Insulation impedance detection circuit, control method and control apparatus therefor, and photovoltaic device

Abstract

Disclosed are an insulation impedance detection circuit (10), a control method and control apparatus therefor, and a photovoltaic device. The insulation impedance detection circuit (10) is used for detecting a ground impedance of a direct-current bus; the direct-current bus comprises a positive electrode bus (PV+) and negative electrode buses (PV-); the insulation impedance detection circuit (10) comprises sub-detection circuits; the sub-detection circuits each comprise a positive electrode detection resistor (R1) and a negative electrode detection resistor (R2), and are used for detecting bus voltages between the positive electrode bus (PV+) and the negative electrode buses (PV-) by means of the positive electrode detection resistors (R1), and detecting negative ground voltages of the negative electrode buses (PV-) by means of the negative electrode detection resistors (R2); the sub-detection circuits comprise a first sub-detection circuit (102) and a second sub-detection circuit (104); resistance values of the positive electrode detection resistor (R1) and the negative electrode detection resistor (R2) in the first sub-detection circuit (102) are not equal; and resistance values of the positive electrode detection resistor (R1) and the negative electrode detection resistor (R2) in the second sub-detection circuit (104) are equal.

Description

Insulation impedance detection circuit, control method and device thereof, and photovoltaic device

[0001] Priority information

[0002] The present application claims priority to and the benefit of the filing date of Chinese Patent Application No. 202411274066.X, filed September 11, 2024, and which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of photovoltaic technology, in particular, to an insulation impedance detection circuit, a control method and device thereof, and a photovoltaic device. BACKGROUND

[0004] For a photovoltaic power generation system, it is necessary to ensure that the insulation impedance between the photovoltaic panel and the ground (GND) is large enough when working, so it is necessary to detect the insulation impedance of the photovoltaic panel to the ground.

[0005] In the related art, an insulation impedance detection circuit applied to a photovoltaic power generation system sets a detection resistor on the DC bus at the output end of the photovoltaic power generation system, and sets one or more relays, and increases the disturbance by software control of the one or more relays to switch the switch state, thereby realizing insulation impedance detection. Since software control is involved in the detection process, the detection logic is complex and the hardware cost is high. When the relay fails or fails, it will directly cause the insulation impedance detection to fail, resulting in poor reliability of the insulation impedance detection circuit. SUMMARY

[0006] The present application provides an insulation impedance detection circuit, a control method and device thereof, and a photovoltaic device to solve at least one of the above technical problems.

[0007] The first aspect of the present application provides an insulation impedance detection circuit.

[0008] The second aspect of the present application provides a photovoltaic device.

[0009] The third aspect of the present application provides a control method of an insulation impedance detection circuit.

[0010] The fourth aspect of the present application provides a control device of an insulation impedance detection circuit.

[0011] The fifth aspect of the present application provides a readable storage medium.

[0012] Therefore, the first aspect of the present application provides an insulation impedance detection circuit for detecting the impedance of a DC bus to ground, the DC bus comprising a positive bus and a negative bus, the insulation impedance detection circuit comprising: a sub-detection circuit comprising a positive detection resistor and a negative detection resistor, the sub-detection circuit being configured to detect a bus voltage between the positive bus and the negative bus via the positive detection resistor and to detect a negative voltage of the negative bus to ground via the negative detection resistor; wherein the number of sub-detection circuits is two, the two sub-detection circuits comprising a first sub-detection circuit and a second sub-detection circuit, the resistance values of the positive detection resistor and the negative detection resistor in the first sub-detection circuit being unequal, and the resistance values of the positive detection resistor and the negative detection resistor in the second sub-detection circuit being equal.

[0013] In the technical solution, for example, in a scenario such as a photovoltaic system, photovoltaic components as power generation components include N-type photovoltaic components and P-type photovoltaic components, wherein the N-type photovoltaic components mainly conduct electricity through electrons, and the P-type photovoltaic components are hole conductive. In use, taking the N-type photovoltaic component as an example, if the voltage passing through the cell piece is negative and the frame is positively biased, that is, the photovoltaic component is under negative bias, the anode ions will flow into the cell piece.

[0014] When impurities appear in the semiconductor, the impurities form a conductive channel inside the cell, and long-term high voltage at the negative polarity will cause leakage current between the glass and the packaging material. The packaging material of the photovoltaic component can be divided into external packaging material and internal packaging material. The external packaging material includes, for example, glass backboard, TPT (Thermoplastic Polyester Elastome, thermoplastic polyester elastomer) backboard, aluminum frame, and edge sealant. The internal packaging material includes, for example, EVA (ethylene-vinyl acetate copolymer) film, PVB (Polyvinyl Butyral) film, PIB (Polyisobutylene) laminated sealant, and the like.

[0015] When a large amount of electric charges gather on the surface of the cell piece, the passivation effect of the surface of the cell piece deteriorates, resulting in a decrease in the fill factor, short-circuit current, and open-circuit voltage of the cell panel. This phenomenon is called PID (Potential Induced Degradation) effect, which can cause the power generation of the photovoltaic system to decrease, and seriously affect the power generation of the power station. At this time, the performance is that the insulation impedance of the DC bus of the photovoltaic power generation component to ground decreases, and therefore it is necessary to monitor the insulation impedance of the DC bus to ground in real time, and intervene as soon as possible when the insulation impedance to ground is detected to decrease.

[0016] The application provides an asymmetric insulation impedance detection circuit without a signal relay, and the insulation impedance detection circuit does not need to set a complex control process of a software control switch device, and since the switch device is not needed, insulation impedance detection failure caused by switch device failure can be avoided, and low-cost and high-reliability insulation impedance detection is realized. The specific embodiments of the insulation impedance detection circuit are described in detail below.

[0017] Exemplarily, the ground insulation impedance of the positive bus in the bus voltage is Rins+, and the ground insulation impedance of the negative bus in the bus voltage is Rins-. During insulation impedance detection, the voltage values of the positive bus and the negative bus, i.e., the bus voltage Vpv of the direct-current bus, and the voltage value of the negative bus to the ground, i.e., the negative-to-ground voltage Vg, are sampled, and the ground insulation impedance Rins+ of the positive bus and the ground insulation impedance Rins- of the negative bus are determined according to the bus voltage Vpv and the negative-to-ground voltage Vg.

[0018] At this time, the following formula (1) is used for calculation:

[0019] wherein Vpv is the bus voltage, Vg is the negative-to-ground voltage, R1 is the positive detection resistor, R2 is the negative detection resistor, R7 is the second resistor, and R5, R6, R7, R8 and R9 are constants.

[0020] The selection of the positive detection resistor and the negative detection resistor is the key of the insulation impedance detection circuit. When the positive detection resistor and the negative detection resistor are equal, it is generally recorded that the sub-detection circuit is a symmetric detection circuit, and when the positive detection resistor and the negative detection resistor are not equal, it is considered that the sub-detection circuit is an asymmetric detection circuit.

[0021] Let the positive detection resistor be R1 and the negative detection resistor be R2, then in the symmetric detection circuit, i.e., the second sub-detection circuit, R1=R2. The changes of the ground insulation impedance Rins+ of the positive bus and the ground insulation impedance Rins- of the negative bus can be divided into the following three cases:

[0022] Case one, the ground insulation impedance Rins+ of the positive bus changes, and the ground insulation impedance Rins- of the negative bus does not change (at this time, it is defaulted that the resistance value of Rins- is infinite);

[0023] Case two, the ground insulation impedance Rins+ of the positive bus does not change, and the ground insulation impedance Rins- of the negative bus changes;

[0024] Case three, the ground insulation impedance Rins+ of the positive bus and the ground insulation impedance Rins- of the negative bus both change.

[0025] At this time, for the second sub-detection circuit, in case one, the greater Rins+, the smaller the negative bus-to-ground voltage sampling value. In case two, the greater Rins-, the greater the negative bus-to-ground voltage sampling value. In case three, Rins+ and Rins- change at the same time, and the negative bus-to-ground voltage sampling value is basically unchanged. Since the negative bus-to-ground voltage sampling value is basically unchanged when Rins+ and Rins- change at the same time, the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins- cannot be calculated by calculating the difference between the bus voltage Vpv of the DC bus and the negative-to-ground voltage Vg.

[0026] To solve the above problems, the application adds an asymmetric detection circuit, that is, the first sub-detection circuit described above. In the first sub-detection circuit, R1≠R2. Assuming R1=k×R2, where k is a proportionality coefficient, for example, k takes 10 / 7. For the asymmetric first sub-detection circuit, in the above case one, case two and case three, the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins- can be calculated by the difference between the bus voltage Vpv of the DC bus and the negative-to-ground voltage Vg.

[0027] If only the asymmetric detection circuit is set, in a specific case, for example, when k takes 10 / 7 and R1=10 / 7×R2, if Rins+ exactly equals 10 / 7×Rins-, it will cause R1×Rins-=R2×Rins+, at this time, it can be known from the above formula (1) that the difference between the bus voltage and the negative bus-to-ground voltage sampling value is basically unchanged.

[0028] To this end, the asymmetric detection circuit and the symmetric detection circuit are set in the application, that is, the first sub-detection circuit and the second sub-detection circuit described above. The insulation of the bus circuit is detected by the two sub-detection circuits respectively. When the ground insulation impedance detected by the two sub-detection circuits both meet the requirements, it is confirmed that the ground insulation of the device is normal, otherwise it is considered that the ground insulation of the device is abnormal.

[0029] The insulation impedance detection circuit proposed in the embodiment of the application does not need to set a complex control process of a software-controlled switching device, and since no switching device needs to be set, the insulation impedance detection failure caused by the failure of the switching device can be avoided, thereby realizing low-cost and high-reliability insulation impedance detection.

[0030] In addition, the insulation impedance detection circuit in the above technical solution provided by the application can also have the following additional technical features:

[0031] In some technical solutions of the application, optionally, the insulation impedance detection circuit further comprises a controller, the controller being electrically connected with the first sub-detection circuit and the second sub-detection circuit, and the controller being configured to:

[0032] determine first impedance detection information according to the first bus voltage and the first negative electrode-to-ground voltage, wherein the first bus voltage and the first negative electrode-to-ground voltage are detected by the first sub-detection circuit; determine second impedance detection information according to the second bus voltage and the second negative electrode-to-ground voltage, wherein the second bus voltage and the second negative electrode-to-ground voltage are detected by the second sub-detection circuit; and determine the insulation impedance detection result of the DC bus based on the first impedance detection information and the second impedance detection information.

[0033] In this technical solution, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in scenarios other than the simultaneous change of the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins-. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0034] In this technical solution, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in scenarios other than the simultaneous change of the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins-. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0035] In this technical solution, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in scenarios other than the simultaneous change of the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins-. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0036] The insulation impedance detection result of the DC bus is determined by comparing whether the first detection information and the second detection information both satisfy the ground insulation impedance threshold required for safe and stable operation of the system.

[0037] For example, when the first detection information and the second detection information both satisfy the ground insulation impedance threshold, it is determined whether the detection result meets the requirements. When either of the first detection information and the second detection information does not satisfy the ground insulation impedance threshold, it is determined that the detection result does not meet the requirements.

[0038] In this technical solution, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in scenarios other than the simultaneous change of the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins-. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0039] In some embodiments of the application, the sub-detection circuit comprises: a positive electrode detection resistor, a first end of the positive electrode detection resistor being electrically connected to the positive bus, and a second end of the positive electrode detection resistor being grounded; and a first comparator, a first input end of the first comparator being electrically connected to the negative bus, a second input end of the first comparator being electrically connected to the first end of the positive electrode detection resistor, and an output end of the first comparator being configured to output the bus voltage.

[0040] In this embodiment, the positive electrode detection resistor R1 has one end connected to the positive bus and the other end grounded and connected to the first input end (input positive) of the first comparator. The second input end (input negative) of the first comparator is connected to the negative bus through a voltage dividing resistor. The simple circuit structure described above can accurately detect the insulation impedance of the DC bus to ground without additional switching devices, simplifies the structure of the insulation impedance detection circuit, and improves the reliability of the insulation impedance detection circuit.

[0041] In some embodiments of the application, the sub-detection circuit further comprises: a first capacitor, a first end of the first capacitor being electrically connected to the second input end of the first comparator, and a second end of the first capacitor being electrically connected to the negative bus; and a first resistor, the first resistor being connected in parallel with the first capacitor.

[0042] In this embodiment, the first capacitor and the first resistor are connected in parallel between the first input end of the first comparator and the positive electrode detection resistor, which can reliably absorb noise signals in the circuit and improve detection accuracy.

[0043] In some embodiments of the application, the sub-detection circuit further comprises: a negative electrode detection resistor, a first end of the negative electrode detection resistor being grounded; and a second comparator, a first input end of the second comparator being electrically connected to the negative bus, a second input end of the second comparator being electrically connected to a second end of the negative electrode detection resistor, and an output end of the second comparator being configured to output the negative-to-ground voltage.

[0044] In this embodiment, the negative electrode detection resistor R2 has one end connected to the negative bus and the other end grounded and connected to the first input end (input positive) of the second comparator. The second input end (input negative) of the second comparator is connected to the negative bus through a voltage dividing resistor. The simple circuit structure described above can accurately detect the insulation impedance of the DC bus to ground without additional switching devices, simplifies the structure of the insulation impedance detection circuit, and improves the reliability of the insulation impedance detection circuit.

[0045] In some technical solutions of the present application, the sub-detection circuit further comprises: a second capacitor, a first end of the second capacitor being electrically connected to the second input end of the second comparator, and a second end of the second capacitor being electrically connected to the negative bus; and a second resistor, the second resistor being connected in parallel with the second capacitor.

[0046] In this technical solution, the second capacitor and the second resistor are connected in parallel between the second input end of the second comparator and the positive detection resistor, which can reliably absorb noise signals in the circuit and improve detection accuracy.

[0047] The second aspect of the present application provides a photovoltaic device, comprising: a photovoltaic power generation assembly, an output end of the photovoltaic power generation assembly being electrically connected to a direct current bus; and an insulation impedance detection circuit as provided in any of the above technical solutions, the insulation impedance detection circuit being electrically connected to the direct current bus and being used for detecting the ground impedance of the direct current bus.

[0048] In this technical solution, the photovoltaic device comprises the insulation impedance detection circuit as provided in any of the above technical solutions, and thus also comprises all the beneficial effects of the insulation impedance detection circuit as provided in any of the above technical solutions. To avoid repetition, no further description is given here.

[0049] The third aspect of the present application provides a control method of an insulation impedance detection circuit, the insulation impedance detection circuit comprising a first sub-detection circuit and a second sub-detection circuit, the resistance values of the positive detection resistor and the negative detection resistor in the first sub-detection circuit being unequal, and the resistance values of the positive detection resistor and the negative detection resistor in the second sub-detection circuit being equal; the control method comprising:

[0050] obtaining a first bus voltage, a first negative ground voltage, a second bus voltage and a second negative ground voltage of the direct current bus; wherein the first bus voltage and the first negative ground voltage are detected by the first sub-detection circuit, and the second bus voltage and the second negative ground voltage are detected by the second sub-detection circuit; determining first impedance detection information according to the first bus voltage and the first negative ground voltage, and determining second impedance detection information according to the second bus voltage and the second negative ground voltage; and determining an insulation impedance detection result of the direct current bus based on the first impedance detection information and the second impedance detection information.

[0051] In this technical solution, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the direct current bus in scenarios other than the simultaneous change of the ground insulation impedance Rins+ of the positive bus and the ground insulation impedance Rins- of the negative bus. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the direct current bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0052] The first bus voltage Vpv1 and the first negative electrode to ground voltage Vg1 are detected by the first sub-detection circuit, and Rins1+ and Rins1- are calculated by using the above formula (1). Similarly, the second bus voltage Vpv2 and the second negative electrode to ground voltage Vg2 are detected by the second sub-detection circuit, and Rins2+ and Rins2- are calculated by using the above formula (1).

[0053] Rins1+ and Rins1- are the first impedance detection information, and Rins2+ and Rins2- are the second impedance detection information.

[0054] The insulation impedance detection result of the DC bus is determined by comparing whether the first detection information and the second detection information both satisfy the ground insulation impedance threshold required for safe and stable operation of the system.

[0055] The symmetric detection circuit and the asymmetric detection circuit are combined to ensure that the detection result of the ground insulation impedance is accurate and reliable in any case.

[0056] In some technical solutions of the present application, the insulation impedance detection result of the DC bus is determined based on the first impedance detection information and the second impedance detection information, including: in the case that the first impedance detection information and the second impedance detection information both satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result passes the insulation detection; or in the case that any one of the first impedance detection information and the second impedance detection information does not satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result fails the insulation detection.

[0057] In this technical solution, let the positive detection resistance be R1 and the negative detection resistance be R2. In the symmetric detection circuit, i.e., the second sub-detection circuit, R1=R2, and in the asymmetric detection circuit, i.e., the first sub-detection circuit, R1≠R2. For the second sub-detection circuit, Rins+ and Rins- change simultaneously, and the negative bus to ground voltage sampling value is basically unchanged. For the first sub-detection circuit, in a specific case, if R1×Rins- exactly equals R2×Rins+, the difference between the bus voltage and the negative bus to ground voltage sampling value is basically unchanged.

[0058] To this end, the asymmetric detection circuit and the symmetric detection circuit are provided in the present application, i.e., the first sub-detection circuit and the second sub-detection circuit, and the insulation of the bus circuit is detected by the two sub-detection circuits. When the ground insulation impedance detected by the two sub-detection circuits both meet the requirements, it is confirmed that the equipment ground insulation is normal, otherwise it is considered that the equipment ground insulation is abnormal.

[0059] Exemplarily, when the first detection information and the second detection information both satisfy the above ground insulation impedance threshold value, it is determined whether the detection result meets the requirement. When either one of the first detection information and the second detection information does not satisfy the above ground insulation impedance threshold value, it is determined that the detection result does not meet the requirement.

[0060] The application achieves accurate and reliable ground insulation impedance detection by combining the asymmetric detection circuit and the symmetric detection circuit without the need of setting a switching device and a complex switching control logic.

[0061] The fourth aspect of the application provides a control device of an insulation impedance detection circuit, which comprises a memory for storing programs or instructions and a processor for executing the programs or instructions to realize the control method of the insulation impedance detection circuit according to any one of the above technical solutions, and thus comprises all the beneficial effects of the control method of the insulation impedance detection circuit according to any one of the above technical solutions, which will not be repeated here to avoid repetition.

[0062] The fifth aspect of the application provides a readable storage medium having programs or instructions stored thereon, which are executed by a processor to realize the control method of the insulation impedance detection circuit according to any one of the above technical solutions, and thus comprises all the beneficial effects of the control method of the insulation impedance detection circuit according to any one of the above technical solutions, which will not be repeated here to avoid repetition.

[0063] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0064] The above and / or additional aspects and advantages of the application will become apparent and be readily appreciated from the following description, including the appended drawings, wherein:

[0065] FIG. 1 shows a circuit diagram of an insulation impedance detection circuit according to some embodiments of the application;

[0066] FIG. 2 shows a circuit diagram of a first sub-detection circuit according to some embodiments of the application;

[0067] FIG. 3 shows a circuit diagram of a second sub-detection circuit according to some embodiments of the application;

[0068] FIG. 4 shows a flowchart of a control method of an insulation impedance detection circuit according to some embodiments of the application;

[0069] FIG. 5 shows a structural block diagram of a control device of an insulation impedance detection circuit according to some embodiments of the application.

[0070] Reference signs: 10 insulation impedance detection circuit, R1 positive detection resistor, R2 negative detection resistor, 102 first sub-detection circuit, 104 second sub-detection circuit, 106 controller, Q1 first comparator, C1 first capacitor, R4 first resistor, Q2 second comparator, C2 second capacitor, R7 second resistor, PV+ positive bus, PV- negative bus. DETAILED DESCRIPTION

[0071] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals and letters throughout the figures denote the same or like elements or elements having the same or similar functionality. The embodiments described below are exemplary and intended to explain the present application, and are not intended to limit the present application.

[0072] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the elements of the different examples of the present application are described in the following description with reference to the drawings. Of course, they are merely examples and are not intended to limit the present application. The reference numerals and / or reference letters of the embodiments of the present application can be repeated in different examples, and such repetition is for the purpose of simplification and clarity, and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, the embodiments of the present application provide examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0073] The insulation impedance detection circuit and its control method, control device and photovoltaic device provided according to some embodiments of the present application are described below with reference to Figures 1 to 5.

[0074] In some embodiments of the present application, an insulation impedance detection circuit is provided, Figure 1 shows a circuit diagram of the insulation impedance detection circuit according to some embodiments of the present application, Figure 2 shows a circuit diagram of a first sub-detection circuit according to some embodiments of the present application, and Figure 3 shows a circuit diagram of a second sub-detection circuit according to some embodiments of the present application, as shown in Figures 1, 2 and 3, the insulation impedance detection circuit 10 is used to detect the impedance of the DC bus to ground, the DC bus includes a positive bus and a negative bus, the insulation impedance detection circuit 10 includes:

[0075] The sub-detection circuit includes a positive electrode detection resistor R1 and a negative electrode detection resistor R2, and is used for detecting the bus voltage between the positive bus PV+ and the negative bus PV- through the positive electrode detection resistor R1, and detecting the negative electrode-to-ground voltage of the negative bus PV- through the negative electrode detection resistor R2; wherein the number of sub-detection circuits is two, and the two sub-detection circuits include a first sub-detection circuit 102 and a second sub-detection circuit 104, the resistance values of the positive electrode detection resistor R1 and the negative electrode detection resistor R2 in the first sub-detection circuit 102 are not equal, and the resistance values of the positive electrode detection resistor R1 and the negative electrode detection resistor R2 in the second sub-detection circuit 104 are equal.

[0076] In this embodiment, an example is given for a scene such as a photovoltaic system, wherein the photovoltaic components as power generation components include N-type photovoltaic components and P-type photovoltaic components, wherein the N-type photovoltaic components mainly conduct electricity through electrons, and the P-type photovoltaic components are hole conductive. In use, taking the N-type photovoltaic component as an example, if the voltage passing through the cell piece is negative, the frame is positively biased, that is, the photovoltaic component is under negative bias, and the anode ions flow into the cell piece.

[0077] When impurities appear in the semiconductor, the impurities form a conductive channel inside the cell, and long-term high voltage under negative polarity will cause leakage current between the glass and the packaging material. The packaging material of the photovoltaic component can be divided into external packaging material and internal packaging material. The external packaging material includes, for example, glass backboard, TPT (Thermoplastic Polyester Elastome, thermoplastic polyester elastomer) backboard, aluminum frame, and edge sealant. The internal packaging material includes, for example, EVA (ethylene-vinyl acetate copolymer) film, PVB (Polyvinyl Butyral) film, PIB (Polyisobutylene) laminated sealant, etc.

[0078] When a large amount of electric charges gather on the surface of the cell piece, the passivation effect of the surface of the cell piece is deteriorated, resulting in a decrease in the fill factor, short-circuit current, and open-circuit voltage of the cell panel. This phenomenon is called PID (Potential Induced Degradation) effect, which can cause the power generation of the photovoltaic system to decrease, and seriously affect the power generation of the power station. At this time, the performance is that the ground insulation impedance of the direct current bus of the photovoltaic power generation component decreases, so it is necessary to monitor the ground insulation impedance of the direct current bus in real time, and intervene as soon as possible when the ground insulation impedance is detected to decrease.

[0079] The application provides an asymmetric insulation impedance detection circuit 10 without a signal relay, and the insulation impedance detection circuit 10 does not need to set a complex control process of a software control switch device, and because the switch device is not needed, insulation impedance detection failure caused by switch device failure can be avoided, and low-cost and high-reliability insulation impedance detection is realized. The specific embodiment of the insulation impedance detection circuit 10 is described in detail below.

[0080] For example, as shown in FIG. 1, PV+ is a positive bus PV+, PV- is a negative bus PV-, the insulation impedance of the positive bus PV+ in the bus voltage to ground is Rins+, and the insulation impedance of the negative bus PV- in the bus voltage to ground is Rins-. When the insulation impedance is detected, the voltage value of the positive bus PV+ to the negative bus PV-, that is, the bus voltage Vpv of the DC bus, and the voltage value of the negative bus PV- to ground, that is, the negative voltage Vg to ground, are sampled, and the insulation impedance Rins+ of the positive bus PV+ to ground and the insulation impedance Rins- of the negative bus PV- to ground are determined according to the bus voltage Vpv and the negative voltage Vg to ground.

[0081] At this time, the following formula (1) is used for calculation:

[0082] Wherein, Vpv is the bus voltage, Vg is the negative voltage to ground, R1 is the positive detection resistance, R2 is the negative detection resistance, R5, R6, R7, R8 and R9 are resistors shown in FIG. 1, and R5, R6, R7, R8 and R9 are constants.

[0083] The selection of the positive detection resistance R1 and the negative detection resistance R2 is the key of the insulation impedance detection circuit 10. When the positive detection resistance R1 and the negative detection resistance R2 are equal, it is generally recorded that the sub-detection circuit is a symmetric detection circuit, and when the positive detection resistance and the negative detection resistance R2 are not equal, it is considered that the sub-detection circuit is an asymmetric detection circuit.

[0084] Let the positive detection resistance be R1 and the negative detection resistance be R2, then in the symmetric detection circuit, that is, the second sub-detection circuit 104, R1=R2. The change of the insulation impedance Rins+ of the positive bus PV+ to ground and the insulation impedance Rins- of the negative bus PV- to ground can be divided into the following three cases:

[0085] Case one, the insulation impedance Rins+ of the positive bus PV+ to ground changes, and the insulation impedance Rins- of the negative bus PV- to ground does not change (at this time, it is defaulted that the resistance value of Rins- is infinite);

[0086] Case two, the ground insulation impedance Rins+ of the positive bus PV+ is unchanged, and the ground insulation impedance Rins- of the negative bus PV- is changed.

[0087] Case three, the ground insulation impedance Rins+ of the positive bus PV+ and the ground insulation impedance Rins- of the negative bus PV- are both changed.

[0088] At this time, for the second sub-detection circuit 104, in case one, the greater Rins+, the smaller the negative bus PV- ground voltage sampling value. In case two, the greater Rins-, the greater the negative bus PV- ground voltage sampling value. In case three, Rins+, Rins- changes at the same time, and the negative bus PV- ground voltage sampling value is basically unchanged. The detection data of the second sub-detection circuit 104 is shown in Table 1 as follows:

[0089] Table 1

[0090] Since the PV- ground voltage sampling value basically does not change when Rins+, Rins- changes at the same time, the insulation impedance value cannot be calculated by calculating the difference between the bus voltage Vpv of the DC bus and the negative ground voltage Vg to calculate the ground insulation impedance Rins+ of the positive bus PV+ and the ground insulation impedance Rins- of the negative bus PV-.

[0091] In view of the above problems, the application adds an asymmetric detection circuit, that is, the above-mentioned first sub-detection circuit 102. In the first sub-detection circuit 102, R1≠R2. Assuming that R1=k×R2, where k is a proportionality coefficient, for example, k takes 10 / 7, and the data of the first sub-detection circuit 102 is shown in Table 2 as follows:

[0092] Table 2

[0093] As shown in Table 2, for the asymmetric first sub-detection circuit 102, in the above-mentioned case one, case two and case three, the ground insulation impedance Rins+ of the positive bus PV+ and the ground insulation impedance Rins- of the negative bus PV- can be calculated by the difference between the bus voltage Vpv of the DC bus and the negative ground voltage Vg.

[0094] If only the asymmetric detection circuit is set, in a specific case, for example, when k takes 10 / 7, R1=10 / 7×R2, if Rins+ = 10 / 7×Rins- is satisfied, then R1×Rins- = R2×Rins+ will be caused, at this time, it can be known from the above formula (1) that the difference between the bus voltage and the negative bus PV- ground voltage sampling value is basically unchanged.

[0095] To this end, the asymmetric detection circuit and the symmetric detection circuit are simultaneously provided in the application, that is, the first sub-detection circuit 102 and the second sub-detection circuit 104, insulation detection is performed on the bus circuit through the two sub-detection circuits respectively, when the ground insulation impedance detected by the two sub-detection circuits both meet the requirements, it is confirmed that the ground insulation of the equipment is normal, otherwise, it is considered that the ground insulation of the equipment is abnormal.

[0096] The insulation impedance detection circuit 10 provided in the embodiment of the application does not need to set a complex control process of a software control switch device, and since no switch device needs to be set, the insulation impedance detection failure caused by the failure of the switch device can be avoided, thereby realizing low-cost and high-reliability insulation impedance detection.

[0097] In addition, the insulation impedance detection circuit 10 in the above embodiment provided by the application can also have the following additional technical features:

[0098] In some embodiments of the application, optionally, the insulation impedance detection circuit 10 further comprises a controller 106, the controller 106 is electrically connected with the first sub-detection circuit 102 and the second sub-detection circuit 104, and the controller 106 is configured to:

[0099] determine the first impedance detection information according to the first bus voltage and the first negative electrode-to-ground voltage, wherein the first bus voltage and the first negative electrode-to-ground voltage are detected by the first sub-detection circuit 102; determine the second impedance detection information according to the second bus voltage and the second negative electrode-to-ground voltage, wherein the second bus voltage and the second negative electrode-to-ground voltage are detected by the second sub-detection circuit 104; and determine the insulation impedance detection result of the DC bus based on the first impedance detection information and the second impedance detection information.

[0100] In this embodiment, the first sub-detection circuit 102 is an asymmetric detection circuit, and the second sub-detection circuit 104 is a symmetric detection circuit. Among them, for the second sub-detection circuit 104, it can accurately detect the ground insulation impedance of the DC bus in the scene where the ground insulation impedance Rins+ of the positive bus PV+ and the ground insulation impedance Rins- of the negative bus PV- change at the same time. For the first sub-detection circuit 102, it can accurately detect the ground insulation impedance of the DC bus in all scenes except that R1 x Rins- = R2 x Rins+ is met.

[0101] The first bus voltage Vpv1 and the first negative pole-to-ground voltage Vg1 are detected by the first sub-detection circuit 102, and Rins1+ and Rins1- are calculated according to the above formula (1). Similarly, the second bus voltage Vpv2 and the second negative pole-to-ground voltage Vg2 are detected by the second sub-detection circuit 104, and Rins2+ and Rins2- are calculated according to the above formula (1).

[0102] Rins1+ and Rins1- are the first impedance detection information, and Rins2+ and Rins2- are the second impedance detection information.

[0103] The insulation impedance detection result of the DC bus is determined by comparing whether the first detection information and the second detection information both satisfy the ground insulation impedance threshold required for system safe and stable operation.

[0104] Exemplarily, when the first detection information and the second detection information both satisfy the above ground insulation impedance threshold, it is determined whether the detection result meets the requirements. When either of the first detection information and the second detection information does not satisfy the above ground insulation impedance threshold, it is determined that the detection result does not meet the requirements.

[0105] The application combines the symmetric detection circuit and the asymmetric detection circuit, and can ensure that the detection result of the ground insulation impedance is accurate and reliable in any case.

[0106] In some embodiments of the application, the sub-detection circuit includes: a positive detection resistor R1, a first end of the positive detection resistor R1 being electrically connected to the positive bus PV+, and a second end of the positive detection resistor R1 being grounded; and a first comparator Q1, a first input end of the first comparator Q1 being electrically connected to the negative bus PV-, a second input end of the first comparator Q1 being electrically connected to the first end of the positive detection resistor R1, and an output end of the first comparator Q1 being used for outputting a bus voltage.

[0107] In this embodiment, the positive detection resistor is R1, one end of the positive detection resistor R1 being connected to the positive bus PV+, the other end being grounded, and being connected to the first input end (input positive) of the first comparator Q1. The second input end (input negative) of the first comparator Q1 is connected to the negative bus PV- through a voltage dividing resistor. The above simple circuit structure can realize accurate detection of the insulation impedance of the DC bus without setting additional switching devices, simplifies the structure of the insulation impedance detection circuit 10, and improves the reliability of the insulation impedance detection circuit 10.

[0108] In some embodiments of the present application, optionally, the sub-detection circuit further comprises: a first capacitor C1, a first end of the first capacitor C1 being electrically connected with a second input end of the first comparator Q1, and a second end of the first capacitor C1 being electrically connected with the negative bus PV-; and a first resistor R4, the first resistor R4 being connected in parallel with the first capacitor C1.

[0109] In this embodiment, the first capacitor C1 and the first resistor R4 are arranged in parallel between the first input end of the first comparator Q1 and the positive detection resistor R1, so that the noise signal in the circuit can be reliably absorbed, and the detection precision is improved.

[0110] In some embodiments of the present application, optionally, the sub-detection circuit further comprises: a negative detection resistor R2, a first end of the negative detection resistor R2 being grounded; and a second comparator Q2, a first input end of the second comparator Q2 being electrically connected with the negative bus PV-, a second input end of the second comparator Q2 being electrically connected with a second end of the negative detection resistor R2, and an output end of the second comparator Q2 being used for outputting the negative voltage to ground.

[0111] In this embodiment, the negative detection resistor R2 has one end connected to the negative bus PV- and the other end grounded, and is connected to the first input end (input positive) of the second comparator Q2 through the resistor R6, while the first input end of the second comparator Q2 is connected to the negative bus PV- through the resistor R6 and the filter capacitor C3. The second input end (input negative) of the second comparator Q2 is connected to the negative bus PV- through the voltage dividing resistor. Through the above simple circuit structure, the accurate detection of the DC bus-to-ground insulation impedance can be realized without setting additional switching devices, the structure of the insulation impedance detection circuit 10 is simplified, and the reliability of the insulation impedance detection circuit 10 is improved.

[0112] In some embodiments of the present application, optionally, the sub-detection circuit further comprises: a second capacitor C2, a first end of the second capacitor C2 being electrically connected with the second input end of the second comparator Q2, and a second end of the second capacitor C2 being electrically connected with the negative bus PV-; and a second resistor R7, the second resistor R7 being connected in parallel with the second capacitor C2.

[0113] In this embodiment, the second capacitor C2 and the second resistor R7 are arranged in parallel between the second input end of the second comparator Q2 and the positive detection resistor R1, so that the noise signal in the circuit can be reliably absorbed, and the detection precision is improved.

[0114] In some embodiments of the present application, a photovoltaic device is provided, comprising: a photovoltaic power generation assembly, an output end of the photovoltaic power generation assembly being electrically connected with a DC bus; and an insulation impedance detection circuit as provided in any of the above embodiments, the insulation impedance detection circuit being electrically connected with the DC bus and being used for detecting the impedance of the DC bus to ground.

[0115] In this embodiment, the photovoltaic device comprises the insulation impedance detection circuit provided in any of the above embodiments, and thus also comprises all the beneficial effects of the insulation impedance detection circuit provided in any of the above embodiments. To avoid repetition, no further elaboration is made here.

[0116] In some embodiments of the present application, a control method of an insulation impedance detection circuit is provided, the insulation impedance detection circuit comprising a first sub-detection circuit and a second sub-detection circuit, the resistance values of the positive and negative detection resistors in the first sub-detection circuit are not equal, and the resistance values of the positive and negative detection resistors in the second sub-detection circuit are equal.

[0117] FIG. 4 shows a flowchart of the control method of the insulation impedance detection circuit according to some embodiments of the present application. As shown in FIG. 4, the control method comprises:

[0118] Step 402: obtaining a first bus voltage, a first negative pole-to-ground voltage, a second bus voltage, and a second negative pole-to-ground voltage of a DC bus; wherein the first bus voltage and the first negative pole-to-ground voltage are detected by the first sub-detection circuit, and the second bus voltage and the second negative pole-to-ground voltage are detected by the second sub-detection circuit;

[0119] Step 404: determining first impedance detection information according to the first bus voltage and the first negative pole-to-ground voltage, and determining second impedance detection information according to the second bus voltage and the second negative pole-to-ground voltage;

[0120] Step 406: determining an insulation impedance detection result of the DC bus based on the first impedance detection information and the second impedance detection information.

[0121] In this embodiment, the first sub-detection circuit is an asymmetric detection circuit, and the second sub-detection circuit is a symmetric detection circuit. For the second sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in scenarios other than the simultaneous change of the positive bus-to-ground insulation impedance Rins+ and the negative bus-to-ground insulation impedance Rins-. For the first sub-detection circuit, it can accurately detect the ground insulation impedance of the DC bus in all scenarios except that R1 x Rins- = R2 x Rins+ is met.

[0122] The present application combines the first sub-detection circuit and the second sub-detection circuit, detects the first bus voltage Vpv1 and the first negative pole-to-ground voltage Vg1 through the first sub-detection circuit, and calculates Rins1+ and Rins1- according to the above formula (1). Similarly, the second bus voltage Vpv2 and the second negative pole-to-ground voltage Vg2 are detected through the second sub-detection circuit, and Rins2+ and Rins2- are calculated according to the above formula (1).

[0123] wherein, Rins1+ and Rins1- are the first impedance detection information, and Rins2+ and Rins2- are the second impedance detection information.

[0124] The insulation impedance detection result of the DC bus is determined by comparing whether the first detection information and the second detection information both satisfy the ground insulation impedance threshold required for system safe and stable operation.

[0125] The application combines the symmetric detection circuit and the asymmetric detection circuit, and can ensure the detection result of the ground insulation impedance to be accurate and reliable in any case.

[0126] In some embodiments of the application, the insulation impedance detection result of the DC bus is determined based on the first impedance detection information and the second impedance detection information, including: in the case that the first impedance detection information and the second impedance detection information both satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result passes the insulation detection; or in the case that any one of the first impedance detection information and the second impedance detection information does not satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result fails the insulation detection.

[0127] In this embodiment, assuming that the positive detection resistance is R1 and the negative detection resistance is R2, then in the symmetric detection circuit, i.e. the second sub-detection circuit, R1 = R2, and in the asymmetric detection circuit, i.e. the first sub-detection circuit, R1 ≠ R2. For the second sub-detection circuit, Rins+ and Rins- change simultaneously, and the negative bus voltage sampling value is basically unchanged. For the first sub-detection circuit, in a specific case, if R1 × Rins- = R2 × Rins+ is exactly satisfied, then the difference between the bus voltage and the negative bus voltage sampling value is basically unchanged.

[0128] To this end, the asymmetric detection circuit and the symmetric detection circuit are both provided in the application, i.e. the first sub-detection circuit and the second sub-detection circuit, and the insulation of the bus circuit is detected by the two sub-detection circuits respectively. When the ground insulation impedance detected by the two sub-detection circuits both satisfy the requirement, it is confirmed that the equipment is normally insulated from the ground, otherwise it is considered that the equipment is abnormally insulated from the ground.

[0129] Exemplarily, when the first detection information and the second detection information both satisfy the above ground insulation impedance threshold, it is determined whether the detection result satisfies the requirement. When any one of the first detection information and the second detection information does not satisfy the above ground insulation impedance threshold, it is determined that the detection result does not satisfy the requirement. The specific conditions are shown in Table 3:

[0130] Table 3

[0131] The application combines the asymmetric detection circuit and the symmetric detection circuit, and realizes accurate and reliable ground insulation impedance detection without setting a switching device and a complex switching control logic.

[0132] In some embodiments of the application, a control device of an insulation impedance detection circuit is provided. FIG. 5 shows a structural block diagram of the control device of the insulation impedance detection circuit according to some embodiments of the application. As shown in FIG. 5, the control device 500 of the insulation impedance detection circuit includes a memory 502 for storing programs or instructions, and a processor 504 for executing the programs or instructions to implement the control method of the insulation impedance detection circuit according to any of the above embodiments. Therefore, the control device of the insulation impedance detection circuit also includes all the beneficial effects of the control method of the insulation impedance detection circuit according to any of the above embodiments, which will not be repeated here.

[0133] In some embodiments of the application, a readable storage medium is provided, which stores programs or instructions. When the programs or instructions are executed by a processor, the control method of the insulation impedance detection circuit according to any of the above embodiments is implemented. Therefore, the readable storage medium also includes all the beneficial effects of the control method of the insulation impedance detection circuit according to any of the above embodiments, which will not be repeated here.

[0134] The methods can be implemented in a variety of different ways according to particular features and / or example applications. For example, these methods can be implemented in hardware, firmware, and / or software, and can be implemented with combinations thereof. For example, in a hardware implementation, a processor can be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, micro-controllers, microprocessors, electronic devices, other devices for performing the above-described functions, and / or combinations thereof.

[0135] The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium can be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media, or electrical signals through a wire, cable, or other transmission media.

[0136] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "certain embodiments", "an example", "a specific example", or "some examples" and the like means that a specific feature, structure, material or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present application. Descriptive terms of the above terms do not necessarily refer to the same embodiment or example throughout the specification. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in an appropriate manner.

[0137] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, alternatives and variations to these embodiments can be made without departing from the principles and spirit of the application, and the scope of the application is defined by the claims and their equivalents.

Claims

1. An insulation impedance detection circuit, wherein, The insulation impedance detection circuit is used for detecting the impedance of the DC bus to ground, the DC bus includes a positive bus and a negative bus, and the insulation impedance detection circuit includes: A sub-detection circuit, the sub-detection circuit includes a positive detection resistor and a negative detection resistor, the sub-detection circuit is used for detecting a bus voltage between the positive bus and the negative bus through the positive detection resistor, and detecting a negative voltage of the negative bus to ground through the negative detection resistor; Wherein, the number of the sub-detection circuit is two, the two sub-detection circuits include a first sub-detection circuit and a second sub-detection circuit, the resistance values of the positive detection resistor and the negative detection resistor in the first sub-detection circuit are not equal, and the resistance values of the positive detection resistor and the negative detection resistor in the second sub-detection circuit are equal.

2. The insulation impedance detection circuit of claim 1, wherein, Also includes: A controller, the controller is electrically connected with the first sub-detection circuit and the second sub-detection circuit, and the controller is used for: According to the first bus voltage and the first negative voltage to ground, determining the first impedance detection information; wherein, the first bus voltage and the first negative voltage to ground are detected by the first sub-detection circuit; According to the second bus voltage and the second negative voltage to ground, determining the second impedance detection information; wherein, the second bus voltage and the second negative voltage to ground are detected by the second sub-detection circuit; And, based on the first impedance detection information and the second impedance detection information, determining the insulation impedance detection result of the DC bus.

3. The insulation impedance detection circuit of claim 2, wherein, The controller is also used for: In the case that the first impedance detection information and the second impedance detection information both satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result is passed insulation detection; Or, in the case that any one of the first impedance detection information and the second impedance detection information does not satisfy the insulation detection condition of the DC bus, determining that the insulation impedance detection result is failed insulation detection.

4. The insulation impedance detection circuit according to any one of claims 1-3, wherein, The sub-detection circuit includes: The positive detection resistor, a first end of the positive detection resistor is electrically connected with the positive bus, and a second end of the positive detection resistor is grounded; A first comparator, a first input end of the first comparator is electrically connected with the negative bus, a second input end of the first comparator is electrically connected with the first end of the positive detection resistor, and an output end of the first comparator is used for outputting the bus voltage.

5. The insulation impedance detection circuit of claim 4, wherein, The sub-detection circuit further includes: A first capacitor, a first end of the first capacitor is electrically connected with the second input end of the first comparator, and a second end of the first capacitor is electrically connected with the negative bus; A first resistor, the first resistor is connected in parallel with the first capacitor.

6. The insulation impedance detection circuit according to any one of claims 1-5, wherein, The sub-detection circuit further includes: The negative detection resistor, a first end of the negative detection resistor is grounded; A second comparator, a first input end of the second comparator is electrically connected with the negative bus, a second input end of the second comparator is electrically connected with a second end of the negative detection resistor, and an output end of the second comparator is used for outputting the negative voltage to ground.

7. The insulation impedance detection circuit of claim 6, wherein, The sub-detection circuit further includes: A second capacitor, a first end of the second capacitor being electrically connected to the second input end of the second comparator, and a second end of the second capacitor being electrically connected to the negative bus; A second resistor, the second resistor being connected in parallel with the second capacitor.

8. A photovoltaic device, wherein, The application comprises: A photovoltaic power generation assembly, an output end of the photovoltaic power generation assembly being electrically connected to a direct current bus; The insulation impedance detection circuit according to any one of claims 1 to 7, the insulation impedance detection circuit being electrically connected to the direct current bus, and being configured to detect an impedance of the direct current bus to ground.

9. A control method of an insulation impedance detection circuit, wherein, The insulation impedance detection circuit comprises a first sub-detection circuit and a second sub-detection circuit, resistance values of a positive detection resistor and a negative detection resistor in the first sub-detection circuit are not equal, and resistance values of the positive detection resistor and the negative detection resistor in the second sub-detection circuit are equal; and the control method comprises: Obtaining a first bus voltage, a first negative voltage to ground, a second bus voltage, and a second negative voltage to ground of the direct current bus; wherein the first bus voltage and the first negative voltage to ground are detected by the first sub-detection circuit, and the second bus voltage and the second negative voltage to ground are detected by the second sub-detection circuit; According to the first bus voltage and the first negative voltage to ground, determining first impedance detection information, and according to the second bus voltage and the second negative voltage to ground, determining second impedance detection information; Based on the first impedance detection information and the second impedance detection information, determining an insulation impedance detection result of the direct current bus.

10. The control method of the insulation impedance detection circuit according to claim 9, wherein The determining of the insulation impedance detection result of the direct current bus based on the first impedance detection information and the second impedance detection information comprises: In a case where the first impedance detection information and the second impedance detection information both satisfy an insulation detection condition of the direct current bus, determining that the insulation impedance detection result passes the insulation detection; Or, in a case where any one of the first impedance detection information and the second impedance detection information does not satisfy the insulation detection condition of the direct current bus, determining that the insulation impedance detection result fails the insulation detection.

11. A control device of an insulation impedance detection circuit, wherein, The application comprises: A memory, configured to store programs or instructions; A processor, configured to execute the programs or instructions to implement the control method of the insulation impedance detection circuit according to claim 9 or 10.

12. A readable storage medium, on which a program or instructions are stored, wherein, The programs or instructions are executed by the processor to implement the control method of the insulation impedance detection circuit according to claim 9 or 10. The programs or instructions are executed by the processor to implement the control method of the insulation impedance detection circuit according to claim 9 or 10.

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