Patent ID: 9604543
Date: 2017-03-28
CPC Classifications: B60L,G01R,H02H,H02M,H02P,Y02T

Claim:
1. A method for identifying a suspected ground fault location in a multi-drive system having a plurality of drives, the method comprising: using at least one processor, while a given drive is operating, determining whether an operating frequency of the given drive is within a range including a fault frequency corresponding to a detected ground fault condition in the system; and using the at least one processor, selectively identifying the given drive as a suspected ground fault location if the operating frequency of the given drive is within the range including the fault frequency, wherein selectively identifying the given drive comprises: using the at least one processor, identifying a set of drives in the multi-drive system operating at corresponding frequencies within the range including the fault frequency; if the set includes a single drive, selectively identifying the single drive as a ground fault location in the system; and if the set includes more than one drive, using the at least one processor: (i) changing an operating frequency of a single selected drive in the set while any remaining drives in the set continue operation at their respective current operating frequencies, (ii) selectively identifying the single selected drive as a ground fault location in the system if the fault frequency changes by more than a threshold amount in response to changing the operating frequency of the single selected drive, (iii) selectively confirming the single selected drive is not a ground fault location if the fault frequency does not change by more than the threshold amount in response to changing the operating frequency of the single selected drive, and (iv) selectively repeating steps (i)-(iii) for the remaining drives in the set.