WO2020011742A1 - Ground fault detection circuit and apparatus - Google Patents
Ground fault detection circuit and apparatus Download PDFInfo
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- WO2020011742A1 WO2020011742A1 PCT/EP2019/068320 EP2019068320W WO2020011742A1 WO 2020011742 A1 WO2020011742 A1 WO 2020011742A1 EP 2019068320 W EP2019068320 W EP 2019068320W WO 2020011742 A1 WO2020011742 A1 WO 2020011742A1
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- circuit
- ground fault
- voltage
- fault detection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
Definitions
- the present invention relates to the technical field of power electronics, in particular to a ground fault detection circuit and apparatus .
- the operating processes of electrical equipment such as three- phase frequency converters and current transformers which are commonly seen in IT systems (Isolation terra systems) all include a rectification stage, a DC bus stage and an inversion stage. If a ground fault occurs at any point in these three stages, the equipment will develop an abnormality, and the equipment should issue an alarm or fault prompt. However, since a single-point ground fault will generally not affect the normal operation of equipment, it is very difficult to determine whether a ground fault has occurred if ground faults are detected by detecting inter-phase voltage and main circuit current signals, etc. Ground faults can only be detected using more precise specialized detection equipment, so the cost of detection is high.
- an object of the present invention is to provide a ground fault detection circuit and apparatus, to solve the problem of the high cost of ground fault detection in the prior art .
- an embodiment of the present invention provides a ground fault detection circuit, comprising: a resistance voltage-dividing branch, comprising a sampling resistor and at least one voltage-dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least one voltage-dividing resistor being connected in parallel and then connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded; a signal sampling branch, connected to the sampling resistor and collecting an electrical signal on the sampling resistor.
- the circuit to be tested comprises a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence; the first end of the at least one voltage-dividing resistor is correspondingly connected to at least one of an input end of the rectifying circuit, the DC bus and an output end of the inverting circuit respectively.
- the input end of the rectifying circuit is a three- phase input end
- the output end of the inverting circuit is a three-phase output end
- the DC bus comprises positive and negative DC buses
- the first end of the at least one voltage- dividing resistor is correspondingly connected to at least one of three single-phase input ends of the rectifying circuit, the positive and negative DC buses and three single-phase output ends of the inverting circuit.
- the number of the voltage-dividing resistors is at least two; the first ends of the at least two voltage-dividing resistors are connected, in one-to-one correspondence, to at least two of the three single-phase input ends of the rectifying circuit, the positive and negative DC buses and the three single-phase output ends of the inverting circuit respectively; the second ends of the at least two voltage- dividing resistors are connected in parallel and then connected to the first end of the sampling resistor.
- the circuit to be tested comprises multiple cascaded unit circuits, each of the unit circuits comprising a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence; or the circuit to be tested comprises a rectifying unit, a DC bus circuit and an inverting circuit connected in sequence, the rectifying unit comprising multiple cascaded rectifying circuits.
- the signal sampling branch comprises a voltage sampling branch, connected to two ends of the sampling resistor and collecting voltage data of the two ends of the sampling resistor .
- the signal sampling branch comprises a current sampling branch, connected in series to the first end or the second end of the sampling resistor and collecting current data on the sampling resistor.
- An embodiment of the present invention also provides a ground fault detection apparatus, comprising the ground fault detection circuit in any one of the embodiments of the present invention described above, and a processor, the processor being connected to the signal sampling branch in the ground fault detection circuit, and determining whether a ground fault has occurred in the circuit to be tested according to an electrical signal sampled by the signal sampling branch.
- the processor determines that a ground fault has occurred in the circuit to be tested when a change amount of the electrical signal within a preset length of time reaches a preset threshold.
- the ground fault detection apparatus further comprises: an alarm, connected to the processor, and issuing alarm information when the processor determines that a ground fault has occurred in the circuit to be tested.
- the ground fault detection apparatus is a current transforming device or a frequency converting device.
- the ground fault detection circuit and apparatus in embodiments of the present invention by providing a resistance voltage- dividing branch connected between the circuit to be tested and a grounded end, and a signal sampling branch for detecting an electrical signal on a sampling resistor, can effectively detect an electrical signal in a loop formed by a fault grounded end and the resistance voltage-dividing branch when a ground fault occurs in the circuit to be tested, and can thereby determine accurately whether a ground fault has occurred in the circuit to be tested according to the value of the collected electrical signal and a change in the electrical signal; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost.
- Fig. 1 is a structural schematic diagram of a circuit to be tested, provided in an embodiment of the present invention.
- Fig. 2 is a first structural schematic diagram of a circuit system provided in an embodiment of the present invention.
- Fig. 3 is a three-phase common-mode equivalent circuit diagram of fig. 1.
- Fig. 4 is a three-phase common-mode equivalent circuit diagram of fig. 2.
- Fig. 5 is a schematic diagram of a first application state of a ground fault detection circuit provided in an embodiment of the present invention.
- Fig. 6 is a first structural schematic diagram of a ground fault detection circuit provided in an embodiment of the present invention.
- Fig. 7 is a schematic diagram of a second application state of a ground fault detection circuit provided in an embodiment of the present invention.
- Figs. 8a - 8f are 2nd - 7th structural schematic diagrams respectively of a circuit system provided in an embodiment of the present invention.
- Fig. 9 is a third structural schematic diagram of a ground fault detection circuit provided in an embodiment of the present invention.
- Fig. 10 is an eighth structural schematic diagram of a circuit system provided in an embodiment of the present invention.
- a ground fault detection circuit in embodiments of the present invention comprises a resistance voltage-dividing branch and a signal sampling branch, the resistance voltage-dividing branch comprising a sampling resistor and at least one voltage- dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least one voltage-dividing resistor being connected in parallel and then connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded; the signal sampling branch being connected to the sampling resistor and collecting an electrical signal on the sampling resistor.
- the ground fault detection circuit in embodiments of the present invention is used to subject a circuit to be tested in an IT system to ground fault testing.
- the resistance voltage-dividing branch is connected, in one-to-one correspondence, to at least one different branch in the circuit to be tested via the first end of the at least one voltage-dividing resistor, and grounded via the second end of the sampling resistor; i.e. the resistance voltage-dividing branch is connected between a grounded end and at least one branch of the circuit to be tested.
- the signal sampling branch cannot collect an electrical signal on the sampling resistor, or a collected electrical signal such as current or voltage is zero; if a ground fault occurs in the circuit to be tested, then the branch in which the ground fault occurs will form a loop with the resistance voltage-dividing branch, a current arises on the sampling resistor, there is a voltage across the sampling resistor, and the signal sampling branch can collect an electrical signal such as a current signal on the sampling resistor and a voltage signal of two ends of the sampling resistor.
- the resistance voltage-dividing branch may be composed of ordinary resistors, and the signal sampling branch may employ conventional equipment for collecting signals such as current and voltage; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost .
- the at least one voltage-dividing resistor in the resistance voltage-dividing branch may be respectively connected to a branch having a different voltage signal in the circuit to be tested, e.g. connected to an input end or output end of a different device in the circuit to be tested .
- the signal sampling branch may be a voltage sampling branch connected to two ends of the sampling resistor, and the voltage sampling branch collects voltage data of the two ends of the sampling resistor.
- the signal sampling branch could also be a current sampling branch connected in series to the first end or second end of the sampling resistor, to collect current data on the sampling resistor.
- the current sampling branch may be connected between the second end of the sampling resistor and the grounded end, or connected between the first end of the sampling resistor and a connection end resulting from the parallel connection of the second end of the at least one voltage-dividing resistor.
- a circuit to be tested may comprise a rectifying circuit (AC/DC) , a DC bus circuit (DC bus) and an inverting circuit (DC/AC) .
- AC/DC rectifying circuit
- DC bus DC bus
- DC/AC inverting circuit
- a ground fault detection circuit is used to subject the circuit to be tested to ground fault testing, a first end of at least one voltage-dividing resistor is correspondingly connected to at least one of an input end of the rectifying circuit, the DC bus circuit, and an output end of the inverting circuit respectively.
- the AC located at an input side of the rectifying circuit is an AC source, equivalent to an electricity grid side
- the M located at an output side of the rectifying circuit is an electric machine, equivalent to a load side.
- electrical energy transmitted in the circuit to be tested may be three-phase electricity; the input end of the rectifying circuit is a three-phase input end, the output end of the inverting circuit is a three-phase output end, and the DC bus comprises positive and negative DC buses.
- a first end of at least one voltage-dividing resistor may be connected, in one-to-one correspondence, to at least one of three single-phase input ends in the three-phase input end of the rectifying circuit, the positive and negative DC buses, and three single-phase input ends of the inverting circuit.
- A, B and C are arbitrary points on input lines corresponding to each of the three single-phase input ends of the rectifying circuit respectively; D and E are arbitrary points on the positive and negative DC buses respectively; F, G and H are arbitrary points on output lines corresponding to each of the three single-phase output ends of the inverting circuit respectively.
- a first end of a voltage-dividing resistor may be connected to any one of the points A, B, C, D, E, F, G and H.
- the ground fault detection circuit comprises a sampling resistor R0 and a voltage-dividing resistor Rl, and a first end of the voltage-dividing resistor Rl may be connected to any one of the points A, B, C, D, E, F, G and H (in the figure, the solid line marks the actual connection position, while the dotted lines mark alternative connection positions) .
- a signal sampling branch is a voltage sampling branch; the specific structure of the voltage sampling branch is not shown, but merely indicated by a voltage across the sampling resistor R0; no further superfluous description of this will be given in the description of other figures hereinbelow.
- the rectifying circuit, DC bus circuit and inverting circuit in the circuit to be tested shown in fig. 1 may all be regarded as short- circuited, hence the circuit to be tested shown in fig. 1 may be equivalent to the circuit shown in fig. 3.
- a common-mode loop thereof is open.
- AC1 is a common-mode component in an AC source
- AC2 is a common-mode component in an inverted output voltage .
- a common-mode loop of the circuit to be tested in fig. 2 is as shown in fig. 4 (in the figure, the solid line marks the actual connection position, while the dotted lines mark alternative connection positions) .
- the common-mode loop thereof is also open, there is no current flowing through the sampling resistor R0, and voltage data collected by a voltage sampling circuit is zero.
- a ground fault occurs in the circuit to be tested, as shown in fig.
- the output end of the inverting circuit is grounded (Rg is the resistance of a grounded end) , R0 and Rg are connected, and the common-mode loop conducts; at this time, a current flows through the sampling resistor R0, the voltage data collected by the voltage sampling circuit is not zero, and based on the change in the collected voltage data, a determination can be made that a ground fault has occurred in the circuit to be tested .
- the number of voltage-dividing resistors in the ground fault detection circuit is at least two. First ends of the at least two voltage-dividing resistors are connected, in one-to-one correspondence, to at least two of the three single-phase input ends of the rectifying circuit, the positive and negative DC buses, and the three single-phase output ends of the inverting circuit respectively; second ends of the at least two voltage-dividing resistors are connected in parallel and then connected to a first end of a sampling resistor .
- fig. 6 shows a ground fault detection circuit comprising two voltage-dividing resistors (Rl and R2)
- fig. 7 shows an equivalent circuit diagram in which the ground fault detection circuit is connected into the circuit to be tested shown in fig. 1.
- the normal-mode loop thereof is open;
- Rg is the resistance of a grounded end
- R0 and Rg are connected, and the common mode loop conducts; at this time, a current flows through the sampling resistor R0, the voltage data collected by the voltage sampling circuit is not zero, and based on the change in the collected voltage data, a determination can be made that a ground fault has occurred in the circuit to be tested.
- A, B and C are arbitrary points on input lines (electricity grid side) corresponding to the three-phase input end of the rectifying circuit respectively; these three points are symmetric, and any two of these three points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, with a total of three similar manners of connection.
- the connection manner example used in the circuit system shown in fig. 8a may be referred to: the first ends of Rl and R2 are connected to point A and point B respectively.
- D and E are arbitrary points on the positive and negative DC buses respectively; if these two points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, there is only one manner of connection, i.e. the connection manner example used in the circuit system shown in fig. 8b: the first ends of Rl and R2 are connected to point D and point E respectively .
- F, G and H are arbitrary points on output lines (electric machine side) corresponding to the three-phase output end of the inverting circuit respectively; these three points are also symmetric, and any two of these three points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, with a total of three similar manners of connection.
- the connection manner example used in the circuit system shown in fig. 8b may be referred to: the first ends of Rl and R2 are connected to point G and point H respectively.
- Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the three-phase input end of the rectifying circuit and the three-phase output end of the inverting circuit respectively, i.e. one sampling point is selected from the three points A, B and C, and one sampling point is selected from the three points F, G and H, with a total of 9 similar manners of connection.
- the connection manner example used in the circuit system shown in fig. 8d may be referred to: the first ends of Rl and R2 are connected to point B and point H respectively .
- Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the three-phase input end of the rectifying circuit and the positive and negative DC buses respectively, i.e. one sampling point is selected from the three points A, B and C, and one sampling point is selected from the two points D and E, with a total of 6 similar manners of connection.
- the connection manner example used in the circuit system shown in fig. 8e may be referred to: the first ends of Rl and R2 are connected to point B and point E respectively.
- Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the positive and negative DC buses and the three-phase output end of the inverting circuit respectively, i.e. one sampling point is selected from the two points D and E, and one sampling point is selected from the three points F, G and H, with a total of 6 similar manners of connection.
- the connection manner example used in the circuit system shown in fig. 8f may be referred to: the first ends of Rl and R2 are connected to point D and point H respectively.
- the number of voltage-dividing resistors in the ground fault detection circuit is a plurality, e.g. the ground fault detection circuit comprising n voltage- dividing resistors (Rl, R2...Rn) shown in fig. 9.
- the ground fault detection circuit is connected to the circuit to be tested shown in fig. 1, any n points may be selected from A, B, C, D, E, F, G and H, and first ends of n voltage-dividing resistors are connected, in one-to-one correspondence, to the selected n points respectively, with a total of C g manners of connection.
- n is less than 8.
- the ground fault detection circuit comprises 4 voltage-dividing resistors (Rl, R2, R3 and R4); the 4 voltage-dividing resistors are connected to points B, E, F and H respectively.
- the number of voltage-dividing resistors in the ground fault detection circuit is at least two, even if a ground fault occurs at the point of connection between one voltage-dividing resistor and the circuit to be tested (if there is only one voltage-dividing resistor, and a ground fault occurs at the point of connection between the voltage-dividing resistor and the circuit to be tested, then despite the fact that a loop is formed, there is no voltage difference in the loop, the voltage data sampled by the voltage sampling branch is zero, and it is not possible to determine that a ground fault has occurred in the circuit to be tested) , or an open circuit fault occurs at the point of connection of one voltage-dividing resistor (if there is only one voltage-dividing resistor, and an open circuit occurs at the point of connection between the voltage-dividing resistor and the circuit to be tested, then the voltage sampling branch cannot sample a voltage signal, with the result that it is not possible to determine that a ground fault has occurred in the circuit to be tested) , another voltage-dividing resistor can still be used to form
- each voltage-dividing resistor in embodiments of the present invention may be implemented using a single resistor, or using multiple resistors connected in series; and the resistance values of the voltage-dividing resistors may be equal or unequal.
- embodiments of the present invention only use the circuit to be tested shown in fig. 1 as an example to illustrate the ground fault detection circuit, the manner of connection with the circuit to be tested and the ground fault detection method in embodiments of the present invention; however, those skilled in the art should understand that the specific manner of connection of the rectifying circuit, the DC bus circuit and the inverting circuit in the circuit to be tested in embodiments of the present invention is not limited to that shown in fig.
- the ground fault detection circuit in embodiments of the present invention is not limited to the testing of a circuit system comprising a rectifying circuit, a DC bus circuit and an inverting circuit; in other embodiments, it is also possible to connect the ground fault detection circuit in embodiments of the present invention to any other circuit with reference to these embodiments, in order to perform ground fault detection.
- the circuit to be tested could also be a multiple unit circuit cascade structure, with each unit circuit comprising a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence, i.e. each unit may be the circuit to be tested shown in fig. 1.
- each unit may be the circuit to be tested shown in fig. 1.
- the circuit to be tested could also comprise a rectifying unit, a DC bus circuit and an inverting circuit connected in sequence, with the rectifying unit comprising multiple cascaded rectifying circuits, i.e. the rectifying unit formed by cascading multiple rectifying circuits is connected to the DC bus circuit and the inverting circuit.
- the rectifying unit comprising multiple cascaded rectifying circuits, i.e. the rectifying unit formed by cascading multiple rectifying circuits is connected to the DC bus circuit and the inverting circuit.
- the ground fault detection circuit in embodiments of the present invention by providing a resistance voltage-dividing branch connected between the circuit to be tested and a grounded end, and a signal sampling branch for detecting an electrical signal on a sampling resistor, can effectively detect an electrical signal in a loop formed by a fault grounded end and the resistance voltage-dividing branch when a ground fault occurs in the circuit to be tested, and can thereby determine accurately whether a ground fault has occurred in the circuit to be tested according to the value of the collected electrical signal and a change in the electrical signal; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost.
- a ground fault detection apparatus comprising the ground fault detection circuit in embodiments of the present invention as described above, and a processor connected to the signal sampling branch in the ground fault detection circuit; the processor is used to acquire an electrical signal on the sampling resistor collected by the signal sampling branch, and determine whether a ground fault has occurred in the circuit to be tested according to the acquired electrical signal.
- the processor can determine whether a ground fault has occurred in the circuit to be tested according to whether the acquired electrical signal is zero, or a change amount within a preset length of time. For example, when an acquired current signal or voltage signal is zero, it is determined that no ground fault has occurred in the circuit to be tested; or when a change amount of an acquired current signal or voltage signal within a preset length of time reaches a preset threshold, it is determined that a ground fault has occurred in the circuit to be tested.
- the ground fault detection apparatus in embodiments of the present invention may also comprise an alarm, which is connected to the processor in order to issue alarm information when the processor determines that a grounding fault has occurred in the circuit to be tested, to notify a worker to promptly carry out an overhaul of the circuit to be tested, to prevent the ground fault from causing a major loss.
- the alarm may be an audible-visual alarm device, to issue an audible-visual alarm signal when the processor determines that a ground fault has occurred in a device to be tested, or a communication device for sending a WeChat message or SMS message, to issue information, indicating that a ground fault has occurred on the device to be tested, to an associated worker' s communication device when the processor determines that a ground fault has occurred in the device to be tested .
- the ground fault detection apparatus in embodiments of the present invention may be a current transforming device (e.g. a three-phase current transformer) or a frequency converting device (e.g. a three- phase frequency converter) .
- the ground fault detection circuit in embodiments of the present invention may be provided, in order to integrate a ground fault detection function in devices such as current transformers and frequency converters, so as to perform ground fault testing of the internal circuitry of devices such as rectifying circuits, DC bus circuits and inverting circuits, so as to be able to promptly and accurately detect a ground fault that has occurred in a device.
- the ground fault detection apparatus in embodiments of the present invention could also be an independent device, for connecting to a circuit to be tested in a device such as a current transformer or frequency converter, to subject the device such as a current transformer or frequency converter to accurate ground fault testing .
- each component described in embodiments of the present invention may be split into a greater number of components according to the needs of implementation, and two or more components or parts of components may be combined to form a new component, to achieve the object of embodiments of the present invention.
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Abstract
Provided in embodiments of the present invention are a ground fault detection circuit and apparatus. The ground fault detection circuit comprises: a resistance voltage-dividing branch, the resistance voltage-dividing branch comprising a sampling resistor and at least one voltage-dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least one voltage-dividing resistor being connected in parallel and connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded; a signal sampling branch, connected to the sampling resistor and collecting an electrical signal on the sampling resistor. Using the technical solution of the present invention, it is possible to effectively detect an electrical signal in a loop formed by a fault grounded end and the resistance voltage-dividing branch when a ground fault occurs in the circuit to be tested, thereby making it easier to determine whether a ground fault has occurred in the circuit to be tested according to the collected electrical signal, to realize precise detection of ground faults at a lower cost.
Description
GROUND FAULT DETECTION CIRCUIT AND APPARATUS
Technical field
The present invention relates to the technical field of power electronics, in particular to a ground fault detection circuit and apparatus .
Background art
The operating processes of electrical equipment such as three- phase frequency converters and current transformers which are commonly seen in IT systems (Isolation terra systems) all include a rectification stage, a DC bus stage and an inversion stage. If a ground fault occurs at any point in these three stages, the equipment will develop an abnormality, and the equipment should issue an alarm or fault prompt. However, since a single-point ground fault will generally not affect the normal operation of equipment, it is very difficult to determine whether a ground fault has occurred if ground faults are detected by detecting inter-phase voltage and main circuit current signals, etc. Ground faults can only be detected using more precise specialized detection equipment, so the cost of detection is high.
Content of the invention
In view of the above, an object of the present invention is to provide a ground fault detection circuit and apparatus, to solve the problem of the high cost of ground fault detection in the prior art .
To achieve the abovementioned object, an embodiment of the present invention provides a ground fault detection circuit, comprising: a resistance voltage-dividing branch, comprising a sampling resistor and at least one voltage-dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least
one voltage-dividing resistor being connected in parallel and then connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded; a signal sampling branch, connected to the sampling resistor and collecting an electrical signal on the sampling resistor.
In an illustrative embodiment of the ground fault detection circuit, the circuit to be tested comprises a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence; the first end of the at least one voltage-dividing resistor is correspondingly connected to at least one of an input end of the rectifying circuit, the DC bus and an output end of the inverting circuit respectively.
In an illustrative embodiment of the ground fault detection circuit, the input end of the rectifying circuit is a three- phase input end, the output end of the inverting circuit is a three-phase output end, and the DC bus comprises positive and negative DC buses; the first end of the at least one voltage- dividing resistor is correspondingly connected to at least one of three single-phase input ends of the rectifying circuit, the positive and negative DC buses and three single-phase output ends of the inverting circuit.
In an illustrative embodiment of the ground fault detection circuit, the number of the voltage-dividing resistors is at least two; the first ends of the at least two voltage-dividing resistors are connected, in one-to-one correspondence, to at least two of the three single-phase input ends of the rectifying circuit, the positive and negative DC buses and the three single-phase output ends of the inverting circuit respectively; the second ends of the at least two voltage- dividing resistors are connected in parallel and then connected to the first end of the sampling resistor.
In an illustrative embodiment of the ground fault detection circuit, the circuit to be tested comprises multiple cascaded
unit circuits, each of the unit circuits comprising a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence; or the circuit to be tested comprises a rectifying unit, a DC bus circuit and an inverting circuit connected in sequence, the rectifying unit comprising multiple cascaded rectifying circuits.
In an illustrative embodiment of the ground fault detection circuit, the signal sampling branch comprises a voltage sampling branch, connected to two ends of the sampling resistor and collecting voltage data of the two ends of the sampling resistor .
In an illustrative embodiment of the ground fault detection circuit, the signal sampling branch comprises a current sampling branch, connected in series to the first end or the second end of the sampling resistor and collecting current data on the sampling resistor.
An embodiment of the present invention also provides a ground fault detection apparatus, comprising the ground fault detection circuit in any one of the embodiments of the present invention described above, and a processor, the processor being connected to the signal sampling branch in the ground fault detection circuit, and determining whether a ground fault has occurred in the circuit to be tested according to an electrical signal sampled by the signal sampling branch.
In an illustrative embodiment of the ground fault detection apparatus, the processor determines that a ground fault has occurred in the circuit to be tested when a change amount of the electrical signal within a preset length of time reaches a preset threshold.
In an illustrative embodiment of the ground fault detection apparatus, the ground fault detection apparatus further comprises: an alarm, connected to the processor, and issuing
alarm information when the processor determines that a ground fault has occurred in the circuit to be tested.
In an illustrative embodiment of the ground fault detection apparatus, the ground fault detection apparatus is a current transforming device or a frequency converting device.
The ground fault detection circuit and apparatus in embodiments of the present invention, by providing a resistance voltage- dividing branch connected between the circuit to be tested and a grounded end, and a signal sampling branch for detecting an electrical signal on a sampling resistor, can effectively detect an electrical signal in a loop formed by a fault grounded end and the resistance voltage-dividing branch when a ground fault occurs in the circuit to be tested, and can thereby determine accurately whether a ground fault has occurred in the circuit to be tested according to the value of the collected electrical signal and a change in the electrical signal; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost.
Description of the accompanying drawings
Preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, to give those skilled in the art a clearer understanding of the abovementioned and other features and advantages of the present invention. Drawings:
Fig. 1 is a structural schematic diagram of a circuit to be tested, provided in an embodiment of the present invention.
Fig. 2 is a first structural schematic diagram of a circuit system provided in an embodiment of the present invention.
Fig. 3 is a three-phase common-mode equivalent circuit diagram of fig. 1.
Fig. 4 is a three-phase common-mode equivalent circuit diagram of fig. 2.
Fig. 5 is a schematic diagram of a first application state of a ground fault detection circuit provided in an embodiment of the
present invention.
Fig. 6 is a first structural schematic diagram of a ground fault detection circuit provided in an embodiment of the present invention.
Fig. 7 is a schematic diagram of a second application state of a ground fault detection circuit provided in an embodiment of the present invention.
Figs. 8a - 8f are 2nd - 7th structural schematic diagrams respectively of a circuit system provided in an embodiment of the present invention.
Fig. 9 is a third structural schematic diagram of a ground fault detection circuit provided in an embodiment of the present invention.
Fig. 10 is an eighth structural schematic diagram of a circuit system provided in an embodiment of the present invention.
Particular embodiments
In order to clarify the object, technical solution and advantages of the present invention, the present invention is explained in further detail below by way of embodiments.
A ground fault detection circuit in embodiments of the present invention comprises a resistance voltage-dividing branch and a signal sampling branch, the resistance voltage-dividing branch comprising a sampling resistor and at least one voltage- dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least one voltage-dividing resistor being connected in parallel and then connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded; the signal sampling branch being connected to the sampling resistor and collecting an electrical signal on the sampling resistor.
The ground fault detection circuit in embodiments of the present invention is used to subject a circuit to be tested in an IT system to ground fault testing. In the ground fault
detection circuit, the resistance voltage-dividing branch is connected, in one-to-one correspondence, to at least one different branch in the circuit to be tested via the first end of the at least one voltage-dividing resistor, and grounded via the second end of the sampling resistor; i.e. the resistance voltage-dividing branch is connected between a grounded end and at least one branch of the circuit to be tested. In the course of operation of the circuit to be tested, if no ground fault has occurred in the circuit to be tested, then no current arises in the resistance voltage-dividing branch, and the signal sampling branch cannot collect an electrical signal on the sampling resistor, or a collected electrical signal such as current or voltage is zero; if a ground fault occurs in the circuit to be tested, then the branch in which the ground fault occurs will form a loop with the resistance voltage-dividing branch, a current arises on the sampling resistor, there is a voltage across the sampling resistor, and the signal sampling branch can collect an electrical signal such as a current signal on the sampling resistor and a voltage signal of two ends of the sampling resistor.
It is possible to determine accurately whether a ground fault has occurred in the circuit to be tested according to whether the electrical signal collected by the signal sampling branch, such as the current signal or voltage signal, is zero, and a change in the current signal or voltage signal; moreover, the resistance voltage-dividing branch may be composed of ordinary resistors, and the signal sampling branch may employ conventional equipment for collecting signals such as current and voltage; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost .
In actual applications, the at least one voltage-dividing resistor in the resistance voltage-dividing branch may be respectively connected to a branch having a different voltage signal in the circuit to be tested, e.g. connected to an input
end or output end of a different device in the circuit to be tested .
Furthermore, the signal sampling branch may be a voltage sampling branch connected to two ends of the sampling resistor, and the voltage sampling branch collects voltage data of the two ends of the sampling resistor. The signal sampling branch could also be a current sampling branch connected in series to the first end or second end of the sampling resistor, to collect current data on the sampling resistor. Here, the current sampling branch may be connected between the second end of the sampling resistor and the grounded end, or connected between the first end of the sampling resistor and a connection end resulting from the parallel connection of the second end of the at least one voltage-dividing resistor.
According to a demonstrative embodiment of the present invention, as shown in fig. 1, a circuit to be tested may comprise a rectifying circuit (AC/DC) , a DC bus circuit (DC bus) and an inverting circuit (DC/AC) . When a ground fault detection circuit is used to subject the circuit to be tested to ground fault testing, a first end of at least one voltage-dividing resistor is correspondingly connected to at least one of an input end of the rectifying circuit, the DC bus circuit, and an output end of the inverting circuit respectively. In the figure, the AC located at an input side of the rectifying circuit is an AC source, equivalent to an electricity grid side; the M located at an output side of the rectifying circuit is an electric machine, equivalent to a load side.
Here, electrical energy transmitted in the circuit to be tested may be three-phase electricity; the input end of the rectifying circuit is a three-phase input end, the output end of the inverting circuit is a three-phase output end, and the DC bus comprises positive and negative DC buses. When the ground fault detection circuit is connected to the circuit to be tested, a first end of at least one voltage-dividing resistor may be connected, in one-to-one correspondence, to at least one of
three single-phase input ends in the three-phase input end of the rectifying circuit, the positive and negative DC buses, and three single-phase input ends of the inverting circuit.
In the circuit to be tested shown in fig. 1 : A, B and C are arbitrary points on input lines corresponding to each of the three single-phase input ends of the rectifying circuit respectively; D and E are arbitrary points on the positive and negative DC buses respectively; F, G and H are arbitrary points on output lines corresponding to each of the three single-phase output ends of the inverting circuit respectively.
When the ground fault detection circuit is connected to the circuit to be tested, a first end of a voltage-dividing resistor may be connected to any one of the points A, B, C, D, E, F, G and H.
In an optional embodiment, in a circuit system as shown in fig. 2 (including a circuit to be tested and a ground fault detection circuit) , the ground fault detection circuit comprises a sampling resistor R0 and a voltage-dividing resistor Rl, and a first end of the voltage-dividing resistor Rl may be connected to any one of the points A, B, C, D, E, F, G and H (in the figure, the solid line marks the actual connection position, while the dotted lines mark alternative connection positions) . Here, a signal sampling branch is a voltage sampling branch; the specific structure of the voltage sampling branch is not shown, but merely indicated by a voltage across the sampling resistor R0; no further superfluous description of this will be given in the description of other figures hereinbelow.
In the case of a three-phase common-mode model, the rectifying circuit, DC bus circuit and inverting circuit in the circuit to be tested shown in fig. 1 may all be regarded as short- circuited, hence the circuit to be tested shown in fig. 1 may be equivalent to the circuit shown in fig. 3. When the circuit to be tested is operating normally, a common-mode loop thereof is open. In the figure, AC1 is a common-mode component in an AC
source; AC2 is a common-mode component in an inverted output voltage .
When the voltage-dividing resistor Rl has been connected to any one of the points A, B, C, D, E, F, G and H, a common-mode loop of the circuit to be tested in fig. 2 is as shown in fig. 4 (in the figure, the solid line marks the actual connection position, while the dotted lines mark alternative connection positions) . When the circuit to be tested is operating normally, the common-mode loop thereof is also open, there is no current flowing through the sampling resistor R0, and voltage data collected by a voltage sampling circuit is zero. When a ground fault occurs in the circuit to be tested, as shown in fig. 5, the output end of the inverting circuit is grounded (Rg is the resistance of a grounded end) , R0 and Rg are connected, and the common-mode loop conducts; at this time, a current flows through the sampling resistor R0, the voltage data collected by the voltage sampling circuit is not zero, and based on the change in the collected voltage data, a determination can be made that a ground fault has occurred in the circuit to be tested .
In another optional embodiment, the number of voltage-dividing resistors in the ground fault detection circuit is at least two. First ends of the at least two voltage-dividing resistors are connected, in one-to-one correspondence, to at least two of the three single-phase input ends of the rectifying circuit, the positive and negative DC buses, and the three single-phase output ends of the inverting circuit respectively; second ends of the at least two voltage-dividing resistors are connected in parallel and then connected to a first end of a sampling resistor .
For example, fig. 6 shows a ground fault detection circuit comprising two voltage-dividing resistors (Rl and R2); fig. 7 shows an equivalent circuit diagram in which the ground fault detection circuit is connected into the circuit to be tested shown in fig. 1. When the circuit to be tested is operating
normally, the normal-mode loop thereof is open; when a ground fault occurs in the circuit to be tested (Rg is the resistance of a grounded end) , R0 and Rg are connected, and the common mode loop conducts; at this time, a current flows through the sampling resistor R0, the voltage data collected by the voltage sampling circuit is not zero, and based on the change in the collected voltage data, a determination can be made that a ground fault has occurred in the circuit to be tested.
When the ground fault detection circuit is connected into the circuit to be tested shown in fig. 1, first ends of the voltage-dividing resistors Rl and R2 are correspondingly connected to any two of the points A, B, C, D, E, F, G and H. There are a total of 28 specific manners of connection (
= 28) ; six examples of manners of connection are shown in the circuit systems in figs. 8a - 8f.
In the circuit system, A, B and C are arbitrary points on input lines (electricity grid side) corresponding to the three-phase input end of the rectifying circuit respectively; these three points are symmetric, and any two of these three points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, with a total of three similar manners of connection. For a specific manner of connection, the connection manner example used in the circuit system shown in fig. 8a may be referred to: the first ends of Rl and R2 are connected to point A and point B respectively.
D and E are arbitrary points on the positive and negative DC buses respectively; if these two points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, there is only one manner of connection, i.e. the connection manner example used in the circuit system shown in fig. 8b: the first ends of Rl and R2 are connected to point D and point E respectively .
F, G and H are arbitrary points on output lines (electric machine side) corresponding to the three-phase output end of the inverting circuit respectively; these three points are also
symmetric, and any two of these three points are selected to correspondingly connect the voltage-dividing resistors Rl and R2, with a total of three similar manners of connection. For a specific manner of connection, the connection manner example used in the circuit system shown in fig. 8b may be referred to: the first ends of Rl and R2 are connected to point G and point H respectively.
Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the three-phase input end of the rectifying circuit and the three-phase output end of the inverting circuit respectively, i.e. one sampling point is selected from the three points A, B and C, and one sampling point is selected from the three points F, G and H, with a total of 9 similar manners of connection. For a specific manner of connection, the connection manner example used in the circuit system shown in fig. 8d may be referred to: the first ends of Rl and R2 are connected to point B and point H respectively .
Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the three-phase input end of the rectifying circuit and the positive and negative DC buses respectively, i.e. one sampling point is selected from the three points A, B and C, and one sampling point is selected from the two points D and E, with a total of 6 similar manners of connection. For a specific manner of connection, the connection manner example used in the circuit system shown in fig. 8e may be referred to: the first ends of Rl and R2 are connected to point B and point E respectively.
Two sampling points for connecting the voltage-dividing resistors Rl and R2 may also be selected from the positive and negative DC buses and the three-phase output end of the inverting circuit respectively, i.e. one sampling point is selected from the two points D and E, and one sampling point is selected from the three points F, G and H, with a total of 6 similar manners of connection. For a specific manner of
connection, the connection manner example used in the circuit system shown in fig. 8f may be referred to: the first ends of Rl and R2 are connected to point D and point H respectively.
In another optional embodiment, the number of voltage-dividing resistors in the ground fault detection circuit is a plurality, e.g. the ground fault detection circuit comprising n voltage- dividing resistors (Rl, R2...Rn) shown in fig. 9. When the ground fault detection circuit is connected to the circuit to be tested shown in fig. 1, any n points may be selected from A, B, C, D, E, F, G and H, and first ends of n voltage-dividing resistors are connected, in one-to-one correspondence, to the selected n points respectively, with a total of Cg manners of connection. Here, n is less than 8.
For example, in the circuit system shown in fig. 10, the ground fault detection circuit comprises 4 voltage-dividing resistors (Rl, R2, R3 and R4); the 4 voltage-dividing resistors are connected to points B, E, F and H respectively.
In the embodiments of the present invention, when the number of voltage-dividing resistors in the ground fault detection circuit is at least two, even if a ground fault occurs at the point of connection between one voltage-dividing resistor and the circuit to be tested (if there is only one voltage-dividing resistor, and a ground fault occurs at the point of connection between the voltage-dividing resistor and the circuit to be tested, then despite the fact that a loop is formed, there is no voltage difference in the loop, the voltage data sampled by the voltage sampling branch is zero, and it is not possible to determine that a ground fault has occurred in the circuit to be tested) , or an open circuit fault occurs at the point of connection of one voltage-dividing resistor (if there is only one voltage-dividing resistor, and an open circuit occurs at the point of connection between the voltage-dividing resistor and the circuit to be tested, then the voltage sampling branch cannot sample a voltage signal, with the result that it is not possible to determine that a ground fault has occurred in the
circuit to be tested) , another voltage-dividing resistor can still be used to form a loop with a grounded end in the circuit to be tested, ensuring that there is at least one closed current loop flowing through the ground, and thereby increasing the reliability of the ground fault detection circuit.
It is explained here that each voltage-dividing resistor in embodiments of the present invention (including Rl, R2...Rn) may be implemented using a single resistor, or using multiple resistors connected in series; and the resistance values of the voltage-dividing resistors may be equal or unequal.
Moreover, embodiments of the present invention only use the circuit to be tested shown in fig. 1 as an example to illustrate the ground fault detection circuit, the manner of connection with the circuit to be tested and the ground fault detection method in embodiments of the present invention; however, those skilled in the art should understand that the specific manner of connection of the rectifying circuit, the DC bus circuit and the inverting circuit in the circuit to be tested in embodiments of the present invention is not limited to that shown in fig. 1, and the ground fault detection circuit in embodiments of the present invention is not limited to the testing of a circuit system comprising a rectifying circuit, a DC bus circuit and an inverting circuit; in other embodiments, it is also possible to connect the ground fault detection circuit in embodiments of the present invention to any other circuit with reference to these embodiments, in order to perform ground fault detection.
For example, in some embodiments of the present invention, the circuit to be tested could also be a multiple unit circuit cascade structure, with each unit circuit comprising a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence, i.e. each unit may be the circuit to be tested shown in fig. 1. In such a situation, with reference to embodiments of the present invention, it is possible to correspondingly connect a first end of at least one voltage-
dividing resistor in the ground fault detection circuit to at least one of an input end (including a three-phase input end) of the rectifying circuit, positive and negative DC buses and an output end (including a three-phase output end) of the inverting circuit in each unit circuit.
As another example, in some other embodiments of the present invention, the circuit to be tested could also comprise a rectifying unit, a DC bus circuit and an inverting circuit connected in sequence, with the rectifying unit comprising multiple cascaded rectifying circuits, i.e. the rectifying unit formed by cascading multiple rectifying circuits is connected to the DC bus circuit and the inverting circuit. In such a situation, with reference to embodiments of the present invention, it is possible to correspondingly connect a first end of at least one voltage-dividing resistor in the ground fault detection circuit to at least one of an input end (including a three-phase input end) of the rectifying circuit, positive and negative DC buses and an output end (including a three-phase output end) of the inverting circuit.
The ground fault detection circuit in embodiments of the present invention, by providing a resistance voltage-dividing branch connected between the circuit to be tested and a grounded end, and a signal sampling branch for detecting an electrical signal on a sampling resistor, can effectively detect an electrical signal in a loop formed by a fault grounded end and the resistance voltage-dividing branch when a ground fault occurs in the circuit to be tested, and can thereby determine accurately whether a ground fault has occurred in the circuit to be tested according to the value of the collected electrical signal and a change in the electrical signal; ground fault detection can be performed without the need to use more precise specialized detection equipment, and precise detection of ground faults is realized at a lower cost.
On this basis, also provided in embodiments of the present invention is a ground fault detection apparatus, comprising the
ground fault detection circuit in embodiments of the present invention as described above, and a processor connected to the signal sampling branch in the ground fault detection circuit; the processor is used to acquire an electrical signal on the sampling resistor collected by the signal sampling branch, and determine whether a ground fault has occurred in the circuit to be tested according to the acquired electrical signal.
Specifically, the processor can determine whether a ground fault has occurred in the circuit to be tested according to whether the acquired electrical signal is zero, or a change amount within a preset length of time. For example, when an acquired current signal or voltage signal is zero, it is determined that no ground fault has occurred in the circuit to be tested; or when a change amount of an acquired current signal or voltage signal within a preset length of time reaches a preset threshold, it is determined that a ground fault has occurred in the circuit to be tested.
In some embodiments of the present invention, the ground fault detection apparatus in embodiments of the present invention may also comprise an alarm, which is connected to the processor in order to issue alarm information when the processor determines that a grounding fault has occurred in the circuit to be tested, to notify a worker to promptly carry out an overhaul of the circuit to be tested, to prevent the ground fault from causing a major loss. For example, the alarm may be an audible-visual alarm device, to issue an audible-visual alarm signal when the processor determines that a ground fault has occurred in a device to be tested, or a communication device for sending a WeChat message or SMS message, to issue information, indicating that a ground fault has occurred on the device to be tested, to an associated worker' s communication device when the processor determines that a ground fault has occurred in the device to be tested .
In actual application scenarios, the ground fault detection apparatus in embodiments of the present invention may be a
current transforming device (e.g. a three-phase current transformer) or a frequency converting device (e.g. a three- phase frequency converter) . In other words, in commonly used devices such as current transformers and frequency converters, the ground fault detection circuit in embodiments of the present invention may be provided, in order to integrate a ground fault detection function in devices such as current transformers and frequency converters, so as to perform ground fault testing of the internal circuitry of devices such as rectifying circuits, DC bus circuits and inverting circuits, so as to be able to promptly and accurately detect a ground fault that has occurred in a device. Of course, the ground fault detection apparatus in embodiments of the present invention could also be an independent device, for connecting to a circuit to be tested in a device such as a current transformer or frequency converter, to subject the device such as a current transformer or frequency converter to accurate ground fault testing .
It must be pointed out that each component described in embodiments of the present invention may be split into a greater number of components according to the needs of implementation, and two or more components or parts of components may be combined to form a new component, to achieve the object of embodiments of the present invention.
The embodiments above are merely preferred embodiments of the present invention, which are not intended to limit it. Any amendments, equivalent substitutions or improvements etc. made within the spirit and principles of the present invention shall be included in the scope of protection thereof.
Claims
1. A ground fault detection circuit, characterized by comprising :
a resistance voltage-dividing branch, comprising a sampling resistor and at least one voltage-dividing resistor, with a first end of the at least one voltage-dividing resistor being correspondingly connected to at least one branch in a circuit to be tested respectively, a second end of the at least one voltage-dividing resistor being connected in parallel and then connected to a first end of the sampling resistor, and a second end of the sampling resistor being grounded;
a signal sampling branch, connected to the sampling resistor and collecting an electrical signal on the sampling resistor.
2. The ground fault detection circuit as claimed in claim 1, characterized in that the circuit to be tested comprises a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence;
the first end of the at least one voltage-dividing resistor is correspondingly connected to at least one of an input end of the rectifying circuit, the DC bus and an output end of the inverting circuit respectively.
3. The ground fault detection circuit as claimed in claim 2, characterized in that the input end of the rectifying circuit is a three-phase input end, the output end of the inverting circuit is a three-phase output end, and the DC bus comprises positive and negative DC buses;
the first end of the at least one voltage-dividing resistor is correspondingly connected to at least one of three single-phase input ends of the rectifying circuit, the positive and negative DC buses and three single-phase output ends of the inverting circuit .
4. The ground fault detection circuit as claimed in claim 3, characterized in that the number of the voltage-dividing
resistors is at least two;
the first ends of the at least two voltage-dividing resistors are connected, in one-to-one correspondence, to at least two of the three single-phase input ends of the rectifying circuit, the positive and negative DC buses and the three single-phase output ends of the inverting circuit respectively;
the second ends of the at least two voltage-dividing resistors are connected in parallel and then connected to the first end of the sampling resistor.
5. The ground fault detection circuit as claimed in claim 2, characterized in that the circuit to be tested comprises multiple cascaded unit circuits, each of the unit circuits comprising a rectifying circuit, a DC bus circuit and an inverting circuit connected in sequence; or
the circuit to be tested comprises a rectifying unit, a DC bus circuit and an inverting circuit connected in sequence, the rectifying unit comprising multiple cascaded rectifying circuits .
6. The ground fault detection circuit as claimed in any one of claims 1 to 5, characterized in that the signal sampling branch comprises a voltage sampling branch, connected to two ends of the sampling resistor and collecting voltage data of the two ends of the sampling resistor.
7. The ground fault detection circuit as claimed in any one of claims 1 to 5, characterized in that the signal sampling branch comprises a current sampling branch, connected in series to the first end or the second end of the sampling resistor and collecting current data on the sampling resistor.
8. A ground fault detection apparatus, characterized in that the ground fault detection apparatus comprises the ground fault detection circuit as claimed in any one of claims 1 to 7, and a processor, the processor being connected to the signal sampling
branch in the ground fault detection circuit, and determining whether a ground fault has occurred in the circuit to be tested according to an electrical signal sampled by the signal sampling branch.
9. The ground fault detection apparatus as claimed in claim 8, characterized in that the processor determines that a ground fault has occurred in the circuit to be tested when a change amount of the electrical signal within a preset length of time reaches a preset threshold.
10. The ground fault detection apparatus as claimed in claim 8, characterized in that the ground fault detection apparatus further comprises:
an alarm, connected to the processor, and issuing alarm information when the processor determines that a ground fault has occurred in the circuit to be tested.
11. The ground fault detection apparatus as claimed in any one of claims 8 to 10, characterized in that the ground fault detection apparatus is a current transforming device or a frequency converting device.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810759363.1A CN110780224A (en) | 2018-07-11 | 2018-07-11 | Ground fault detection circuit and device |
| CN201810759363.1 | 2018-07-11 |
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| WO2020011742A1 true WO2020011742A1 (en) | 2020-01-16 |
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| PCT/EP2019/068320 WO2020011742A1 (en) | 2018-07-11 | 2019-07-09 | Ground fault detection circuit and apparatus |
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| WO (1) | WO2020011742A1 (en) |
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| WO2023245480A1 (en) * | 2022-06-22 | 2023-12-28 | 深圳市大疆创新科技有限公司 | Fault detection method and apparatus for phase voltage sampling circuit, and movable platform |
| WO2024082089A1 (en) * | 2022-10-17 | 2024-04-25 | Siemens Aktiengesellschaft | Motor driver and method for using the motor driver |
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| US8964423B2 (en) * | 2011-08-17 | 2015-02-24 | Honeywell International Inc. | Low weight 3-phase 5-output wire power conversion system for micro-grid |
| CN103066554B (en) * | 2012-12-12 | 2015-02-25 | 常州联力自动化科技有限公司 | Single-phase source leakage detection circuit for isolated neutral system |
| CN105720830A (en) * | 2014-12-02 | 2016-06-29 | 永济新时速电机电器有限责任公司 | Traction converter with bus voltage grounding protection voltage-division sampling circuit |
| CN104730407B (en) * | 2015-02-03 | 2017-12-12 | 南车株洲电力机车研究所有限公司 | A kind of grounded inspection circuit |
| CN105067940A (en) * | 2015-08-06 | 2015-11-18 | 株洲南车时代电气股份有限公司 | Grounding diagnostic method for main loop of locomotive traction converter |
| CN106671782B (en) * | 2015-11-09 | 2019-06-21 | 中车大连电力牵引研发中心有限公司 | A kind of AC electric locomotive trailer system |
| CN107305233A (en) * | 2016-04-22 | 2017-10-31 | 刘晓博 | One kind 20 to 10kV distribution lines are grounded strategy, algorithm and circuit between constituency |
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- 2018-07-11 CN CN201810759363.1A patent/CN110780224A/en active Pending
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| US20140008970A1 (en) * | 2012-07-09 | 2014-01-09 | Honda Motor Co., Ltd. | Ground fault detecting device for an ungrounded circuit |
| JP2018009875A (en) * | 2016-07-13 | 2018-01-18 | 株式会社ケーヒン | Ground fault detection device |
| CN107797018A (en) * | 2017-11-03 | 2018-03-13 | 中车大连电力牵引研发中心有限公司 | Diesel locomotive grounded inspection circuit, device and method |
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