Insulation resistance detection circuit

Abstract

The utility model discloses an insulation resistance detection circuit, which relates to the technical field of insulation resistance detection, and comprises a loop to be detected, an insulation resistance detection branch and a total voltage monitoring branch, a power supply is arranged in the loop to be detected, and the anode of the power supply is connected with one end of an anode insulation resistor to be detected. The cathode of the power supply is connected with one end of a to-be-tested cathode insulation resistor. The other end of the anode insulation resistor and the other end of the cathode insulation resistor are connected with a grounding protection end. The insulation resistance detection branch comprises at least two change-over switches and a plurality of first preset resistors, and a node voltage sampling end is output in the insulation resistance detection branch; the total voltage monitoring branch comprises a plurality of second preset resistors, and an output voltage division ratio sampling end is arranged in the total voltage monitoring branch; based on the improvement of a traditional unbalanced bridge method, an integrated multi-module architecture is adopted, and high-precision insulation parameter detection is achieved through hardware cooperation and a dynamic algorithm.

Description

Technical Field

[0001] This utility model relates to the field of insulation resistance detection technology, and more specifically, to an insulation resistance detection circuit. Background Technology

[0002] Insulation resistance is a core indicator for evaluating the insulation performance of electrical equipment, directly affecting equipment safety and system stability. In new energy industries such as new energy vehicles and energy storage systems, as well as industrial high-voltage equipment, insulation failure can lead to major accidents such as leakage, short circuits, and even fires. Therefore, developing high-precision, high-real-time insulation resistance detection technology is crucial for preventing faults and ensuring reliable equipment operation.

[0003] Traditional insulation resistance testing is achieved using the unbalanced bridge method, such as... Figure 1 As shown, this method has significant drawbacks: First, while it reconstructs the voltage divider network through switch switching, sudden load changes can cause fluctuations in the total voltage between buses, leading to the use of abnormal total voltage values ​​in the calculations and consequently, errors in resistance calculations. Second, the continuous monitoring of the total bus voltage is interrupted during switch switching, making it impossible to capture total voltage fluctuations under dynamic operating conditions and potentially missing transient insulation faults. Furthermore, this method lacks sensitivity to high-resistance insulation resistance in the megaohm range. Due to the small amplitude of voltage division changes, it is easily limited by the ADC resolution, resulting in quantization errors and creating detection blind spots. These shortcomings make it difficult to meet the stringent real-time and accuracy requirements of new energy high-voltage systems. Utility Model Content

[0004] The purpose of this invention is to provide an insulation resistance detection circuit, which is based on an improvement of the traditional unbalanced bridge method and adopts an integrated multi-module architecture to achieve high-precision insulation parameter detection through hardware collaboration and dynamic algorithms.

[0005] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0006] This application provides an insulation resistance detection circuit, including the circuit under test, an insulation resistance detection branch, and a total voltage monitoring branch, wherein:

[0007] A power supply is provided in the circuit under test. The positive terminal of the power supply is connected to one end of the positive insulation resistance to be tested, and the negative terminal of the power supply is connected to one end of the negative insulation resistance to be tested. The other ends of the positive and negative insulation resistances are both connected to the grounding protection terminal.

[0008] The insulation resistance detection branch includes at least two switching switches and multiple first preset resistors. The multiple first preset resistors are connected in series, with one end of the series connection connected to the positive terminal of the power supply and the other end connected to the negative terminal of the power supply. One end of each of the at least two switching switches is connected to the grounding protection terminal, and at least one first preset resistor is connected between the other ends of the two switching switches. The insulation resistance detection branch also includes the output node voltage sampling terminal.

[0009] The total voltage monitoring branch includes multiple second preset resistors, which are connected in series. One end of the series connection is connected to the positive terminal of the power supply, and the other end is connected to the negative terminal of the power supply. The total voltage monitoring branch also includes a voltage division ratio sampling terminal.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the aforementioned insulation resistance detection branch includes a switching switch S1, a switching switch S2, a first preset resistor R1, a first preset resistor R2, a first preset resistor R3, and a first preset resistor R4, with a node voltage sampling terminal V1 formed between the first preset resistor R3 and the first preset resistor R4, wherein:

[0012] The first preset resistors R1, R2, R3 and R4 are connected in series, and the unconnected end of the first preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the first preset resistor R4 is connected to the negative terminal of the power supply.

[0013] One end of switch S1 and one end of switch S2 are both connected to the grounding protection terminal, and the other ends of switch S1 and switch S2 are respectively connected to the two ends of the first preset resistor R2.

[0014] Furthermore, the aforementioned total pressure monitoring branch includes a second preset resistor R1, a second preset resistor R2, a second preset resistor R3, and a second preset resistor R4, and a voltage divider ratio sampling terminal V2 is formed between the second preset resistor R3 and the second preset resistor R4, wherein:

[0015] The second preset resistors R1, R2, R3, and R4 are connected in series. The unconnected end of the second preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the second preset resistor R4 is connected to the negative terminal of the power supply.

[0016] Furthermore, the number of the first preset resistors is the same as the number of the second preset resistors.

[0017] Furthermore, among the first preset resistors and second preset resistors arranged in sequence, the first preset resistors and second preset resistors with the same sequence number have the same resistance value.

[0018] Furthermore, the negative terminal of the aforementioned power supply is also connected to a common ground terminal.

[0019] Furthermore, the aforementioned switching switch employs relays, optocoupler isolation, mechanical methods, or other means to enable the connection and switching of the insulation resistance detection branch.

[0020] Furthermore, the aforementioned insulation resistance detection circuit includes mode 0, mode 1, and mode 2.

[0021] Furthermore, mode 0 is used to calibrate the voltage value at the node voltage sampling terminal and the voltage value at the voltage divider ratio sampling terminal.

[0022] Furthermore, the resistance values ​​of the positive and negative insulation resistances are obtained by collecting the voltage values ​​at the node voltage sampling terminal and the voltage division ratio sampling terminal in mode 1, and collecting the voltage values ​​at the node voltage sampling terminal and the voltage division ratio sampling terminal in mode 2, and then solving them together.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] In this application, the circuit topology is dynamically reconstructed based on the closed and open states of each switching switch. By adjusting the voltage divider network structure in real time, the limitation of fixed bridge arm ratio is overcome, and high-precision measurement over a wide resistance range is achieved.

[0025] In this application, the accuracy of the circuit reference is verified by voltage balance monitoring, the total voltage between the busbars is monitored in real time, and the grounding interference channel is automatically isolated and protected in non-detection state to avoid interference with insulation characteristics.

[0026] In this application, the proportional coefficient is dynamically calculated based on the total voltage between the busbars collected in real time at the voltage divider sampling terminal to compensate for the interference of total voltage fluctuations on the voltage divider calculation during switch switching, thereby improving the accuracy of insulation resistance calculation. Attached Figure Description

[0027] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a circuit diagram of the traditional unbalanced bridge method in the embodiments of this utility model;

[0029] Figure 2 This is a schematic diagram of the insulation resistance detection circuit in an embodiment of the present invention;

[0030] Figure 3 For the reason Figure 2 The simplified circuit schematic. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of the embodiments of this utility model, "a plurality of" means at least two.

[0035] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0036] Example 1: This example provides an insulation resistance detection circuit, including the circuit to be tested and an insulation resistance detection branch ( Figure 2 The insulation resistance detection module and the total voltage monitoring branch (in the middle) Figure 2 The total pressure monitoring module in the middle), wherein:

[0037] The circuit under test described above is equipped with a power supply, such as... Figure 2 As shown, the positive terminal of the power supply is connected to one end of the positive insulation resistance to be tested, the negative terminal of the power supply is connected to one end of the negative insulation resistance to be tested, and the other ends of both the positive and negative insulation resistances are connected to the grounding protection terminal.

[0038] The aforementioned insulation resistance detection branch includes at least two switching switches and multiple first preset resistors, such as... Figure 2As shown, multiple first preset resistors are connected in series, with one end of the series connection connected to the positive terminal of the power supply and the other end connected to the negative terminal of the power supply; at least one end of each of the two switching switches is connected to the grounding protection terminal, and at least one first preset resistor is connected between the other ends of the two switching switches, and the voltage sampling terminal of the output node in the insulation resistance detection branch is also connected.

[0039] Optionally, the above-mentioned insulation resistance detection branch includes a switching switch S1, a switching switch S2, a first preset resistor R1, a first preset resistor R2, a first preset resistor R3, and a first preset resistor R4, and a node voltage sampling terminal V1 is formed between the first preset resistor R3 and the first preset resistor R4. (See [reference]) Figure 2 ,in:

[0040] The first preset resistors R1, R2, R3, and R4 are connected in series. The unconnected end of the first preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the first preset resistor R4 is connected to the negative terminal of the power supply. One end of the switch S1 and one end of the switch S2 are both connected to the grounding protection terminal, and the other ends of the switch S1 and the other ends of the switch S2 are respectively connected to the two ends of the first preset resistor R2.

[0041] The aforementioned total pressure monitoring branch includes multiple second preset resistors, such as... Figure 2 As shown, multiple second preset resistors are connected in series, with one end of the series connection connected to the positive terminal of the power supply and the other end connected to the negative terminal of the power supply. The output voltage division ratio sampling terminal is located in the total voltage monitoring branch.

[0042] Optionally, the above-mentioned total pressure monitoring branch includes a second preset resistor R1, a second preset resistor R2, a second preset resistor R3, and a second preset resistor R4, and the second preset resistor R3 and the second preset resistor R4 form a voltage division ratio sampling terminal V2, see [link to documentation]. Figure 2 ,in:

[0043] The second preset resistors R1, R2, R3, and R4 are connected in series. The unconnected end of the second preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the second preset resistor R4 is connected to the negative terminal of the power supply.

[0044] Specifically, in the resistance detection circuit described above, the number of first preset resistors is the same as the number of second preset resistors; and among the sequentially arranged first preset resistors and sequentially arranged second preset resistors, the first preset resistors and second preset resistors with the same arrangement number have the same resistance value.

[0045] Furthermore, the negative terminal of the aforementioned power supply is also connected to a common grounding terminal, and the switching switch uses relays, optocouplers, mechanical or other methods to realize the access and switching of the insulation resistance detection branch.

[0046] Optionally, the insulation resistance detection circuit described above includes three operating modes: mode 0, mode 1, and mode 2. Mode 0 is used to calibrate the voltage values ​​at the node voltage sampling terminal and the voltage values ​​at the voltage division ratio sampling terminal. The positive and negative insulation resistance values ​​are obtained by jointly solving the voltage values ​​at the node voltage sampling terminal and the voltage division ratio sampling terminal in mode 1 and mode 2.

[0047] Example 2: This application provides an insulation resistance detection method, including the following specific steps:

[0048] S1 sets all switches in the insulation resistance detection branch to the open state, and in this state, the calibration voltage signals of the node voltage sampling terminal and the voltage divider ratio sampling terminal are collected.

[0049] The insulation resistance detection circuit described above has three operating modes: Mode 0, Mode 1, and Mode 2.

[0050] The calibration voltage signal is obtained through mode 0;

[0051] The first voltage signal is obtained through mode 1;

[0052] The second voltage signal is obtained through mode 2.

[0053] S2, so that one of the switches in the insulation resistance detection branch is closed and the rest are open, and in this state, the first voltage signal of the node voltage sampling terminal and the voltage division ratio sampling terminal is collected.

[0054] Optionally, the above-mentioned insulation resistance detection branch includes a switching switch S1, a switching switch S2, a first preset resistor R1, a first preset resistor R2, a first preset resistor R3, and a first preset resistor R4, and a node voltage sampling terminal V1 is formed between the first preset resistor R3 and the first preset resistor R4. (See [reference]) Figure 2 ,in:

[0055] The first preset resistors R1, R2, R3, and R4 are connected in series. The unconnected end of the first preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the first preset resistor R4 is connected to the negative terminal of the power supply. One end of the switch S1 and one end of the switch S2 are both connected to the grounding protection terminal, and the other ends of the switch S1 and the other ends of the switch S2 are respectively connected to the two ends of the first preset resistor R2.

[0056] S3, the switch in the insulation resistance detection branch that was closed in step S2 is opened, and all other switches are closed. In this state, the second voltage signal of the node voltage sampling terminal and the voltage division ratio sampling terminal is collected.

[0057] Optionally, the above-mentioned total pressure monitoring branch includes a second preset resistor R1, a second preset resistor R2, a second preset resistor R3, and a second preset resistor R4, and the second preset resistor R3 and the second preset resistor R4 form a voltage division ratio sampling terminal V2, see [link to documentation]. Figure 2 ,in:

[0058] The second preset resistors R1, R2, R3, and R4 are connected in series, with the unconnected end of the second preset resistor R1 connected to the positive terminal of the power supply and the unconnected end of the second preset resistor R4 connected to the negative terminal of the power supply. The resistance values ​​of the first preset resistor R1 and the second preset resistor R2, the first preset resistor R3 and the second preset resistor R4 are the same.

[0059] S4. The first voltage signal and the second voltage signal are calibrated using the calibration voltage signal, and the resistance values ​​of the positive and negative insulation resistances are calculated using the calibrated first and second voltage signals.

[0060] Specifically, the resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are as follows:

[0061]

[0062] in:

[0063]

[0064] In the formula, RH represents the resistance of the positive electrode insulation, RL represents the resistance of the negative electrode insulation, C1, C2, B1, and B2 represent intermediate variables, and V1 represents the resistance of the negative electrode insulation. 模式0 V2 represents the calibration voltage signal at the node voltage sampling terminal in mode 0. 模式0 V1 represents the calibration voltage signal at the voltage divider sampling terminal in mode 0. 模式1 V2 represents the first voltage signal at the node voltage sampling terminal in mode 1. 模式1 V1 represents the first voltage signal at the voltage divider sampling terminal in mode 1. 模式2 V2 represents the second voltage signal at the node voltage sampling terminal in mode 2. 模式2This represents the second voltage signal at the voltage divider sampling terminal in mode 2. R1 represents the resistance value of the first preset resistor R1 or the second preset resistor R1, R2 represents the resistance value of the first preset resistor R2 or the second preset resistor R2, R3 represents the resistance value of the first preset resistor R3 or the second preset resistor R3, and R4 represents the resistance value of the first preset resistor R4 or the second preset resistor R4.

[0065] Specifically, the circuit diagram for calculating insulation resistance (from...) Figure 2 (Simplified insulation resistance detection module) See Figure 3 The calculation method is as follows:

[0066] By circuit Figure 3 We can obtain:

[0067]

[0068] Where RH and RL are the resistance values ​​to be measured, which are unknown. VB, VF, RS, and RX are known.

[0069] make We can obtain:

[0070]

[0071] make We can obtain:

[0072]

[0073] make C = K′, therefore:

[0074] RL+B·RH·RL+C·RH=0 (4)

[0075] When RS and RX change, we can obtain the following system of equations:

[0076]

[0077] Solving the system of equations, we get the solution:

[0078]

[0079] See Figure 2 By acquiring the V2 signal in real time and dynamically adjusting the proportional coefficient to compensate for the influence of total pressure fluctuations in the V1 signal, the values ​​of VB and VF can be accurately obtained.

[0080]

[0081] Calculating C1, C2, B1, and B2, we get:

[0082]

[0083] By combining the parameter calibration relationship of equations (6) and (8), the precise values ​​of RH and RL are finally calculated.

[0084] The following analysis will be conducted through simulation experiments:

[0085] This solution reconstructs the bridge arm resistor network by dynamically adjusting the states of switching switches S1 and S2, increasing the voltage division ratio in high-resistance scenarios, allowing the ADC to capture significant voltage changes, thereby expanding the insulation resistance detection range; for example... Figure 2 As shown, taking VB=1000V, R1=360kΩ, R2=240kΩ, R3=360kΩ, and R4=0.68kΩ as examples, the design effectiveness is verified by calculating the changes in V1 sample values ​​under four insulation resistance conditions (Table 1). The simulation analysis assumes that the total voltage between the busbars remains constant and is not affected by load changes.

[0086] Table 1 - V1 Sample Value Variation (Calculation results are rounded to two decimal places)

[0087] state RH / kΩ RL / kΩ V1 / mV (Mode 0) V1 / mV (Mode 1) V1 / mV (Mode 2) <![CDATA[△V1 min / mV]]> 1 10000 10000 703.35 697.17 713.09 6.18 2 10000 40 703.35 109.22 111.05 1.83 3 40 10000 703.35 1054.29 1676.22 350.94 4 40 40 703.35 571.95 908.88 131.4

[0088] Specifically, taking a 12-bit ADC (reference voltage 3.3V) as an example, its theoretical resolution is approximately 0.8mV. Considering noise and error, the actual effective resolution can reach 1.2mV. Table 1 shows that the variation amplitude of the sampled values ​​under the four insulation resistance conditions all exceed the effective resolution threshold, verifying the detection reliability of this scheme over a wide resistance range. This overcomes the problem of the traditional unbalanced bridge method, where the voltage division ratio cannot adapt to a wide resistance range due to the fixed bridge arm resistance ratio.

[0089] Example 3: This application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method in Example 2.

[0090] Example 4: This application provides a non-transitory computer-readable storage medium that stores computer instructions that cause a computer to execute the method in Example 2.

[0091] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An insulation resistance detection circuit, characterized in that, This includes the circuit under test, the insulation resistance detection branch, and the total voltage monitoring branch, among which: The circuit under test is equipped with a power supply. The positive terminal of the power supply is connected to one end of the positive insulation resistance to be tested, and the negative terminal of the power supply is connected to one end of the negative insulation resistance to be tested. The other ends of the positive insulation resistance and the other ends of the negative insulation resistance are both connected to the grounding protection terminal. The insulation resistance detection branch includes at least two switching switches and multiple first preset resistors. The multiple first preset resistors are connected in series, with one end of the series connection connected to the positive terminal of the power supply and the other end connected to the negative terminal of the power supply. One end of each of the at least two switching switches is connected to the grounding protection terminal, and at least one first preset resistor is connected between the other ends of the two switching switches. The insulation resistance detection branch outputs a node voltage sampling terminal. The total pressure monitoring branch includes multiple second preset resistors, which are connected in series. One end of the series resistors is connected to the positive terminal of the power supply, and the other end is connected to the negative terminal of the power supply. The total pressure monitoring branch also has an output voltage division ratio sampling terminal.

2. The insulation resistance detection circuit according to claim 1, characterized in that, The insulation resistance detection branch includes a switching switch S1, a switching switch S2, a first preset resistor R1, a first preset resistor R2, a first preset resistor R3, and a first preset resistor R4, wherein a node voltage sampling terminal V1 is formed between the first preset resistor R3 and the first preset resistor R4, wherein: The first preset resistor R1, the first preset resistor R2, the first preset resistor R3 and the first preset resistor R4 are connected in series, and the unconnected end of the first preset resistor R1 is connected to the positive terminal of the power supply, and the unconnected end of the first preset resistor R4 is connected to the negative terminal of the power supply. One end of the switching switch S1 and one end of the switching switch S2 are both connected to the grounding protection terminal, and the other ends of the switching switch S1 and the other ends of the switching switch S2 are respectively connected to the two ends of the first preset resistor R2.

3. The insulation resistance detection circuit according to claim 1, characterized in that, The total pressure monitoring branch includes a second preset resistor R1, a second preset resistor R2, a second preset resistor R3, and a second preset resistor R4, and a voltage division ratio sampling terminal V2 is formed between the second preset resistor R3 and the second preset resistor R4, wherein: The second preset resistors R1, R2, R3, and R4 are connected in series, with the unconnected end of the second preset resistor R1 connected to the positive terminal of the power supply and the unconnected end of the second preset resistor R4 connected to the negative terminal of the power supply.

4. The insulation resistance detection circuit according to claim 1, characterized in that, The number of the first preset resistors is the same as the number of the second preset resistors.

5. The insulation resistance detection circuit according to claim 4, characterized in that, In the sequential arrangement of each first preset resistor and each sequential arrangement of each second preset resistor, the first preset resistor and the second preset resistor with the same arrangement number have the same resistance value.

6. The insulation resistance detection circuit according to claim 1, characterized in that, The negative terminal of the power supply is also connected to a common ground terminal.

7. The insulation resistance detection circuit according to claim 1, characterized in that, The switching switch uses any one of relay, optocoupler isolation, or mechanical type to realize the connection and switching of the insulation resistance detection branch.

8. The insulation resistance detection circuit according to claim 1, characterized in that, The insulation resistance detection circuit includes mode 0, mode 1 and mode 2.

9. An insulation resistance detection circuit according to claim 8, characterized in that, Mode 0 is used to calibrate the voltage value at the node voltage sampling terminal and the voltage value at the voltage divider ratio sampling terminal.

10. An insulation resistance detection circuit according to claim 8, characterized in that, The resistance values ​​of the positive electrode insulation resistance and the negative electrode insulation resistance are obtained by collecting the voltage values ​​at the node voltage sampling terminal and the voltage division ratio sampling terminal in mode 1, and collecting the voltage values ​​at the node voltage sampling terminal and the voltage division ratio sampling terminal in mode 2, and solving them together.

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