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

Claim 5:
6. An electric propulsion system comprising:
a battery pack comprising a plurality of strings of battery modules;
a busbar connected to receive DC power from the battery pack;
a power line connected to receive DC power from the busbar;
a motor controller comprising power switches which are connected to receive DC power from the power line and configured to convert the DC power to AC power;
an AC motor connected to receive the AC power from the motor controller;
one or more first current sensors connected to sense a first current supplied by the battery pack to a first end of a protection zone that includes at least a portion of the power line and configured to output first sensor data representing a magnitude of the first current;
a second current sensor connected to sense a second current supplied to the motor controller at a second end of the protection zone and configured to output second sensor data representing a magnitude of the second current; and
a differential protection control module connected to receive the first and second sensor data, wherein the differential protection control module is configured to perform operations comprising:
(a) calculating a current difference equal to a difference between the magnitude of the first current and the magnitude of the second current;
(b) determining that the current difference exceeds a difference threshold indicating a fault in the protection zone; and
(c) commanding the electric propulsion system to operate in a mode that isolates the fault in response to operation (b) by changing states of the power switches in the motor controller to short the AC motor, thereby blocking current regenerated by the AC motor from reaching the power line.