Systems and methods for electrical short detection

Abstract

To provide methods and systems of detecting short circuits in an electrical system, such as a dynamic braking grid of a vehicle.SOLUTION: The methods and systems measure a characteristic of an electrical current that is conducted through one or more resistive elements of an electrical system 104. The electrical current is supplied to the electrical system from a power source 102 as an applied voltage. A resistance change signal representative of a change in one or more electrical resistances of the one or more resistive elements is determined. The resistance change signal is based at least in part on a difference between the characteristic of the electrical current that is measured and a low pass filtered value of one or more of the characteristic of the electrical current that is measured or the applied voltage supplied by the power source. A short circuit event is identified based at least in part on the resistance change signal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the inventive subject matter described herein relate to the detection of electrical short circuits in an electronic system, such as a power resistor.

Background Art

[0002] Known electronic systems exist that conduct current to a resistor to dissipate the current. For example, some vehicles include a grid having conductive ribbons that receive power generated by a motor during regenerative braking or dynamic braking. This power is generated by the motor and acts to slow or stop the movement of the vehicle. The power is conducted to the grid to be dissipated as heat from the vehicle's regenerative braking system.

[0003] The grid can be formed from one or more series of resistors. These resistors can be implemented in conductive plates that are relatively close to each other. Over time, due to damage to the grid, standard wear, or other reasons, the relative positions of the resistors can begin to change. If the resistors come into contact with each other (e.g., due to vibration or other movement), an internal electrical short circuit can occur between the resistors. This short circuit can damage the grid, damage the regenerative braking system, and otherwise have an adverse effect on the operation of the vehicle.

Summary of the Invention

[0004] In one embodiment, a method (e.g., for detecting a short circuit in an electrical system) includes measuring characteristics of a current conducted through one or more resistive elements of the electrical system. The current is supplied to the electrical system from a power source as an applied voltage. The method also includes determining a resistance change signal representative of a change in one or more electrical resistances of the one or more resistive elements. The resistance change signal can be at least partially based on a difference between the measured characteristics of the current and one or more low-pass filtered values of the measured characteristics of the current or the applied voltage supplied by the power source. The method can also include identifying a short circuit event at least partially based on the resistance change signal.

[0005] In another embodiment, a system (e.g., a detection system) includes a sensing device and a processing assembly. The sensing device is configured to measure characteristics of a current conducted through one or more resistive elements of the electrical system. The current can be supplied to the electrical system from a power source as an applied voltage. The processing assembly can be configured to determine a resistance change signal representative of a change in one or more electrical resistances of the one or more resistive elements. The resistance change signal can be at least partially based on a difference between the measured characteristics of the current and one or more low-pass filtered values of the measured characteristics of the current or the applied voltage supplied by the power source. The processing assembly can be configured to identify a short circuit event at least partially based on the resistance change signal.

Brief Description of the Drawings

[0006] Reference is now made briefly to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

[0007] One or more embodiments of the inventive subject matter described herein detect an electrical short circuit in an electronic system. In one aspect, the systems and methods described herein can be used to detect an electrical short circuit in a dynamic braking grid (DBG) of a vehicle, such as a railway vehicle or other off-highway vehicle (OHV). However, not all embodiments are limited to DBGs or railway vehicles. One or more embodiments can be used to detect short circuits in other systems, including non-vehicle systems and vehicle systems other than railway vehicles or OHVs.

[0008] During operation of the DBG, the conductive plate of the DBG may cause an electrical short circuit, and the current of the DBG may bypass at least a portion of the electrical resistance formed by the plate. The plate may cause a short circuit, for example, when shaken by the air flow created by a blower (e.g., a fan) that dissipates heat generated by the current into the air around the plate. However, the plate may also cause a short circuit due to the thermal cycle of the DBG, which can cause distortion and / or migration of metal elements. These short circuits can form local hot spots between two or more plates, which can ultimately lead to sparks, melting, arc discharge, and failure of the DBG.

[0009] To prevent failure of the DBG, the systems and methods described herein can provide early detection of electrical short circuits. By detecting short circuits early, preventive maintenance inspections can be scheduled, thereby avoiding more serious damage and / or downtime of the DBG or other electrical systems.

[0010] FIG. 1 illustrates a power system (100) in one embodiment. Although the power system (100) is shown as a locomotive, alternatively it may be a different type of system that is not a vehicle or a different type of vehicle. The system (100) includes a power source (102), such as a traction motor that generates power, for example, during regenerative braking operation. Alternatively, the power source (102) may represent an alternator, a generator, a battery, or other power source. The power source (102) generates an electric current, and the electric current is conducted to an electrical system (104). The electrical system (104) includes one or more resistive elements, such as power resistors. These resistive elements convert the electric current from the power source (102) into heat. The heat can be dissipated from the power system (100) by, for example, a blower (e.g., a fan). In the illustrated embodiment, the power source (102) may include a traction motor that generates an electric current during regenerative braking of the electric system (100). The electrical system (104) may include a DBG that converts power into heat and dissipates it.

[0011] FIG. 2 illustrates a schematic diagram of an electrical system (104) and an electrical short circuit detection system (200) (referred to as the "detection system" in FIG. 2) in one embodiment. The system (104) includes several electrical resistive elements (202) connected in series with each other in a conductive state. In the illustrated embodiment, the resistive elements (202) are conductive plates, such as a conductive two-dimensional body having an outer shape in which two orthogonal directions are longer than a third direction orthogonal to them. Alternatively, the resistive elements (202) may be other types of resistors. During operation of the system (104), power from the power source (102) is conducted through the resistive elements (202). The resistive elements (202) reduce the flow of the electric current through the electrical system (104) and convert the power into heat. As one example, during regenerative braking of a vehicle, the power generated by the traction motor of the vehicle can be conducted to the resistive elements (202) (e.g., DBG) and dissipated as heat.

[0012] The resistive elements (202) can be arranged at relatively close intervals. During operation, the resistive elements (202) may change their relative positions with respect to each other due to the air flow generated by the blower, and / or bend or deform due to the heat generated by the power conducted to the resistive elements (202). Due to this position change and / or deformation, the resistive elements (202) may come into contact with each other and cause an electrical short circuit. The short circuit may damage the power system (100) and / or limit the operation of the power system (100).

[0013] The detection system (200) is conductively connected to the electrical system (104) at one or more locations and monitors the electrical characteristics of the current conducted through the electrical system (104). The detection system (200) monitors the change in the electrical resistance of the electrical system (104) over time and detects an electrical short circuit based on these changes. For example, while the resistive elements (202) are not in contact with each other, the voltage and / or current conducted through the resistive elements (202) may be proportional to the voltage generated by the power supply (102). Since the voltage and / or current generated by the power supply (102) and conducted to the electrical system (104) is the voltage or current applied to the resistive elements (202), it can be referred to as the applied voltage (V dc ) or the applied current. The voltage and / or current conducted through the resistive elements (202) (referred to herein as the conduction voltage or conduction current) may be proportional to the applied voltage and / or applied current by one or more proportionality constants. For example, the product of the conduction voltage and the proportionality constant is equal to the input voltage, and / or the product of the conduction current and the same or a different proportionality constant is equal to the input voltage. The proportionality constants are the same or substantially the same over time.

[0014] However, if two or more of the resistive elements (202) come into contact with each other at least momentarily and cause an electrical short circuit, the proportionality constant may change abruptly. Thus, an abrupt change in the ratio of the conduction voltage and / or the conduction current may signify an electrical short circuit. The detection system (200) monitors changes in the conduction voltage and conduction current, and / or changes in the ratio of these voltages and / or currents, in order to quickly identify a short circuit before it can damage the operation of the electrical system (104) and / or the power system (100).

[0015] Figure 3 is a circuit diagram of one embodiment for the electrical system (104) and the detection system (200). Various groups of resistive elements (202) are connected in parallel with each other, and the resistive elements (202) within those groups of resistive elements are connected in series with each other. For example, the resistive elements (202) labeled "1", "2", and "3" are connected in series with each other in the first group, the resistive elements (202) labeled "4", "5", and "6" are connected in series with each other in the second group, the resistive elements (202) labeled "7", "8", and "9" are connected in series with each other in the third group, and the resistive elements (202) labeled "10", "11", and "12" are connected in series with each other in the fourth group, and the first group, the second group, the third group, and the fourth group may be parallel to each other. A switch (304) is disposed on the opposite side of the resistive elements (202) of each group, and it is possible to control which resistive element (202) receives the applied current from the power supply (102).

[0016] The detection system (200) includes a sensing device (300) that is conductively connected to a resistive element (202). The sensing device (300) represents one or more device pars that measure characteristics of a current supplied by a power source (102) to an electrical system (104). For example, the sensing device (300) can measure a conductive voltage and / or a conductive current. For example, the sensing device (300) can include one or more voltmeters and / or ammeters (302) ("VAM" in FIG. 3), a high voltage filter (306) ("High V" in FIG. 3), and / or a low voltage filter (308) ("Low V" in FIG. 3). The voltmeter / ammeter (302) and / or filters (306, 308) can measure the voltage between resistive elements (202) at the locations shown in FIG. 3 and / or other locations, and / or the voltage drop between two or more resistive elements (202). Alternatively, the sensing device (300) can include another type of sensor that measures a voltage and / or a current conducted between and / or through resistive elements (202).

[0017] The detection system (200) may also include a processing assembly (310) operably connected to the sensing device (300). For example, the processing assembly (310) and the sensing device (300) can be connected by one or more wired and / or wireless connections. The processing assembly (310) includes one or more processors (312) (such as "Processing" in FIG. 3, for example, a microprocessor, a controller, or other electrical logic-based devices), and / or includes hardware circuits and / or electrical circuits connected thereto. This circuit can include an input / output module (314) (such as "I / O" in FIG. 3) and an input / output board (316) (such as "CIO" in FIG. 3). The input / output module (314) can represent hardware circuits and / or electrical circuits that include one or more processors that generate signals to be output for presentation to an operator (for example, signals transmitted to a display device to warn the operator of a detected short circuit), and / or are connected thereto. The input / output board (316) can represent hardware circuits and / or electrical circuits that include one or more processors that transmit signals to a display device or other output device, and / or are connected thereto. Optionally, the input / output board (316) can receive signal inputs from one or more other devices, such as signals representing an applied voltage generated by the power supply (102) and conducted to the electrical system (104).

[0018] FIG. 4 is a flowchart relating to one embodiment of a method (400) for detecting a short circuit event. The method (400) can be implemented by a detection system (300) in one embodiment. At (402), the conduction voltage and conduction current are measured by the sensing device (300). At (404), the applied voltage and / or applied current supplied to the electrical system (104) by the power supply (102) is determined. For example, the sensing device (300) is connected to the electrical system (104) at one or more locations and measures the applied voltage from the power supply (102).

[0019] (406) calculates the difference between the measured voltage and / or measured current (e.g., conduction voltage and / or conduction current) and the ratio after filtering between the measured voltage and / or measured current and the applied voltage and / or applied current. These differences can be called resistance change signals.

[0020] The processing assembly (310) can calculate the ratio of the conduction voltage and / or conduction current and determine the proportionality constant of the electrical system (104). For example, the processing assembly (310) divides the conduction voltage measured between the second and third resistance elements (202) (elements "2" and "3" in FIG. 3) by the conduction voltage measured between the fifth and sixth resistance elements (202) (elements "5" and "6" in FIG. 3), between the eighth and ninth resistance elements (202) (elements "8" and "9" in FIG. 3), between the tenth and eleventh resistance elements (202) (elements "10" and "11" in FIG. 3), or between another pair of resistance elements (202). Further ratios can be measured to calculate additional proportionality constants for the electrical system (104).

[0021] During normal operation (e.g., when there is no short circuit), the proportionality constant is the same or substantially the same (varying within a specified threshold, e.g., 1%, 3%, 5% or another value). However, over time, the resistance provided by the resistance element (202) can change slowly with time. As a result, the proportionality constant can change slowly with time. The proportionality constant can be called a resistance change signal. In a normal state (e.g., when there is no short circuit), the change in the proportionality constant may simply contain noise and is not an actual change in the proportionality constant. A short circuit can occur during a contact event between two or more resistance elements (202). In such a contact event, the resistance change signal rises above the noise and can indicate a short circuit.

[0022] In one embodiment, the processing assembly (310) can calculate a resistance change signal from an applied voltage and a conduction voltage. Alternatively, the resistance change signal can be calculated from an applied current and a conduction current. Although the description herein focuses on calculating the resistance change signal from a voltage, not all embodiments are limited to the use of voltage.

[0023] One example of a resistance change signal that can be calculated by the processing assembly (310) is a ratio deviation signal. In one embodiment, the processing assembly (310) calculates the ratio deviation signal as follows: TIFF2025096460000002.tif14170 (Equation 1) At this time, RatioDeviation(t) represents the ratio deviation signal, V grid (t) represents the voltage of the electrical system (104) or the grid (e.g., the conduction voltage), V base (t) represents the applied voltage or the base voltage, or the applied voltage divided by a constant such as 6 or other numbers, and TIFF2025096460000003.tif14170 is TIFF2025096460000004.tif14170 represents the low-pass filter processing of. TIFF2025096460000005.tif14170 By performing low-pass filter processing on the value of, TIFF2025096460000006.tif14170 changes that occur within a short time less than the specified time can be made unnecessary. For example, starting and ending within 100 milliseconds, 50 milliseconds, 0.1 second, or other time intervals TIFF2025096460000007.tif14170 Increases or decreases can be ignored, while those lasting longer than the specified time TIFF2025096460000008.tif14170 Increases or decreases are TIFF2025096460000009.tif14170 Used as the value of

[0024] TIFF2025096460000010.tif14170 The value of can be used as the baseline or expected value for the ratio deviation signal. Within a time period when the proportionality constant does not change significantly TIFF2025096460000011.tif14170 The value of and TIFF2025096460000012.tif14170 The value of are close numerical values, and as a result, the ratio deviation signal is smaller or zero. However, within a time period when the proportionality constant changes significantly TIFF2025096460000013.tif14170 The value of and TIFF2025096460000014.tif14170 The value of are distant numerical values, and as a result, the ratio deviation signal becomes larger.

[0025] Another example of a resistance change signal that can be calculated by the processing assembly (310) is a voltage deviation signal. In one embodiment, the processing assembly (310) calculates the voltage deviation signal as follows: TIFF2025096460000015.tif22170 (Equation 2) At this time, VoltageDeviation(t) represents the voltage deviation signal.

[0026] Another example of the resistance change signal that can be calculated by the processing assembly (310) is a deviation squared signal as follows: TIFF2025096460000016.tif7170 TIFF2025096460000017.tif7170 (Equation 3) At this time, TIFF2025096460000018.tif7170 represents the deviation squared signal, TIFF2025096460000019.tif7170 is TIFF2025096460000020.tif7170 represents the low-pass filter processing of TIFF2025096460000021.tif7170 is TIFF2025096460000022.tif7170 represents the low-pass filter processing of

[0027] (408) Determine whether the difference between the measured voltage and / or measured current (e.g., conduction voltage and / or conduction current) and the ratio of the filtered measured voltage and / or measured current to the applied voltage and / or applied current suggests a short circuit event. For example, the processing assembly (310) can examine the resistance change signal to identify a short circuit event.

[0028] Regarding the ratio deviation signal (RatioDeviation(t)) described above, a short circuit event can be identified corresponding to the absolute value of the ratio deviation signal exceeding a threshold value (K). The threshold value is selectable, thereby changing the sensitivity of the detection system (200). For example, when the threshold value (K) is relatively small, the sensitivity to short circuits is high, but the possibility of misidentifying short circuit events is also high. When the threshold value (K) is relatively large, the sensitivity to short circuits is low, but the possibility of misidentifying short circuit events is low.

[0029] Regarding the voltage deviation signal (VoltageDeviation(t)) described above, a short circuit event can be identified by the processing assembly (312) that monitors the value of the voltage deviation signal. For example, a short circuit event can be identified corresponding to the absolute value of the voltage deviation signal exceeding the product of the threshold value (K) and V base (t).

[0030] Regarding the squared deviation signal (VoltageSquaredDeviation(t)) described above, a short circuit event can be identified by the processing assembly (312) that monitors the value of the squared deviation signal. For example, a short circuit event can be identified corresponding to the absolute value of the squared deviation signal exceeding the product of the threshold value (K), V base (t), and <V base (t)>.

[0031] When a short circuit event is detected, the flow of the method (400) can proceed to (410). Otherwise, the flow of the method (400) can return to (402) to additionally monitor the electrical system (104). At (410), the cumulative value of the short circuit event is changed. For example, in contrast to determining that a short circuit event has occurred each time the resistance change signal indicates a short circuit, the processing assembly (310) can track a cumulative value that changes the value based on the number, duration, and / or energy of the short circuit event.

[0032] As an example, the processing assembly (310) can calculate the cumulative value of the short-circuit events as the total number of short-circuit events. An increase in the value of such a cumulative value may indicate an increase in the severity of the short-circuit events.

[0033] As another example, the processing assembly (310) can calculate the cumulative value as the total duration of the short-circuit events. For example, the total duration during which the resistance change signal exceeds one or more of the above-described thresholds can be calculated as the cumulative value. If a short-circuit event lasts for 1 second, followed by a 0.5-second short-circuit event and then another 2-second short-circuit event, the total duration of the short-circuit events can be 3.5. An increase in the total duration may mean an increase in the damage to the resistive element (202) compared to a shorter total duration. The total duration can be reset to 0, for example, after the power system (100) has moved from the starting position to the target position.

[0034] As another example, the processing assembly (310) can calculate the cumulative value as the energy of the short-circuit events. For example, the processing assembly (310) can calculate the cumulative value as the time integral of the squared deviation signal during short-circuit event detection. This cumulative value may indicate, and / or be proportional to, the thermal energy or heat quantity towards the contact point between the resistive elements (202) where the short-circuit event is occurring.

[0035] At (412), a determination is made as to whether the cumulative value indicates that the electrical system (104) is damaged (and thus a short-circuit event is occurring). In one embodiment, the processing assembly (310) can compare one or more of the cumulative values with a specified threshold value associated therewith. If the cumulative value exceeds the threshold value, the processing assembly (310) can determine that the electrical system (104) appears to be damaged. As a result, the flow can continue to (414). Otherwise, the flow of the method (400) can return to (402).

[0036] (414) A warning signal is generated. This warning signal is generated by the processing assembly (310) and can be presented to the operator of the power system (100). The warning signal can indicate to the operator that the electrical system (104) is in an initial stage of damage such as detachment. In one aspect, the cumulative value can be compared to several different threshold values (e.g., various detachment stages) representing different levels of damage. The threshold values can be determined by testing the electrical system (104) to a destructive state while measuring the above quantity, and during that time, setting the threshold values based on engineering judgment. The warning signal can be used to control the operation of the power system (100). For example, the warning signal can disable the power system (100) to reduce the power output, or otherwise reduce the operation of the power system (100) to prevent further damage to the electrical system (104).

[0037] The method (400) can be repeated one or more times during the operation of the power system (100). For example, the flow of the method (400) can return to (402) for additional monitoring of the electrical system (104).

[0038] In one embodiment, the method (for example, for short - circuit detection in an electrical system) includes measuring the characteristics of a current conducted through one or more resistive elements of the electrical system. The current is supplied to the electrical system from a power source as an applied voltage. The method further includes determining a resistance change signal representing a change in the electrical resistance of one or more of the one or more resistive elements. The resistance change signal can be at least partially based on the difference between the measured characteristics of the current and one or more low - pass - filtered values of the measured characteristics of the current or the applied voltage supplied by the power source. The method can further include identifying a short - circuit event based at least partially on the resistance change signal.

[0039] In one aspect, the applied voltage can be generated by the traction motor of the vehicle during regenerative braking of the vehicle, the one or more resistive elements can include one or more resistors of the regenerative braking grid, and / or the conductive voltage can include a voltage drop across the one or more resistors.

[0040] In one aspect, the resistance change signal can represent a change in one or more electrical resistances caused by an increase in heat within the one or more resistive elements due to a short circuit event.

[0041] In one aspect, the characteristics of the measured current can include a voltage drop across at least one of the resistive elements.

[0042] In one aspect, the resistance change signal can represent the difference between the ratio of the voltage drop across at least one of the resistive elements to the applied voltage and the value after low-pass filtering of the ratio of the voltage drop across at least one of the resistive elements to the applied voltage.

[0043] In one aspect, the short circuit event can be identified corresponding to the absolute value of the resistance change signal exceeding a specified non-zero threshold.

[0044] In one aspect, the resistance change signal can represent the difference between the voltage drop across at least one of the resistive elements and the product of the applied voltage and the value after low-pass filtering of the ratio of the voltage drop across at least one of the resistive elements to the applied voltage.

[0045] In one aspect, the short circuit event can be identified corresponding to the absolute value of the resistance change signal exceeding the product of the applied voltage and a specified non-zero threshold.

[0046] In one aspect, the resistance change signal can represent the difference between a first product of the voltage drop across at least one of the resistive elements and the value after low-pass filtering of the applied voltage and a second product of the value after low-pass filtering of the applied voltage and the voltage drop across at least one of the resistive elements.

[0047] In one aspect, a short - circuit event can be identified corresponding to the absolute value of a resistance change signal that exceeds the product of an applied voltage, a voltage drop across at least one resistive element, and a specified non - zero threshold.

[0048] In one aspect, the method can further include monitoring the number of times a short - circuit event is identified, and generating a warning signal indicative of damage to the electrical system corresponding to the number of times a short - circuit event is identified that exceeds a specified non - zero threshold.

[0049] In one aspect, the method can further include monitoring the combined duration of short - circuit events, and generating a warning signal indicative of damage to the electrical system corresponding to a combined duration that exceeds a specified non - zero threshold.

[0050] In one aspect, the method can further include monitoring the time integral of the resistance change signal, and generating a warning signal representative of damage to the electrical system corresponding to a time integral that exceeds a specified non - zero threshold.

[0051] In one aspect, the method can further include generating a warning signal, at least in part based on the identification of a short - circuit event. The warning signal can indicate to an operator of a power system including the electrical system that damage has occurred to the electrical system.

[0052] In another embodiment, a system (e.g., a detection system) includes a sensing device and a processing assembly. The sensing device is configured to measure characteristics of a current conducted through one or more resistive elements of an electrical system. The current may be supplied to the electrical system from a power source as an applied voltage. The processing assembly may be configured to determine a resistance change signal representative of a change in one or more electrical resistances of the one or more resistive elements. The resistance change signal may be at least partially based on a difference between the measured characteristics of the current and one or more low-pass filtered values of the measured characteristics of the current or the applied voltage supplied by the power source. The processing assembly may further be configured to identify a short circuit event at least partially based on the resistance change signal.

[0053] In one aspect, the applied voltage can be generated by a traction motor of a vehicle during regenerative braking of the vehicle, the one or more resistive elements can include one or more resistors of a regenerative braking grid, and the conduction voltage can include a voltage drop across the one or more resistors.

[0054] In one aspect, the resistance change signal can represent a change in one or more electrical resistances caused by an increase in heat in the one or more resistive elements due to a short circuit event.

[0055] In one aspect, the measured characteristics of the current can include a voltage drop across at least one of the resistive elements.

[0056] In one aspect, the resistance change signal can represent a difference between a ratio of a voltage drop across at least one of the resistive elements to the applied voltage and a low-pass filtered value of the ratio of the voltage drop across at least one of the resistive elements to the applied voltage.

[0057] In one aspect, the processing assembly can be configured to identify a short circuit event in response to an absolute value of the resistance change signal exceeding a specified non-zero threshold.

[0058] In one aspect, the resistance change signal can represent the difference between the voltage drop across at least one of the resistive elements and the product of the applied voltage and the value after low-pass filtering of the ratio of the voltage drop across at least one of the resistive elements to the applied voltage.

[0059] In one aspect, the processing assembly can be configured to identify a short-circuit event corresponding to the absolute value of the resistance change signal that exceeds the product of the applied voltage and a specified non-zero threshold.

[0060] In one aspect, the resistance change signal can represent the difference between a first product of the values after low-pass filtering of at least one resistive element and the applied voltage and a second product of the values after low-pass filtering of the applied voltage and the voltage drop across at least one resistive element.

[0061] In one aspect, the processing assembly can be configured to identify a short-circuit event corresponding to the absolute value of the resistance change signal that exceeds the product of the applied voltage, the voltage drop across at least one resistive element, and a specified non-zero threshold.

[0062] In one aspect, the processing assembly can be configured to monitor the number of times a short-circuit event is identified and generate a warning signal representing damage to the electrical system corresponding to the number of times a short-circuit event is identified that exceeds a specified non-zero threshold.

[0063] In one aspect, the processing assembly can be configured to monitor the total duration of the short-circuit event and generate a warning signal representing damage to the electrical system corresponding to the total duration that exceeds a specified non-zero threshold.

[0064] In one aspect, the processing assembly can be configured to monitor the time integral of the resistance change signal and generate a warning signal representing damage to the electrical system corresponding to the time integral that exceeds a specified non-zero threshold.

[0065] In one aspect, the processing assembly may be configured to generate a warning signal based at least in part on the identification of a short circuit event. The warning signal can indicate to an operator of a power system, including the electrical system, damage to the electrical system.

[0066] It is to be understood that the above description is illustrative and not restrictive. For example, the embodiments (and / or aspects thereof) described above may be used in combination with each other. Additionally, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from the scope of the present invention. The dimensions and types of the materials described herein are intended to define parameters of the inventive subject matter, but they are in no way limiting and are typical embodiments. Many other embodiments will be apparent to those skilled in the art upon review of the above description. Accordingly, the scope of the inventive subject matter should be determined with reference to the appended claims, along with the full scope of equivalents to which the claims are entitled. In the appended claims, the terms "including" and "in which" are used as plain English equivalents of the terms "comprising" and "wherein", respectively. Also, in the following claims, the terms "first", "second", and "third", etc. are used merely as labels and are not intended to impose numerical requirements on their objects. Further, the limitations in the following claims are not written in means-plus-function format and are not intended to be interpreted under 35 U.S.C. § 112(f) unless the claim limitations explicitly use the phrase "means for" followed by a description of the function and then no further structure or followed by further structure.

[0067] In this written description, examples are used to disclose several embodiments of the subject matter of the present invention, and also to enable those skilled in the art to practice the embodiments of the subject matter of the present invention, including the creation and use of any device or system, and the implementation of the methods included. The patentable scope of the subject matter of the present invention is defined by the claims, and other examples that can be conceived by those skilled in the art can be included. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include the equivalence of structural elements that do not differ substantially from the literal language of the claims.

[0068] The foregoing description of specific embodiments of the subject matter of the present invention will be better understood when read in conjunction with the accompanying drawings. To the extent that the figures show schematic diagrams of functional blocks of various embodiments, the functional blocks are not necessarily indicative of a separation between hardware circuits. Thus, for example, one or more functional blocks (e.g., a processor or memory) can be implemented in a single piece of hardware (e.g., a general-purpose message processor, a microcontroller, a random access memory, a hard disk, etc.). Similarly, a program can be an independent program, incorporated as a subroutine into an operating system, or a function of an installed software package. The various embodiments are not limited to the arrangements and means shown in the drawings.

[0069] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood to exclude a plurality of such elements or steps unless explicitly stated otherwise. Further, reference to "one embodiment" of the subject matter of the present invention is not intended to be construed as excluding the existence of additional embodiments that also include the features recited. Moreover, unless explicitly stated to the contrary, embodiments "comprising," "including," or "having" one or more elements having a particular property may include additional elements not having that property.

Claims

1. measuring a characteristic of a current provided as an applied voltage from a power source (102) to an electrical system (104) and conducted through one or more resistive elements (202) of said electrical system (104); determining a change in resistance of the one or more resistive elements (202) based at least in part on a difference between the characteristic of the measured current and one or more filtered values ​​of the characteristic of the measured current or the applied voltage provided by the power source (102); and identifying a short circuit event based at least in part on the resistance change.

2. 2. The method of claim 1, wherein the applied voltage is generated by a traction motor of the vehicle during dynamic braking of the vehicle, the one or more resistive elements (202) include one or more resistors of a dynamic braking electrical grid, and the applied voltage is a voltage drop across the one or more resistive elements (202).

3. The method of claim 1 , wherein the characteristic of the current that is measured is a voltage drop across at least one of the one or more resistive elements (202).

4. 4. The method of claim 3, wherein the resistance change represents a difference between a ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage and a filtered value of the ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage.

5. The method of claim 4 , wherein the short circuit event is identified in response to the resistance change exceeding a specified non-zero threshold.

6. 4. The method of claim 3, wherein the resistance change represents a difference between the voltage drop across the at least one of the one or more resistive elements (202) and a product of a filtered value of a ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage and the applied voltage.

7. The method of claim 6 , wherein the short circuit event is identified in response to the resistance change exceeding a product of the applied voltage and a specified non-zero threshold.

8. 4. The method of claim 3, wherein the resistance change represents a difference between a first product of the voltage drop across the at least one of the one or more resistive elements (202) and a first filtered value of the applied voltage and a second product of the applied voltage and a second filtered value of the voltage drop across the at least one of the one or more resistive elements (202).

9. monitoring one or more of the number of times the short circuit event is identified, the total time interval duration of the short circuit event, or the time integral of the resistance change; and generating a warning signal indicative of damage to the electrical system in response to one or more of the number of times the short circuit event is identified that exceeds a first specified non-zero threshold, the total duration that exceeds a second specified non-zero threshold, or the time integral that exceeds a third specified non-zero threshold.

10. a sensing device (300) configured to measure a characteristic of an electrical current provided as an applied voltage from a power source (102) to an electrical system (104) and conducted through one or more resistive elements (202) of the electrical system; a processing assembly configured to determine a resistance change representative of a change in one or more electrical resistances of the one or more resistive elements (202), the resistance change being based, at least in part, on a difference between the characteristic of the measured current and a filtered value of one or more of the characteristics of the measured current or the applied voltage provided by the power source (102), The system, wherein the processing assembly (310) is also configured to identify a short circuit event based, at least in part, on the resistance change.

11. 11. The system of claim 10, wherein the applied voltage is generated by a traction motor of the vehicle during dynamic braking of the vehicle, the one or more resistive elements (202) include one or more resistors of a dynamic braking electrical grid, and the conducted voltage is a voltage drop across the one or more resistors.

12. The system of claim 10 , wherein the sensing device (300) is configured to measure a voltage drop across at least one of the one or more resistive elements (202) as the characteristic of the current.

13. The sensing device (300) measures the resistance change as: a difference between a ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage and a filtered value of the ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage; a difference between the voltage drop across the at least one of the one or more resistive elements (202) and the product of a filtered value of the ratio of the voltage drop across the at least one of the one or more resistive elements (202) to the applied voltage and the applied voltage; or 13. The system of claim 12, configured to measure one or more of a difference between a first product of the voltage drop across the at least one of the one or more resistive elements (202) and a filtered value of the applied voltage and a second product of a low pass filtered value of the voltage drop across the at least one of the one or more resistive elements (202) and the applied voltage.

14. 11. The system of claim 10, wherein the processing assembly (310) is configured to monitor one or more of the number of times the short circuit event is identified, the total time interval duration of the short circuit event, or the time integral of the resistance change, and generate a warning signal indicative of damage to the electrical system in response to one or more of the number of times the short circuit event is identified exceeding a specified non-zero threshold, the total duration exceeding a specified non-zero threshold, or the time integral exceeding a specified non-zero threshold.

15. a sensing device (300) configured to measure a characteristic of an electrical current provided as an applied voltage from a traction motor of a vehicle to an electrical system (104) of the vehicle and conducted through one or more resistors of the electrical system (104); 1. A system comprising: a processing assembly (310) configured to determine a resistance change indicative of a change in one or more electrical resistances of the one or more resistors of the electrical system, the resistance change being based, at least in part, on a difference between the characteristic of the measured current and a low pass filtered value of one or more of the characteristics of the measured current or the applied voltage supplied by the traction motor, the processing assembly (310) also configured to identify, based, at least in part, on the resistance change, an increase in heat in the electrical system (104) indicative of a short circuit event in the electrical system.

16. The system of claim 15 , wherein the sensing device (300) is configured to measure a voltage drop across at least one of the one or more resistors as the characteristic of the current.

17. The sensing device (300) measures the resistance change as: a difference between a ratio of the voltage drop across the at least one of the one or more resistors to the applied voltage and a low pass filtered value of the ratio of the voltage drop across the at least one of the one or more resistors to the applied voltage; a difference between the voltage drop across the at least one of the one or more resistors and the product of a low pass filtered ratio of the voltage drop across the at least one of the one or more resistors to the applied voltage and the applied voltage; or 17. The system of claim 16, configured to measure as one or more of a difference between a first product of the voltage drop across the at least one of the one or more resistors and a filtered value of the applied voltage and a second product of the applied voltage and a low pass filtered value of the voltage drop across the at least one of the one or more resistors.

18. 20. The system of claim 17, wherein the processing assembly (310) is configured to identify an increase in heat as a function of an absolute value of the resistance change exceeding one or more of the product of the applied voltage and a specified non-zero threshold value or the product of the applied voltage, the voltage drop across the at least one of the one or more resistors and the specified non-zero threshold value.

19. 16. The system of claim 15, wherein the processing assembly (310) is configured to monitor one or more of the number of times the short circuit event is identified, the total time interval duration of the short circuit event, or the time integral of the resistance change, and generate a warning signal indicative of damage to the electrical system in response to one or more of the number of times the short circuit event is identified exceeding a specified non-zero threshold, the total duration exceeding a specified non-zero threshold, or the time integral exceeding a specified non-zero threshold.

20. The system of claim 15, wherein the electrical system (104) is a dynamic braking electrical grid.

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