Earth fault detector

Abstract

The present invention provides a ground fault detector that can detect ground faults with a constant sensitivity, regardless of the potential difference between the positive and negative poles of a DC bus, while suppressing unnecessary current consumption that flows when no ground fault occurs. [Solution] The ground fault detector 1 of the present invention includes a detection unit Du in which a first rectifier element D1 having a cathode connected to a positive wire Vp, a first internal power supply V1 having an anode connected to the anode of the first rectifier element D1, a second internal power supply V2 having an anode connected to the cathode of the first internal power supply V1, and a second rectifier element D2 having a cathode connected to the cathode of the second internal power supply V2 and an anode connected to a negative wire Vn are connected in series, a ground wire GL is provided extending from the connection point between the cathode of the first internal power supply V1 and the anode of the second internal power supply V2 to ground G, and the detection unit Du has a detection resistor Rd to which the voltage of the first internal power supply V1 or the second internal power supply V2 is applied when a ground fault occurs.

Description

[Technical field]

[0001] The present invention relates to a ground fault detector that detects a ground fault in a DC circuit that utilizes a DC bus. [Background technology]

[0002] A ground fault detector has been proposed in the past that includes two constant voltage elements each having a breakdown voltage that is approximately half the DC power supply voltage in order to suppress the consumption current that flows in from the anode side of a DC circuit when no ground fault occurs in the DC circuit (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-017690 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional earth fault detector described above, the magnitude of the earth fault current that flows in the event of an earth fault is based on the potential difference between the positive or negative side of the DC bus and the location where the earth fault occurs. Therefore, if the potential difference between the positive and negative poles of the DC bus in a single DC circuit differs from area to area, the detection resistance value is constant, so the magnitude of the earth fault current changes from area to area, and the sensitivity of the earth fault detector that detects the earth fault current differs.

[0005] An object of the present invention is to provide a ground fault detector that can detect ground faults with a constant sensitivity, regardless of the potential difference between the positive and negative poles of a DC bus, while suppressing unnecessary consumption current that flows in when no ground fault occurs. [Means for solving the problem]

[0006] In consideration of the current situation, the inventor conducted extensive research and discovered that by providing an internal power supply having a predetermined voltage within the earth fault detector, when an earth fault occurs, the potential difference between the internal power supply and the earth fault location within the earth fault detector is applied to the detection section, so that an earth fault can be detected with a constant sensitivity regardless of the potential difference between the positive and negative poles of the DC bus, thereby leading to the present invention.

[0007] The ground fault detector of the present invention includes a detection unit having a detection resistor to which the voltage of the first internal power supply or the second internal power supply is applied when a ground fault occurs, the detection unit including a first rectifier element having a cathode connected to the positive pole of a DC bus extending from a DC power supply, a first internal power supply having an anode connected to the anode of the first rectifier element, a second internal power supply having an anode connected to the cathode of the first internal power supply, and a second rectifier element having a cathode connected to the cathode of the second internal power supply and an anode connected to the negative pole of a DC bus extending from the DC power supply, the detection unit including a ground wire extending to ground from the connection point between the cathode of the first internal power supply and the anode of the second internal power supply, the detection unit including a detection resistor to which the voltage of the first internal power supply or the second internal power supply is applied when a ground fault occurs.

[0008] With this type of ground fault detector, the first and second rectifying elements suppress the unnecessary consumption current that flows in when no ground fault occurs, while the potential difference between either the first or second internal power supply and the point where the ground fault occurs is applied to the detection unit, and the detection unit detects the detected current. Therefore, the detection unit can detect a ground fault with a constant sensitivity, regardless of the potential difference between the positive and negative lines of the DC bus.

[0009] The detection portion is preferably provided on the ground line.

[0010] With such a ground fault detector, the detection current passes through the ground wire whether a ground fault occurs on the positive line or the negative line, so by providing a detection unit in the ground wire, ground faults can be detected efficiently.

[0011] It is also preferable that the detection unit is provided between the anode of the first rectifier element and the anode of the first internal power supply, and between the cathode of the second internal power supply and the cathode of the second rectifier element.

[0012] With this type of ground fault detector, a detection unit provided between the anode of the first rectifier element and the anode of the first internal power supply detects a ground fault that occurs on the positive line side, and a detection unit provided between the cathode of the second internal power supply and the cathode of the second rectifier element detects a ground fault that occurs on the negative line side. Therefore, depending on which detection unit detects the ground fault, it is easy to know whether the ground fault has occurred on the positive line side or the negative line side.

[0013] In addition, the ground fault detector of the present invention comprises a first rectifier element having a cathode connected to the positive wire of a DC bus extending from a DC power source and a second rectifier element having an anode connected to the negative wire of a DC bus extending from a DC power source, connected in series, a ground wire extending from a connection point connecting the anode of the first rectifier element and the cathode of the second rectifier element to ground, and an internal power source having an anode connected between the anode of the first rectifier element and the connection point and a cathode connected between the connection point and the cathode of the second rectifier element, and a detection unit having a detection resistor to which the voltage of the internal power source is applied when a ground fault occurs is provided in the ground wire.

[0014] With this type of ground fault detector, the first and second rectifier elements suppress the unnecessary consumption current that flows in when no ground fault occurs, while the potential difference between either the anode or cathode of the internal power supply and the ground fault location is applied to the detection unit, which detects the detected current, so that the detection unit can detect ground faults with a constant sensitivity, regardless of the potential difference between the positive and negative lines of the DC bus.

[0015] It is also preferable that a first resistive element is provided between the anode of the internal power supply and the connection point, and a second resistive element is provided between the connection point and the cathode of the internal power supply.

[0016] According to such a ground fault detector, a circuit for detecting a ground fault in the internal power supply can be configured by providing two resistive elements between the anode and cathode of the internal power supply provided in the ground fault detector.

[0017] It is also preferable that a first constant voltage element is provided between the anode of the internal power supply and the connection point, and a second constant voltage element is provided between the connection point and the cathode of the internal power supply.

[0018] According to this type of ground fault detector, by providing two constant voltage elements between the anode and cathode of the internal power supply provided within the ground fault detector, it is possible not only to detect ground faults but also to suppress unnecessary current consumption when no ground fault occurs.

[0019] Furthermore, the ground fault detector of the present invention comprises a first rectifier element having a cathode connected to the positive pole line of a DC bus extending from a DC power source, a second rectifier element having an anode connected to the negative pole line of a DC bus extending from a DC power source, and an internal power supply circuit having an anode connected to the anode of the first rectifier element and a cathode connected to the cathode of the second rectifier element, connected in series, wherein the internal power supply circuit has a ground wire extending to ground, and a detection unit having a detection resistor to which the voltage of the internal power supply is applied when a ground fault occurs is provided in the ground wire.

[0020] With this type of ground fault detector, the first and second rectifier elements suppress the unnecessary consumption current that flows in when no ground fault occurs, while the potential difference between either the anode or cathode of the internal power supply circuit and the ground fault location is applied to the detection unit, which detects the detected current, so that the detection unit can detect ground faults with a constant sensitivity, regardless of the potential difference between the positive and negative lines of the DC bus. Effect of the Invention

[0021] This makes it possible to provide a ground fault detector that can detect ground fault currents with a constant sensitivity regardless of the potential difference between the positive and negative poles of the DC bus, while suppressing unnecessary current consumption that flows in when no ground fault occurs. [Brief description of the drawings]

[0022] [Figure 1] 1 is a circuit diagram showing a configuration of a ground fault detector according to a first embodiment of the present invention. [Diagram 2]2 is a schematic diagram showing an operation when a first detection current is detected by the ground fault detector shown in FIG. 1. [Diagram 3] 4 is a schematic diagram showing an operation when a second detection current is detected by the ground fault detector shown in FIG. 1. [Figure 4] FIG. 6 is a circuit diagram showing a configuration of a ground fault detector according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a circuit diagram showing a configuration of a ground fault detector according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a circuit diagram showing a configuration of a ground fault detector according to a fourth embodiment of the present invention. [Figure 7] FIG. 11 is a circuit diagram showing a configuration of a ground fault detector according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a ground fault detector according to the present invention will be described with reference to the drawings. In the drawings, the same reference numerals are used to denote the same configuration, and the description thereof will be omitted.

[0024] Fig. 1 is a circuit diagram showing a configuration of a ground fault detector 1 according to a first embodiment of the present invention. The ground fault detector 1 shown in Fig. 1 is provided between a positive electrode line Vp and a negative electrode line Vn, which are DC bus lines extending from a DC power supply (not shown) to a load (not shown), and one end is connected to a ground G. The DC power supply is not limited to a solar panel, a storage battery, or the like, as long as it supplies a DC current to the load.

[0025] The ground fault detector 1 is composed of a first rectifier element D1, a second rectifier element D2, a first internal power supply V1, a second internal power supply V2, and a detection unit Du. In the ground fault detector 1, the first rectifier element D1, the first internal power supply V1, the second internal power supply V2, and the second rectifier element D2 are connected in series between the positive pole line Vp and the negative pole line Vn. The first rectifier element and the second rectifier element may be diodes or the like as long as they are elements that can pass current only in one direction. The internal power supply may be a battery, a capacitor, or the like as long as it is an element that supplies DC voltage.

[0026] The first rectifier element D1 has a cathode connected to the positive line Vp and an anode connected to the anode of the first internal power supply V1. The second rectifier element D2 has a cathode connected to the cathode of the second internal power supply V2 and an anode connected to the negative line Vn.

[0027] In the ground fault detector 1, one end of the cathode of the first internal power source V1 is connected to one end of the anode of the second internal power source V2 to form a connection point P1. A ground line GL extending toward the ground G is provided at the connection point P1. A detection unit Du having a detection resistor Rd is provided at the ground line GL.

[0028] The operation of each of the ground fault detectors will be described below. Note that the voltage between the positive pole line Vp and the negative pole line Vn of the DC bus does not affect the detection of a ground fault by the ground fault detector 1, so a description thereof will be omitted.

[0029] In the normal state where no ground fault occurs, the first rectifier D1 and the second rectifier D2 of the ground fault detector 1 suppress a current (not shown) flowing from the positive pole line Vp to the negative pole line Vn. When a ground fault occurs on either the positive pole line Vp side or the negative pole line Vn side, the part where the ground fault occurs is connected to the ground G, and a first closed loop circuit CL1 including the first rectifier D1, the first internal power supply V1, and the detection unit Du, or a second closed loop circuit CL2 including the second rectifier D2, the second internal power supply V2, and the detection unit Du is formed. FIG. 2 is a schematic diagram showing the operation of the ground fault detector 1 shown in FIG. 1 when the first detection current Id1 is detected. FIG. 3 is a schematic diagram showing the operation of the ground fault detector shown in FIG. 1 when the second detection current is detected.

[0030] When the first closed loop circuit CL1 is formed, the voltage of the first internal power supply V1 is applied to the detection resistor Rd of the detection unit Du, as shown in Fig. 2. The voltage of the first internal power supply V1 applied to the detection resistor Rd generates a first detection current Id1 that flows in the forward direction of the first rectifier element D1. The detection unit Du detects the first detection current Id1 to detect that the ground fault detector 1 has occurred.

[0031] When the second closed loop circuit CL2 is formed, the voltage of the second internal power supply V2 is applied to the detection resistor Rd of the detection unit Du, as shown in Fig. 3. The voltage of the second internal power supply V2 applied to the detection resistor Rd generates a second detection current Id2 that flows in the forward direction of the second rectifier element D2. The detection unit Du detects the second detection current Id2 to detect that the ground fault detector 1 has occurred.

[0032] Since the voltage of the first internal power supply V1 applied to the detection resistor Rd in the first closed loop circuit CL1 is equal to the voltage of the second internal power supply V2 applied to the detection resistor Rd in the second closed loop circuit CL2, the first detection current Id1 detected by the detection unit Du in the first closed loop circuit CL1 and the second detection current Id2 detected by the detection unit Du in the second closed loop circuit CL2 are also equal. Also, the first internal power supply V1 and the second internal power supply V2 have the same voltage.

[0033] Fig. 4 is a circuit diagram showing a configuration of a ground fault detector 1A according to a second embodiment of the present invention. The ground fault detector 1A shown in Fig. 4 differs from the above-mentioned ground fault detector 1 in that a detection unit Du is included in each of the closed loop circuits CL1 and CL2. The first detection unit Du1 included in the first closed loop circuit CL1 is provided between the anode of the first rectifier element D1 and the anode of the first internal power supply V1. The second detection unit Du2 included in the second closed loop circuit CL2 is provided between the cathode of the second internal power supply V2 and the cathode of the second rectifier element D2.

[0034] When the first detection unit Du1 detects the first detection current Id1, the ground fault detector 1A can detect that a ground fault has occurred on the positive electrode line Vp side. When the second detection unit Du2 detects the second detection current Id2, the ground fault detector 1A can detect that a ground fault has occurred on the negative electrode line Vn side. This makes it easy to know whether the ground fault has occurred on the positive electrode line Vp side or the negative electrode line Vn side depending on whether the ground fault has been detected by the first detection unit Du1 or the second detection unit Du2.

[0035] Fig. 5 is a circuit diagram showing the configuration of a ground fault detector 1B according to a third embodiment of the present invention. Unlike the above-mentioned ground fault detectors 1 and 1A, the ground fault detector 1B shown in Fig. 5 is configured with one internal power supply V12, and the internal power supply V12 is equal to the sum of the first internal power supply V1 and the second internal power supply V2.

[0036] In the ground fault detector 1B, a first rectifier element D1 and a second rectifier element D2 are connected in series, and the forward direction is from the negative electrode line Vn side to the positive electrode line Vp side. The anode of the first rectifier element D1 and the cathode of the second rectifier element D2 are connected to form a connection point P2. The ground fault detector 1B is provided with a ground line GL that extends from the connection point P2 toward the ground G, and a detection unit Du is provided on the ground line GL.

[0037] The ground fault detector 1B further includes a first resistor R1 and a second resistor R2 having the same resistance value. The first resistor R1 is provided between the anode of the internal power supply V12 and a connection point P2, and the second resistor R2 is provided between the connection point P2 and the cathode of the internal power supply V12.

[0038] When a ground fault occurs on either the positive pole line Vp side or the negative pole line Vn side, the voltage of the internal power supply V12 applied to the detection resistor Rd of the detection unit Du is divided by the first resistance element R1 and the second resistance element R2, thereby forming a circuit that detects a ground fault in the internal power supply. As a result, the detection unit Du detects the first detection current Id1 or the second detection current Id2, and the ground fault detector 1B detects that a ground fault has occurred on either the positive pole line Vp side or the negative pole line Vn side. In addition, by detecting the voltage applied to the first resistance element R1 and the second resistance element R2 at the time of a ground fault, it is possible to determine whether a ground fault has occurred on the positive pole line Vp side or the negative pole line Vn side.

[0039] Fig. 6 is a circuit diagram showing the configuration of a ground fault detector 1C according to a fourth embodiment of the present invention. The ground fault detector 1C shown in Fig. 5 differs from the above-mentioned ground fault detector 1B in that a first constant-voltage element ZD1 is provided between the anode of the internal power supply V12 and a connection point P2, and a second constant-voltage element ZD2 is provided between the connection point P2 and the cathode of the internal power supply V12. The first constant-voltage element ZD1 and the second constant-voltage element ZD2 are connected in series in the same manner as the first rectifier element D1 and the second rectifier element D2, and are in the forward direction from the negative pole line Vn side to the positive pole line Vp side.

[0040] The first constant-voltage element ZD1 and the second constant-voltage element ZD2 can suppress unnecessary current consumption that flows into the detection unit Du when no ground fault occurs. As a result, when a ground fault occurs on either the positive electrode line Vp side or the negative electrode line Vn side, the ground fault detector 1C can detect the occurrence of a ground fault with the detection unit Du while suppressing current consumption with the first constant-voltage element ZD1 and the second constant-voltage element ZD2.

[0041] Fig. 7 is a circuit diagram showing the configuration of a ground fault detector 1D according to a fifth embodiment of the present invention. The ground fault detector 1D shown in Fig. 7 differs from the above ground fault detectors 1, 1A, 1B, and 1C in that it uses an internal power supply circuit PC instead of the internal power supplies V12, V1, and V2.

[0042] The ground fault detector 1D has a first rectifier element D1 having a cathode connected to the positive electrode line Vp, a second rectifier element D2 having an anode connected to the negative electrode line Vn, and an internal power supply circuit PC having an anode connected to the anode of the first rectifier element D1 and a cathode connected to the cathode of the second rectifier element D2, which are connected in series. The internal power supply circuit PC has a ground line GL extending from the inside toward the ground G, and the detection unit Du is provided on the ground line GL. The internal power supply circuit PC provides an internal voltage Vc to be applied to a detection resistor Rd of the detection unit Du. The value of the internal voltage Vc is equal to the first internal power supply V1 and the second internal power supply V2.

[0043] When a ground fault occurs on either the positive electrode line Vp side or the negative electrode line Vn side, the voltage of the internal power supply circuit PC is applied to the detection resistor Rd, and a first detection current Id1 or a second detection current Id2 flows. The detection unit Du detects the first detection current Id1 or the second detection current Id2, and the ground fault detector 1D detects that a ground fault has occurred on either the positive electrode line Vp side or the negative electrode line Vn side. Note that the internal power supply circuit PC is not limited to this as long as it is a circuit that can supply a DC voltage necessary for the ground fault detector 1D and can supply a DC voltage necessary for the detection unit Du to detect a ground fault.

[0044] Although the embodiment of the present invention has been described above, the present invention is not limited to these embodiments, and it is of course possible to carry out the present invention in various forms without departing from the gist of the present invention. [Explanation of symbols]

[0045] 1,1A,1B,1C,1D Earth fault detector CL1 First closed loop circuit CL2 Second closed loop circuit Du detection unit Du1 First detector Du2 Second detector G ground GL ground wire Id1 First detection current Id2 Second detection current P1 Attachment Point P2 Attachment Point PC internal power circuit Rd Detection resistor V12,V1,V2,Vc Internal power supply Vn negative pole line Vp positive wire

Claims

1. a first rectifier element having a cathode connected to a positive pole line of a DC bus extending from a DC power source; a first internal power supply having an anode connected to the anode of the first rectifier; a second internal power supply having an anode connected to a cathode of the first internal power supply; a second rectifier element having a cathode connected to the cathode of the second internal power supply and an anode connected to a negative pole line of a DC bus extending from a DC power supply; a ground line is provided extending from a connection point between the cathode of the first internal power supply and the anode of the second internal power supply to ground; A ground fault detector including a detection section having a detection resistor to which a voltage of the first internal power supply or the second internal power supply is applied when a ground fault occurs.

2. The ground fault detector according to claim 1 , wherein the detection portion is provided on the ground wire.

3. 2. The ground fault detector according to claim 1, wherein the detection units are provided between an anode of the first rectifier element and an anode of the first internal power supply, and between a cathode of the second internal power supply and a cathode of the second rectifier element.

4. a first rectifier element having a cathode connected to a positive pole line of a DC bus extending from a DC power source, and a second rectifier element having an anode connected to a negative pole line of the DC bus extending from the DC power source, the first rectifier element being connected in series; a ground line extending from a connection point between the anode of the first rectifying element and the cathode of the second rectifying element to ground; an internal power supply having an anode connected between the anode of the first rectifier element and the connection point and a cathode connected between the connection point and the cathode of the second rectifier element; A ground fault detector, comprising: a detection section provided on the ground line, the detection section having a detection resistor to which a voltage of the internal power supply is applied when a ground fault occurs.

5. a first resistor element is provided between the anode of the internal power supply and the connection point; The ground fault detector according to claim 4 , further comprising a second resistive element provided between the connection point and the cathode of the internal power supply.

6. a first constant voltage element is provided between the anode of the internal power supply and the connection point; The ground fault detector according to claim 4 , further comprising a second constant voltage element provided between the connection point and the cathode of the internal power supply.

7. a first rectifier element having a cathode connected to a positive pole line of a DC bus extending from a DC power source; a second rectifier element having an anode connected to a negative pole line of a DC bus extending from a DC power source; an internal power supply circuit having an anode connected to the anode of the first rectifier element and a cathode connected to the cathode of the second rectifier element; the internal power supply circuit is provided with a ground line extending to ground; a detection section provided on the ground line, the detection section having a detection resistor to which a voltage of the internal power supply circuit is applied when a ground fault occurs;

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