Directional insulation resistance detection device and method and ungrounded direct current system

Abstract

The invention provides a directional insulation resistance detection device and method and an ungrounded direct current system, and the device comprises a control module which is connected to a first switch module and a second switch module, and is used for controlling the connection / disconnection of the first switch module and the second switch module, the circuit enters a first switch state or a second switch state; the detection module is used for detecting the corresponding first voltage or second voltage according to the first switch state or the second switch state. According to the application, the insulation resistance in the upstream direction and the downstream direction can be accurately calculated through the positive-end voltage to ground and the negative-end voltage to ground connected to the circuit in the first switching state and the second switching state, and the position where insulation damage occurs is determined. A protection mechanism similar to leakage protection of an alternating current system can also be constructed in an ungrounded direct current system, and a foundation is laid for large-scale networking operation of the direct current system.

Description

Technical Field

[0001] This application belongs to the technical field of power electronics, and relates to a directional insulation resistance detection device, in particular to a directional insulation resistance detection device, method and ungrounded DC system. Background Art

[0002] In ordinary civil and industrial AC electrical systems, the neutral line of a single-phase system or the neutral line of a three-phase system is connected to the ground. When implementing electric shock protection or leakage protection to protect personal safety, it only needs to detect the algebraic sum of the currents in the live wire and the neutral wire (or the currents in the three phase lines and the neutral line) through a very mature leakage current sensor. When there is no leakage current theoretically, the current measured by the leakage current sensor should be 0, otherwise there is a leakage current to the ground. When the leakage current level reaches a certain limit, the protection will be triggered.

[0003] With the application of new energy such as photovoltaic, DC systems are becoming increasingly popular. DC systems are often powered by positive and negative poles, and both poles are insulated from the ground. In this case, it is no longer possible to use a leakage current sensor for protection, because even if one pole is completely short-circuited to the ground, no loop can be formed with the ground, so the existence of leakage current cannot be detected. However, in practice, protection must be carried out when the insulation resistance between any pole and the ground drops to a certain threshold. Therefore, in practical applications, an online insulation resistance detection method is used for protection.

[0004] There are many methods for online detection of insulation resistance. However, so far, these methods can only detect the insulation resistance of the entire system, and there is no method with directionality that can accurately calculate the equivalent insulation resistance in each direction. At the same time, the problem is that the insulation resistance detection device installed anywhere in the system detects the equivalent insulation resistance of the entire system, but cannot determine the specific branch where the insulation fault occurs. Once protection is carried out, the entire system can only be powered off, and selective protection cannot be carried out, which greatly limits the application scale of DC systems. With the expansion of the application scope of DC systems, there is an urgent need for a directional insulation resistance detection and protection scheme. Summary of the Invention

[0005] The purpose of this application is to provide a directional insulation resistance detection device, method and ungrounded DC system, which are used to solve the problem that there is no method with directionality that can accurately calculate the equivalent insulation resistance in each direction in the prior art for directional insulation resistance detection.

[0006] In a first aspect, the present application provides a directional insulation resistance detection device, which includes: a first switch module, a second switch module, a control module, and a detection module; the control module is respectively connected to the first switch module and the second switch module, and is used to control the closing / opening of the first switch module and the second switch module, so that the circuit enters a first switch state or a second switch state; the detection module is used to detect a corresponding first voltage or a second voltage according to the first switch state or the second switch state.

[0007] In an implementation manner of the first aspect, the first switch state includes: controlling the first switch module connected to the circuit to be closed and the second switch module connected to the circuit to be opened; the second switch state includes: controlling the first switch module connected to the circuit to be opened and the second switch module connected to the circuit to be closed.

[0008] In an implementation manner of the first aspect, the first switch module includes: a first switch and a first grounding resistor; one end of the first grounding resistor is connected to the positive terminal of the circuit, and the other end is connected to the first switch; one end of the first switch is connected to one end of the first grounding resistor, and the other end is grounded; when the first switch is closed, the first grounding resistor is connected to the circuit, and the positive terminal of the circuit is connected to the grounding resistor and grounded through the first switch.

[0009] In an implementation manner of the first aspect, the second switch module includes: a second switch and a second grounding resistor; one end of the second grounding resistor is connected to the negative terminal of the circuit, and the other end is connected to the second switch; one end of the second switch is connected to one end of the second grounding resistor, and the other end is grounded; when the second switch is closed, the second grounding resistor is connected to the circuit, and the negative terminal of the circuit is connected to the grounding resistor and grounded through the second switch.

[0010] In an implementation manner of the first aspect, the detection module further includes a leakage current sensor to detect the leakage current of the circuit.

[0011] In an implementation manner of the first aspect, the first voltage includes: the first positive terminal voltage to ground, the first negative terminal voltage to ground, and the first leakage current; the second voltage includes: the second positive terminal voltage to ground, the second negative terminal voltage to ground, and the second leakage current.

[0012] In an implementation manner of the first aspect, the detection module is further used to obtain the insulation resistance value of the power supply side and the insulation resistance value of the load side connected to the circuit according to the first voltage and the second voltage.

[0013] In an implementation of the first aspect, the directional insulation resistance detection module further includes a communication module, which is connected to the detection module to transmit the insulation resistance values of the power supply side and the load side of the access circuit to the main controller of the circuit.

[0014] In a second aspect, the present application provides a method for detecting directional insulation resistance. The method for detecting directional insulation resistance includes: controlling the circuit to enter a first switch state and detecting the corresponding first voltage; controlling the circuit to enter a second switch state and detecting the corresponding second voltage; obtaining the insulation resistance values of the power supply side and the load side of the access circuit according to the first voltage and the second voltage.

[0015] In an implementation of the second aspect, the first switch state includes: controlling the first switch module of the access circuit to be closed and the second switch module of the access circuit to be opened; the second switch state includes: controlling the first switch module of the access circuit to be opened and the second switch module of the access circuit to be closed.

[0016] In an implementation of the second aspect, the first voltage includes: the positive terminal voltage to ground, the negative terminal voltage to ground, and the first leakage current; the second voltage includes: the positive terminal voltage to ground, the negative terminal voltage to ground, and the second leakage current.

[0017] In a third aspect, the present application provides an ungrounded DC system. The ungrounded DC system includes the directional insulation resistance detection device according to any one of the first aspects of the present application, a DC power supply, and a load; the DC power supply is used to input direct current to the directional insulation resistance detection device and the load; the load operates based on the direct current.

[0018] As described above, the directional insulation resistance detection device, method, and ungrounded DC system of the present application have the following beneficial effects:

[0019] First, the present application can accurately calculate the insulation resistance in the upstream and downstream directions and determine the location of insulation damage through the positive terminal voltage to ground and the negative terminal voltage to ground of the access circuit in the first switch state and the second switch state.

[0020] Second, the directional insulation resistance detection device of the present application only protects the insulation resistance of the downstream. It can also build a protection mechanism similar to the leakage protection of the AC system in the ungrounded DC system, laying a foundation for the large-scale network operation of the DC system. Description of the Drawings

[0021] Figure 1 It shows a schematic structural diagram of the directional insulation resistance detection device described in the embodiments of the present application.

[0022] Figure 2It shows a schematic structural diagram of the directional insulation resistance detection device described in another embodiment of the present application.

[0023] Figure 3 It shows a schematic structural diagram of the directional insulation resistance detection device described in the embodiment of the present application being arranged in an ungrounded DC system.

[0024] Figure 4 It shows a schematic diagram of the directional insulation resistance detection method described in the embodiment of the present application.

[0025] Figure 5 It shows a schematic structural diagram of the ungrounded DC system described in the embodiment of the present application.

[0026] Figure 6 It shows a schematic structural diagram of the ungrounded DC system described in another embodiment of the present application

[0027] Description of component numbers

[0028] 100 Directional insulation resistance detection device

[0029] 10 First switch module

[0030] 20 Second switch module

[0031] 30 Control module

[0032] 40 Detection module

[0033] 401 Leakage current sensor

[0034] 50 Communication module

[0035] 1000 Ungrounded DC system

[0036] 1001 DC power supply

[0037] 1002 Load Detailed implementation manners

[0038] The following uses specific specific examples to illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0039] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. Therefore, only the components related to the present application are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0040] In addition, in the present application, descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0041] An embodiment of the present application provides a directional insulation resistance detection device, which is arranged in an ungrounded DC system to obtain the positive terminal equivalent insulation resistance from the power supply to the insulation resistance detection device and the negative terminal equivalent insulation resistance from the insulation resistance detection device to the load, and perform directional insulation resistance detection based on the positive terminal equivalent insulation resistance and the negative terminal equivalent insulation resistance.

[0042] The directional insulation resistance detection device of the present application can accurately calculate the insulation resistance in two directions, upstream and downstream, of the detection device, determine the location of insulation damage, and the detection device only protects the insulation resistance downstream. A protection mechanism similar to the leakage protection of the AC system can also be constructed in the ungrounded DC system, laying a foundation for the large-scale network operation of the DC system.

[0043] The following will combine Figure 1 to Figure 6 elaborate in detail the principles and implementation methods of the directional insulation resistance detection device, method, and ungrounded DC system described in the embodiments of the present application, so that those skilled in the art can understand the directional insulation resistance detection device, method, and ungrounded DC system of this embodiment without creative labor.

[0044] Please refer to Figure 1 , which shows a schematic structural diagram of the directional insulation resistance detection device described in the embodiment of the present application.

[0045] As Figure 1 shown, the directional insulation resistance detection device 100 includes: a first switch module 10, a second switch module 20, a control module 30, and a detection module 40.

[0046] Specifically, the control module 30 is connected to the first switch module 10 and the second switch module 20 respectively, and is used to control the closing / opening of the first switch module 10 and the second switch module 20 so that the circuit enters the first switch state or the second switch state; the detection module 40 is used to detect the corresponding first voltage or second voltage according to the first switch state or the second switch state.

[0047] Specifically, when the equivalent insulation resistance at all points in the circuit to which the directional insulation resistance detection device 100 is connected is high, connecting a grounding resistor to the positive or negative end of the circuit will result in very little leakage current. However, when insulation resistance is reduced at a certain point due to insulation damage, a significant leakage current will result after the grounding resistor is connected. By measuring the voltage to ground at the positive and negative ends, as well as the leakage current, the equivalent insulation resistance at each point can be calculated.

[0048] It should be noted that when the first switch module 10 and the second switch module 20 are both in the off state, the directional insulation resistance detection device 100 does not measure the circuit voltage to ground.

[0049] Furthermore, the first switch state includes: controlling the first switch module 10 connected to the circuit to be closed and the second switch module 20 connected to the circuit to be open; the second switch state includes: controlling the first switch module 10 connected to the circuit to be open and the second switch module 20 connected to the circuit to be closed.

[0050] In one embodiment, the first switch module 10 includes: a first switch and a first grounding resistor; one end of the first grounding resistor is connected to the positive end of the circuit, and the other end is connected to the first switch; one end of the first switch is connected to one end of the first grounding resistor, and the other end is grounded; when the first switch is closed, the first grounding resistor is connected to the circuit, and the positive end of the circuit is connected to the grounding resistor and grounded via the first switch.

[0051] The second switch module 20 includes: a second switch and a second grounding resistor; one end of the second grounding resistor is connected to the negative end of the circuit, and the other end is connected to the second switch; one end of the second switch is connected to one end of the second grounding resistor, and the other end is grounded; when the second switch is closed, the second grounding resistor is grounded through the second switch.

[0052] In one embodiment, the detection module 40 further includes a leakage current sensor 401 to detect leakage current of the circuit.

[0053] Specifically, the first voltage includes: a first positive terminal voltage to ground, a first negative terminal voltage to ground, and a first leakage current; the second voltage includes: a second positive terminal voltage to ground, a second negative terminal voltage to ground, and a second leakage current.

[0054] Specifically, the detection module 40 is further configured to obtain the insulation resistance value of the power supply side of the access circuit and the insulation resistance value of the load 1002 side according to the first voltage and the second voltage.

[0055] In one embodiment, as Figure 2 shown, the directional insulation resistance detection device 100 is connected to an ungrounded DC system 1000. The directional insulation resistance detection device 100 is disposed between the ungrounded Vdc and the DC load Rload. The ungrounded DC power supply Vdc supplies direct current to the DC load Rload and the directional insulation resistance.

[0056] Set the positive terminal equivalent insulation resistance between the ungrounded DC power supply Vdc and the directional insulation resistance detection device 100 as Rps, the negative terminal equivalent resistance as Rns, set the positive terminal equivalent insulation resistance between the directional insulation resistance detection device 100 and the DC load Rload as Rpl, and the negative terminal equivalent resistance as Rnl.

[0057] Control the first switch module 10 of the access circuit to be closed and the second switch module 20 of the access circuit to be opened, so that the first grounding resistor is connected to the circuit. The detection module 40 obtains the positive terminal voltage Vp1 to the ground, the negative terminal voltage to the ground denoted as Vn1, and the first leakage current I01 between the ungrounded DC power supply Vdc and the directional insulation resistance detection device 100; control the first switch module 10 of the access circuit to be opened and the second switch module 20 of the access circuit to be closed, so that the second grounding resistor is connected to the circuit. The detection module 40 obtains the positive terminal voltage Vp2 to the ground and the negative terminal voltage to the ground denoted as Vn2, and the second leakage current I02 between the directional insulation resistance detection device 100 and the DC load Rload.

[0058] It should be noted that the positive terminal voltage Vp1 to the ground and the negative terminal voltage to the ground denoted as Vn1, that is, the first positive terminal voltage Vp1 and the first negative terminal voltage Vn1; the positive terminal voltage Vp2 to the ground and the negative terminal voltage to the ground denoted as Vn2, that is, the second positive terminal voltage Vp2 and the second negative terminal voltage Vn2.

[0059] According to the voltage and current values obtained according to the first switch state and the second switch state, the following equations can be obtained:

[0060]

[0061] According to the above equations, it can be obtained that:

[0062]

[0063] Among them, V p1 is the first positive terminal voltage to the ground, Rps is the equivalent insulation resistance of the positive terminal on the power supply side, V n1 is the voltage of the first negative terminal to ground, R ns is the equivalent resistance of the negative terminal on the power supply side, I 01 is the value of the first leakage current, V p2 is the voltage of the second positive terminal to ground, V n2 is the voltage of the second negative terminal to ground, I 02 is the value of the second leakage current, R pl is the equivalent insulation resistance of the positive terminal on the load side, R nl is the equivalent resistance of the negative terminal on the load side, and R0 is the grounding resistance for testing inside the device.

[0064] According to the obtained insulation resistance values of the power supply side and the load side, protection can be provided for the insulation resistance of the load side, so that the insulation resistance detection has directionality and can protect the circuit more accurately.

[0065] Furthermore, in one embodiment, the directional insulation resistance detection device 100 further includes a communication module 50. The communication module 50 is connected to the detection module 40 to transmit the insulation resistance values of the DC power supply 1001 side and the load 1002 side of the access circuit to the main controller of the circuit.

[0066] In one embodiment, as Figure 3 shown, the directional insulation detection device is arranged between the ungrounded DC power supply and the load of the ungrounded DC system. The detection outputs of the positive terminal voltage to ground, the negative terminal voltage to ground, and the DC leakage current sensor 401 are used as the inputs of the directional insulation detection device. Two MOS transistors Q1 and Q2 connected to the ground are built in. Among them, MOS transistor Q1 is responsible for turning on and off the grounding resistance R1 connected to the positive terminal, and MOS transistor Q2 is responsible for turning on and off the grounding resistance R2 connected to the negative terminal. According to the detection logic of the directional insulation detection device described in the above embodiment, the input data is substituted into the above equations to obtain the actual resistance values of the insulation resistances of both ends of the leakage current sensor 401 to the ground, and the obtained actual resistance values of the insulation resistances to the ground are sent to the main controller of the ungrounded DC system through the communication module 50.

[0067] It should be noted that it should be understood that the above division of each module is only a division of logical functions. In actual implementation, it can be fully or partially integrated into a physical entity, or physically separated. And these modules can all be implemented in the form of software called by processing elements; they can also all be implemented in the form of hardware; or some modules can be implemented in the form of software called by processing elements, and some modules can be implemented in the form of hardware. For example, the x module can be a separately established processing element, or can be integrated in a certain chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and the function of the above x module is called and executed by a certain processing element of the above device. The implementation of other modules is similar. In addition, all or part of these modules can be integrated together or can be independently implemented. The processing element mentioned here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by the integrated logic circuit in the processor element or the instruction in the form of software.

[0068] For example, the above-mentioned modules can be one or more integrated circuits configured to implement the above method, such as: one or more Application Specific Integrated Circuits (ASICs), or, one or more Digital Signal Processors (DSPs), or, one or more Field Programmable Gate Arrays (FPGAs), etc. Again, when a certain module above is implemented in the form of a processing element scheduling program code, the processing element can be a general-purpose processor, such as a Central Processing Unit (CPU) or other processors that can call program code. Again, these modules can be integrated together and implemented in the form of a System-On-a-Chip (SOC).

[0069] Please refer to Figure 4 , which shows the directional insulation resistance detection method described in the embodiments of the present application. The method includes: controlling the circuit to enter a first switch state and detecting the corresponding first voltage; controlling the circuit to enter a second switch state and detecting the corresponding second voltage;

[0070] Obtaining the power supply side insulation resistance value and the load side insulation resistance value of the access circuit according to the first voltage and the second voltage.

[0071] As Figure 4 shown, the directional insulation resistance detection method includes:

[0072] Step S1: The control circuit enters the first switch state and detects the corresponding first voltage.

[0073] Step S2: The control circuit enters the second switch state and detects the corresponding second voltage.

[0074] Specifically, the first switch state includes: controlling the first switch module 10 connected to the circuit to be closed and the second switch module 20 connected to the circuit to be opened; the second switch state includes: controlling the first switch module 10 connected to the circuit to be opened and the second switch module 20 connected to the circuit to be closed.

[0075] The first voltage includes: the voltage of the first positive terminal to the ground, the voltage of the first negative terminal to the ground, and the first leakage current; the second voltage includes: the voltage of the second positive terminal to the ground, the voltage of the second negative terminal to the ground, and the second leakage current.

[0076] Step S3: Obtain the insulation resistance value of the power supply side and the insulation resistance value of the load side of the circuit connected according to the first voltage and the second voltage.

[0077] It should be noted that for Steps 1 and 2, the order can be adjusted according to actual detection, that is, obtaining the first voltage first or obtaining the second voltage first does not affect the result of this application.

[0078] The directional insulation resistance detection method described in this embodiment corresponds to the directional insulation resistance detection device described in the above embodiment, so it will not be elaborated again here.

[0079] It should be noted that the protection scope of the directional insulation resistance detection method described in this application is not limited to the execution order of the steps listed in this embodiment. Any solution achieved by adding or subtracting steps of the prior art or replacing steps according to the principle of this application is included in the protection scope of this application.

[0080] Please refer to Figure 5 , which shows the structural schematic diagram of the ungrounded DC system described in the embodiment of this application.

[0081] As Figure 5 shown, the ungrounded DC system 1000 includes the directional insulation resistance detection device 100, the DC power supply 1001, and the load 1002 described in any embodiment of this application.

[0082] Specifically, the DC power supply 1001 is used to input direct current to the directional insulation resistance detection device 100 and the load 1002; the load 1002 operates based on the direct current.

[0083] In one embodiment, the ungrounded DC system 1000 is a DC charging station system with a system voltage of 800V. The power supply end generates a DC bus voltage of 800V and transmits the DC bus voltage to a number of DC input charging piles through the DC bus. A directional insulation detection device is provided in each DC charging pile, and a directional insulation detection device is provided on the output side of the power supply end to form two-level protection in the ungrounded DC system 1000: when the charging pile and its downstream circuit have insulation damage, the equipment on the charging pile will provide protection; when the cable between the power supply and the charging pile has insulation damage, the equipment on the power supply will provide protection; when there is insulation damage at the charging pile and the protection equipment on the pile does not respond, the equipment on the power supply will also provide protection.

[0084] As Figure 6 shown, in the DC charging station system, there are charging piles 1 and 2 connected. A directional insulation detection device IR0 is provided on the DC power supply 1001 side, located at the output end of the DC power supply 1001 side. Directional insulation resistance detection devices IR1 and IR2 are provided on the load 1002 side of the DC charging station system and are respectively connected to the charging piles 1 and 2.

[0085] Specifically, when the insulation resistance between the negative terminal of the charging pile 2 and the ground drops to Rnb, the detection device IR2 provided at the charging pile 2 will detect this fault; when the insulation resistance between the positive terminal of the power supply and the ground drops to Rpa, the detection device IR0 provided on the power supply side will detect this fault and take corresponding measures. IR2 and IR1 can also detect abnormalities in the insulation resistance on the power supply side, but will not take measures.

[0086] The descriptions of the processes or structures corresponding to the above various drawings each have their own focuses. For parts not detailed in a certain process or structure, reference can be made to the relevant descriptions of other processes or structures.

[0087] In summary, through the positive terminal-to-ground voltage and negative terminal-to-ground voltage connected to the circuit in the first switch state and the second switch state, the present application can accurately calculate the insulation resistance in the upstream and downstream directions and determine the location of insulation damage; the directional insulation resistance detection device of the present application only protects the insulation resistance in the downstream direction, and a protection mechanism similar to the leakage protection of the AC system can also be constructed in the ungrounded DC system, laying a foundation for the large-scale network operation of the DC system. Therefore, the present application effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0088] The above embodiments are only illustrative of the principles and effects of the present application and are not intended to limit the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present application should still be covered by the claims of the present application.

Claims

1. A directional insulation resistance detection device, characterized in that, The directional insulation resistance detection device includes: a first switch module, a second switch module, a control module, and a detection module; The control module is respectively connected to the first switch module and the second switch module, and is used to control the closing / opening of the first switch module and the second switch module, so that the circuit enters a first switch state or a second switch state; The detection module is used to detect a corresponding first voltage or second voltage according to the first switch state or the second switch state.

2. The directional insulation resistance detection device according to claim 1, wherein, The first switch state includes: controlling the first switch module connected to the circuit to be closed and the second switch module connected to the circuit to be opened; The second switch state includes: controlling the first switch module connected to the circuit to be opened and the second switch module connected to the circuit to be closed.

3. The directional insulation resistance detection device according to claim 2, wherein, The first switch module includes: a first switch and a first grounding resistor; One end of the first grounding resistor is connected to the positive end of the circuit, and the other end is connected to the first switch; One end of the first switch is connected to one end of the first grounding resistor, and the other end is grounded; When the first switch is closed, the first grounding resistor is grounded through the first switch.

4. The directional insulation resistance detection device according to claim 2, characterized in that, The second switch module includes: a second switch and a second grounding resistor; One end of the second grounding resistor is connected to the negative end of the circuit, and the other end is connected to the second switch; One end of the second switch is connected to one end of the second grounding resistor, and the other end is grounded; When the second switch is closed, the second grounding resistor is grounded through the second switch.

5. The directional insulation resistance detection device according to claim 1, characterized in that The detection module further includes a leakage current sensor to detect the leakage current of the circuit.

6. The directional insulation resistance detection device according to claim 5, characterized in that, The first voltage includes: the first positive terminal-to-ground voltage, the first negative terminal-to-ground voltage, and the first leakage current; the second voltage includes: the second positive terminal-to-ground voltage, the second negative terminal-to-ground voltage, and the second leakage current.

7. The directional insulation resistance detection device according to claim 6, characterized in that, The detection module is further used to obtain the power supply side insulation resistance value and the load side insulation resistance value of the circuit connected to the circuit according to the first voltage and the second voltage.

8. The directional insulation resistance detection device according to claim 7, characterized in that, The directional insulation resistance detection module further includes a communication module, and the communication module is connected to the detection module to transmit the power supply side insulation resistance value and the load side insulation resistance value of the circuit connected to the circuit to the main controller of the circuit.

9. A method for detecting the directional insulation resistance, characterized in that, The method includes: Controlling the circuit to enter the first switch state and detecting the corresponding first voltage; Controlling the circuit to enter the second switch state and detecting the corresponding second voltage; Obtaining the power supply side insulation resistance value and the load side insulation resistance value of the circuit connected to the circuit according to the first voltage and the second voltage.

10. The directional insulation resistance detection method according to claim 9, characterized in that, The first switch state includes: controlling the first switch module connected to the circuit to be closed and the second switch module connected to the circuit to be opened; The second switch state includes: controlling the first switch module connected to the circuit to be opened and the second switch module connected to the circuit to be closed.

11. The directional insulation resistance detection method according to claim 9, characterized in that, The first voltage includes: the first positive terminal-to-ground voltage, the first negative terminal-to-ground voltage, and the first leakage current; the second voltage includes: the second positive terminal-to-ground voltage, the second negative terminal-to-ground voltage, and the second leakage current.

12. A non-grounded DC system, characterized in that, The ungrounded DC system includes the directional insulation resistance detection device according to any one of claims 1 to 8, a DC power supply, and a load; The DC power supply is used to input direct current to the directional insulation resistance detection device and the load; The load operates based on the direct current electricity.

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