Ground fault detection system and method

A system comprising:

• a power system having a DC link, a battery bank selectively connectable to the DC link, a link capacitor unit connected to the DC link, and power converters connected to the DC link, the power converters configured to convert first DC power from the DC link to at least one of AC power or second DC power for powering at least one electrical load;
• and
• a control unit operably connected to the power system, wherein the control unit is configured to:
• determine a ground fault based on a comparison of a first DC component of a sensed voltage signal between a terminal of the DC link and a chassis or other electrical ground to a first designated DC threshold, and responsive to detection of the ground fault, compare a second DC voltage component of the DC link to a second threshold, and identify the ground fault as a DC ground fault responsive to the second DC voltage component being greater than the second threshold;
• determine an AC ground fault based on a comparison of a first AC component of the sensed voltage signal to a first designated AC threshold;
• responsive to determination of the AC ground fault or the DC ground fault, to disconnect the battery bank from the DC link and deactivate operation of the power converters;
• and
• responsive to the determination of the AC ground fault, to sequentially at least partially activate, with power from the link capacitor unit, each of the power converters individually until a second DC component of the sensed voltage signal is indicative of the AC ground fault being associated with a first power converter of the power converters.

A method comprising:

• disconnecting, by a control unit operably connected to a power system, a battery bank of the power system from a DC link of the power system responsive to detection of a ground fault by the control unit;
• deactivating operation of power converters that convert power from the DC link for operation of at least one load of the power system;
• sequentially at least partially activating, by the control unit, with power from a link capacitor unit of the power system, each of the power converters individually until a sensed voltage signal of the DC link is indicative of the ground fault being associated with a first power converter of the power converters, wherein the sensed voltage signal comprises a first DC voltage component of the DC link after sequential individual activation of the first power converter, and the control unit is configured to determine that the sensed voltage signal is indicative of the ground fault being associated with the first power converter responsive to the first DC voltage component being greater than a first designated threshold;
• responsive to the detection of the ground fault, comparing, by the control unit, a second DC voltage component of the DC link to a second threshold;
• and
• identifying, by the control unit, the ground fault as a DC ground fault responsive to the second DC voltage component being greater than the second threshold.

A method comprising:

• determining, by a control unit operably connected to a power system, a DC ground fault based on a comparison of a first DC component of a sensed voltage signal between a terminal of a DC link and a chassis or other electrical ground to a first designated DC threshold;
• determining, by the control unit, an AC ground fault based on a comparison of a first AC component of the sensed voltage signal to a first designated AC threshold;
• responsive to determination of the AC ground fault or the DC ground fault, disconnecting, by the control unit, a battery bank from the DC link and deactivating operation of power converters of the power system that covert power from the DC link for operating at least one load of the power system;
• and
• responsive to the determination of the AC ground fault, sequentially at least partially activating, by the control unit, with power from a link capacitor unit of the power system, each of the power converters individually until a second DC voltage component of the sensed voltage signal is indicative of the AC ground fault being associated with a first power converter of the power converters, wherein the second DC voltage component of the DC link is compared to a second threshold, and identified the AC ground fault responsive to the second DC voltage component being greater than the second threshold.