Patent ID: 11901809
Assignee: VESTAS WIND SYSTEMS A/S
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 0:
1. A method comprising:
driving a bypass current from an auxiliary power source through a plurality of bypass switches included in a corresponding plurality of cells;
in response to a summed voltage across a plurality of cell capacitors included in the plurality of cells satisfying a drive threshold, driving an insert current through a plurality of insert switches included in the plurality of cells; and
in response to a voltage across a DC link capacitor satisfying a pre-charge threshold when driving the insert current, opening a circuit breaker connecting the auxiliary power source with the plurality of cells and connecting a generator with external power line rails between which the DC link capacitor is connected,
wherein driving the bypass current includes tuning a rate at which individual bypass switches switch to equalize charges in the plurality of cell capacitors as the cell capacitors charge, and
wherein driving the insert current includes tuning a rate at which individual insert switches switch to equalize charges in the plurality of cell capacitors as the cell capacitors discharge, and
wherein the method further comprises:
while driving the bypass current, the insert current, or both, measuring a difference in voltage level of each of the cell capacitors of the plurality of cell capacitors; and
in response to the difference exceeding a difference threshold, stopping the auxiliary power source from charging the cell capacitors and the cell capacitors from charging the DC link capacitor.