Insulation resistance detection circuit and photovoltaic equipment

Abstract

The utility model provides an insulation resistance detection circuit and photovoltaic equipment. The insulation resistance detection circuit includes: a processing device; the first end of the upper bridge arm is connected with the anode of the photovoltaic module, and the second end is grounded; the first end of the lower bridge arm is grounded, and the second end is connected with the cathode of the photovoltaic module; the first end of the switch resistance circuit is connected with the anode of the photovoltaic module, the second end is grounded, and the control end is connected with the second output port of the processing device; the first voltage sampling circuit is connected in parallel with the upper bridge arm, and the output end is connected with the first input port of the processing device; the second voltage sampling circuit is connected in parallel with the lower bridge arm, and the output end is connected with the second input port of the processing device; and the third voltage sampling circuit is connected between the positive electrode and the negative electrode of the photovoltaic module, and the output end is connected with the third input port of the processing device. Thus, two sets of bridge arm voltage sampling circuits are arranged, the insulation resistance is determined by combining the sampling results of the two sets of sampling circuits, and the detection precision of the insulation resistance is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic power generation, in particular to an insulation resistance detection circuit and a photovoltaic device. Background Art

[0002] During grid-connected photovoltaic power generation, if the PV array's insulation resistance to ground falls below a certain threshold or if the insulation resistance fails, it can endanger the PV power generation equipment or the personal safety of users. Therefore, it is necessary to test the PV array's insulation resistance before connecting it to the grid.

[0003] At present, when conducting insulation resistance testing, Figure 4 As shown, the voltage V between the positive pole PV+ and the negative pole PV- of the photovoltaic array is detected. pv , and detect the voltage V between the grounding point PE and the negative pole PV- of the photovoltaic array iso , V is obtained by dividing the voltage with resistors (R+, R-, R1 and R2). iso With V pv The magnitude relationship formula is obtained, and then the two relationship formulas before and after the disturbance of switch K1 are combined to solve the impedance R+ of PV+ to PE and the impedance R- of PV- to PE.

[0004] However, the existing insulation resistance detection scheme is not suitable for small R- or V pv When it is small, due to V pv and R1 are fixed, V iso The voltage difference before and after the switch K1 is disturbed is not much, or V iso In this case, the detection error of the insulation resistance will be relatively large, which reduces the detection accuracy of the insulation resistance. Utility Model Content

[0005] The utility model aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0006] To this end, a first aspect of the present invention is to provide an insulation resistance detection circuit.

[0007] The second aspect of the present invention is to provide a photovoltaic device.

[0008] In view of this, according to one aspect of the present invention, an insulation resistance detection circuit is proposed, which is applied to a photovoltaic device, wherein the photovoltaic device includes a photovoltaic module, and the insulation resistance detection circuit includes: a processing device, including a first output port for outputting an insulation resistance detection result; an upper bridge arm, wherein the first end of the upper bridge arm is connected to the positive electrode of the photovoltaic module, and the second end of the upper bridge arm is grounded; a lower bridge arm, wherein the first end of the lower bridge arm is grounded, and the second end of the lower bridge arm is connected to the negative electrode of the photovoltaic module; a switch resistance circuit, wherein the first end of the switch resistance circuit is connected to the positive electrode of the photovoltaic module, the second end of the switch resistance circuit is grounded, and the control end of the switch resistance circuit is connected to the second output port of the processing device; a first voltage sampling a sampling circuit, wherein a first end of the first voltage sampling circuit is connected to the positive electrode of the photovoltaic module, a second end of the first voltage sampling circuit is grounded, and an output end of the first voltage sampling circuit is connected to the first input port of the processing device; a second voltage sampling circuit, wherein a first end of the second voltage sampling circuit is grounded, a second end of the second voltage sampling circuit is connected to the negative electrode of the photovoltaic module, and an output end of the second voltage sampling circuit is connected to the second input port of the processing device; and a third voltage sampling circuit, wherein a first end of the third voltage sampling circuit is connected to the positive electrode of the photovoltaic module, a second end of the third voltage sampling circuit is connected to the negative electrode of the photovoltaic module, and an output end of the third voltage sampling circuit is connected to the third input port of the processing device.

[0009] The insulation resistance detection circuit provided by the utility model is applied to photovoltaic equipment, and the photovoltaic equipment includes photovoltaic modules.

[0010] Specifically, the insulation resistance detection circuit provided by the present invention includes a processing device, an upper bridge arm, a lower bridge arm, a switch resistance circuit, a first voltage sampling circuit, a second voltage sampling circuit, and a third voltage sampling circuit.

[0011] The processing device includes a first output port, a second output port, a first input port, a second input port, and a third input port.

[0012] The first output port is used to output the insulation resistance test result.

[0013] Furthermore, a first end of the upper bridge arm is connected to the positive electrode of the photovoltaic module, and a second end of the upper bridge arm is grounded.

[0014] Furthermore, the first end of the lower bridge arm is grounded, and the second end of the lower bridge arm is connected to the negative electrode of the photovoltaic module.

[0015] Furthermore, a first end of the switch resistance circuit is connected to the positive electrode of the photovoltaic module, a second end of the switch resistance circuit is grounded, and a control end of the switch resistance circuit is connected to the second output port of the processing device.

[0016] During the operation of the insulation resistance detection circuit, the processing device can send a control signal to the switch resistance circuit through the second output port to control the switch in the switch resistance circuit to open or close, so as to achieve switch disturbance control in the switch resistance circuit.

[0017] Furthermore, a first end of the first voltage sampling circuit is connected to the positive electrode of the photovoltaic component, a second end of the first voltage sampling circuit is grounded, and an output end of the first voltage sampling circuit is connected to a first input port of the processing device.

[0018] During the operation of the insulation resistance detection circuit, the first voltage sampling circuit can sample the voltage at both ends of the upper bridge arm, that is, the first voltage sampling circuit can sample the first voltage between the grounding point and the positive pole of the photovoltaic component, and pass the sampling result to the processing device through the first input port for processing.

[0019] Furthermore, a first end of the second voltage sampling circuit is grounded, a second end of the second voltage sampling circuit is connected to the negative electrode of the photovoltaic module, and an output end of the second voltage sampling circuit is connected to the second input port of the processing device.

[0020] During the operation of the insulation resistance detection circuit, the second voltage sampling circuit can sample the voltage at both ends of the lower bridge arm, that is, the second voltage sampling circuit can sample the second voltage between the grounding point and the negative pole of the photovoltaic component, and pass the sampling result to the processing device through the second input port for processing.

[0021] Furthermore, a first end of the third voltage sampling circuit is connected to the positive electrode of the photovoltaic component, a second end of the third voltage sampling circuit is connected to the negative electrode of the photovoltaic component, and an output end of the third voltage sampling circuit is connected to the third input port of the processing device.

[0022] During the operation of the insulation resistance detection circuit, the third voltage sampling circuit can sample the third voltage between the positive and negative electrodes of the photovoltaic module, and transmit the sampling result to the processing device through the third input port for processing.

[0023] Specifically, during the operation of the insulation resistance detection circuit, the processing device can receive the third voltage sampled by the third voltage sampling circuit and control the switch in the switch resistance circuit to open or close. Furthermore, the processing device can receive the first voltage sampled by the first voltage sampling circuit and the second voltage sampled by the second voltage sampling circuit when the switch in the switch resistance circuit is open, and receive the first voltage sampled by the first voltage sampling circuit and the second voltage sampled by the second voltage sampling circuit when the switch in the switch resistance circuit is closed. On this basis, the processing device can determine the magnitude relationship between the sampled first voltage and the second voltage and the third voltage based on the principle of resistance voltage division, and then solve the relationship before and after the switch disturbance respectively to obtain two sets of insulation resistance data. Furthermore, the processing device can obtain one set of insulation resistance data by comparing the two sets of insulation resistance data. In this way, two sets of bridge arm voltage sampling circuits are set up, and the insulation resistance is determined by combining the sampling results of the two sets of sampling circuits, thereby improving the detection accuracy of the insulation resistance.

[0024] The insulation resistance detection circuit according to the present invention may also have the following additional technical features:

[0025] In some technical solutions, optionally, the upper bridge arm includes one or more first resistors.

[0026] In this technical solution, the upper bridge arm may include a first resistor, and the upper bridge arm may also include a plurality of first resistors connected in series, which is not specifically limited here.

[0027] In some technical solutions, optionally, the lower bridge arm includes one or more second resistors.

[0028] In this technical solution, the lower bridge arm may include a second resistor, and the lower bridge arm may also include a plurality of second resistors connected in series, which is not specifically limited here.

[0029] In some technical solutions, optionally, the total impedance of the upper bridge arm is equal to the total impedance of the lower bridge arm.

[0030] In this technical solution, the total impedance of the upper bridge arm is equal to the total impedance of the lower bridge arm, and the sampling impedances of the first and second voltage sampling circuits are identical. This results in symmetrical static impedances, or static impedance balance, and avoids the voltage imbalance between the positive and negative poles of the photovoltaic module relative to the ground point caused by the voltage sampling circuit.

[0031] In some technical solutions, optionally, the switch resistor circuit includes: an electronically controlled switch, a first end of the electronically controlled switch is connected to the positive pole of the photovoltaic module; a third resistor, a first end of the third resistor is connected to the second end of the electronically controlled switch, and a second end of the third resistor is grounded.

[0032] In this technical solution, the switch resistor circuit includes an electronically controlled switch and a third resistor.

[0033] The first end of the electronically controlled switch is connected to the positive electrode of the photovoltaic component, the second end of the electronically controlled switch is connected to the first end of the third resistor, and the second end of the third resistor is grounded.

[0034] During operation of the insulation resistance detection circuit, the processing device may receive a third voltage sampled by the third voltage sampling circuit and control the electronically controlled switch in the switch resistance circuit to open or close. Furthermore, the processing device may receive a first voltage sampled by the first voltage sampling circuit and a second voltage sampled by the second voltage sampling circuit when the electronically controlled switch is open, and receive a first voltage sampled by the first voltage sampling circuit and a second voltage sampled by the second voltage sampling circuit when the electronically controlled switch is closed.

[0035] On this basis, the processing device can calculate the insulation impedance of the two photovoltaic modules, i.e., the parallel value of the impedance at the positive and negative terminals of the photovoltaic modules, based on the sampled third voltage, the two sets of first and second voltages, and the relationship between the internal components of the insulation resistance detection circuit. This system then compares the insulation impedance of the two photovoltaic modules and determines the final insulation impedance of the photovoltaic modules. In this way, by providing two sets of bridge arm voltage sampling circuits and combining the sampling results of the two sampling circuits before and after the switching disturbance to determine the insulation resistance, the insulation resistance detection accuracy is improved.

[0036] In some technical solutions, optionally, the electronically controlled switch includes a relay, a switch tube or an optocoupler.

[0037] In this technical solution, the above-mentioned electronically controlled switches include but are not limited to: relays, switch tubes or optocouplers. Those skilled in the art can select the specific type of the above-mentioned electronically controlled switches according to actual conditions, and no specific restrictions are made here.

[0038] In some technical solutions, optionally, the photovoltaic device further includes a boost conversion circuit and an inverter circuit, and the processing device further includes: a third output port connected to both the boost conversion circuit and the inverter circuit.

[0039] In this technical solution, the photovoltaic device also includes a boost conversion circuit and an inverter circuit. The output end of the boost conversion circuit is connected to the DC side of the inverter circuit, and the voltage at the connection point between the boost conversion circuit and the inverter circuit is the DC bus voltage of the photovoltaic device.

[0040] Furthermore, the processing device further includes a third output port, and the third output port is connected to both the boost conversion circuit and the inverter circuit.

[0041] Specifically, the insulation resistance detection circuit is disposed between the inverter circuit and the boost converter circuit of the photovoltaic device. During operation of the insulation resistance detection circuit, before the photovoltaic device is connected to the grid, the processing device can send a control signal to the boost converter circuit via the third output port to control the boost converter circuit to boost the voltage. After the DC bus voltage of the photovoltaic device increases, the processing device controls the electronically controlled switch in the switch resistance circuit to implement a disturbance, and performs subsequent processing to obtain the insulation resistance of the photovoltaic module.

[0042] In some technical solutions, optionally, the insulation resistance detection circuit further includes: an alarm device connected to the fourth output port of the processing device.

[0043] In this technical solution, the insulation resistance detection circuit further includes an alarm device, and the processing device further includes a fourth output port.

[0044] The alarm device is connected to the fourth output port of the processing device.

[0045] During the operation of the insulation resistance detection circuit, when the detected insulation resistance is lower than the index requirement or the insulation resistance fails, the processing device sends a control signal to the alarm device through the fourth output port to control the alarm device to sound an alarm, thereby reminding the user that there is a safety hazard in the photovoltaic equipment and it cannot be connected to the grid.

[0046] In some technical solutions, optionally, the processing device includes a microprocessor, a central processing unit, a microcontroller or a system on a chip.

[0047] In this technical solution, the above-mentioned processing device includes but is not limited to: a microprocessor, a central processing unit, a microcontroller or a system on a chip, and is not specifically limited here.

[0048] According to a second aspect of the present utility model, a photovoltaic device is proposed, comprising: a photovoltaic module; a boost conversion circuit, wherein the input end of the boost conversion circuit is connected to the photovoltaic module; an inverter circuit, wherein the DC side of the inverter circuit is connected to the output end of the boost conversion circuit; and an insulation resistance detection circuit such as in any of the above technical solutions, which is connected to the photovoltaic module, the boost conversion circuit and the inverter circuit.

[0049] The photovoltaic device provided by the utility model comprises a photovoltaic component, a boost conversion circuit, an inverter circuit and an insulation resistance detection circuit in any of the above technical solutions.

[0050] Among them, the input end of the boost conversion circuit is connected to the photovoltaic module, the output end of the boost conversion circuit is connected to the DC side of the inverter circuit, and the insulation resistance detection circuit is connected to the photovoltaic module, the boost conversion circuit and the inverter circuit.

[0051] The photovoltaic device proposed in the second aspect of the present invention includes the insulation resistance detection circuit of any of the above technical solutions. Therefore, the photovoltaic device proposed in the second aspect of the present invention has all the beneficial effects of the insulation resistance detection circuit of any of the above technical solutions, which will not be repeated here.

[0052] Additional aspects and advantages of the present invention will become apparent in the following description or will be understood through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0054] Figure 1 Shows a structural block diagram of an insulation resistance detection circuit according to an embodiment of the present utility model;

[0055] Figure 2 FIG1 shows one of the circuit structure diagrams of the insulation resistance detection circuit according to an embodiment of the present utility model;

[0056] Figure 3 The second circuit structure diagram of the insulation resistance detection circuit according to the embodiment of the present utility model is shown;

[0057] Figure 4 A schematic diagram of the circuit structure of an insulation resistance detection circuit in the related art is shown;

[0058] Figure 5 The structure block diagram of the photovoltaic device according to the embodiment of the present utility model is shown.

[0059] Reference numerals:

[0060] 100 Insulation resistance detection circuit, 102 Processing device, 104 First output port, 106 Upper bridge arm, 108 Lower bridge arm, 110 Switch resistance circuit, 112 Second output port, 114 First voltage sampling circuit, 116 First input port, 118 Second voltage sampling circuit, 120 Second input port, 122 Third voltage sampling circuit, 124 Third input port, 126 First resistor, 128 Second resistor, 130 Electronically controlled switch, 132 Third resistor, 134 Third output port, 136 Alarm device, 138 Fourth output port, 200 Photovoltaic device, 202 Photovoltaic module, 204 Boost conversion circuit, 206 Inverter circuit. DETAILED DESCRIPTION

[0061] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features therein can be combined with each other without conflict.

[0062] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0063] The following combination Figures 1 to 5 , the insulation resistance detection circuit and photovoltaic device provided in the embodiments of the present application are described in detail through specific embodiments and their application scenarios.

[0064] In one embodiment of the present invention, Figure 1 As shown, an insulation resistance detection circuit 100 is provided, which is applied to a photovoltaic device 200 . The photovoltaic device 200 includes a photovoltaic component 202 .

[0065] In actual application, the photovoltaic component 202 may be a photovoltaic array, a photovoltaic cell, etc., which is not specifically limited here.

[0066] Specifically, if Figure 1 As shown, the insulation resistance detection circuit 100 provided by the present invention includes a processing device 102 , an upper bridge arm 106 , a lower bridge arm 108 , a switch resistance circuit 110 , a first voltage sampling circuit 114 , a second voltage sampling circuit 118 and a third voltage sampling circuit 122 .

[0067] The processing device 102 includes a first output port 104 , a second output port 112 , a first input port 116 , a second input port 120 , and a third input port 124 .

[0068] The first output port 104 is used to output the insulation resistance detection result.

[0069] Furthermore, a first end of the upper bridge arm 106 is connected to the positive electrode PV+ of the photovoltaic assembly 202 , and a second end of the upper bridge arm 106 is grounded.

[0070] Furthermore, a first end of the lower bridge arm 108 is grounded, and a second end of the lower bridge arm 108 is connected to the negative electrode PV− of the photovoltaic assembly 202 .

[0071] Furthermore, a first end of the switch resistor circuit 110 is connected to the positive electrode PV+ of the photovoltaic module 202 , a second end of the switch resistor circuit 110 is grounded, and a control end of the switch resistor circuit 110 is connected to the second output port 112 of the processing device 102 .

[0072] During the operation of the insulation resistance detection circuit 100 , the processing device 102 may send a control signal to the switch resistance circuit 110 through the second output port 112 to control the switch in the switch resistance circuit 110 to open or close, thereby achieving switch disturbance control in the switch resistance circuit 110 .

[0073] Furthermore, a first terminal of the first voltage sampling circuit 114 is connected to the positive electrode PV+ of the photovoltaic component 202 , a second terminal of the first voltage sampling circuit 114 is grounded, and an output terminal of the first voltage sampling circuit 114 is connected to the first input port 116 of the processing device 102 .

[0074] During the operation of the insulation resistance detection circuit 100, the first voltage sampling circuit 114 can sample the voltage across the upper bridge arm 106, that is, the first voltage sampling circuit 114 can sample the first voltage between the ground point PE and the positive pole PV+ of the photovoltaic component 202, and transmit the sampling result to the processing device 102 through the first input port 116 for processing.

[0075] Furthermore, a first terminal of the second voltage sampling circuit 118 is grounded, a second terminal of the second voltage sampling circuit 118 is connected to the negative pole PV- of the photovoltaic assembly 202 , and an output terminal of the second voltage sampling circuit 118 is connected to the second input port 120 of the processing device 102 .

[0076] During the operation of the insulation resistance detection circuit 100, the second voltage sampling circuit 118 can sample the voltage across the lower bridge arm 108, that is, the second voltage sampling circuit 118 can sample the second voltage between the ground point PE and the negative pole PV- of the photovoltaic component 202, and transmit the sampling result to the processing device 102 through the second input port 120 for processing.

[0077] Furthermore, a first end of the third voltage sampling circuit 122 is connected to the positive pole PV+ of the photovoltaic component 202 , a second end of the third voltage sampling circuit 122 is connected to the negative pole PV- of the photovoltaic component 202 , and an output end of the third voltage sampling circuit 122 is connected to the third input port 124 of the processing device 102 .

[0078] During operation of the insulation resistance detection circuit 100 , the third voltage sampling circuit 122 may sample the third voltage between the positive electrode PV+ and the negative electrode PV− of the photovoltaic assembly 202 , and transmit the sampling result to the processing device 102 for processing via the third input port 124 .

[0079] Specifically, during operation of the insulation resistance detection circuit 100, the processing device 102 can receive the third voltage sampled by the third voltage sampling circuit 122 and control the switch in the switch resistance circuit 110 to open or close. Furthermore, the processing device 102 can receive the first voltage sampled by the first voltage sampling circuit 114 and the second voltage sampled by the second voltage sampling circuit 118 when the switch in the switch resistance circuit 110 is open, and receive the first voltage sampled by the first voltage sampling circuit 114 and the second voltage sampled by the second voltage sampling circuit 118 when the switch in the switch resistance circuit 110 is closed. Based on this, the processing device 102 can determine the magnitude relationship between the sampled first and second voltages and the third voltage based on the principle of resistor voltage division, and then solve the relationship before and after the switch disturbance to obtain two sets of insulation resistance data. Furthermore, the processing device 102 can compare the two sets of insulation resistance data to obtain one set of insulation resistance data. In this way, by providing two sets of bridge arm voltage sampling circuits and combining the sampling results of the two sampling circuits to determine the insulation resistance, the insulation resistance detection accuracy is improved.

[0080] The specific form of the comparison processing of the two sets of insulation resistance data can be selected by those skilled in the art according to actual conditions. For example, the above-mentioned comparison processing can be average processing, weighted processing, etc., which is not specifically limited here.

[0081] In some embodiments of the present invention, optionally, as Figure 2 As shown, the upper bridge arm 106 may include a first resistor 126 , or may include a plurality of first resistors 126 connected in series, which is not specifically limited herein.

[0082] In some embodiments of the present invention, optionally, as Figure 2 As shown, the lower bridge arm 108 may include a second resistor 128 , or may include a plurality of second resistors 128 connected in series, which is not specifically limited herein.

[0083] In some embodiments of the present invention, the total impedance of the upper bridge arm 106 is optionally equal to the total impedance of the lower bridge arm 108, and the sampling impedances of the first voltage sampling circuit 114 and the second voltage sampling circuit 118 are the same. This results in symmetrical static impedances, i.e., balanced static impedances, and avoids the voltage imbalance between the positive electrode PV+ and the negative electrode PV- of the photovoltaic module 202 relative to the ground point PE caused by the voltage sampling circuit.

[0084] It is understandable that existing insulation resistance detection solutions, such as Figure 4 As shown, when switch K1 is not operating, the impedance between PV+ and PE is smaller than the impedance between PV- and PE due to the presence of R1, ultimately leading to voltage imbalance between PV+ and PV- relative to PE, necessitating the addition of a balancing circuit. In the insulation resistance detection circuit 100 of the present invention, by limiting the total impedance of upper bridge arm 106 to equal the total impedance of lower bridge arm 108, and by ensuring that the sampling impedances of first voltage sampling circuit 114 and second voltage sampling circuit 118 are the same, static impedance balance is achieved, thus avoiding voltage imbalance between PV+ and PV- relative to PE.

[0085] In some embodiments of the present invention, optionally, as Figure 2 As shown, the switch resistor circuit 110 includes an electronically controlled switch 130 and a third resistor 132 .

[0086] The first end of the electronically controlled switch 130 is connected to the positive electrode PV+ of the photovoltaic assembly 202 , the second end of the electronically controlled switch 130 is connected to the first end of the third resistor 132 , and the second end of the third resistor 132 is grounded.

[0087] During operation of the insulation resistance detection circuit 100, the processing device 102 may receive the third voltage sampled by the third voltage sampling circuit 122 and control the electronically controlled switch 130 in the switch resistance circuit 110 to open or close. Furthermore, the processing device 102 may receive the first voltage sampled by the first voltage sampling circuit 114 and the second voltage sampled by the second voltage sampling circuit 118 when the electronically controlled switch 130 is open, and receive the first voltage sampled by the first voltage sampling circuit 114 and the second voltage sampled by the second voltage sampling circuit 118 when the electronically controlled switch 130 is closed.

[0088] On this basis, processing device 102 can calculate the insulation impedance of the two photovoltaic modules 202 using a set of simultaneous equations based on the sampled third voltage, the two sets of first voltages, and the second voltages, combined with the relationships between the internal components of insulation resistance detection circuit 100. This is the parallel value of the impedance of the positive pole PV+ of photovoltaic module 202 at the connection point PE and the impedance of the negative pole PV- of photovoltaic module 202 at the connection point PE. The final insulation impedance of photovoltaic module 202 is then obtained through comparison processing. In this way, by providing two sets of bridge arm voltage sampling circuits and combining the sampling results of the two sampling circuits before and after the switching disturbance to determine the insulation resistance, the insulation resistance detection accuracy is improved.

[0089] Specifically, the processing device 102 may determine the magnitude relationship between the two sets of sampled first and second voltages and the third voltage based on the insulation resistance R+ of the positive electrode PV+ of the photovoltaic module 202 relative to the ground point PE, the insulation resistance R- of the negative electrode PV- of the photovoltaic module 202 relative to the ground point PE, and the voltage division principle of the first resistor 126, the second resistor 128, and the third resistor 132:

[0090] When the electric control switch 130 is disconnected:

[0091]

[0092] When the electric switch 130 is closed:

[0093]

[0094] Among them, V iso+,x is the first voltage when the electronically controlled switch 130 is turned off, V iso-,x is the second voltage when the electronically controlled switch 130 is turned off, V pv is the third voltage, V iso+,y is the first voltage when the electronically controlled switch 130 is closed, V iso-,y is the second voltage when the electronically controlled switch 130 is closed, R1 is the resistance of the first resistor 126, R2 is the resistance of the second resistor 128, R3 is the resistance of the third resistor 132, and R + is the insulation resistance value of the positive electrode PV+ of the photovoltaic module 202 relative to the grounding point PE, R - is the insulation resistance value of the negative electrode PV- of the photovoltaic module 202 relative to the grounding point PE, R1 / / R + For R1 and R + The parallel resistance value, R2 / / R - For R2 and R - The parallel resistance value, R1 / / R + / / R3 is R1, R + and the parallel resistance value of R3.

[0095] Furthermore, the processing device 102 can respectively combine the relationship equations before and after the disturbance of the electronically controlled switch 130, that is, the relationship equations (1) and (3), (2) and (4), and solve them to obtain two sets of R + and R - Furthermore, the processing device 102 can process the two groups of R + and R - The values ​​of R are compared and processed to obtain a set of accurate R + and R - .

[0096] In actual application, Figure 3 As shown, the switch resistor circuit 110 can also be connected in parallel with the lower bridge arm 108. That is, the first end of the switch resistor circuit 110 is grounded, and the second end of the switch resistor circuit 110 is connected to the negative electrode PV- of the photovoltaic module 202. In this case, the detection principle of the insulation resistance is the same as the detection principle when the switch resistor circuit 110 is connected in parallel with the upper bridge arm 106, and will not be repeated here.

[0097] In some embodiments of the present invention, optionally, the above-mentioned electronically controlled switch 130 includes but is not limited to: a relay, a switch tube or an optocoupler. Those skilled in the art can select the specific type of the above-mentioned electronically controlled switch 130 according to actual conditions, and no specific limitation is made here.

[0098] In some embodiments of the present invention, optionally, the photovoltaic device 200 also includes a boost conversion circuit 204 and an inverter circuit 206, the output end of the boost conversion circuit 204 is connected to the DC side of the inverter circuit 206, and the voltage at the connection point between the boost conversion circuit 204 and the inverter circuit 206 is the DC bus voltage of the photovoltaic device 200.

[0099] Furthermore, if Figure 1 As shown, the processing device 102 further includes a third output port 134 , which is connected to both the boost conversion circuit 204 and the inverter circuit 206 .

[0100] Specifically, the insulation resistance detection circuit 100 is disposed between the inverter circuit 206 and the boost conversion circuit 204 of the photovoltaic device 200. During operation of the insulation resistance detection circuit 100, before the photovoltaic device 200 is connected to the grid, the processing device 102 can send a control signal to the boost conversion circuit 204 via the third output port 134 to control the boost conversion circuit 204 to boost the voltage. After the DC bus voltage of the photovoltaic device 200 is increased, the processing device 102 controls the electronically controlled switch 130 in the switch resistance circuit 110 to implement a disturbance, and performs subsequent processing to obtain the insulation resistance of the photovoltaic module 202.

[0101] In some embodiments of the present invention, optionally, as Figure 1As shown, the insulation resistance detection circuit 100 further includes an alarm device 136 , and the processing device 102 further includes a fourth output port 138 .

[0102] The alarm device 136 is connected to the fourth output port 138 of the processing device 102 .

[0103] During the operation of the insulation resistance detection circuit 100, when the detected insulation resistance is lower than the index requirement or the insulation resistance fails, the processing device 102 sends a control signal to the alarm device 136 through the fourth output port 138 to control the alarm device 136 to issue an alarm, thereby reminding the user that the photovoltaic equipment 200 has a safety hazard and cannot be connected to the grid.

[0104] In actual application, the alarm device 136 includes but is not limited to: a speaker, a buzzer, etc., and is not specifically limited here.

[0105] In some embodiments of the present invention, optionally, the processing device 102 includes but is not limited to: MPU (Micro Processor Unit), CPU (Central Processing Unit), MCU (Micro Control Unit) or SOC (System on a Chip), and no specific restrictions are made here.

[0106] In one embodiment of the present invention, a photovoltaic device is also provided. Figure 5 As shown, the photovoltaic device 200 provided by the present invention includes a photovoltaic component 202, a boost conversion circuit 204, an inverter circuit 206 and the insulation resistance detection circuit 100 in any of the above embodiments.

[0107] Among them, the input end of the boost conversion circuit 204 is connected to the photovoltaic component 202, the output end of the boost conversion circuit 204 is connected to the DC side of the inverter circuit 206, and the insulation resistance detection circuit 100 is connected to the photovoltaic component 202, the boost conversion circuit 204 and the inverter circuit 206.

[0108] The photovoltaic device 200 proposed in the present invention includes the insulation resistance detection circuit 100 in any of the above embodiments. Therefore, the photovoltaic device 200 proposed in the present invention has all the beneficial effects of the insulation resistance detection circuit 100 in any of the above embodiments, which will not be described in detail here.

[0109] In actual applications, photovoltaic device 200 may further include an inverter, which may be a three-phase inverter or a single-phase inverter. When the inverter is a string inverter, boost converter circuit 204 and inverter circuit 206 may both be disposed within the inverter, or boost converter circuit 204 may be disposed externally to the inverter, without specific limitation herein. Furthermore, the number of boost converter circuits 204 may also be determined based on the specific application environment, also without specific limitation herein.

[0110] In this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, unless otherwise expressly specified or limited. Terms such as "connect," "install," and "fix" should be interpreted broadly. For example, "connect" can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection or an indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this utility model based on specific circumstances.

[0111] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0112] In addition, the technical solutions of the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this utility model. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this utility model should be included in the scope of protection of this utility model.

Claims

1. An insulation resistance detection circuit, characterized in that: Applied to a photovoltaic device, the photovoltaic device includes a photovoltaic module, and the insulation resistance detection circuit includes: The processing device includes a first output port for outputting the insulation resistance test result; an upper bridge arm, wherein a first end of the upper bridge arm is connected to the positive electrode of the photovoltaic module, and a second end of the upper bridge arm is grounded; a lower bridge arm, wherein a first end of the lower bridge arm is grounded, and a second end of the lower bridge arm is connected to the negative electrode of the photovoltaic module; a switch resistor circuit, wherein a first end of the switch resistor circuit is connected to the positive electrode of the photovoltaic module, a second end of the switch resistor circuit is grounded, and a control end of the switch resistor circuit is connected to the second output port of the processing device; a first voltage sampling circuit, wherein a first terminal of the first voltage sampling circuit is connected to the positive electrode of the photovoltaic module, a second terminal of the first voltage sampling circuit is grounded, and an output terminal of the first voltage sampling circuit is connected to the first input port of the processing device; a second voltage sampling circuit, wherein a first terminal of the second voltage sampling circuit is grounded, a second terminal of the second voltage sampling circuit is connected to the negative electrode of the photovoltaic module, and an output terminal of the second voltage sampling circuit is connected to the second input port of the processing device; a third voltage sampling circuit, wherein a first end of the third voltage sampling circuit is connected to the positive electrode of the photovoltaic component, a second end of the third voltage sampling circuit is connected to the negative electrode of the photovoltaic component, and an output end of the third voltage sampling circuit is connected to the third input port of the processing device.

2. The insulation resistance detection circuit according to claim 1, wherein: The upper bridge arm includes one or more first resistors.

3. The insulation resistance detection circuit according to claim 1, wherein: The lower bridge arm includes one or more second resistors.

4. The insulation resistance detection circuit according to claim 1, wherein: The total impedance of the upper bridge arm is equal to the total impedance of the lower bridge arm.

5. The insulation resistance detection circuit according to claim 1, wherein: The switch resistor circuit comprises: an electrically controlled switch, wherein a first end of the electrically controlled switch is connected to the positive electrode of the photovoltaic module; a third resistor, wherein a first end of the third resistor is connected to the second end of the electronically controlled switch, and a second end of the third resistor is grounded.

6. The insulation resistance detection circuit according to claim 5, characterized in that: The electronically controlled switch includes a relay, a switching tube or an optical coupler.

7. The insulation resistance detection circuit according to claim 1, wherein: The photovoltaic device further includes a boost conversion circuit and an inverter circuit, and the processing device further includes: The third output port is connected to both the boost conversion circuit and the inverter circuit.

8. The insulation resistance detection circuit according to any one of claims 1 to 7, characterized in that: Also includes: An alarm device is connected to the fourth output port of the processing device.

9. The insulation resistance detection circuit according to any one of claims 1 to 7, characterized in that: The processing device includes a microprocessor, a central processing unit, a microcontroller or a system on a chip.

10. A photovoltaic device, characterized in that: include: Photovoltaic panels; A boost conversion circuit, wherein an input end of the boost conversion circuit is connected to the photovoltaic module; an inverter circuit, wherein a DC side of the inverter circuit is connected to an output end of the boost conversion circuit; The insulation resistance detection circuit according to any one of claims 1 to 9, connected to the photovoltaic module, the boost conversion circuit and the inverter circuit.

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