Patent ID: 11878594
Assignee: THE BOEING COMPANY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC B  H  G  Y | IPC B  G

Claim 17:
18. A method for protecting an electric propulsion system, the method comprising:
(a) sensing a DC current supplied by a battery pack at a first end of a protection zone that includes at least a portion of a power line that is connected to receive DC current from the battery pack and supply DC current to a motor controller;
(b) sensing AC currents supplied to an AC motor by the motor controller at a second end of the protection zone;
(c) sensing a DC voltage at the first end of the protection zone;
(d) sensing AC voltages at the second end of the protection zone;
(e) receiving sensor data representing a magnitude of the DC current sensed in step (a);
(f) receiving sensor data representing magnitudes of the AC currents sensed in step (b);
(g) receiving sensor data representing a magnitude of the DC voltage sensed in step (c);
(h) receiving sensor data representing magnitudes of the AC voltages sensed in step (d);
(i) calculating an integrated power difference based on the magnitudes received in steps (e) through (h) at a succession of instants during a window of time and a magnitude of power losses inside the motor controller, wherein the integrated power difference is derived by integrating a difference between a first power at the first end of the protection zone and a second power at the second end of the protection zone minus the power losses;
(j) determining that the integrated power difference exceeds an integrated difference threshold indicating a fault in the protection zone;
(k) commanding the electric propulsion system to operate in a mode that isolates the fault in response to step (j); and
(l) operating the electric propulsion system in a mode that isolates the fault,
wherein steps (e) through (k) are performed by a differential protection control module, and
wherein step (l) comprises changing states of power switches in the motor controller to short an AC motor connected to the motor controller, thereby blocking current regenerated by the AC motor from reaching the power line.