Insulation detection circuit and electrical equipment

Abstract

The invention provides an insulation detection circuit and electrical equipment. The insulation detection circuit is used for detecting positive electrode ground insulation resistance connected between a power supply positive electrode and a protection ground and negative electrode ground insulation resistance connected between the protection ground and a power supply negative electrode. The insulation detection circuit comprises a first resistance circuit which is connected between a power supply anode and a protection ground; the second resistance circuit is connected between the protection ground and the negative electrode of the power supply; the switch module is connected with the third resistance circuit in series and then is connected with the first resistance circuit in parallel to form a controllable parallel branch; the signal output end of the signal processing circuit is connected to the controlled end of the switch module, and the first isolation type current detection circuit is connected to the first input end of the signal processing circuit; and the second isolated current detection circuit is connected to the second input end of the signal processing circuit. According to the technical scheme, the symmetrical insulation fault can be effectively detected, the circuit structure is simplified, and the detection cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of insulation testing technology, and in particular to an insulation testing circuit and electrical equipment. Background Technology

[0002] In DC systems such as photovoltaic power generation and energy storage, the insulation performance between the DC bus and the protective earth (PE) is crucial. Degraded insulation performance can lead to system leakage and inefficiency, and may also cause electric shock and fire risks.

[0003] Existing insulation testing methods mainly include the following two types:

[0004] Option 1: Connect voltage divider resistors R1 and R2 with equal resistance between the positive terminal PV+ of the DC bus and the protective earth PE, and between the negative terminal PV- of the DC bus and the protective earth PE, respectively. Determine the insulation condition by measuring the voltage values ​​V1 and V2 at the midpoints of these two resistors relative to ground. Under ideal insulation conditions, the bridge is balanced, and voltage V1 equals V2. When an insulation fault to ground occurs at either PV+ or PV-, the bridge balance is disrupted, resulting in unequal voltage values ​​V1 and V2. The fault resistance value can be determined by calculating the voltage difference.

[0005] However, in this scheme, if the insulation resistance of PV+ and PV- to PE decreases by the same value at the same time, the bridge remains in a balanced state, and the voltage values ​​V1 and V2 remain unchanged. The detection system cannot identify the fault, which poses a serious safety hazard.

[0006] Option 2: To overcome the shortcomings of Option 1, Option 2 connects a positive resistor branch consisting of switch KM1 and resistor R3 in series across the voltage divider resistor R1, and a negative resistor branch consisting of switch KM2 and resistor R4 in series across the voltage divider resistor R2, forming an actively adjustable bridge arm resistance network. By controlling the opening and closing of KM1 and KM2, the network structure of the bridge arm resistance is actively changed, thus generating identifiable voltage changes even under symmetrical faults. By comparing the voltage values ​​V1 and V2 before and after the switch operation, the insulation resistance of the positive and negative terminals to ground can be calculated, thereby solving the problem of symmetrical fault detection.

[0007] However, this scheme not only requires setting up two switches KM1 and KM2, but also the voltage sampling points V1 and V2 are still on the high-voltage side. The signal transmission to the low-voltage processing unit still requires two isolated sampling circuits, which significantly increases the complexity and cost of the circuit. Summary of the Invention

[0008] This invention proposes an insulation detection circuit and electrical equipment that can effectively detect symmetrical insulation faults, simplify the circuit structure, and reduce detection costs.

[0009] To achieve the above objectives, the present invention provides an insulation detection circuit for detecting the positive-to-ground insulation resistance connected between the positive terminal of the power supply and the protective ground, and the negative-to-ground insulation resistance connected between the protective ground and the negative terminal of the power supply. The insulation detection circuit includes:

[0010] The first resistor circuit is connected between the positive terminal of the power supply and the protective ground.

[0011] The second resistor circuit is connected between the protective ground and the negative terminal of the power supply.

[0012] The switching module and the third resistor circuit are connected in series and then connected in parallel with the first resistor circuit to form a controllable parallel branch.

[0013] The signal processing circuit has a signal output terminal, a first input terminal, and a second input terminal. The signal output terminal is connected to the controlled terminal of the switching module to output a control signal to control the switching module to open and close.

[0014] A first isolated current detection circuit is connected to the first input terminal; it is configured to detect and output a first current flowing through the first resistor circuit when the switch module is open, and to detect and output a third current flowing through the controllable parallel branch when the switch module is closed.

[0015] A second isolated current detection circuit is connected to the second input terminal; it is configured to detect and output a second current flowing through the second resistor circuit when the switch module is open, and to detect and output a fourth current flowing through the second resistor circuit when the switch module is closed.

[0016] The signal processing circuit is configured to calculate the resistance value of the positive electrode insulation resistance to ground and the resistance value of the negative electrode insulation resistance to ground based on the first current, the second current, the third current, and the fourth current, combined with the resistance values ​​of the first resistor circuit, the second resistor circuit, and the third resistor circuit.

[0017] Furthermore, the first resistor circuit includes a first resistor;

[0018] The first resistor is connected between the positive terminal of the power supply and the protective ground.

[0019] Furthermore, the second resistor circuit includes a second resistor;

[0020] The second resistor is connected between the protective ground and the negative terminal of the power supply.

[0021] Furthermore, the third resistor circuit includes a third resistor;

[0022] The third resistor is connected in series with the switching module and then in parallel with the first resistor.

[0023] Furthermore, the switching module is a relay or a contactor.

[0024] Furthermore, the first isolated current detection circuit includes a first Hall current sensor, and the second isolated current detection circuit includes a second Hall current sensor.

[0025] Furthermore, the insulation detection circuit also includes a first alarm circuit and a second alarm circuit, which are respectively connected to the first output terminal and the second output terminal of the signal processing circuit.

[0026] The signal processing circuit is further configured to compare the resistance value of the positive electrode to ground insulation resistance with the positive electrode to ground insulation resistance threshold, and when the resistance value of the positive electrode to ground insulation resistance is less than the positive electrode to ground insulation resistance threshold, send a first alarm signal to the first alarm circuit to trigger the first alarm circuit to issue an alarm prompt.

[0027] The signal processing circuit is further configured to compare the resistance value of the negative electrode to ground insulation resistance with a negative electrode to ground insulation resistance threshold, and when the resistance value of the negative electrode to ground insulation resistance is less than the negative electrode to ground insulation resistance threshold, send a second alarm signal to the second alarm circuit to trigger the second alarm circuit to issue an alarm prompt.

[0028] Furthermore, the signal processing circuit is communicatively connected to a remote monitoring system;

[0029] The signal processing circuit is further configured to send the first alarm signal and the second alarm signal to the remote monitoring system.

[0030] To achieve the above objectives, the present invention also provides an electrical device comprising an insulation detection circuit as described in any of the preceding claims.

[0031] Furthermore, the electrical equipment is a photovoltaic inverter.

[0032] The technical solution of this invention uses a first resistor circuit, a second resistor circuit, a switch module, and a third resistor circuit to form a variable circuit topology. The signal processing circuit controls the switch module to open and close by outputting a control signal to change the circuit topology. At the same time, the first isolated current detection circuit collects the first current flowing through the first resistor circuit when the switch module is open and the third current flowing through the controllable parallel branch when the switch module is closed. The second isolated current detection circuit collects the second current flowing through the second resistor circuit when the switch module is open and the fourth current flowing through the second resistor circuit when the switch module is closed. Finally, based on these four current values ​​and combined with the known resistance values ​​of the first, second, and third resistor circuits, the signal processing circuit calculates the insulation resistance values ​​of the positive terminal to ground and the insulation resistance values ​​of the negative terminal to ground. Because the equivalent resistance of the controllable parallel branch can be actively changed by controlling the on / off state of the switch module, even if a symmetrical fault occurs where the positive-to-ground insulation resistance and the negative-to-ground insulation resistance decrease by the same value, the specific resistance values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance can be effectively calculated by the current difference under the two different topologies. At the same time, because the isolated current detection circuit is used for current sampling, its inherent electrical isolation characteristics allow the high-voltage side current signal to be safely read by the low-voltage side signal processing circuit without the need for additional signal isolation circuits, which simplifies the system structure and reduces hardware costs and design complexity. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a structural block diagram of an embodiment of the insulation detection circuit of the present invention;

[0035] Figure 2 This is a schematic diagram of the circuit structure of an embodiment of the insulation detection circuit of the present invention.

[0036] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] This invention employs a controllable parallel branch consisting of a switch module 30 and a third resistor circuit 40 connected in series, combined with an isolated current detection circuit. By switching the switch state, current values ​​under two topologies are obtained, thereby accurately detecting insulation resistance, including symmetrical faults, without the need for additional isolation circuitry. This solves the problem of existing technologies that detect insulation faults by sampling the voltage across a resistor, requiring additional isolation circuits and power supply circuits, resulting in complex circuit structures and high costs.

[0039] Example 1

[0040] Reference Figure 1 This invention provides an insulation detection circuit for detecting the positive-to-ground insulation resistance R+ connected between the positive terminal of the power supply and the protective ground, and the negative-to-ground insulation resistance R- connected between the protective ground and the negative terminal of the power supply. The insulation detection circuit includes:

[0041] The first resistor circuit 10 is connected between the positive terminal PV+ of the power supply and the protective ground PE;

[0042] The second resistor circuit 20 is connected between the protective ground PE and the negative power supply PV-.

[0043] The switch module 30 and the third resistor circuit 40 are connected in series and then connected in parallel with the first resistor circuit 10 to form a controllable parallel branch.

[0044] The signal processing circuit 50 has a signal output terminal, a first input terminal and a second input terminal. Its signal output terminal is connected to the controlled terminal of the switch module 30 to output a control signal to control the switch module 30 to open and close.

[0045] The first isolated current detection circuit 60 is connected to the first input terminal of the signal processing circuit 50; it is configured to detect and output the first current I1 flowing through the first resistor circuit 10 when the switch module 30 is open, and to detect and output the third current I3 flowing through the controllable parallel branch (i.e. the total current of the first resistor circuit 10 and the third resistor circuit 40 in parallel) when the switch module 30 is closed.

[0046] The second isolated current detection circuit 70 is connected to the second input terminal of the signal processing circuit 50; it is configured to detect and output the second current I2 flowing through the second resistor circuit 20 when the switch module 30 is open, and to detect and output the fourth current I4 flowing through the second resistor circuit 20 when the switch module 30 is closed.

[0047] The signal processing circuit 50 is configured to calculate the resistance value of the positive electrode to ground insulation resistance R+ and the resistance value of the negative electrode to ground insulation resistance R- based on the first current I1, the second current I2, the third current I3 and the fourth current I4, combined with the resistance value of the first resistor circuit 10, the resistance value of the second resistor circuit 20 and the resistance value of the third resistor circuit 40.

[0048] In this embodiment, the first resistor circuit 10, the second resistor circuit 20, and the third resistor circuit 40 can all be composed of a single resistor, or multiple resistors connected in series, parallel, or mixed to obtain the required resistance value, and the resistance value of the first resistor circuit 10, the second resistor circuit 20, or the third resistor circuit 40 is known.

[0049] In this embodiment, the switch module 30 is a controllable switch device, such as a contactor or relay, whose control coil is electrically isolated from the main contacts.

[0050] In this embodiment, the signal processing circuit 50 may be a microcontroller, a digital signal processor, or a microprocessor. The signal processing circuit 50 is used to control the opening and closing of the switch module 30, and to calculate the insulation resistance of the positive and negative poles to ground based on the resistance values ​​of each resistor circuit and the current detected by the first isolated current detection circuit 60 and the second isolated current detection circuit 70.

[0051] The first isolated current detection circuit 60 and the second isolated current detection circuit 70 can be composed of a Hall current sensor and a current transformer, or they can be composed of a sampling resistor and an isolation circuit.

[0052] In one specific embodiment, the first isolated current detection circuit 60 employs a first Hall current sensor, and the second isolated current detection circuit 70 employs a second Hall current sensor. During assembly, the magnetic core of the Hall current sensor, such as a toroidal core, is fitted around the conductors carrying the operating current in the first resistor circuit 10 and the second resistor circuit 20. This fitting structure enables physical isolation between the Hall current sensor and the measured resistor circuit at the electrical level: the Hall current sensor, based on the principle of electromagnetic induction, generates current by sensing the magnetic field strength generated by the current around the conductor, without needing to form a direct electrical connection with the measured conductor. This hardware structure blocks the conductive path between the high and low voltage sides, meeting the requirements of electrical isolation, and simultaneously avoiding the risk of common-mode interference introduced during the sampling process.

[0053] The working principle of this embodiment is as follows:

[0054] When the switch module 30 is in the off state, the third resistor circuit 40 is not connected to the circuit. At this time, the current flowing through the first resistor circuit 10 is detected by the first isolated current detection circuit 60 and recorded as the first current I1; the current flowing through the second resistor circuit 20 is detected by the second isolated current detection circuit 70 and recorded as the second current I2.

[0055] When the switch module 30 is in the closed state, the third resistor circuit 40 is connected to the circuit and forms a controllable parallel branch with the first resistor circuit 10. At this time, the total current flowing through the parallel first resistor circuit 10 and the third resistor circuit 40 is detected by the first isolated current detection circuit 60 and recorded as the third current I3; the current flowing through the second resistor circuit 20 is detected by the second isolated current detection circuit 70 and recorded as the fourth current I4.

[0056] The signal processing circuit 50, based on the first current I1, the second current I2, the third current I3, and the fourth current I4, and combined with the known resistance values ​​of the first resistor circuit 10, the second resistor circuit 20, and the third resistor circuit 40, calculates the resistance value of the positive electrode insulation resistance R+ and the negative electrode insulation resistance R- by solving a set of equations established based on circuit principles.

[0057] For ease of understanding, let the total resistance of the first resistor circuit 10 be R1, the total resistance of the second resistor circuit 20 be R2, and the total resistance of the third resistor circuit 40 be R3. Then, the calculation process for the insulation resistance R+ of the positive terminal to ground and the insulation resistance R- of the negative terminal to ground is as follows:

[0058] When the switch module 30 is in the off state, the third resistor circuit 40 is not connected to the circuit. At this time, the first isolated current detection circuit 60 detects the first current I1 flowing through the first resistor circuit 10; the second isolated current detection circuit 70 detects the third current I2 flowing through the second resistor circuit 20. In this case, the following relationship exists between each current and each resistor:

[0059] Since the first current I1, the second current I2, the resistance R1 of the first resistor circuit 10, and the resistance R2 of the second resistor circuit 20 are known quantities, we set... Since R1 = R2 = R, then Formula 1 can be simplified to...

[0060] When the switch module 30 is in the closed state, the third resistor circuit 40 is connected to the circuit in parallel with the first resistor circuit 10. At this time, the first isolated current detection circuit 60 detects the third current I3 flowing through the parallel first resistor circuit 10 and the third resistor circuit 40, which is also the total current of the controllable parallel branch; the second isolated current detection circuit 70 detects the fourth current I4 flowing through the second resistor circuit 20. In this case, the following relationship exists between each current and each resistor:

[0061] Since the third current I3, the fourth current I4, the resistance R1 of the first resistor circuit 10, the resistance R2 of the second resistor circuit 20, and the resistance R3 of the third resistor circuit 40 are known quantities, if the total resistance of the parallel first resistor circuit 10 and the third resistor circuit 40 is R... 13 ,That set up Since R1 = R2 = R, then formula 3 can be simplified to:

[0062] Combining Equations 2 and 4 above yields a system of two equations concerning the insulation resistance between the positive and negative poles. Then, using elimination, the resistance values ​​of the positive and negative poles to ground can be calculated as follows:

[0063]

[0064] This invention employs a controllable parallel branch consisting of a single switch module 30 connected in series with a third resistor circuit 40, combined with an isolated current detection circuit. By switching the switch state, the current values ​​under two topologies are obtained, thereby accurately detecting insulation resistance, including symmetrical faults, without the need for additional isolation circuits. This simplifies the circuit structure and reduces circuit costs.

[0065] In an alternative embodiment, refer to Figure 2 As shown, the components of this insulation detection circuit can be implemented using mature and reliable devices. Specifically:

[0066] The first resistor circuit 10 includes a single first resistor R1; and the first resistor R1 is connected between the positive power supply PV+ and the protective ground PE.

[0067] The second resistor circuit 20 includes a single second resistor R2; and the second resistor R2 is connected between the protective ground PE and the negative power supply PV-.

[0068] The third resistor circuit 40 includes a single third resistor R3; the switch module 30 uses a relay KM1, and the third resistor R3 is connected in series with the relay KM1 between the positive power supply PV+ and the protective ground PE.

[0069] The first resistor circuit 10, the second resistor circuit 20, and the third resistor circuit 40 are all constructed using single resistors, which simplifies the circuit topology, improves the stability of the resistance parameters, and provides a more accurate basis of known parameters for subsequent current sampling and insulation resistance calculation. The inherent isolation characteristics of the coil-main contact of relay KM1 further strengthen the electrical safety boundary between the control circuit and the main circuit, preventing control signals from interfering with the main circuit sampling. At the same time, the on / off response speed of the relay matches the sampling period of the insulation detection, ensuring the timeliness and reliability of circuit topology switching.

[0070] Both the first isolated current detection circuit 60 and the second isolated current detection circuit 70 use Hall current sensors, namely the first Hall current sensor and the second Hall current sensor, respectively.

[0071] Hall current sensors can accurately capture current changes under different insulation conditions. Their non-contact sampling method based on magnetic field induction can achieve complete electrical isolation from the high-voltage side circuit under test. They can meet the safety requirements of high and low voltage without the need for additional isolation circuits. At the same time, they can effectively avoid the influence of DC side common-mode interference on the sampling signal, ensuring the accuracy of current data and providing reliable input for accurate calculation of insulation resistance.

[0072] Example 2

[0073] In this embodiment, the insulation detection circuit further includes a first alarm circuit and a second alarm circuit (not shown), which are respectively connected to the first output terminal and the second output terminal of the signal processing circuit 50.

[0074] The signal processing circuit 50 is also used to compare the resistance value of the positive electrode to ground insulation resistance R+ with a preset positive electrode to ground insulation resistance threshold. When the resistance value of the positive electrode to ground insulation resistance R+ is less than the positive electrode to ground insulation resistance threshold, a first alarm signal is sent to the first alarm circuit to trigger the first alarm circuit to issue an alarm prompt.

[0075] The signal processing circuit 50 is also used to compare the resistance value of the negative electrode to ground insulation resistance R- with a preset negative electrode to ground insulation resistance threshold. When the resistance value of the negative electrode to ground insulation resistance R- is less than the negative electrode to ground insulation resistance threshold, a second alarm signal is sent to the second alarm circuit to trigger the second alarm circuit to issue an alarm prompt.

[0076] Its alarm logic and workflow are as follows:

[0077] Positive Insulation Fault Alarm: After calculating the resistance value of the positive electrode to ground insulation resistance R+, the signal processing circuit 50 compares it with an internally preset safety threshold, namely the positive electrode to ground insulation resistance threshold. When it is determined that the resistance value of the positive electrode to ground insulation resistance R+ is less than this threshold, it indicates that the insulation performance of the positive power supply PV+ to the protective ground PE has decreased to a dangerous level. Immediately, the signal processing circuit 50 sends a first alarm signal to the first alarm circuit through its first output terminal. Upon receiving the signal, the first alarm circuit is triggered and begins to operate, issuing an alarm prompt in a perceptible form such as sound and light, indicating a positive electrode insulation fault.

[0078] Negative Insulation Fault Alarm: Similarly, the signal processing circuit 50 will compare the calculated negative-to-ground insulation resistance R- with the negative-to-ground insulation resistance threshold. When the negative-to-ground insulation resistance R- is less than the negative-to-ground insulation resistance threshold, it indicates that the insulation performance of the protective ground to the negative power supply PV- has deteriorated to a dangerous level. At this time, the signal processing circuit 50 sends a second alarm signal to the second alarm circuit through its second output terminal, triggering it to issue an alarm message that is different from the positive insulation fault alarm.

[0079] This embodiment, by setting up a first alarm circuit and a second alarm circuit, enables potential insulation faults to be detected and handled early, effectively preventing accidents from occurring. The positive-to-ground insulation resistance threshold and the negative-to-ground insulation resistance threshold can be set to be equal, or different thresholds can be set according to the different safety design requirements of the positive and negative poles, thus providing a flexible and precise protection strategy.

[0080] Example 3

[0081] In this embodiment, the signal processing circuit 50 is also communicatively connected to a remote monitoring system;

[0082] The signal processing circuit 50 is also used to send the first alarm signal and the second alarm signal to the remote monitoring system.

[0083] In this embodiment, the signal processing circuit 50 establishes a stable communication connection with a remote monitoring system through its built-in or external communication interface, such as RS485, Ethernet, wireless communication module, etc.

[0084] When the first or second alarm signal is triggered, the signal processing circuit 50 also uploads and sends an alarm data packet containing key information such as the alarm type (positive or negative insulation fault), the resistance values ​​of the positive and negative poles to ground insulation resistance, and a timestamp, in real time to the remote monitoring system via the communication connection. This ensures that the remote monitoring system, such as a power plant centralized monitoring platform, a cloud server, or a mobile terminal of maintenance personnel, can respond promptly upon receiving these alarm signals.

[0085] The present invention also provides an electrical device including the insulation detection circuit described above. The detailed structure of the insulation detection circuit can be found in the above embodiments and will not be repeated here. It is understood that, since the above-described insulation detection circuit is used in the electrical device of the present invention, the embodiments of the electrical device of the present invention include all the technical solutions of all embodiments of the above-described insulation detection circuit, and the achieved technical effects are completely the same, and will not be repeated here.

[0086] In one alternative embodiment, the electrical device is a photovoltaic inverter.

[0087] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An insulation detection circuit for detecting the insulation resistance to ground of the positive terminal connected between the positive terminal of the power supply and the protective ground, and the insulation resistance to ground of the negative terminal connected between the protective ground and the negative terminal of the power supply, characterized in that, The insulation detection circuit includes: The first resistor circuit is connected between the positive terminal of the power supply and the protective ground. The second resistor circuit is connected between the protective ground and the negative terminal of the power supply. The switching module and the third resistor circuit are connected in series and then connected in parallel with the first resistor circuit to form a controllable parallel branch. The signal processing circuit has a signal output terminal, a first input terminal, and a second input terminal. The signal output terminal is connected to the controlled terminal of the switching module to output a control signal to control the switching module to open and close. A first isolated current detection circuit is connected to the first input terminal; it is configured to detect and output a first current flowing through the first resistor circuit when the switch module is open, and to detect and output a third current flowing through the controllable parallel branch when the switch module is closed. A second isolated current detection circuit, connected to the second input terminal, is configured to detect and output a second current flowing through the second resistor circuit when the switch module is open, and to detect and output a fourth current flowing through the second resistor circuit when the switch module is closed. The signal processing circuit is configured to calculate the resistance value of the positive electrode insulation resistance to ground and the resistance value of the negative electrode insulation resistance to ground based on the first current, the second current, the third current and the fourth current, and in combination with the resistance values ​​of the first resistor circuit, the second resistor circuit and the third resistor circuit.

2. The insulation detection circuit as described in claim 1, characterized in that, The first resistor circuit includes a first resistor; The first resistor is connected between the positive terminal of the power supply and the protective ground.

3. The insulation detection circuit as described in claim 2, characterized in that, The second resistor circuit includes a second resistor; The second resistor is connected between the protective ground and the negative terminal of the power supply.

4. The insulation detection circuit as described in claim 3, characterized in that, The third resistor circuit includes a third resistor; The third resistor is connected in series with the switching module and then in parallel with the first resistor.

5. The insulation detection circuit as described in claim 4, characterized in that, The switching module is a relay or a contactor.

6. The insulation detection circuit as described in claim 1, characterized in that, The first isolated current detection circuit includes a first Hall current sensor, and the second isolated current detection circuit includes a second Hall current sensor.

7. The insulation detection circuit as described in claim 1, characterized in that, The insulation detection circuit further includes a first alarm circuit and a second alarm circuit, which are respectively connected to the first output terminal and the second output terminal of the signal processing circuit. The signal processing circuit is further configured to compare the resistance value of the positive electrode to ground insulation resistance with the positive electrode to ground insulation resistance threshold, and when the resistance value of the positive electrode to ground insulation resistance is less than the positive electrode to ground insulation resistance threshold, send a first alarm signal to the first alarm circuit to trigger the first alarm circuit to issue an alarm prompt. The signal processing circuit is further configured to compare the resistance value of the negative electrode to ground insulation resistance with a negative electrode to ground insulation resistance threshold, and when the resistance value of the negative electrode to ground insulation resistance is less than the negative electrode to ground insulation resistance threshold, send a second alarm signal to the second alarm circuit to trigger the second alarm circuit to issue an alarm prompt.

8. The insulation detection circuit as described in claim 7, characterized in that, The signal processing circuit is communicatively connected to a remote monitoring system. The signal processing circuit is further configured to send the first alarm signal and the second alarm signal to the remote monitoring system.

9. An electrical device, characterized in that, The electrical equipment includes an insulation detection circuit as described in any one of claims 1 to 8.

10. The electrical equipment as claimed in claim 9, characterized in that, The electrical equipment is a photovoltaic inverter.

Images