Alternating current power supply insulation impedance and grounding detection circuit and alternating current power supply

Abstract

The AC power supply insulation impedance and grounding detection circuit is used for detecting whether the insulation impedance of the AC power supply relative to a casing and the casing are grounded or not, and comprises an auxiliary DC power supply with a grounded cathode; the anode of the first diode is connected with the anode of the auxiliary direct-current power supply, and the cathode of the first diode is connected with the first output end of the alternating-current power supply; the anode of the second diode is connected with the anode of the auxiliary direct-current power supply, and the cathode of the second diode is connected with the second output end of the alternating-current power supply; and the sampling detection unit is connected with the first detection branch and the second detection branch. The sampling detection unit detects whether the loop is connected or not when the AC power supply is not input so as to judge whether the casing is grounded or not, and after the casing is grounded and when the AC power supply is input, electric signal sampling is performed on the first detection branch and the second detection branch so as to detect whether the insulation impedance is abnormal or not, so that the hidden danger of electric leakage can be found in time.

Description

Technical Field

[0001] This application relates to the technical field of AC power supply grounding, and in particular to an AC power supply insulation impedance and grounding detection circuit and an AC power supply. Background Technology

[0002] When AC power supplies, such as those used in vehicles, supply power to household appliances via inverters, if the insulation resistance between the neutral wire (N) or the live wire (L) and the appliance casing is abnormally low, leakage current can occur. This poses a risk of electric shock if a person touches the casing. Furthermore, if the casing is not connected to ground (PE), any leakage will cause current to flow through the person's body and then to the ground. Therefore, testing the grounding and insulation resistance of the power input / output terminals (L and N) is crucial. Utility Model Content

[0003] The purpose of this application is to overcome the shortcomings of existing technologies where the AC power supply casing is not grounded or the insulation resistance is too low, which may cause electric shock to personnel. This application provides an AC power supply insulation resistance and grounding detection circuit and AC power supply to detect potential electric shock hazards in a timely manner.

[0004] The technical solution of this application provides an AC power supply insulation impedance and grounding detection circuit for detecting the insulation impedance of the AC power supply relative to the chassis and whether the chassis is grounded. The detection circuit includes:

[0005] Auxiliary DC power supply with negative terminal grounded;

[0006] The first detection branch includes a first diode, wherein the anode of the first diode is connected to the positive terminal of the auxiliary DC power supply, and the cathode is connected to the first output terminal of the AC power supply.

[0007] The second detection branch includes a second diode, wherein the anode of the second diode is connected to the positive terminal of the auxiliary DC power supply, and the cathode is connected to the second output terminal of the AC power supply.

[0008] A sampling and detection unit that connects the first detection branch and the second detection branch.

[0009] Furthermore, the first detection branch also includes a first sampling resistor connected in series with the first diode, and the second detection branch also includes a second sampling resistor connected in series with the second diode. The sampling detection unit is used to acquire the voltage of the first sampling resistor and the second sampling resistor.

[0010] Furthermore, the sampling and detection unit includes a first sampling module, a second sampling module, and a control module;

[0011] The first sampling module is connected in parallel across the two ends of the first sampling resistor, the second sampling module is connected in parallel across the two ends of the second sampling resistor, and the control module is communicatively connected to the first sampling module and the second sampling module.

[0012] Furthermore, the control module includes a grounding determination module for determining whether the chassis is grounded based on whether the sampling voltages of the first sampling module and the second sampling module are both greater than or equal to zero when the AC power is connected.

[0013] Furthermore, the control module includes an impedance judgment module for determining whether the insulation impedance is abnormal based on whether the sampling voltage of the first sampling module and the second sampling module is greater than a preset voltage threshold when the equipment casing is grounded and AC power is connected.

[0014] Furthermore, the first detection branch also includes a first capacitor, which is connected in parallel between the first input terminal of the AC power supply and the ground terminal;

[0015] The second detection branch also includes a second capacitor, which is connected in parallel between the second input terminal of the AC power supply and the ground terminal.

[0016] Furthermore, the first detection branch is connected in series with a first voltage divider resistor, and the second detection branch is connected in series with a second voltage divider resistor.

[0017] Furthermore, the auxiliary DC power supply is also connected in series with a grounding indicator element.

[0018] The technical solution of this application also provides an AC power supply, including the AC power supply insulation impedance and grounding detection circuit as described above.

[0019] The above technical solution has the following beneficial effects:

[0020] This application sets up a first detection branch and a second detection branch to form a loop between the first output terminal and the second output terminal of the AC power supply and the ground terminal, respectively. Both the first detection branch and the second detection branch are connected to an auxiliary DC power supply. When the AC power supply is not input, the sampling and detection unit detects whether the loop is connected to determine whether the chassis is grounded. After the chassis is grounded and the AC power supply is input, the first detection branch and the second detection branch are sampled to detect whether the insulation impedance is abnormal, so as to detect potential leakage hazards in time. Attached Figure Description

[0021] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. In the drawings:

[0022] Figure 1This is a circuit diagram of an AC power supply insulation impedance and grounding detection circuit according to one embodiment of this application;

[0023] Figure 2 This is an equivalent circuit diagram of the chassis grounding during grounding detection by the AC power supply insulation impedance and grounding detection circuit in one embodiment of this application;

[0024] Figure 3 This is an equivalent circuit diagram of the chassis not being grounded when the AC power supply insulation impedance and grounding detection circuit performs grounding detection in one embodiment of this application;

[0025] Figure 4 This is the equivalent circuit for insulation impedance detection of the AC power supply insulation impedance and grounding detection circuit in one embodiment of this application. Figure 1 ;

[0026] Figure 5 This is the equivalent circuit for insulation impedance detection of the AC power supply insulation impedance and grounding detection circuit in one embodiment of this application. Figure 2 .

[0027] Appendix Label Reference Table:

[0028] First sampling module 01, second sampling module 02, control module 03. Detailed Implementation

[0029] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0030] It is readily understood that, based on the technical solution of this application, various structural and implementation methods can be interchanged by those skilled in the art without altering the essential spirit of this application. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this application and should not be considered as the entirety of this application or as limitations or restrictions on the technical solution of the application.

[0031] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meanings of the above in this application according to the specific circumstances.

[0033] The AC power supply insulation impedance and grounding detection circuit in the embodiments of this application, such as Figure 1 As shown, the detection circuit used to detect the insulation resistance of the AC power supply relative to the chassis and whether the chassis is grounded includes:

[0034] Auxiliary DC power supply with negative terminal grounded;

[0035] The first detection branch includes the first diode D1, where the anode of the first diode D1 is connected to the positive terminal of the auxiliary DC power supply VDC, and the cathode is connected to the first output terminal of the AC power supply.

[0036] The second detection branch includes the second diode D2, where the anode of the second diode D2 is connected to the positive terminal of the auxiliary DC power supply VDC, and the cathode is connected to the second output terminal of the AC power supply.

[0037] A sampling and detection unit that connects the first detection branch and the second detection branch.

[0038] Specifically, the negative terminal of the auxiliary DC power supply VDC is grounded, and the positive terminal is connected to the first output terminal L of the AC power supply through the first detection branch. The first detection branch is equipped with a first diode D1, allowing current to flow from the positive terminal of the auxiliary DC power supply VDC to the first output terminal L of the AC power supply. Figure 2 The diagram shows the first insulation resistance R2 of the first output terminal L of the AC power supply relative to the chassis, which is connected in series between the cathode of the first diode D1 and the ground wire. The positive terminal of the auxiliary DC power supply VDC is also connected to the second output terminal N of the AC power supply through a second detection branch. The second detection branch includes a second diode D2, allowing current to flow from the positive terminal of the auxiliary DC power supply VDC to the second output terminal of the AC power supply. Figure 2 The second insulation resistance R1 of the second output terminal N of the AC power supply relative to the chassis is shown, which is connected in series between the cathode of the second diode D2 and the ground wire.

[0039] When the AC power is not connected, such as Figure 2As shown, if the casing is grounded, since the negative terminal of the auxiliary DC power supply VDC is also grounded, the auxiliary DC power supply VDC, the first detection branch, and the first insulation impedance R2 form a loop, and the auxiliary DC power supply VDC, the second detection branch, and the second insulation impedance R1 form a loop. Therefore, the sampling and detection unit can detect electrical signals in the first and second detection branches. Figure 3 As shown, if the casing is not grounded, the casing and the auxiliary DC power supply VDC are not connected. At this time, neither the first detection branch nor the second detection branch forms a loop with the auxiliary DC power supply VDC, so the sampling detection unit cannot detect the electrical signal.

[0040] When the AC power is turned on, the first detection branch is activated when the first output terminal L of the AC power is negative. At this time, the circuit is equivalent to... Figure 4 The equivalent circuit diagram shown; when the second output terminal N of the AC power supply is negative, the second detection branch is turned on, and the circuit is equivalent to this. Figure 5 The equivalent circuit diagram shown is as follows: In the AC power supply, the first output terminal L and the second output terminal N of the AC power supply alternately output negative voltage. Then, the sampling and detection unit alternately detects the electrical signals of the first detection branch and the second detection branch. Based on the circuit structure of the first detection branch and the second detection branch, it can determine whether the first insulation impedance R2 and the second insulation impedance R1 are within the normal range according to the detected electrical signal values.

[0041] In this embodiment, a first detection branch and a second detection branch are respectively configured to form a loop between the first output terminal L and the second output terminal N of the AC power supply and the ground terminal. Both the first and second detection branches are connected to an auxiliary DC power supply VDC. When the AC power supply is not input, the sampling and detection unit detects whether the loop is connected to determine whether the chassis is grounded. After the chassis is grounded and the AC power supply is input, the first and second detection branches are sampled to detect whether the insulation impedance is abnormal, thereby enabling timely detection of potential leakage. The first and second detection branches are switched on and off using diodes, eliminating the need for complex switching components and simplifying the circuit structure.

[0042] In one embodiment, such as Figure 1 As shown, the first detection branch also includes a first sampling resistor R3 connected in series with the first diode D1, and the second detection branch also includes a second sampling resistor R4 connected in series with the second diode D2. The sampling detection unit is used to collect the voltage of the first sampling resistor R3 and the second sampling resistor R4.

[0043] Specifically, the first and second detection branches are equipped with a first sampling resistor R3 and a second sampling resistor R4, respectively. The sampling and detection unit collects the voltages of the first sampling resistor R3 and the second sampling resistor R4 to perform grounding detection and insulation impedance detection. Based on the voltage divider principle, the voltage range for grounding detection and insulation impedance detection can be determined, thereby determining whether the chassis is grounded and whether the insulation impedance is within the normal range.

[0044] In one embodiment, such as Figure 1 As shown, the sampling and detection unit includes a first sampling module 01, a second sampling module 02, and a control module 03;

[0045] The first sampling module 01 is connected in parallel across the two ends of the first sampling resistor R3, the second sampling module 02 is connected in parallel across the two ends of the second sampling resistor R4, and the control module 03 is communicatively connected to the first sampling module 01 and the second sampling module 02.

[0046] In this embodiment, a first sampling module 01 and a second sampling module 02 are configured to collect the voltages across the first sampling resistor R3 and the second sampling resistor R4, respectively, and send the data to a control module 03 for judgment. The first sampling module 01 and the second sampling module 02 can employ voltage sampling circuits from the prior art, and the control module 03 can be a microcontroller or other component with control and calculation functions.

[0047] Furthermore, the control module includes a grounding judgment module for determining whether the casing is grounded based on whether the sampling voltages of the first sampling module and the second sampling module are both greater than or equal to zero when the AC power is turned on, and an impedance judgment module for determining whether the insulation impedance is abnormal based on whether the sampling voltages of the first sampling module and the second sampling module are greater than a preset voltage threshold when the equipment casing is grounded and the AC power is turned on.

[0048] The grounding detection module is used to determine whether the chassis is grounded, and the impedance detection module is used to determine whether the insulation impedance is within the normal range.

[0049] In one embodiment, such as Figure 1 As shown, the first detection branch also includes a first capacitor, which is connected in parallel between the first input terminal of the AC power supply and the ground terminal.

[0050] The second detection branch also includes a second capacitor, which is connected in parallel between the second input terminal of the AC power supply and the ground terminal.

[0051] In fact, the first capacitor CY2 is connected in parallel across the first insulation impedance R2, and the second capacitor CY1 is connected in parallel across the second insulation impedance R1. The two capacitors serve as safety capacitors, playing the role of filtering and protecting the circuit.

[0052] In one embodiment, the first detection branch is further connected in series with a first voltage divider resistor, and the second detection branch is further connected in series with a second voltage divider resistor.

[0053] Specifically, a first voltage-dividing resistor and a second voltage-dividing resistor can be connected in series in the first and second detection branches to divide the voltage in their respective detection branches, thus preventing the sampling voltage of the sampling resistor from being too high. The first voltage-dividing resistor can be connected in series between the first sampling resistor R3 and the auxiliary DC power supply VDC, or between the first sampling resistor R3 and the first diode D1; similarly, the second voltage-dividing resistor can be connected in series between the second sampling resistor R4 and the auxiliary DC power supply VDC, or between the second sampling resistor R4 and the second diode D2.

[0054] In one embodiment, the auxiliary DC power supply VDC is also connected in series with a grounding indicator. The grounding indicator may be an indicator light that illuminates when the chassis is grounded, indicating that the chassis is grounded, thereby reducing the detection workload of the sampling and detection unit.

[0055] In a preferred embodiment, the AC power supply insulation resistance and grounding detection circuit is as follows: Figure 1 As shown, it includes:

[0056] Auxiliary DC power supply VDC with negative terminal grounded;

[0057] The first detection branch includes a first diode D1 and a first sampling resistor R3. The anode of the first diode D1 is connected to the positive terminal of the auxiliary DC power supply VDC through the first sampling resistor R3, and the cathode is connected to the first output terminal of the AC power supply.

[0058] The second detection branch includes a second diode D2 and a second sampling resistor R4. The anode of the second diode D2 is connected to the positive terminal of the auxiliary DC power supply VDC through the second sampling resistor R4, and the cathode is connected to the second output terminal of the AC power supply.

[0059] The first capacitor is connected in parallel between the first input terminal of the AC power supply and the ground terminal;

[0060] A second capacitor connected in parallel between the second input terminal of the AC power supply and the ground terminal;

[0061] The sampling and detection unit connecting the first detection branch and the second detection branch includes a first sampling module 01, a second sampling module 02 and a control module 03. The first sampling module 01 is connected in parallel across the two ends of the first sampling resistor R3, the second sampling module 02 is connected in parallel across the two ends of the second sampling resistor R4, and the control module 03 is communicatively connected to the first sampling module 01 and the second sampling module 02.

[0062] Grounding detection operation:

[0063] When the AC power is not connected, the detection circuit is equivalent to Figure 2 In the circuit shown, if the chassis is grounded, since the negative terminal of the auxiliary DC power supply VDC is also grounded, the auxiliary DC power supply VDC, the first sampling resistor R3, and the first insulation impedance R2 form a loop, and the auxiliary DC power supply VDC, the second sampling resistor R4, and the second insulation impedance R1 form a loop. Therefore, both the first sampling module 01 and the second sampling module 02 can acquire voltage signals greater than zero. For example... Figure 3 As shown, if the casing is not grounded, the casing and the auxiliary DC power supply VDC are not connected. At this time, neither the first detection branch nor the second detection branch forms a loop with the auxiliary DC power supply VDC, so the sampling detection unit cannot detect the voltage signal.

[0064] Insulation impedance testing procedure:

[0065] When the AC power is turned on, the first output terminal L and the second output terminal N of the AC power supply alternately output negative voltage.

[0066] When the first output terminal L of the AC power supply is negative, the first detection branch is activated. At this time, the circuit is equivalent to... Figure 4 The equivalent circuit diagram shown shows the voltage across the first sampling resistor R3:

[0067] V R3 =V N&L -V R1 -V DC V N&L V is the AC power supply voltage. DC This is to assist the DC power supply voltage. When the first insulation impedance R2 remains normal, if the second insulation impedance R1 abnormally decreases, the voltage V across the first sampling resistor R3 will be... R3 It then grows larger.

[0068] When the second output terminal N of the AC power supply is negative, the second detection branch is activated. At this time, the circuit is equivalent to... Figure 5 The equivalent circuit diagram shown shows the voltage across the second sampling resistor R4:

[0069] V R4 =V N&L -V R2 -V DC V N&L V is the AC power supply voltage. DC This is to assist the DC power supply voltage. When the second insulation impedance R1 remains normal, if the first insulation impedance R2 abnormally decreases, the voltage V across the second sampling resistor R4 will be... R4 It then grows larger.

[0070] Therefore, based on the normal range of the first insulation impedance R2 and the second insulation impedance R1, as well as the parameters of the AC power supply, DC auxiliary power supply, first sampling resistor R3 and second sampling resistor R4 in the detection circuit, the voltage threshold of the sampling resistor can be set. When the voltage of the first sampling resistor R3 and the second sampling resistor R4 is greater than or equal to the voltage threshold, the judgment is triggered as an insulation impedance abnormality.

[0071] AC power supply:

[0072] The AC power supply of this application includes the AC power supply insulation impedance and grounding detection circuit of any of the foregoing embodiments.

[0073] The above description is merely the principle and preferred embodiment of this application. It should be noted that for those skilled in the art, implementation methods obtained by appropriately combining the technical solutions disclosed in different embodiments are also included within the technical scope of this invention. Based on the principle of this application, several other modifications can also be made, which should also be considered within the protection scope of this application.

Claims

1. An alternating current power supply insulation impedance and ground detection circuit, characterized by, The application relates to an alternating-current power supply insulation impedance and ground detection circuit. A negative ground auxiliary direct-current power supply; A first detection branch comprising a first diode, the anode of the first diode being connected to the positive pole of the auxiliary direct-current power supply, and the cathode being connected to the first output end of the alternating-current power supply; A second detection branch comprising a second diode, the anode of the second diode being connected to the positive pole of the auxiliary direct-current power supply, and the cathode being connected to the second output end of the alternating-current power supply; A sampling detection unit connected to the first detection branch and the second detection branch.

2. The AC power supply insulation impedance and ground detection circuit of claim 1, wherein, The first detection branch further comprises a first sampling resistor connected in series with the first diode, and the second detection branch further comprises a second sampling resistor connected in series with the second diode, and the sampling detection unit is used for collecting the voltage of the first sampling resistor and the second sampling resistor.

3. The AC power supply insulation impedance and ground detection circuit of claim 2, wherein, The sampling detection unit comprises a first sampling module, a second sampling module and a control module; The first sampling module is connected in parallel across the first sampling resistor, the second sampling module is connected in parallel across the second sampling resistor, and the control module is in communication connection with the first sampling module and the second sampling module.

4. The AC power supply insulation impedance and ground detection circuit of claim 3, wherein, The control module comprises a ground judgment module used for judging whether the device cabinet is grounded according to whether the sampling voltages of the first sampling module and the second sampling module are both greater than or equal to zero when the alternating-current power supply is turned on.

5. The AC power supply insulation resistance and ground detection circuit of claim 3, wherein, The control module comprises an impedance judgment module used for judging whether the insulation impedance is abnormal according to whether the sampling voltages of the first sampling module and the second sampling module are greater than a preset voltage threshold when the device cabinet is grounded and the alternating-current power supply is turned on.

6. The alternating-current power supply insulation impedance and ground detection circuit according to claim 3, wherein The first detection branch further comprises a first capacitor connected in parallel between the first input end of the alternating-current power supply and the ground end; The second detection branch further comprises a second capacitor connected in parallel between the second input end of the alternating-current power supply and the ground end.

7. The AC power supply insulation resistance and ground detection circuit according to any one of claims 1-6, wherein, The first detection branch further comprises a first voltage dividing resistor connected in series, and the second detection branch further comprises a second voltage dividing resistor connected in series.

8. The AC power supply insulation impedance and ground detection circuit according to any one of claims 1-6, wherein, The auxiliary direct-current power supply further comprises a ground indication element connected in series.

9. An alternating current power supply, characterised in that, An alternating-current power supply insulation impedance and ground detection circuit as claimed in any one of claims 1-8.

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