Exact coupled three-phase evaluation with a free star point

Derive an exact coupled three-phase evaluation of reconfigurable battery systems with a free star point, replacing the zeroth-order analysis that removes triplen harmonics from independently evaluated single-string spectra.

Background

The three-phase results use a zeroth-order approximation: triplen orders are removed from exactly computed single-string spectra, the phase patterns are shifted by one third of a period, and feedback from phase coupling is neglected.

Because the star point is allowed to shift and the phase currents are coupled in a three-wire star-connected system, an exact evaluation could change the predicted harmonic distribution and the optimization results. The paper explicitly leaves this coupled analysis unresolved.