation have been demonstrated to be extremely effective.