Real-time vector-based open-circuit fault diagnosis scheme for three-phase dual active bridge converter
Various examples are provided related to fault detection of power converters. In one example, a method includes sensing phase currents of a three-phase transformer; determining a centroid vector in an alpha-beta stationary reference frame based upon averaged values of the sensed phase currents; identifying a fault on a side of the transformer based upon a location of the centroid vector within the alpha-beta stationary reference frame, the location defined by a magnitude and an angle of the centroid vector; and adjusting operation of the power converter in response to the identified fault. In another example, a power converter includes a three-phase transformer connected between primary and secondary side three-phase bridges and control circuitry that can determine a centroid vector based upon sensed phase currents; identify a fault on a side of the three-phase transformer; and adjust operation of the power converter in response to the identified fault.
1 . A method for fault diagnosis, comprising:
sensing phase currents on a single side of a three-phase transformer of a power converter;
determining a centroid vector in an alpha-beta stationary reference frame based upon averaged values of the sensed phase currents;
identifying a fault on a primary side or a secondary side of the three-phase transformer based upon a location of the centroid vector within the alpha-beta stationary reference frame, the location defined by a magnitude and an angle of the centroid vector; and
adjusting operation of the power converter in response to the identified fault.
2 . The method of claim 1 , wherein the alpha-beta stationary reference frame is divided into a plurality of regions, each region associated with a no-fault condition or a fault in a corresponding primary side switching device or a corresponding secondary side switching device.
3 . The method of claim 2 , wherein the plurality of regions comprises a central region associated with the no-fault condition, 6 regions each associated with one of the primary side switching devices and 6 regions each associated with one of the secondary side switching devices.
4 . The method of claim 2 , wherein the alpha-beta stationary reference frame is divided into six 60-degree sectors, each 60-degree sector comprising a first region associated with one of the primary side switching devices and a second region associated with one of the secondary side switching devices.
5 . The method of claim 4 , wherein the first region and the second region are separated based upon a defined magnitude of the centroid vector.
6 . The method of claim 1 , wherein the phase currents are sensed on only one side of the three-phase transformer.
7 . The method of claim 1 , wherein the phase currents are sensed on only a low current side of the three-phase transformer.
8 . The method of claim 1 , wherein the sensed phase currents are filtered to generate averaged values.
9 . The method of claim 1 , wherein the fault is identified within 3 or 4 switching cycles of the power converter.
10 . A power converter, comprising:
a three-phase transformer connected between a primary side three-phase bridge and a secondary side three-phase bridge; and
control circuitry configured to:
determine a centroid vector in an alpha-beta stationary reference frame based upon averaged values of phase currents sensed on a side of the three-phase transformer;
identify a fault on a primary side or a secondary side of the three-phase transformer based upon a location of the centroid vector within the alpha-beta stationary reference frame, the location defined by a magnitude and an angle of the centroid vector; and
adjust operation of the power converter in response to the identified fault.
11 . The power converter of claim 10 , wherein the alpha-beta stationary reference frame is divided into a plurality of regions, each region associated with a no-fault condition or a fault in a corresponding primary side switching device or a corresponding secondary side switching device.
12 . The power converter of claim 11 , wherein the plurality of regions comprises a central region associated with the no-fault condition, 6 regions each associated with one of the primary side switching devices and 6 regions each associated with one of the secondary side switching devices.
13 . The power converter of claim 11 , wherein the alpha-beta stationary reference frame is divided into six 60-degree sectors, each 60-degree sector comprising a first region associated with one of the primary side switching devices and a second region associated with one of the secondary side switching devices.
14 . The power converter of claim 13 , wherein the first region and the second region are separated based upon a defined magnitude of the centroid vector.
15 . The power converter of claim 10 , wherein the phase currents are sensed on a single side of the three-phase transformer.
16 . The power converter of claim 15 , wherein the phase currents are sensed on only a low current side of the three-phase transformer.
17 . The power converter of claim 16 , comprising current sensors on the low current side of the three-phase transformer without having current sensors on a high current side of the three-phase transformer.
18 . The power converter of claim 10 , wherein the sensed phase currents are filtered to generate averaged values.
19 . The power converter of claim 10 , wherein the fault is identified within 3 or 4 switching cycles of the power converter.