Fault elimination in electrical systems with injected signal or voltage amplification

Abstract

A power supply system for providing power to a load connected between first and second connectors. The system includes a generator that produces alternating current and a rectifier that receives the alternating current and converts it to direct current and provides direct current between the first and second connectors. The system also includes a filter connected to the rectifier and between the connectors, which smooths the direct current output. The filter includes a center point configured to be connected to ground. The system also includes a fault neutralization source connected to the first connector that provides a neutralization voltage to the first connector when a ground fault occurs on the first connector. Figure 1

Description

Title of the invention: Elimination of faults in electrical systems with injected signal or voltage amplification Technical field

[0001] The subject matter disclosed herein relates generally to ground fault clearance and, more particularly, to fault clearance for electrical systems that may be used in airborne applications.

[0002] In typical electrical power generation and distribution systems, protection of the wiring, as well as connected equipment, is necessary in the event of a fault such as a ground fault. An aircraft is an illustrative example of application of these systems.

[0003] For aircraft systems, electrical power is essential to continued flight when it comes to fly-by-wire controls, and it is also essential to flight for electrically driven hydraulic pumps. Aircraft electrical power systems may utilize a variety of power supply characteristics, including alternating current (AC) or direct current (DC) systems. Other typical variations in power supply types may include power sources, loads, and distribution of nominal voltages, including, but not limited to, 28Vdc, 270Vdc, or 540Vdc, 115Vac, and 230Vac.

[0004] AC system types may also include constant frequency (CF) or variable frequency (VF) systems with a wide variation in output current and power rating. Severe wiring faults or internal faults in these systems and in the panels or wiring of the power distribution equipment can result in a loss of power for these flight-critical systems. Protective features and assemblies within power distribution systems enhance flight safety by preventing or minimizing the effect of system or wiring faults. Rapid detection and isolation, as well as separation of faults from ground circuits, are desirable due to localized heating and damage that high currents or arcing can cause. Summary

[0005] According to one embodiment, a power supply system for supplying power to a load connected between a first and a second connector is provided. The system comprises: a power source that produces a power output; a power converter that receives the output of the generator and converts it to a direct current output and supplies the direct current (DC) output between the first and the second connectors; a filter connected to the rectifier and between the connectors and which smooths the direct current (DC) output; and a fault neutralization source connected to the first connector which provides a neutralization voltage to the first connector when a ground fault occurs on the first connector. The neutralization voltage includes an identifiable characteristic

[0006] The identifiable characteristic may be a frequency, a square wave, a sine wave, a pulse, or any other distinctive and detectable pattern.

[0007] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source may be a battery.

[0008] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source is powered by the second connector.

[0009] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the power source is a direct current (DC) source and the power converter is a direct current to direct current (DC-DC) converter.

[0010] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the power source is an alternating current (AC) generator and the power converter is a rectifier that receives the alternating current from the generator and converts it to a direct current (DC) output and provides the DC output between the first and second connectors.

[0011] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the rectifier is a two-level active rectifier.

[0012] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the system may also include a contactor / SSPC connected to the first connector that may open and close to clear the fault while the fault override source provides the override voltage to the first contactor / SSPC.

[0013] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source is connected between the first connector and a ground.

[0014] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the mass is an aircraft structural mass.

[0015] The invention also relates to a power supply system for powering a load connected between the first and second connectors which, in addition to one of the above embodiments, comprises a second neutralizing source fault connected to the second connector that provides a second neutralization voltage to the second connector when a ground fault occurs on the second connector. In this embodiment, at least one of the first and second neutralization voltages includes an identifiable characteristic such as those described above.

[0016] According to one embodiment, a power supply system for supplying power to a load connected between a first and a second connector is provided. The system includes: a power source that produces a power output; a power converter that receives the output from the generator and converts it to a direct current output and provides the direct current (DC) output between the first and second connectors; a filter connected to the rectifier and between the connectors and that smooths the DC output; and a fault neutralization source connected to the first connector that provides a neutralization voltage to the first connector when a ground fault occurs on the first connector. The neutralization voltage increases over time.

[0017] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source may be a battery.

[0018] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source is powered by the second connector.

[0019] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the power source is a direct current (DC) source and the power converter is a direct current to direct current (DC-DC) converter.

[0020] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the power source is an AC generator and the power converter is a rectifier that receives AC from the generator and converts it to a DC output and provides the DC output between the first and second connectors.

[0021] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the rectifier is a two-level active rectifier.

[0022] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the system may also include a contactor / SSPC connected to the first connector that can open and close to clear the fault while the fault override source provides the override voltage to the first contactor / SSPC.

[0023] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the fault neutralization source is connected between the first connector and a ground.

[0024] In addition to one or more of the features described above, or as an alternative to one of the preceding embodiments, the mass is an aircraft structural mass

[0025] Also provided is a power supply system for powering a load connected between the first and second connectors which, in addition to one of the above embodiments, includes a second fault neutralization source connected to the second connector which provides a second neutralization voltage to the second connector when a ground fault occurs on the second connector. In this embodiment, at least one of the first and second neutralization voltages increases over time.

[0026] The above-mentioned features and elements may be combined in various ways, without exclusivity, unless expressly indicated otherwise. These features and elements and their operation will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are illustrative and explanatory in nature and are not limiting. Brief description of the figures

[0027] The foregoing and other features and advantages of the present disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0028] [Fig.l] represents a system in which the generator has its neutral connected to the system ground;

[0029] [Fig.2a]-2f show various currents and voltages in the system of [Fig.l] before and after a ground fault occurs in the positive, DC connector of the system;

[0030] [Fig. 3] illustrates a system that includes a filter having its low impedance midpoint grounded and that includes a fault neutralization source according to one embodiment;

[0031] [Fig.4a]-4f show various currents and voltages in the system of [Fig.3] before and after a ground fault occurs in the positive, DC connector of the system if the fault neutralizing source is not present;

[0032] [Fig.5a]-5f show various currents and voltages in the system of [Fig.3] before and after a ground fault occurs in the positive DC connector of the system with the addition of the fault neutralizing source;

[0033] [Fig.6] shows a system that includes a filter with its midpoint grounded and that includes fault neutralization sources connected to each DC connector of the system according to one embodiment;

[0034] [Fig.7a]-7c show high impedance ground systems at the midpoint of the rectifier that include a filter including fault neutralization sources connected to each DC connector of the system according to one embodiment; and

[0035] FIGS. 8a-8b show different ways of powering the fault neutralization sources according to one embodiment. Detailed description

[0036] Embodiments described herein relate to a system and method for providing a current used to neutralize or identify a ground fault in electrical systems. The system includes a current / voltage source that provides the current when one or more connectors or other elements of a DC power supply have a ground fault. The current / voltage sources may provide a ramped voltage, be current limited, and / or inject a time-varying signal to clear ground faults.

[0037] [Fig. 1] shows an exemplary grounded generator DC power generation system 100. The system 100 includes a power source 102, illustrated as a grounded generator in [Fig. 1] (generally represented as stator coils 104). As illustrated, the coils 104 are connected to each other at the neutral of the generator 106. As is common in the prior art, the neutral of the generator 106 is connected to ground. It is understood, however, that the generator 102 may be replaced by another power source of a different configuration.Thus, the DC power sources 102 and 108 could be a DC source with a DC to DC converter (DC / DC), a multi-phase generator with a suitable rectifier (e.g., a 12-phase generator with a 12-pulse parallel active rectifier), a 12-phase generator with a 12-pulse active rectifier.

[0038] The illustrated power source 102 produces three-phase alternating current and is connected to a passive rectifier 108. The rectifier 108 converts the alternating current to direct current. The rectifier 108 is shown as a full-wave passive rectifier. One skilled in the art will recognize that other types of rectifiers may be used in this and other embodiments described herein. For example, the rectifier could be a two-level active rectifier.

[0039] The output of rectifier 108 can generally be described as a direct current DC output and is presented across positive and negative connections 110, 112. The connections may be cables, rails, or other means of high-voltage power transmission. In [Fig.l], the voltage on these connections is indicated as Vpos and Vneg, respectively.

[0040] In some cases, the output of rectifier 108 is connected to an output filter 120 to smooth the output of rectifier 108 to provide a smoothed or otherwise more stable output across the positive and negative connections 110, 112. As illustrated, filter 120 is implemented by an output capacitor (or filter) 122 that is connected between the positive and negative rails 110, 112, but other types of filters are possible.

[0041] In normal operation, the smoothed output may be provided to a load 130. However, in some cases such as a fault, one or both of the positive and negative rails 110, 112 may be shorted to ground. This possibility is illustrated graphically by the ground fault connection 140. The connection is illustrated as a resistor, but it may be considered a short circuit in some cases. Such a fault may occur when, for example, the housing or other part of the output of the connection 110 is damaged and the current-carrying portion of the connection 110 may be directly connected to ground (e.g., to the structure of an aircraft). As illustrated, the fault occurs on the positive rail, but it could also occur on the negative rail, or in combination therewith.

[0042] FIGs. 2a-2f show several graphs of typical responses of the system of [Fig.l] to a ground fault. Typically, after detecting the fault, the current of an exciter or other control element of the generator is adjusted to reduce the ground fault current. Bus voltage

[0043] For illustration, note that the fault is modeled to occur at time 0.015 in [Fig.2a]-2f. As shown, the generator phase currents ([Fig.2a]) and DC currents ([Fig.2b]) can be very large until the control algorithm adjusts the exciter current to control the ground fault current ([Fig.2c]). The common mode voltage for this approach can be relatively large. In the example of [Fig.l], the fault is assumed to be in the positive rail 110 so that the voltage across it drops to nearly zero ([Fig.2d]) while the voltage between ground and the negative rail 110 ([Fig.2e]) and the negative bus voltage ([Fig.2f]) collapses to about half the nominal bus voltage for other loads.

[0044] After determining that the fault has occurred, the system 100 may perform a series of tests to identify the location of the fault. In particular, one or more contactors 150 may be opened or closed to identify where the short circuit occurred along the rails. This identification (or "neutralization") requires that current is supplied across rails 110, 112 so that the effect of opening or closing the contactors can be observed. Contactor 150 shown is normally closed during normal operation. As noted above, the fact that ground to negative ([Fig.2e]) can still carry a reduced bus voltage ([Fig.2f]) between rails 110, 112, means that a current source is available to perform these tests.

[0045] This approach provides a system capable of meeting the requirements for DC voltage transients, voltage ripple, and voltage distortion. This approach also provides the DC current required for fault clearance.

[0046] In some cases, it may be preferable to connect a low impedance to the generator / rectifier ground at a midpoint of the output filter. This is the case, for example, in high voltage situations (e.g., 540 V line-to-line voltage systems).

[0047] An example of such a system 300 is illustrated in [Fig. 3]. The system 300 illustrated in [Fig. 3] includes many of the same elements as the system 100. For completeness, a full description of the circuit of [Fig. 3] is provided and the differences between it and the circuit of [Fig. 1] are noted. In particular, the direct current electricity generating system 300 includes a generator 102 (generally represented by stator coils 104). Unlike in [Fig. 1], while the coils 104 are connected to each other at the generator neutral 106, the generator neutral 106 is not directly connected to ground.

[0048] Generator 102 produces three-phase alternating current and is connected to a rectifier 108. Rectifier 108 converts the alternating current to direct current. Rectifier 108 is shown as an uncontrolled full-wave rectifier. One skilled in the art will recognize that other types of rectifiers could be used in this and other embodiments disclosed herein.

[0049] The output of rectifier 108 can generally be described as a direct current output and is presented across positive and negative connections 110, 112. The connections may be cables, rails or other high voltage power transport means as in [Fig.l] and [Fig.3], the voltage across these connections is indicated as Vpos and Vneg, respectively.

[0050] Similar to [Fig.l], in [Fig.3] the output of rectifier 108 is connected to an output filter 302 to smooth the output of rectifier 108 to provide a smoothed or otherwise stable output across positive and negative connections 110, 112. As illustrated, filter 302 is implemented by two series-connected output capacitors 304, 306 that are connected to positive and negative rails 110, 112. The center point of output filter 302 (e.g., where capacitors 304, 306 are connected) is represented by node 310 and is connected to ground to create an output filter connected to the center point. The output capacitors 304, 306 include a first output capacitor 306 connected between connector 110 and ground (e.g., between Vpos and ground) and a second output capacitor 304 connected between connector 112 and ground (e.g., between Vneg and ground). In one embodiment, the ground is outside the generator 104. For example, the ground may be the structural ground of an aircraft.

[0051] Although a split capacitor output filter is illustrated, it is understood that other types of split filters or split bus configurations are possible to create the center point / node 310.

[0052] In normal operation, the smoothed output may be provided to a load 130. The load may be any element that requires current to operate. For example, the load may be an aircraft actuator in one embodiment. However, as noted above, in some cases, one or both of the positive and negative rails 110, 112 may be shorted to ground. This possibility is illustrated graphically by the ground fault connection 140. The connection is illustrated as a resistor, but it may be considered a short circuit in some cases. Such a fault may occur when, for example, the connection 110 has its housing or other production damaged and the load-bearing portion of the connection 110 may be directly connected to ground (e.g., to the structure of an aircraft).As shown, the fault occurs on the positive rail, but it could also occur on the negative rail, or in combination with it.

[0053] The circuit also includes a fault current source 350 which is described in more detail below. As will be seen later, the fault current source 350 provides current when a ground fault occurs to enable the system to clear the fault.

[0054] If fault current source 350 were not present, in the event of a ground fault (e.g., fault 140 is equivalent to a low impedance connection), system 300 of [Fig. 3] would behave as shown in [Fig. 4a]-4f. When fault 140 is a "short circuit" (in this case, and 0.015 s), it effectively couples connector 110 to ground. This results in a rapid increase in current through fault 140 ([Fig. 4c]) and an increase in current through the coils ([Fig. 4a]) and DC current at the rectifier output ([Fig. 4b]). The discharge of the shorted capacitor 304 is the source of the DC fault current ([Fig. 4c]). In general, the DC fault current shown does not contain enough energy to trip a circuit breaker.

[0055] As shown in [Fig.4c] and 4d, the current through the fault and the voltage between connector 110 (Vpos) and ground eventually fall to zero after a brief current surge across fault 140. Note that the voltage drop is not instantaneous and depends on the discharge time of the first output capacitor 304. Once this is discharged, Vpos effectively becomes system ground. It therefore cannot supply current to contactor 150 to clear the fault. In more detail, it is assumed that after the fault occurs, the system will meet the required DC voltage transient, voltage ripple, and voltage distortion requirements (see [Fig.4a]-4d). While this approach can provide a brief burst of DC current, it is not capable of providing the sustained current needed to clear the fault. After the initial current surge, the DC currents and generator phase currents ([Fig.4a], 4b) are similar to the pre-fault values.

[0056] As noted above, after the fault, Vpos becomes ground and therefore all of the generator output voltage is carried between connector 112 (Vneg) and ground as shown in [Fig.4e] and the bus voltage briefly decreases for other loads on the bus when the ground fault occurs as shown in [Fig.4f]. It is particularly interesting to note that once steady state is reached, there is no voltage on Vpos that can allow it to supply the current needed to clear the fault.

[0057] Embodiments presented herein include providing one or more current sources that can supply current after a ground fault. To this end, in [Fig. 3], the system 300 includes a fault neutralization source 350 connected to the first connector 110. A current blocking device 352 may be provided between the first fault neutralization source 350 and the first connector. The current blocking device 352 is illustrated as a diode in [Fig. 3], but other elements may be used as long as they allow current to flow from the current blocking device 352 to the connector experiencing the fault (here, the connector 110).

[0058] The fault neutralization source 350 may be located at other locations in the system. There could even be multiple fault neutralization sources (per rail) to provide redundancy.

[0059] The first fault neutralization source 350 may be, for example, a DC power source such as a battery, a DC power source connected to one of the two connectors 110, 112, or a DC power source connected to other connectors, to name a few. When the fault occurs, the voltage provided by the first fault neutralization source 350 will be higher than the voltage on the first connector. Thus, this voltage differential will allow current to be conducted through the current blocking device 352 and through the fault 140, which will clear the fault. However, in the absence of a fault, the voltage on the first connector 110 will be higher than the voltage supplied by the first fault neutralization source 350. Thus, the current blocking device 352 will not allow current to flow from the first fault neutralization source 350 to the first connector 110 and, therefore, will essentially isolate the first fault neutralization source 350 from the first connector. The different voltages / currents are illustrated in [Fig.5a]-5f for the system where the first fault neutralization source 350 provides a non-zero fault neutralization current after the fault occurs to clear the fault, as illustrated in [Fig.5c]. For simplicity, the fault neutralization current reference in [Fig.5c] is short-lived, as illustrated in [Fig.4c].However, the fault neutralization source period may be longer to allow downstream devices (tcb, sspc) to trip. This duration can range from a few seconds to one or more minutes.

[0060] As illustrated, the first fault neutralization source 350 is connected directly to the anode of the diode used as a current blocking device 352 and the cathode of the diode used as a current blocking device 352 is in direct contact with the positive connector 110. Other elements may be connected between these elements, unless a direct connection is specifically required.

[0061] The fault neutralization source 350 may provide a voltage between 10 and 100 and between 10 and 20 volts in one embodiment. As shown, the fault neutralization source 350 is connected to both connectors 110, 112. These connections 110a, 112a are shown in dotted lines to indicate that one or the other or both are optional. In one embodiment, the fault neutralization source 350 is used to clear a fault on a specific connector and therefore receives power from the other conductor.

[0062] As shown in [Fig. 6], the system 600 may include a separate fault neutralization source for each connector. In more detail, a first fault neutralization source 350 is connected to the first connector 110 to clear a first fault 140 thereon and a second fault neutralization source 650 is connected to the second connector 112 to clear a second fault 640 thereon using, for example, the contactor 652.

[0063] The above description includes systems in which the filter 302 is connected to ground between the capacitors 304, 306. As shown in the systems 700a, 700b, 700c of [Fig.7a]-7c, the filter 302 could be connected between the positive and negative rails 110, 112 and the fault neutralizing sources 350, 650 each connected between an adjacent rail and ground (e.g., the fault source 305 is connected between rail 110 and ground and fault neutralization source 650 is connected between rail 112 and ground). Each fault neutralization source 350, 650 may have a diode 352, 654 connected between it and rail 110, 112 as shown. It should be understood that while different types of power sources 102, 702b, 102 are shown in [Fig. 7a]-7c, the power sources may be interchangeable between the different modes shown herein. For example, power source 102 is a floating neutral generator, power source 702b is a multi-phase generator that has a twelve-pulse passive rectifier 108b, and power source 102 of [Fig. 7c] may be connected to a two-level active rectifier 108c.Of course, as desired, the sources and converters can be mixed and, thus, for example, the passive rectifier 108b could be a two-level active rectifier and vice versa depending on the context.

[0064] In cases where the filter is not grounded at the midpoint with a low impedance connection and as illustrated in [Fig.7a]-7c, each rail 110, 112 may be connected to ground by a high impedance resistor 720, 722. Example voltages of + / - 270 Vdc may exist on the rails 110, 112. However, other voltages may be used. In all embodiments shown herein, a fault may be detected by a solid-state power controller (SSPC) 750 which turns off the power supply in the event that too much power (current / voltage) is supplied to the load. The SSPC 750 may be included in any embodiment.

[0065] As indicated, the fault neutralization sources 350, 650 are so-called voltage boost sources. As in the previous discussion, these sources may provide a base voltage level for use when clearing a fault (e.g., 28 Vdc). The fault may cause the SPPC 750 to isolate the power sources 102, 702b from the load 130 and the respective ground fault 140, 640.

[0066] For example, the sources may provide a minimum voltage level of 28Vdc, which is a historical voltage standard for aircraft. In the event of a fault in the DC power systems described herein, the sources 350, 650 may be configured to provide additional built-in voltage boost functionality for high impedance ground faults. For a given clearing current required to clear the fault, the clearing sources may slightly increase the voltage / current output of the fault source (e.g., above the baseline level). This may be achieved, for example, by providing a boost converter in the clearing sources 350, 650.

[0067] Consider the case of a ground fault of rail 110, 112. In this case, the standard base level may not draw enough current under ground fault conditions. high impedance ground. The fault neutralization voltage boost function provides a ramp voltage / current to the system ground fault and back through the fault neutralization source ground path (e.g., from fault neutralization source 350, through ground fault 140, 640, through the fault neutralization source-ground return path).

[0068] In one embodiment, the SSPC 750 may be configured to sense the fault clearing voltage and manage a pull-up of sufficient magnitude (potentially in combination with or / without common mode voltage shift / signal injection). This may be done while the contactors 150, 652 are being used to energize a ground fault. In this case, after the fault is isolated, a normal common mode voltage level re-establishes, allowing the electrical system to recover and interrupting operation of the built-in voltage boost and fault clearing function. The impact of the utilization equipment during this fault clearing and recovery process is inconsequential, given the stability of the differential mode voltage.

[0069] Thus, the voltage amplification options slightly increase the fault neutralization power level (voltage and current) in order to improve the detection / correction of high impedance ground faults.

[0070] As noted above, in some cases, the fault neutralization sources may provide a static or step voltage. In either case, the sources may be current limited. Current limiting may reduce the level of fault neutralization power handling for low impedance or short to ground to limit damage to the structure, panel, and equipment, and reduce the electrical safety risk to humans.

[0071] Further, the fault neutralization sources may be configured to provide signals with defined / identifiable characteristics (frequency, square wave, sine wave, pulse, or other distinctive and detectable pattern) to the ground fault. The fault neutralization sources 350, 650 with the integrated signal injection enhancement functionality may be configured to produce a detectable signal on the network to increase the fault clearance robustness of the coordinated protection system at a reduced voltage and current level during rail-to-ground faults of + / - 270 Vdc (or an equivalent scaled voltage).

[0072] Further, an optional reset switch may be provided in any prior embodiment. In the event of a failure, in some cases, the fault override sources 350, 650 may include a latching protection mechanism. The reset may activate the recovery functionality. (e.g., restarting sources 350, 650) as a function of time, via a switching interface accessible to the pilot or maintenance personnel (hardware or virtual display style). An automated logical means of resetting the protection, based on deterministic system conditions (such as conditions detected in ground mode or emergency mode), is another possible approach that can be applied.

[0073] As indicated above, the fault neutralization sources 350, 650 may include a DC power source such as a battery. In other embodiments, the fault neutralization sources 350, 650 may include a capacitor 810 charged by the power source ([Fig. 8a]) or may include a rectifier 820 ([Fig. 8b]) that converts the alternating current from the generator to DC voltage (which may be stored in a capacitor / battery or other DC storage device or may provide DC in real time). As shown in [Fig. 8b], the power is three-phase and may come from any generator shown herein or other generators available in the system / aircraft (e.g., a PMG on an aircraft).

[0074] In the preceding embodiments, several configurations of fault neutralization sources have been described. Any of these configurations could be integrated into the packaging of a product (e.g., element 750 of [Fig. 7a]). The packaging may be, for example, a federated unit, an SPDA chassis board, an electric district, a generator, a primary distribution, an energy conversion, an MLC, a high energy storage module (HESM) / battery / charger / fuel cell, a GCU, or as part of current sensing equipment.

[0075] The terminology used herein is for the sole purpose of describing particular embodiments and is not limiting. In this document, the singular forms "a", "an" and "the" are also understood to mean the plural, unless the context clearly indicates otherwise. It is understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of given features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups of these features, integers, steps, operations, elements, components and / or groups of these elements.

[0076] Although this document has been described in detail only in connection with a limited number of embodiments, it should be understood that this document is not limited to these embodiments. Rather, this disclosure may be modified to incorporate any number of variations, alterations, substitutions, combinations, subcombinations, or equivalent arrangements that have not been previously described, but are commensurate with the scope of this disclosure. Further, although various embodiments of this disclosure have been described, it is understood that certain aspects of this disclosure may include only some of the described embodiments.

[0077] The descriptions of the various embodiments have been presented for the purpose of illustration, but are not intended to be exhaustive or limited to the disclosed embodiments. Numerous modifications and variations will occur to those of ordinary skill in the art without departing from the scope and spirit of the disclosed embodiments. The terminology used herein has been chosen to best explain the principles of the embodiments, the practical application or technical improvement over commercially available technologies, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

Claims

1. A power supply system for supplying power to a load connected between first and second connectors, the system comprising: a power source that produces a power output; a power converter configured to receive the power output and convert it to a direct current (DC) output and supply the DC output between the first and second connectors; a filter connected to the rectifier and between the connectors, configured to smooth the DC output; and a fault neutralization source connected to the first connector and configured to supply a neutralization voltage to the first connector when a ground fault occurs on the first connector; wherein the neutralization voltage comprises an identifiable characteristic.

2. The electrical power system of claim 1, wherein the identifiable characteristic is a frequency, square wave, sine wave, pulse, or other distinctive and detectable pattern.

3. The power supply system of claim 1, wherein the fault neutralization source is a battery.

4. The power supply system of claim 1, wherein the fault neutralization source is powered by the second connector.

5. The power supply system of claim 1, wherein the power source is a direct current source and the power converter is a direct current to direct current converter.

6. The power supply system of claim 1, wherein the power source is an AC generator and the power converter is a rectifier configured to receive AC from the generator and convert it to a DC output and provide the DC output between the first and second connectors.

7. The power supply of claim 6, wherein the rectifier is a two-stage active rectifier.

8. The electrical power system of claim 1, further comprising a contactor connected to the first connector configured to open and close to clear the fault while the fault override source provides the override voltage to the first contactor.

9. The power supply system of claim 1, wherein the fault neutralization source is connected between the first connector and a ground.

10. The electrical power system of claim 9, wherein the mass is an aircraft structural mass.

11. A power supply system according to claim 1, wherein the fault neutralization source is a first fault neutralization source configured to provide a first neutralization voltage, and wherein the system further comprises a second fault neutralization source connected to the second connector and configured to provide a second neutralization voltage to the second connector when a ground fault occurs on the second connector; wherein at least one of the first and second neutralization voltages comprises an identifiable characteristic.

12. The electrical power system of claim 11, wherein the identifiable characteristic is a frequency, square wave, sine wave, pulse, or other distinctive and detectable pattern.

13. The power supply system of claim 11, wherein the first and second fault neutralization sources are batteries.

14. The power supply system of claim 11, wherein the first fault neutralization source is powered by the second connector and the second fault neutralization source is powered by the first connector.

15. The power supply system of claim 11, wherein the power source is a direct current source and the power converter is a DC to DC converter.

16. The power supply system of claim 11, wherein the power source is an AC generator and the power converter is a rectifier configured to receive AC from the generator and convert it to a DC output and provide the DC output between the first and second connectors.

17. The power supply system of claim 16, wherein the rectifier is a two-stage active rectifier.

18. The power supply system of claim 11, wherein the first fault neutralization source is connected between the first connector and a ground and the second fault neutralization source is connected between the second connector and ground.

19. The electrical power system of claim 18, wherein the mass is an aircraft structural mass.

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