Differential insulation impedance detection system and electrical equipment monitoring system

Abstract

The application provides a differential insulation impedance detection system and an electrical equipment monitoring system, and belongs to the technical field of electric power. The first detection module is connected between the positive electrode and the shell of the electrical equipment. The second detection module is connected between the negative electrode and the shell. The first sampling module is connected with the first detection module. The second sampling module is connected with the second detection module. The control end of the switch module is connected with the first detection module and the second detection module respectively. The control end of the control module is connected with the signal end of the switch module. The sampling end of the control module is connected with the first sampling module and the second sampling module respectively. The control module calculates the insulation impedance between the positive electrode and the shell and the insulation impedance between the negative electrode and the shell according to the first sampling signal and the second sampling signal, can automatically and intelligently detect the insulation impedance of the electrical equipment, does not need to detect by the impedance test table instrument manually, and solves the problem of low detection efficiency.

Description

Technical Field

[0001] This application belongs to the field of power technology, and in particular relates to a differential insulation impedance detection system and an electrical equipment monitoring system. Background Technology

[0002] To ensure the safe and reliable operation of electrical equipment, various inspections and tests on the insulation performance of the equipment are necessary both during manufacturing and at the operating site. Insulation impedance testing of electrical equipment at the factory verifies the quality of the manufactured equipment and ensures that it meets regulations and standards. Insulation impedance testing at the operating site determines how the equipment's performance changes over time, allowing for preventative maintenance.

[0003] Insulation impedance testing of electrical equipment is crucial for ensuring electrical safety and protecting the equipment. It is essential for safeguarding personal safety, ensuring normal equipment operation, and maintaining project quality. However, current techniques for testing the insulation impedance of electrical equipment typically require manual measurement using impedance testing instruments, resulting in low efficiency. Utility Model Content

[0004] The purpose of this application is to provide a differential insulation impedance detection system and an electrical equipment monitoring system, which aims to solve the problem of low detection efficiency in manual detection in related technologies.

[0005] In a first aspect, embodiments of this application provide a differential insulation impedance detection system, comprising:

[0006] The first detection module is connected between the positive terminal and the housing of the electrical equipment, and is used to detect the insulation resistance between the positive terminal and the housing, and output a first detection signal;

[0007] The second detection module is connected between the negative terminal and the housing of the electrical equipment, and is used to detect the insulation resistance between the negative terminal and the housing, and output a second detection signal;

[0008] The first sampling module is connected to the first detection module and is used to sample the first detection signal and output the first sampling signal;

[0009] The second sampling module is connected to the second detection module and is used to sample the second detection signal and output the second sampling signal;

[0010] A switching module, wherein the control terminal of the switching module is connected to the first detection module and the second detection module respectively, and is used to adjust the resistance of the first detection module and the resistance of the second detection module by means of the on / off state;

[0011] A control module, wherein the control terminal of the control module is connected to the signal terminal of the switch module, and is used to regulate the on / off state of the switch module;

[0012] The sampling terminals of the control module are connected to the first sampling module and the second sampling module respectively, and are used to acquire the first sampling signal and the second sampling signal, and calculate the insulation impedance between the positive electrode and the shell and the insulation impedance between the negative electrode and the shell based on the first sampling signal and the second sampling signal.

[0013] Secondly, embodiments of this application provide an electrical equipment monitoring system, including the differential insulation impedance detection system described in any of the above embodiments.

[0014] The beneficial effects of this utility model embodiment compared with related technologies are:

[0015] The differential insulation impedance detection system provided in this application uses a first detection module and a first sampling module to detect and sample the insulation impedance between the positive electrode and the casing, generating a first detection signal and a first sampling signal. These signals reflect changes in the insulation impedance between the positive electrode and the casing. Similarly, a second detection module and a second sampling module detect and sample the insulation impedance between the negative electrode and the casing, generating a second detection signal and a second sampling signal. These signals also reflect changes in the insulation impedance between the negative electrode and the casing. A control module controls the on / off state of a switch module, adjusting the resistance of the first and second detection modules to generate first and second detection signals under different states, which in turn generate corresponding first and second sampling signals. After acquiring the first and second sampling signals, the control module constructs correlation equations for the insulation impedance between the positive electrode and the casing, and between the negative electrode and the casing, thereby calculating the insulation impedance between the positive electrode and the casing, and between the negative electrode and the casing.

[0016] Therefore, the differential insulation impedance testing system provided in this application enables automated and intelligent testing of the insulation impedance of electrical equipment, eliminating the need for manual testing with impedance meters, thus improving testing efficiency and solving the problem of low testing efficiency caused by human factors. Furthermore, the differential insulation impedance testing system eliminates the need for manual testing with impedance meters, reducing labor costs and significantly lessening the burden on testing personnel during on-site equipment maintenance, thereby avoiding unnecessary personal injury to testing personnel in the event of leakage. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the differential insulation impedance detection system provided in one embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the switch module in one embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the circuit structure of the switching module in one embodiment of this application.

[0020] Figure 4 A schematic diagram of the circuit structure of a differential insulation impedance detection system provided in one embodiment of this application.

[0021] Figure 5 The circuit structure diagram of the first detection module and the second detection module in one embodiment provided in this application is shown.

[0022] Figure 6 This is a schematic diagram of the differential insulation impedance detection system provided in one embodiment of this application.

[0023] Figure 7 In one embodiment provided in this application Figure 6 The circuit structure diagram of the first sampling module and the second sampling module.

[0024] Figure 8 This is a schematic diagram of the control module in one embodiment of this application.

[0025] Figure 9 This is a schematic diagram of the structure of the microcontroller module, optocoupler module, communication module, and DC-DC switching module in one embodiment provided in this application. Detailed Implementation

[0026] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] Please see Figure 1This application provides a differential insulation resistance detection system 100. The differential insulation resistance detection system 100 includes a first detection module 110, a second detection module 120, a first sampling module 210, a second sampling module 220, a switch module 30, and a control module 40. The first detection module 110 is connected between the positive terminal of the electrical device 200 and the housing, and is used to detect the insulation resistance between the positive terminal and the housing, and output a first detection signal. The second detection module 120 is connected between the negative terminal of the electrical device 200 and the housing, and is used to detect the insulation resistance between the negative terminal and the housing, and output a second detection signal.

[0029] The first sampling module 210 is connected to the first detection module 110 and is used to sample the first detection signal and output the first sampled signal. The second sampling module 220 is connected to the second detection module 120 and is used to sample the second detection signal and output the second sampled signal. The control terminal of the switch module 30 is connected to the first detection module 110 and the second detection module 120 respectively, and is used to adjust the resistance of the first detection module 110 and the resistance of the second detection module 120 by means of on / off states.

[0030] The control terminal of the control module 40 is connected to the signal terminal of the switch module 30 and is used to regulate the on / off state of the switch module 30. The sampling terminal of the control module 40 is connected to the first sampling module 210 and the second sampling module 220 respectively, and is used to acquire the first sampling signal and the second sampling signal, and calculate the insulation resistance between the positive electrode and the shell and the insulation resistance between the negative electrode and the shell based on the first sampling signal and the second sampling signal.

[0031] Electrical equipment 200 can be power cables, transformers, distribution boxes, photovoltaic equipment, etc. The casing of electrical equipment 200 is connected to the ground. There is insulation resistance between the positive terminal and the casing of electrical equipment 200. Changes in insulation resistance will cause changes in current, and consequently, changes in voltage. A first detection module 110 is connected between the positive terminal and the casing of electrical equipment 200, in parallel with the insulation resistance between the positive terminal and the casing. When the insulation resistance between the positive terminal and the casing changes, the voltage across the first detection module 110 also changes, forming a first detection signal. By observing the change in the first detection signal of the first detection module 110, the change in the insulation resistance between the positive terminal and the casing can be determined. Similarly, there is insulation resistance between the negative terminal and the casing of electrical equipment 200. A second detection module 120 is connected between the negative terminal and the casing of electrical equipment 200, in parallel with the insulation resistance between the negative terminal and the casing. When the insulation resistance between the negative terminal and the casing changes, the voltage across the second detection module 120 also changes, forming a second detection signal. By observing the changes in the second detection signal of the second detection module 120, the changes in the insulation resistance between the negative electrode and the casing can be determined.

[0032] The first sampling module 210 samples the first detection signal, thereby obtaining information about its changes and forming a first sampled signal. Furthermore, the first sampled signal reveals the change in insulation resistance between the positive electrode and the casing. Similarly, the second sampling module 220 samples the second detection signal, thereby obtaining information about its changes and forming a second sampled signal. Furthermore, the second sampled signal reveals the change in insulation resistance between the negative electrode and the casing.

[0033] The first control terminal of the switch module 30 is connected to the first detection module 110, and its resistance can be adjusted by turning it on or off to generate first detection signals under different states. The second control terminal of the switch module 30 is connected to the second detection module 120, and its resistance can be adjusted by turning it on or off to generate second detection signals under different states. The control module 40 controls the on / off state of the switch module 30, thereby adjusting the resistances of the first detection module 110 and the second detection module 120 to generate first and second detection signals under different states.

[0034] The first and second detection signals under different states correspond to the first and second sampling signals under different states. After the sampling terminal of the control module 40 acquires the first and second sampling signals, it can construct the correlation equations for the insulation impedance between the positive electrode and the casing and the insulation impedance between the negative electrode and the casing, and calculate the insulation impedance between the positive electrode and the casing and the insulation impedance between the negative electrode and the casing. Thus, the differential insulation impedance detection system 100 provided in this application can realize automated and intelligent detection of the insulation impedance of electrical equipment 200, eliminating the need for manual detection using impedance testing instruments, improving detection efficiency, and solving the problem of low detection efficiency caused by human factors. Furthermore, the differential insulation impedance detection system 100 provided in this application eliminates the need for manual detection using impedance testing instruments, reducing labor costs, greatly reducing the burden on testing personnel for on-site equipment maintenance, and thus avoiding unnecessary personal danger to testing personnel in the event of leakage.

[0035] It is understood that in the above embodiments, the electrical equipment 200 is a photovoltaic device. Photovoltaic equipment is a new type of power system in the new energy industry. Photovoltaic equipment is used outdoors or on rooftops, and prolonged exposure to wind and sun accelerates its aging, making it prone to insulation problems. The differential insulation impedance detection system 100 provided in this application can detect the insulation impedance of photovoltaic equipment, identifying any degradation in its insulation performance or any existing faults or abnormalities. This helps engineers quickly locate the fault point, take timely countermeasures, and improve the efficiency of fault diagnosis and repair.

[0036] As the number of photovoltaic (PV) series stages increases, the voltage also rises, posing electrical safety risks. The differential insulation impedance detection system 100 provided in this application enables automated and intelligent detection of the insulation impedance of PV equipment, ensuring its insulation performance and preventing electrical safety issues, thus guaranteeing the safe and reliable operation of the PV system.

[0037] Please see Figure 2 The switching module 30 includes a first switching circuit 310 and a second switching circuit 320. The signal terminal of the first switching circuit 310 is connected to the control terminal of the control module 40. The control terminal of the first switching circuit 310 is connected to the first detection module 110. The first switching circuit 310 is used to adjust the resistance of the first detection module 110 according to a first adjustment signal output from the control terminal of the control module 40. The signal terminal of the second switching circuit 320 is connected to the control terminal of the control module 40. The control terminal of the second switching circuit 320 is connected to the second detection module 120. The second switching circuit 320 is used to adjust the resistance of the second detection module 120 according to a second adjustment signal output from the control terminal of the control module 40.

[0038] The first control signal output from the control terminal of the control module 40 can control the on / off state of the first switching circuit 310, thereby regulating the resistance of the first detection module 110 to form first detection signals under different states, corresponding to first sampling signals under different states. Similarly, the second control signal output from the control terminal of the control module 40 can control the on / off state of the second switching circuit 320, thereby regulating the resistance of the second detection module 120 to form second detection signals under different states, corresponding to second sampling signals under different states. Therefore, after the sampling terminal of the control module 40 acquires the first and second sampling signals, it can construct correlation equations regarding the insulation impedance between the positive electrode and the casing, and the insulation impedance between the negative electrode and the casing, and calculate the insulation impedance between the positive electrode and the casing, and the insulation impedance between the negative electrode and the casing.

[0039] The resistances of the first detection module 110 and the second detection module 120 are adjusted by the first switching circuit 310 and the second switching circuit 320, respectively. The first switching circuit 310, the first detection module 110, the first sampling module 210, the second switching circuit 320, the second detection module 120, and the second sampling module 220 form the differential circuit structure of the differential insulation impedance detection system 100. This system has advantages such as strong anti-interference capability, high gain accuracy, and good linearity, and can more accurately detect the insulation impedance of the electrical equipment 200, realizing automated and intelligent detection of the insulation impedance of the electrical equipment 200.

[0040] It is understood that in the above embodiments, the control module 40 is used to acquire the first sampling signal and the second sampling signal in the first state when the first switching circuit 310 is turned on and the second switching circuit 320 is turned off. The control module 40 is used to acquire the first sampling signal and the second sampling signal in the second state when the first switching circuit 310 is turned off and the second switching circuit 320 is turned on. The control module 40 is used to calculate the insulation resistance between the positive electrode and the casing and the insulation resistance between the negative electrode and the casing based on the first sampling signal and the second sampling signal in the first state and the first sampling signal and the second sampling signal in the second state.

[0041] The first state is that the first switching circuit 310 is on and the second switching circuit 320 is off. The second state is that the first switching circuit 310 is off and the second switching circuit 320 is on. The change from the first state to the second state causes the first switching circuit 310 to change from being on to being off, which in turn causes a change in the resistance of the first detection module 110 controlled by the first switching circuit 310. The change from the first state to the second state causes the second switching circuit 320 to change from being off to being on, which in turn causes a change in the resistance of the second detection module 120 controlled by the second switching circuit 320. Thus, in the first state, a first detection signal and a second detection signal are formed, and correspondingly, a first sampling signal and a second sampling signal are formed. In the second state, a first detection signal and a second detection signal are formed, and correspondingly, a first sampling signal and a second sampling signal are formed.

[0042] The first sampled signal in the first state, the second sampled signal in the first state, the first sampled signal in the second state, and the second sampled signal in the second state correspond to the simultaneous formulas for the insulation impedance between the positive electrode and the casing and the insulation impedance between the negative electrode and the casing in different states. Based on the first sampled signal in the first state, the second sampled signal in the first state, the first sampled signal in the second state, and the second sampled signal in the second state, the control module 40 can calculate the insulation impedance between the positive electrode and the casing and the insulation impedance between the negative electrode and the casing.

[0043] The control module 40 enables signal control and insulation impedance calculation, achieving precise logic control, fast processing speed, and strong response capabilities. Through signal transmission, control, and calculation among the control module 40, the first switching circuit 310, the second switching circuit 320, the first detection module 110, the second detection module 120, the first sampling module 210, and the second sampling module 220, automated and intelligent detection of the insulation impedance of the electrical equipment 200 can be achieved. This allows for more accurate and efficient detection of the insulation impedance of the electrical equipment 200, meeting the needs of various application scenarios.

[0044] It is understood that in the above embodiments, the first switching circuit 310, the second switching circuit 320 and the third switching circuit 330 respectively include electronic components such as transistors, diodes and relays.

[0045] Please see Figure 3 The first switching circuit 310 includes a first transistor 311, a first Zener diode 312, and a first relay 313. The first terminal of the first transistor 311 is connected to the control terminal of the control module 40. The second terminal of the first transistor 311 is grounded. The anode of the first Zener diode 312 is connected to the third terminal of the first transistor 311. The first coil connection terminal of the first relay 313 is connected to the third terminal of the first transistor 311. The second coil connection terminal of the first relay 313 is connected to the cathode of the first Zener diode 312. The first contact connection terminal and the second contact connection terminal of the first relay 313 are respectively connected to the two ends of the first detection module 110.

[0046] The first transistor 311 possesses high-speed switching and precise control characteristics, enabling it to switch on and off in a very short time. The first transistor 311 can be a bipolar transistor or a field-effect transistor, and the transistor type can be selected according to the actual application scenario. The control module 40 outputs a first control signal, which can precisely control the voltage or current at the base (for a bipolar transistor) or gate (for a field-effect transistor) of the first transistor 311, causing the first transistor 311 to turn on or off. The first transistor 311 also has strong anti-interference capabilities and a long service life, which can improve the stability and reliability of the differential insulation resistance detection system 100.

[0047] The anode of the first Zener diode 312 is connected to the first coil connection terminal of the first relay 313, and the cathode of the first Zener diode 312 is connected to the second coil connection terminal of the first relay 313. This can suppress the back electromotive force generated when the coil is de-energized, thus protecting the first transistor 311. Simultaneously, the first Zener diode 312 can stabilize the voltage across the coil, ensuring the normal operation of the first switching circuit 310. Furthermore, by suppressing the back electromotive force and stabilizing the coil voltage, the first Zener diode 312 can reduce the generation of electromagnetic interference during power-on and power-off processes, improving the detection accuracy of the differential insulation resistance detection system 100.

[0048] The two coil connection terminals of the first relay 313 are connected to the anode and cathode terminals of the first Zener diode 312, respectively. The two contact connection terminals of the first relay 313 are connected to the first detection module 110, which can achieve effective isolation between the high-voltage side and the low-voltage side circuit. The first relay 313 has reliable switching performance and flexible control mode, which can improve the automation level and control accuracy of the differential insulation resistance detection system 100.

[0049] When the control terminal of the control module 40 drives the first transistor 311 to conduct, voltage is applied to the two coil connection terminals of the first relay 313. Current flows through the coil, generating a magnetic field that actuates the contacts, causing the previously open contacts to close, thereby regulating the resistance of the first detection module 110. Conversely, when the control terminal of the control module 40 drives the first transistor 311 to turn off, no voltage is applied to the two coil connection terminals of the first relay 313. The current in the coil disappears, and the magnetic field also disappears, causing the previously closed contacts to open, thereby regulating the resistance of the first detection module 110.

[0050] It is understood that in the above embodiment, the first transistor 311 is an NMOS transistor. The gate of the first transistor 311 is connected to the control terminal of the control module 40. The source of the first transistor 311 is grounded. The drain of the first transistor 311 is connected to the first coil connection terminal of the first relay 313.

[0051] Please see Figure 4 The first detection module 110 and the second detection module 120 each include multiple resistors.

[0052] Please see Figure 5 The first detection module 110 includes a seventh resistor 111 and an eighth resistor 112. One end of the seventh resistor 111 is connected to the positive terminal. One end of the eighth resistor 112 is connected to the other end of the seventh resistor 111. The other end of the eighth resistor 112 is connected to the housing. The first contact terminal of the first relay 313 is connected to one end of the eighth resistor 112. The second contact terminal of the first relay 313 is connected to the other end of the eighth resistor 112.

[0053] The seventh resistor 111 and the eighth resistor 112 are connected in series, and are connected to the insulation resistance R from the positive terminal to the casing. X The two contacts of the first relay 313 are connected to the two ends of the eighth resistor 112, respectively. When the contacts of the first relay 313 are closed, the eighth resistor 112 is short-circuited, causing a change in the resistance of the first detection module 110. This change in resistance causes a change in the first detection signal, and consequently, a change in the first sampling signal. When the contacts of the first relay 313 are open, the resistance value of the eighth resistor 112 is added to the resistance of the first detection module 110, causing a change in the resistance of the first detection module 110. This change in resistance causes a change in the first detection signal, and consequently, a change in the first sampling signal. By turning the first relay 313 on or off, two relationships regarding the insulation impedance of the electrical equipment 200 can be established. The combination of the eighth resistor 112 and the first relay 313 allows for precise control of the resistance of the first detection module 110, which is beneficial for subsequent sampling, measurement, and calculation of the insulation impedance of the electrical equipment 200.

[0054] It is understood that in the above embodiments, the second switching circuit 320 includes a second transistor 321, a second Zener diode 322, and a second relay 323. The first terminal of the second transistor 321 is connected to the control terminal of the control module 40. The second terminal of the second transistor 321 is grounded. The anode of the second Zener diode 322 is connected to the third terminal of the second transistor 321. The first coil connection terminal of the second relay 323 is connected to the third terminal of the second transistor 321. The second coil connection terminal of the second relay 323 is connected to the cathode of the second Zener diode 322. The first contact connection terminal and the second contact connection terminal of the second relay 323 are respectively connected to the two ends of the second detection module 120.

[0055] The description of the second transistor 321 can be found in the description of the first transistor 311 in the above embodiments. The description of the second Zener diode 322 can be found in the description of the first Zener diode 312 in the above embodiments. The description of the second relay 323 can be found in the description of the first relay 313 in the above embodiments.

[0056] Please see Figure 5The second detection module 120 includes a ninth resistor 121 and a tenth resistor 122. One end of the ninth resistor 121 is connected to the housing. One end of the tenth resistor 122 is connected to the other end of the ninth resistor 121. The other end of the tenth resistor 122 is connected to the negative terminal. The first contact terminal of the second relay 323 is connected to one end of the ninth resistor 121. The second contact terminal of the second relay 323 is connected to the other end of the ninth resistor 121.

[0057] The ninth resistor 121 and the tenth resistor 122 are connected in series, and are connected to the insulation resistance R from the negative terminal to the casing. Y The two contacts of the second relay 323 are connected in parallel. They are respectively connected to the two ends of the ninth resistor 121. When the contacts of the second relay 323 are closed, the ninth resistor 121 is short-circuited, causing a change in the resistance of the second detection module 120. This change in resistance causes a change in the second detection signal, and consequently, a change in the corresponding second sampling signal. When the contacts of the second relay 323 are open, the resistance value of the ninth resistor 121 is added to the resistance of the second detection module 120, causing a change in the resistance of the second detection module 120. This change in resistance causes a change in the second detection signal, and consequently, a change in the corresponding second sampling signal.

[0058] By switching the second relay 323 on or off, two corresponding equations can be formed regarding the insulation impedance of the electrical equipment 200. The combination of the ninth resistor 121 and the second relay 323 enables precise control of the resistance of the second detection module 120, which is beneficial for subsequent sampling, measurement, and calculation of the insulation impedance of the electrical equipment 200.

[0059] It is understood that in the above embodiments, the switch module 30 includes a third switch circuit 330, such as... Figure 3 As shown. The signal terminal of the third switching circuit 330 is connected to the control terminal of the control module 40. The first control terminal of the third switching circuit 330 is connected to the second terminal of the first detection module 110 and the second terminal of the second detection module 120. The second control terminal of the third switching circuit 330 is connected to the housing. The third switching circuit 330 is used to detect the insulation resistance between the positive terminal and the housing and the insulation resistance between the negative terminal and the housing when the control module 40 controls the third switching circuit 330 to be turned on.

[0060] The third control signal output from the control terminal of the control module 40 is transmitted to the third switching circuit 330 to control the on / off state of the third switching circuit 330. The second terminal of the first detection module 110 and the second terminal of the second detection module 120 are connected to form a common connection terminal. The first control terminal of the third switching circuit 330 is connected to the common connection terminal of the first detection module 110 and the second detection module 120, and the second control terminal of the third switching circuit 330 is connected to the housing. This makes the third switching circuit 330 located on the link where the first detection module 110 and the second detection module 120 are respectively connected to the housing, and on the trunk line connecting the differential insulation resistance detection system 100 and the electrical equipment 200. It can control as a whole whether to detect the insulation resistance from the positive terminal to the housing and the insulation resistance from the negative terminal to the housing.

[0061] When the control module 40 controls the third switch circuit 330 to be turned on, the differential insulation resistance detection system 100 detects the insulation resistance from the positive terminal to the housing and the insulation resistance from the negative terminal to the housing. When the control module 40 controls the third switch circuit 330 to be turned off, the differential insulation resistance detection system 100 stops detecting. By controlling the on / off state of the third switch circuit 330, the control module 40 can control the overall operation of the differential insulation resistance detection system 100, enabling more automated and intelligent insulation resistance detection of the electrical equipment 200.

[0062] It is understood that in the above embodiments, the third switching circuit 330 includes a third transistor 331, a third Zener diode 332, and a third relay 333, such as Figure 3 As shown. The first terminal of the third transistor 331 is connected to the control terminal of the control module 40. The second terminal of the third transistor 331 is grounded. The anode of the third Zener diode 332 is connected to the third terminal of the third transistor 331. The first coil connection terminal of the third relay 333 is connected to the third terminal of the third transistor 331. The second coil connection terminal of the third relay 333 is connected to the cathode of the third Zener diode 332. The first contact connection terminal of the third relay 333 is connected to the common terminal of the first detection module 110 and the second detection module 120. The second contact connection terminal of the third relay 333 is connected to the housing.

[0063] The description of the third transistor 331 can be found in the description of the first transistor 311 in the above embodiments. The description of the third Zener diode 332 can be found in the description of the first Zener diode 312 in the above embodiments. The description of the third relay 333 can be found in the description of the first relay 313 in the above embodiments.

[0064] It is understood that in the above embodiment, the first contact connection terminal of the third relay 333 is connected to the other end of the eighth resistor 112 of the first detection module 110. The first contact connection terminal of the third relay 333 is also connected to one end of the ninth resistor 121 of the second detection module 120. The second contact connection terminal of the third relay 333 is connected to the housing, as shown below. Figure 5 As shown.

[0065] It is understood that in the above embodiments, the first sampling module 210 includes multiple resistors. The multiple resistors are connected in series and / or in parallel.

[0066] It is understood that in the above embodiments, the first sampling module 210 includes a first resistor 211, a second resistor 212, and a third resistor 213, such as... Figure 4 As shown. One end of the first resistor 211 is connected to the first terminal of the first detection module 110. One end of the second resistor 212 is connected to the other end of the first resistor 211. The other end of the second resistor 212 is connected to the second terminal of the first detection module 110. The second terminal of the first detection module 110 is connected to the housing. One end of the third resistor 213 is connected to one end of the second resistor 212. One end of the third resistor 213 is connected to the sampling terminal of the control module 40. The other end of the third resistor 213 is connected to the other end of the second resistor 212.

[0067] The second resistor 212 and the third resistor 213 are connected in parallel and in series with the first resistor 211. The first resistor 211, the second resistor 212, and the third resistor 213 form a common connection terminal, which is connected to the sampling terminal of the control module 40. The other common connection terminal of the parallel circuit of the second resistor 212 and the third resistor 213 is connected to the housing and to ground. The first sampling signal acquired by the sampling terminal of the control module 40 is the voltage signal across the parallel circuit of the second resistor 212 and the third resistor 213.

[0068] The first sampling module 210 includes three resistors connected in series and parallel. The circuit structure of the first sampling module 210 is simple, easy to implement, and inexpensive, effectively reducing the overall cost of the product and enabling mass production. Furthermore, the first sampling module 210, with its three resistors connected in series and parallel, can quickly respond to changes in voltage or current, which is beneficial for the subsequent control module 40 to calculate the insulation impedance.

[0069] It is understood that in the above embodiments, the second sampling module 220 includes multiple resistors. These multiple resistors are connected in series and / or in parallel.

[0070] As can be understood, in the above embodiments, the second sampling module 220 includes a fourth resistor 221, a fifth resistor 222, and a sixth resistor 223. One end of the fourth resistor 221 is connected to the first end of the second detection module 120. One end of the fifth resistor 222 is connected to the other end of the fourth resistor 221. The other end of the fifth resistor 222 is connected to the second end of the second detection module 120. The second end of the second detection module 120 is connected to the housing. One end of the sixth resistor 223 is connected to one end of the fifth resistor 222. One end of the sixth resistor 223 is connected to the sampling end of the control module 40. The other end of the sixth resistor 223 is connected to the other end of the fifth resistor 222.

[0071] The circuit structure of the second sampling module 220 is the same as that of the first sampling module 210, enabling the differential symmetrical structure of the differential insulation impedance detection system 100. The fifth resistor 222 and the sixth resistor 223 are connected in parallel and in series with the fourth resistor 221. The fourth resistor 221, the fifth resistor 222, and the sixth resistor 223 form a common connection terminal, which is connected to the sampling terminal of the control module 40. The other common connection terminal of the parallel circuit of the fifth resistor 222 and the sixth resistor 223 is connected to the housing and to ground. The second sampling signal acquired by the sampling terminal of the control module 40 is the voltage signal across the parallel circuit of the fifth resistor 222 and the sixth resistor 223.

[0072] The second sampling module 220 includes three resistors connected in series and parallel. The circuit structure of the second sampling module 220 is simple, easy to implement, and inexpensive, effectively reducing the overall cost of the product and enabling mass production. Furthermore, the three resistors in the second sampling module 220, connected in series and parallel, can quickly respond to changes in voltage or current, which is beneficial for the subsequent control module 40 to calculate the insulation impedance.

[0073] Please see Figure 6 and Figure 7The first sampling module 210 includes an eleventh resistor 214, a twelfth resistor 215, a thirteenth resistor 216, a fourteenth resistor 217, and a first operational amplifier 218. One end of the eleventh resistor 214 is connected to one end of the seventh resistor 111. One end of the twelfth resistor 215 is connected to the other end of the eleventh resistor 214, and the other end of the twelfth resistor 215 is connected to the power supply. One end of the thirteenth resistor 216 is connected to the other end of the eighth resistor 112. One end of the fourteenth resistor 217 is connected to the other end of the thirteenth resistor 216. The non-inverting input of the first operational amplifier 218 is connected to the other end of the eleventh resistor 214. The inverting input of the first operational amplifier 218 is connected to the other end of the thirteenth resistor 216. The output of the first operational amplifier 218 is connected to the other end of the fourteenth resistor 217. The output of the first operational amplifier 218 is connected to the sampling terminal of the control module 40.

[0074] The settings of the eleventh resistor 214, twelfth resistor 215, thirteenth resistor 216, and fourteenth resistor 217 allow for gain setting, bias setting, and a stable static operating point, matching and adjusting the signal input to the first operational amplifier 218. The resistance values ​​of the eleventh resistor 214, twelfth resistor 215, thirteenth resistor 216, and fourteenth resistor 217 can be adjusted according to the actual application scenario. The first detection signal detected by the first detection module 110 enters the first operational amplifier 218 after passing through the eleventh resistor 214 and the thirteenth resistor 216. The first operational amplifier 218 has characteristics such as high input impedance, high gain, and high common-mode rejection ratio, which can ensure the signal accuracy of the first detection signal, reduce noise interference to the first detection signal, obtain a more accurate first sampling signal, and thus improve the detection accuracy of the differential insulation impedance detection system 100.

[0075] The second sampling module 220 includes a fifteenth resistor 224, a sixteenth resistor 225, a seventeenth resistor 226, an eighteenth resistor 227, and a second operational amplifier 228. One end of the fifteenth resistor 224 is connected to one end of the ninth resistor 121. One end of the ninth resistor 121 is connected to the other end of the eighth resistor 112. Alternatively, one end of the fifteenth resistor 224 can be understood as being connected to the common terminal of the eighth resistor 112 and the ninth resistor 121. One end of the sixteenth resistor 225 is connected to the other end of the fifteenth resistor 224. The other end of the sixteenth resistor 225 is connected to the power supply terminal. The common terminal of the fifteenth resistor 224 and the sixteenth resistor 225 is connected to the non-inverting input terminal of the second operational amplifier 228.

[0076] One end of the seventeenth resistor 226 is connected to the other end of the tenth resistor 122, which can also be understood as one end of the seventeenth resistor 226 being connected to the negative terminal. The other end of the seventeenth resistor 226 is connected to one end of the eighteenth resistor 227. The common terminal of the seventeenth resistor 226 and the eighteenth resistor 227 is connected to the inverting input terminal of the second operational amplifier 228. The output terminal of the second operational amplifier 228 is connected to the other end of the eighteenth resistor 227. The output terminal of the second operational amplifier 228 is connected to the sampling terminal of the control module 40.

[0077] The settings of the fifteenth resistor 224, the sixteenth resistor 225, the seventeenth resistor 226, and the eighteenth resistor 227 allow for gain setting, bias setting, and a stable quiescent operating point, matching and adjusting the signal input to the second operational amplifier 228. The resistance values ​​of the fifteenth resistor 224, the sixteenth resistor 225, the seventeenth resistor 226, and the eighteenth resistor 227 can be adjusted according to the actual application scenario. The second detection signal detected by the second detection module 120 enters the second operational amplifier 228 after passing through the fifteenth resistor 224 and the seventeenth resistor 226. The second operational amplifier 228 has characteristics such as high input impedance, high gain, and high common-mode rejection ratio, which can ensure the signal accuracy of the second detection signal, reduce noise interference to the second detection signal, obtain a more accurate second sampling signal, and thus improve the detection accuracy of the differential insulation impedance detection system 100.

[0078] Please see Figure 8 The control module 40 includes a microcontroller module 410. The control terminal of the microcontroller module 410 is connected to the signal terminal of the switch module 30 and is used to regulate the on / off state of the switch module 30.

[0079] The control terminal of the microcontroller module 410 outputs a control signal to the signal terminal of the switch module 30, controlling the switch module 30 to turn on or off, thereby regulating the resistance of the first detection module 110 and the second detection module 120. The microcontroller module 410 can be a microcontroller unit (MCU), a field programmable gate array (FPGA), or a programmable logic controller (PLC), etc. The microcontroller module 410 can precisely control the switch module 30 according to a preset program and logic, achieving precise regulation of the first switch circuit 310, the second switch circuit 320, and the third switch circuit 330. Simultaneously, the microcontroller module 410 also features fast processing speed and response capability, enabling real-time processing of input signals and making corresponding control decisions. It highly integrates multiple functions, reducing the use of external components.

[0080] Therefore, the circuit structure of the differential insulation impedance detection system 100 provided in this application is a relay differential circuit structure. By controlling the on / off state of the relays in the three switching circuits through the microcontroller module 410, high-precision sampling of signals under different states is achieved, and the insulation impedance of the electrical equipment 200 is further calculated, thereby improving the detection efficiency, detection accuracy and reliability of the system.

[0081] It is understood that in the above embodiments, the control module 40 further includes a first analog-to-digital conversion module 421 and a second analog-to-digital conversion module 422. The first analog-to-digital conversion module 421 is connected to both the first sampling module 210 and the microcontroller module 410. The first analog-to-digital conversion module 421 converts the first sampling signal into a first digital sampling signal and sends the first digital sampling signal to the microcontroller module 410. The second analog-to-digital conversion module 422 is connected to both the second sampling module 220 and the microcontroller module 410. The second analog-to-digital conversion module 422 converts the second sampling signal into a second digital sampling signal and sends the second digital sampling signal to the microcontroller module 410. The microcontroller module 410 calculates the insulation resistance between the positive electrode and the casing, and the insulation resistance between the negative electrode and the casing, based on the first digital sampling signal and the second digital sampling signal.

[0082] The input terminal of the first analog-to-digital converter (ADC) module 421 is connected to the first sampling module 210, and the output terminal of the first ADC module 421 is connected to the microcontroller module 410. The first ADC module 421 converts the first sampled signal output from the first sampling module 210 into a first digital sampled signal and transmits it to the microcontroller module 410. Similarly, the input terminal of the second ADC module 422 is connected to the second sampling module 220, and the output terminal of the second ADC module 422 is connected to the microcontroller module 410. The second ADC module 422 converts the second sampled signal output from the second sampling module 220 into a second digital sampled signal and transmits it to the microcontroller module 410. The microcontroller module 410 can acquire both the first and second digital sampled signals while simultaneously performing logic control on the switch module 30.

[0083] After the analog signal is converted into digital form by the first analog-to-digital converter (ADC) module 421 and the second ADC module 422, it is easier for the microcontroller module 410 to process it, enabling high-precision calculations and avoiding the problems of noise and interference that are easily affected by analog signal processing. Furthermore, the first ADC module 421 and the second ADC module 422 can improve the accuracy and reliability of the differential insulation impedance detection system 100, increasing detection efficiency. Moreover, the digital signal processed by the first ADC module 421 and the second ADC module 422 is more conducive to storage and transmission for subsequent analysis and processing.

[0084] As can be understood, in the above embodiments, the microcontroller module 410 is a microcontroller unit (MCU), which is the control unit of the differential insulation impedance detection system 100. The first analog-to-digital converter module 421 is an analog-to-digital converter chip, and the second analog-to-digital converter module 422 is an analog-to-digital converter chip. They sample the input analog signal at a sampling frequency, and the resolution can be 16 bits or higher to improve detection accuracy. Through the microcontroller module 410, the first analog-to-digital converter module 421, and the second analog-to-digital converter module 422, high-precision detection of insulation impedance is achieved, detection efficiency is improved, and the differential insulation impedance detection system 100 is made more automated and intelligent.

[0085] It is understood that in the above embodiments, the first analog-to-digital conversion module 421 is connected to the common connection terminal formed by the first resistor 211, the second resistor 212, and the third resistor 213 in the first sampling module 210. The second analog-to-digital conversion module 422 is connected to the common connection terminal formed by the fourth resistor 221, the fifth resistor 222, and the sixth resistor 223 in the second sampling module 220.

[0086] Please see Figure 9 The differential insulation impedance detection system 100 also includes an optocoupler module 50. The optocoupler module 50 is connected to the signal output terminal of the microcontroller module 410 and is used to transmit the warning signal output by the microcontroller module 410.

[0087] The optocoupler module 50 is an isolation device that uses an optocoupler to achieve electrical isolation and signal control. The optocoupler module 50 has advantages such as good electrical isolation performance, stable and reliable signal transmission, and fast response speed. Signal transmission between the microcontroller module 410 and external devices can be achieved through the optocoupler module 50. When the insulation impedance detected by the differential insulation impedance detection system 100 does not meet the performance evaluation test standards, a warning signal is output through the optocoupler module 50. Therefore, the optocoupler module 50 provides good electrical isolation between the input and output, ensuring the safe operation of the differential insulation impedance detection system 100.

[0088] It is understood that, in the above embodiments, the differential insulation impedance detection system 100 further includes a communication module 60 and a DC-DC switching module 70. Both the communication module 60 and the DC-DC switching module 70 are isolated modules. The DC-DC switching module 70 provides power to the microcontroller module 410, the first analog-to-digital converter module 421, and the second analog-to-digital converter module 422 in the control module 40. The DC-DC switching module 70 provides power to the first switching circuit 310, the second switching circuit 320, and the third switching circuit 330 in the switching module 30.

[0089] The communication module 60 is connected to the communication terminal of the microcontroller module 410. The communication module 60 can be an isolated RS485 communication module, employing differential signal transmission, which provides strong anti-interference capabilities. Furthermore, the isolated RS485 communication module enables fast data transmission, meeting the needs of applications requiring high data transmission speeds.

[0090] In the differential insulation impedance detection system 100, the optocoupler module 50, the communication module 60, and the DC-DC switching module 70 are all isolated, which ensures that the impedance of the differential insulation impedance detection system 100 will not interfere with the insulation impedance detection of the electrical equipment 200, thereby improving the detection accuracy and avoiding false detection problems caused by coupling.

[0091] It is understood that in the above embodiments, with Figure 4 When the differential insulation impedance detection system 100 provided in this application performs insulation impedance detection on the electrical equipment 200, the microcontroller module 410 controls the third relay 333 to turn on, controls the first relay 313 to turn on, and controls the first analog-to-digital converter module 421 to convert the first sampling signal in the first state into the first digital sampling signal V in the first state. 1s1 The second analog-to-digital converter module 422 controls the second sampling signal in the first state to convert it into a second digital sampling signal V in the first state. 2s1 .

[0092] The microcontroller module 410 controls the first relay 313 to disconnect and the second relay 323 to turn on, and controls the first analog-to-digital converter module 421 to convert the first sampling signal in the second state into the first digital sampling signal V in the second state. 1s2 The second analog-to-digital converter module 422 controls the second sampling signal in the second state to convert it into a second digital sampling signal V in the second state. 2s2 .

[0093] The microcontroller module 410 controls the third relay 333 to disconnect and the second relay 323 to disconnect, thus stopping the differential insulation impedance detection system 100 from acquiring signals of the insulation impedance of the electrical equipment 200. The microcontroller module 410 then uses the first digital sampling signal V from the first state... 1s1 The second digital sampling signal V in the first state 2s1 The first digital sampling signal V in the second state 1s2 And the second digital sampling signal V in the second state 2s2 The correlation equations for the insulation resistance between the positive electrode and the casing, and the insulation resistance between the negative electrode and the casing are constructed as follows:

[0094]

[0095] In the above formula, U0 represents the battery voltage of electrical equipment 200. To simplify the calculation process, R is set... 211 =R 221 R 111 =R 122 R 212 =R 222 R 213 =R 223 R 112 =R 121 Solving the above formulas simultaneously yields the insulation resistance R between the positive electrode and the casing. X and the insulation resistance R between the negative electrode and the casing Y The specific formula is shown below:

[0096]

[0097] The insulation resistance R between the positive electrode and the casing X and the insulation resistance R between the negative electrode and the casing Y As can be seen from the formula, the differential insulation impedance detection system 100 provided in this application can detect the insulation impedance of electrical equipment 200 without being affected by the voltage of the electrical equipment 200 itself. For photovoltaic equipment, the differential insulation impedance detection system 100 provided in this application can detect the insulation impedance of photovoltaic equipment without being affected by fluctuations in photovoltaic voltage U0, thus solving the problem of detection accuracy changes caused by fluctuations in photovoltaic voltage U0 in related technologies.

[0098] by Figure 6 When the differential insulation impedance detection system 100 provided in this application performs insulation impedance detection on the electrical equipment 200, the microcontroller module 410 uses the first digital sampling signal V in the first state. 1s1 The second digital sampling signal V in the first state 2s1 The first digital sampling signal V in the second state 1s2 And the second digital sampling signal V in the second state 2s2 The correlation equations for the insulation resistance between the positive electrode and the casing, and the insulation resistance between the negative electrode and the casing are constructed as follows:

[0099]

[0100] In the above formula, U0 represents the battery voltage of electrical equipment 200, V DD This indicates that the DC-DC switching module 70 provides the voltage to the first sampling module 210 and the second sampling module 220, i.e. Figure 6 As shown in VDD. To simplify the calculation process, R is set to... 214=R 216 =R 224 =R 226 R 111 =R 122 R 215 =R 217 =R 225 =R 227 R 112 =R 121 Solving the above formulas simultaneously yields the insulation resistance R between the positive electrode and the casing. X and the insulation resistance R between the negative electrode and the casing Y The specific formula is shown below:

[0101]

[0102]

[0103] The insulation resistance R between the positive electrode and the casing X and the insulation resistance R between the negative electrode and the casing Y As can be seen from the formula, the differential insulation impedance detection system 100 provided in this application can detect the insulation impedance of electrical equipment 200 without being affected by the voltage of the electrical equipment 200 itself. For photovoltaic equipment, the differential insulation impedance detection system 100 provided in this application can detect the insulation impedance of photovoltaic equipment without being affected by fluctuations in photovoltaic voltage U0, thus solving the problem of detection accuracy changes caused by photovoltaic voltage fluctuations in related technologies.

[0104] This application provides an electrical equipment monitoring system, including the differential insulation impedance detection system 100 described in any of the above embodiments. The electrical equipment monitoring system is a system for detecting and monitoring electrical equipment 200. It can perform insulation impedance detection and arc detection on the electrical equipment 200, thereby achieving automated and intelligent detection of the electrical equipment 200, early detection of faults in the electrical equipment 200, and assessment of equipment operating efficiency, thus ensuring the safe operation and maintenance of the electrical equipment 200.

[0105] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application.

[0106] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0107] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0108] In the embodiments provided in this application, it should be understood that the disclosed apparatus / device can be implemented in other ways. For example, the apparatus / device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0109] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0110] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0111] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the above embodiments of this application can also be implemented by a computer program instructing related hardware, and the computer program can be stored in a computer-readable storage medium. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0112] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A differential insulation resistance detection system, characterized in that, include: The first detection module is connected between the positive terminal and the housing of the electrical equipment, and is used to detect the insulation resistance between the positive terminal and the housing, and output a first detection signal; The second detection module is connected between the negative terminal and the housing of the electrical equipment, and is used to detect the insulation resistance between the negative terminal and the housing, and output a second detection signal; The first sampling module is connected to the first detection module and is used to sample the first detection signal and output the first sampling signal; The second sampling module is connected to the second detection module and is used to sample the second detection signal and output the second sampling signal; A switching module, wherein the control terminal of the switching module is connected to the first detection module and the second detection module respectively, and is used to adjust the resistance of the first detection module and the resistance of the second detection module by means of the on / off state; A control module, wherein the control terminal of the control module is connected to the signal terminal of the switch module, and is used to regulate the on / off state of the switch module; The sampling terminals of the control module are connected to the first sampling module and the second sampling module respectively, and are used to acquire the first sampling signal and the second sampling signal, and calculate the insulation impedance between the positive electrode and the shell and the insulation impedance between the negative electrode and the shell based on the first sampling signal and the second sampling signal.

2. The differential insulation resistance detection system as described in claim 1, characterized in that, The switching module includes: A first switching circuit, wherein the signal terminal of the first switching circuit is connected to the control terminal of the control module, and the control terminal of the first switching circuit is connected to the first detection module, and the first switching circuit is used to adjust the resistance of the first detection module according to the first adjustment signal output by the control terminal of the control module. The second switching circuit has its signal terminal connected to the control terminal of the control module and its control terminal connected to the second detection module. The second switching circuit is used to adjust the resistance of the second detection module according to the second adjustment signal output by the control terminal of the control module.

3. The differential insulation resistance detection system as described in claim 2, characterized in that, The control module is used to acquire a first sampling signal and a second sampling signal in a first state when the first switching circuit is turned on and the second switching circuit is turned off. The control module is used to acquire the first sampling signal and the second sampling signal in the second state when the first switching circuit is turned off and the second switching circuit is turned on. The control module is used to calculate the insulation impedance between the positive electrode and the casing and the insulation impedance between the negative electrode and the casing based on the first sampling signal and the second sampling signal in the first state and the first sampling signal and the second sampling signal in the second state.

4. The differential insulation resistance detection system as described in claim 3, characterized in that, The first switching circuit includes: A first transistor, wherein a first terminal of the first transistor is connected to the control terminal of the control module, and a second terminal of the first transistor is grounded; The first Zener diode, the anode of the first Zener diode is connected to the third terminal of the first transistor; The first relay has its first coil connection terminal connected to the third terminal of the first transistor, its second coil connection terminal connected to the cathode terminal of the first Zener diode, and its first contact connection terminal and second contact connection terminal connected to the two ends of the first detection module, respectively.

5. The differential insulation resistance detection system as described in claim 1, characterized in that, The first sampling module includes: A first resistor, one end of which is connected to a first end of the first detection module; A second resistor, one end of which is connected to the other end of the first resistor, and the other end of which is connected to the second end of the first detection module, and the second end of the first detection module is connected to the housing; A third resistor, one end of which is connected to one end of the second resistor, one end of which is connected to the sampling terminal of the control module, and the other end of which is connected to the other end of the second resistor.

6. The differential insulation impedance detection system as described in claim 5, characterized in that, The second sampling module includes: A fourth resistor, one end of which is connected to the first end of the second detection module; The fifth resistor has one end connected to the other end of the fourth resistor, the other end of the fifth resistor connected to the second end of the second detection module, and the second end of the second detection module connected to the housing. A sixth resistor, one end of which is connected to one end of the fifth resistor, one end of which is connected to the sampling terminal of the control module, and the other end of which is connected to the other end of the fifth resistor.

7. The differential insulation impedance detection system as described in claim 4, characterized in that, The first detection module includes: The seventh resistor, one end of which is connected to the positive terminal; The eighth resistor has one end connected to the other end of the seventh resistor, and the other end of the eighth resistor is connected to the housing. The first contact terminal of the first relay is connected to one end of the eighth resistor, and the second contact terminal of the first relay is connected to the other end of the eighth resistor.

8. The differential insulation impedance detection system as described in claim 7, characterized in that, The first sampling module includes: The eleventh resistor, one end of which is connected to one end of the seventh resistor; The twelfth resistor has one end connected to the other end of the eleventh resistor, and the other end of the twelfth resistor is connected to the power supply terminal. The thirteenth resistor, one end of which is connected to the other end of the eighth resistor; The fourteenth resistor, one end of which is connected to the other end of the thirteenth resistor; The first operational amplifier has its non-inverting input connected to the other end of the eleventh resistor, its inverting input connected to the other end of the thirteenth resistor, its output connected to the other end of the fourteenth resistor, and its output connected to the sampling terminal of the control module.

9. The differential insulation resistance detection system as described in claim 3, characterized in that, The switching module includes: The third switching circuit has its signal terminal connected to the control terminal of the control module, its first control terminal connected to the second terminal of the first detection module and the second terminal of the second detection module, and its second control terminal connected to the housing. The third switching circuit is used to detect the insulation resistance between the positive electrode and the housing and the insulation resistance between the negative electrode and the housing when the control module controls the third switching circuit to be turned on.

10. An electrical equipment monitoring system, characterized in that, Including the differential insulation resistance detection system as described in any one of claims 1 to 9.

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