Insulation detection circuit and circuit breaker system

Abstract

The invention provides an insulation detection circuit and a circuit breaker system. The insulation detection circuit comprises an AC power supply, a voltage division module, a detection loop, a one-way conduction module, an equivalent insulation loop and a controller. The first end of the alternating current power supply is electrically connected with the first end of the one-way conduction module and the first end of the detection loop through the voltage division module, the second end of the one-way conduction module is electrically connected with the first end of the equivalent insulation loop, and the second end of the detection loop and the second end of the equivalent insulation loop are electrically connected with the second end of the alternating current power supply. The controller is electrically connected with the detection loop; the one-way conduction module is used for controlling current one-way flow between the equivalent insulation loop and the voltage division module; and the controller is used for acquiring target voltage distributed by the detection loop, determining target impedance of the equivalent insulation loop according to the target voltage, and determining an insulation fault state of the equivalent insulation loop according to the target impedance. Automatic insulation detection is realized, the detection efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical protection, and in particular to an insulation detection circuit and a circuit breaker system. Background Art

[0002] The power supply end of the AC load is electrically connected to the AC power supply and is used to work normally according to the output of the AC power supply. For electrical safety, insulation treatment is usually performed between the power supply end of the AC load and the position that the operator can easily touch, such as filling with insulating materials. However, in actual use, the insulation performance of the insulated area will deteriorate due to many reasons. If the line between the AC power supply and the power supply end of the AC load is in a connected state during this process, the position that the operator can easily touch will be electrified, posing a safety hazard.

[0003] In order to solve the above problems, the prior art usually tests the insulation performance of the insulation treated area before the line between the AC power source and the power supply end of the AC load is connected. However, the existing testing scheme usually adopts a manual testing method, which has low testing efficiency and high cost. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an insulation detection circuit and a circuit breaker system.

[0005] In a first aspect, in one embodiment, the present invention provides an insulation detection circuit, the insulation detection circuit comprising an AC power supply, a voltage dividing module, a detection circuit, a unidirectional conduction module and a controller;

[0006] The first end of the AC power supply is electrically connected to the first end of the unidirectional conduction module and the first end of the detection circuit respectively through the voltage divider module, the second end of the unidirectional conduction module is used to be electrically connected to the first end of the equivalent insulation circuit, the second end of the detection circuit is electrically connected to the second end of the AC power supply, the second end of the AC power supply is also used to be electrically connected to the second end of the equivalent insulation circuit, and the controller is electrically connected to the detection circuit;

[0007] The unidirectional conduction module is used to control the unidirectional flow of current between the equivalent insulation circuit and the voltage divider module;

[0008] The controller is used to obtain the target voltage distributed by the detection circuit, determine the target impedance of the equivalent insulation circuit according to the target voltage, and determine the insulation fault state of the equivalent insulation circuit according to the target impedance.

[0009] In one embodiment, the unidirectional conduction module includes a diode unit;

[0010] The cathode of the diode unit is electrically connected to the second end of the voltage divider module, and the anode of the diode unit is used to be electrically connected to the equivalent insulating loop; or, the anode of the diode unit is electrically connected to the second end of the voltage divider module, and the cathode of the diode unit is used to be electrically connected to the equivalent insulating loop.

[0011] In one embodiment, the equivalent insulation circuit includes a first insulator circuit and a second insulator circuit, and the diode unit includes a first diode and a second diode;

[0012] The cathode of the first diode is electrically connected to the second end of the voltage divider module, and the anode of the first diode is electrically connected to the first end of the first insulator loop; or, the anode of the first diode is electrically connected to the second end of the voltage divider module, and the cathode of the first diode is electrically connected to the first end of the first insulator loop;

[0013] The cathode of the second diode is electrically connected to the second end of the voltage divider module, and the anode of the second diode is electrically connected to the first end of the second insulator loop; or, the anode of the second diode is electrically connected to the second end of the voltage divider module, and the cathode of the first diode is electrically connected to the first end of the first insulator loop;

[0014] The second end of the AC power source is used to be electrically connected to the second end of the first insulator loop and the second end of the second insulator loop respectively.

[0015] In one embodiment, the detection circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor;

[0016] The first end of the first voltage-dividing resistor is electrically connected to the second end of the voltage-dividing module, the second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor and the controller respectively, and the second end of the second voltage-dividing resistor is electrically connected to the second end of the AC power supply.

[0017] In one embodiment, the detection circuit further includes a first TVS tube and a second TVS tube;

[0018] The anode of the first TVS tube is electrically connected to the first end of the first voltage-dividing resistor and the second end of the voltage-dividing module respectively, the cathode of the first TVS tube is electrically connected to the cathode of the second TVS tube, and the anode of the second TVS tube is electrically connected to the second end of the AC power supply.

[0019] In one embodiment, the detection circuit further includes a third diode and a fourth diode;

[0020] The cathode of the third diode is electrically connected to the second end of the first voltage-dividing resistor and the anode of the fourth diode respectively, the anode of the third diode is electrically connected to the second end of the AC power supply, and the cathode of the fourth diode is electrically connected to the first end of the second voltage-dividing resistor and the controller respectively.

[0021] In one embodiment, the detection circuit further includes a first capacitor and a second capacitor;

[0022] The first end of the first capacitor is electrically connected to the second end of the first voltage-dividing resistor, and the second end of the first capacitor is electrically connected to the cathode of the third diode and the anode of the fourth diode respectively;

[0023] The first end of the second capacitor is electrically connected to the cathode of the fourth diode, the first end of the second voltage-dividing resistor and the controller respectively, and the second end of the second capacitor is electrically connected to the second end of the second voltage-dividing resistor and the second end of the AC power supply respectively.

[0024] In one embodiment, the detection circuit further includes a triode;

[0025] The base of the transistor is electrically connected to the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor respectively, the collector of the transistor is used to access the working voltage and is electrically connected to the controller, and the emitter of the transistor is electrically connected to the second end of the AC power supply;

[0026] The controller is also used to determine the working state of the AC power supply according to the collector voltage of the transistor.

[0027] In one embodiment, the voltage dividing module includes a thermistor and a third voltage dividing resistor;

[0028] The first end of the thermistor is electrically connected to the first end of the AC power supply, the second end of the thermistor is electrically connected to the first end of the third voltage-dividing resistor, and the second end of the third voltage-dividing resistor is electrically connected to the first end of the unidirectional conduction module and the first end of the detection circuit respectively.

[0029] In one embodiment, the insulation detection circuit further includes a switch module;

[0030] The first access end of the switch module is electrically connected to the second end of the voltage dividing module and the first end of the detection loop respectively, the second access end of the switch module is electrically connected to the first end of the unidirectional conduction module, and the controlled end of the switch module is electrically connected to the controller;

[0031] The controller is used to control the switch module to be in the on state when entering the insulation detection process.

[0032] In one embodiment, the insulation detection circuit further comprises a three-phase transformer, the three-phase transformer comprising a three-phase output winding;

[0033] The output end of at least one phase of the three-phase output winding serves as a first end of the AC power source, and the center point of the three-phase output winding serves as a second end of the AC power source.

[0034] In a second aspect, in one embodiment, the present invention provides a circuit breaker system, comprising a circuit breaker and the insulation detection circuit in any one of the above embodiments;

[0035] The first end of the AC power supply is electrically connected to the first end of the voltage dividing module and the first access end of the circuit breaker respectively, the second access end of the circuit breaker is electrically connected to the second end of the unidirectional conduction module and is used to be electrically connected to the first end of the equivalent insulation circuit, and the controlled end of the circuit breaker is electrically connected to the controller;

[0036] The controller is used to control the reclosing of the circuit breaker according to the insulation fault state of the equivalent insulation circuit after the circuit breaker is opened.

[0037] In one embodiment, the insulation detection circuit further includes a micro switch;

[0038] The first access end of the micro switch is electrically connected to the second end of the voltage dividing module and the first end of the detection circuit respectively, and the second access end of the micro switch is electrically connected to the first end of the unidirectional conduction module;

[0039] The micro switch is used to close due to the corresponding mechanical operation when the circuit breaker is switched to the automatic closing state.

[0040] Through the above-mentioned insulation detection circuit and circuit breaker system, a detection circuit is set in parallel with the equivalent insulation circuit. Due to the existence of the voltage divider module, the impedance of the equivalent insulation circuit will affect the voltage division of the detection circuit, so that the controller can determine the target impedance of the equivalent insulation circuit according to the target voltage obtained by the detection circuit, and thus determine the insulation fault state of the equivalent insulation circuit according to the target impedance, thereby realizing automated insulation detection, improving detection efficiency and reducing costs; in addition, the set unidirectional conduction module can make the impedance of the equivalent insulation circuit affect the voltage division of the detection circuit only on a certain half axis of the AC power supply, so that the target voltage obtained by the controller can be kept within a relatively small range, reducing the range requirements of the controller and ensuring the reliability of voltage acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments 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 these drawings without creative work.

[0042] Figure 1 A schematic diagram of the structure of an insulation detection circuit in one embodiment of the present invention;

[0043] Figure 2 It is an equivalent schematic diagram of an insulation detection circuit in a three-phase alternating current scenario in one embodiment of the present invention;

[0044] Figure 3The following is a schematic diagram of a specific circuit implementation of an insulation detection circuit in a three-phase alternating current scenario in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In the present application, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in the present application is not necessarily interpreted as being more preferred or more advantageous than other embodiments. In order to enable any person skilled in the art to implement and use the present invention, the following description is given. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid unnecessary details that make the description of the present invention obscure. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in the present application.

[0047] First, as Figure 1 As shown, in one embodiment, the present invention provides an insulation detection circuit, which includes an AC power supply, a voltage divider module, a detection loop, a unidirectional conduction module and a controller.

[0048] The first end of the AC power supply is electrically connected to the first end of the unidirectional conduction module and the first end of the detection circuit respectively through the voltage divider module, the second end of the unidirectional conduction module is used to be electrically connected to the first end of the equivalent insulation circuit, the second end of the detection circuit is electrically connected to the second end of the AC power supply, the second end of the AC power supply is also used to be electrically connected to the second end of the equivalent insulation circuit, and the controller is electrically connected to the detection circuit.

[0049] Among them, the voltage divider module can be composed of several resistors and / or inductors connected in series, and the end of the resistor or inductor at the head end away from the other resistors and / or inductors serves as the first end of the voltage divider module, and the end of the resistor or inductor at the tail end away from the other resistors and / or inductors serves as the second end of the voltage divider module.

[0050] The unidirectional conduction module can be composed of a controlled switch device, which can be turned on only in the positive half axis or the negative half axis of the AC power supply under the control of the controller, so that when the AC power supply acts on the switch device, there is only a single direction of current. Since the unidirectional conduction module is electrically connected to the voltage divider module and the equivalent insulation circuit respectively, it can control the unidirectional flow of current between the equivalent insulation circuit and the voltage divider module.

[0051] Among them, the unidirectional conduction module and the equivalent insulation circuit are connected in series and then connected in parallel with the detection circuit. The current output by the AC power supply is divided after passing through the voltage divider module. One part returns to the AC power supply after passing through the unidirectional conduction module and the equivalent insulation circuit, and the other part returns to the AC power supply after passing through the detection circuit.

[0052] The controller is used to obtain the target voltage distributed by the detection circuit, determine the target impedance of the equivalent insulation circuit according to the target voltage, and determine the insulation fault state of the equivalent insulation circuit according to the target impedance.

[0053] Among them, when the insulation performance of the equivalent insulation circuit changes, the impedance of the equivalent insulation circuit will also change, which will affect the overall impedance of the equivalent insulation circuit and the detection circuit after parallel connection. Since the impedance of the voltage divider module remains unchanged, the voltage divider on the detection circuit will also change, so that the controller can realize insulation detection of the equivalent insulation circuit based on this change law.

[0054] Specifically, when the insulation performance of the equivalent insulation circuit deteriorates, the impedance of the equivalent insulation circuit decreases, the overall impedance of the equivalent insulation circuit and the detection circuit in parallel decreases, the voltage division on the detection circuit decreases, and the target voltage that the controller can obtain decreases, so that the controller can determine that the target impedance of the current equivalent insulation circuit decreases, and then determine that the insulation performance of the current equivalent insulation circuit deteriorates. Similarly, when the insulation performance of the equivalent insulation circuit improves, the impedance of the equivalent insulation circuit increases, the overall impedance of the equivalent insulation circuit and the detection circuit in parallel increases, the voltage division on the detection circuit increases, and the target voltage that the controller can obtain increases, so that the controller can determine that the target impedance of the current equivalent insulation circuit increases, and then determine that the insulation performance of the current equivalent insulation circuit improves.

[0055] Based on the above analysis, after obtaining the target voltage obtained by the detection circuit, the controller can determine the target impedance of the equivalent insulation circuit, thereby determining the insulation fault state of the equivalent insulation circuit. In this embodiment, the insulation fault state may include two situations: the presence of an insulation fault and the absence of an insulation fault; when the target impedance is too low, the insulation fault state is determined to be the presence of an insulation fault; when the target impedance is too high, the insulation fault state is determined to be the absence of an insulation fault.

[0056] Through the above-mentioned insulation detection circuit, a detection circuit is set in parallel with the equivalent insulation circuit. Due to the existence of the voltage divider module, the impedance of the equivalent insulation circuit will affect the voltage division of the detection circuit, so that the controller can determine the target impedance of the equivalent insulation circuit according to the target voltage obtained by the detection circuit, and thus determine the insulation fault state of the equivalent insulation circuit according to the target impedance, thereby realizing automated insulation detection, improving detection efficiency and reducing costs; in addition, the set unidirectional conduction module can make the impedance of the equivalent insulation circuit affect the voltage division of the detection circuit only on a certain half axis of the AC power supply, so that the target voltage obtained by the controller can be kept within a relatively small range, reducing the range requirements of the controller and ensuring the reliability of voltage acquisition.

[0057] In one embodiment, the unidirectional conduction module includes a diode unit;

[0058] The cathode of the diode unit is electrically connected to the second end of the voltage divider module, and the anode of the diode unit is used to be electrically connected to the equivalent insulating loop; or, the anode of the diode unit is electrically connected to the second end of the voltage divider module, and the cathode of the diode unit is used to be electrically connected to the equivalent insulating loop.

[0059] Among them, the above embodiments have mentioned that a controlled switch device can be used to achieve unidirectional conduction, but a controller is required for control, and the waveform output by the AC power supply in real time needs to be referred to, and the control logic is relatively complex. In this embodiment, a diode can be directly used to utilize the unidirectional conduction characteristics of the diode without any additional control.

[0060] Among them, the diode unit can be composed of several diodes connected in series and / or in parallel. When the diode unit is composed of multiple diodes, the cathode of one of the diodes needs to be electrically connected to the anode of the adjacent diode. Similarly, the anode of one of the diodes needs to be electrically connected to the cathode of the adjacent diode, so as to ensure that the diode unit as a whole can achieve single-phase conduction of current.

[0061] Among them, when the cathode of the diode unit is electrically connected to the voltage divider module and the anode of the diode unit is used to be electrically connected to the equivalent insulating circuit, only negative half-axis current may exist between the voltage divider module and the equivalent insulating circuit; similarly, when the anode of the diode is electrically connected to the voltage divider module and the cathode of the diode unit is used to be electrically connected to the equivalent insulating circuit, only positive half-axis current may exist between the voltage divider module and the equivalent insulating circuit.

[0062] like Figure 2 As shown, in one embodiment, the insulation detection circuit further includes a three-phase transformer T, the three-phase transformer T includes a three-phase output winding (in Figure 2 The output end L1 of the single-phase output winding is used as the first end of the AC power supply, and the center point N of the three-phase output winding is used as the second end of the AC power supply; the equivalent impedance corresponding to the voltage divider module is the resistor R1, the equivalent impedance corresponding to the detection circuit is the resistor R2, and the equivalent insulation circuit includes a first insulator circuit (in Figure 2 The corresponding equivalent impedance is resistance R3) and the second insulator circuit (in Figure 2 The corresponding equivalent impedance is resistor R4), and the diode unit includes a first diode D4 and a second diode D5.

[0063] In this embodiment, the three-phase transformer T1 is used to convert the connected 10KV AC power supply into a single-phase AC230V AC power supply.

[0064] Among them, the output end L1 of the single-phase output winding is electrically connected to the first end of the resistor R1, the cathode of the first diode D4 is electrically connected to the second end of the resistor R1 and the first end of the resistor R2, respectively, the anode of the first diode D4 is electrically connected to the first end of the resistor R3 through the detection end TEST-1, the cathode of the second diode D5 is electrically connected to the second end of the resistor R1 and the first end of the resistor R2, respectively, the anode of the second diode D5 is electrically connected to the first end of the resistor R4 through the detection ground end TEST-2, and the second end of the resistor R3 and the second end of the resistor R4 are electrically connected to the center point N of the three-phase output winding through the protective grounding wire PE, respectively.

[0065] Based on the connection mode of the first diode D4 and the second diode D5, the resistor R3 corresponding to the first insulator circuit and the resistor R4 corresponding to the second insulator circuit are effective only in the negative half axis of the AC power supply.

[0066] Among them, in this embodiment, the detection terminal TEST-1 can refer to the live wire end of the power supply of the AC load, the detection terminal TEST-2 can refer to the neutral wire end of the power supply of the AC load, the resistor R3 refers to the insulation impedance of the live wire end of the power supply of the AC load through insulation treatment, and the resistor R4 refers to the insulation impedance of the neutral wire end of the power supply of the AC load through insulation treatment. When the insulation performance is normal, the resistance value of the resistor R3 and / or the resistance value of the resistor R4 is very large, and in extreme cases, it can be understood as infinite; when the insulation performance is abnormal, the resistance value of the resistor R3 and / or the resistance value of the resistor R4 is small, and in extreme cases, it can be understood as 0.

[0067] The voltage divided by resistor R2 is set to V1. If only the negative half axis of the AC power supply is considered, the voltage division is as follows:

[0068] V1=230*(((R3 / / R4) / / R2) / (((R3 / / R4) / / R2)+R1)) (1)

[0069] In formula (1), / / represents the resistance after parallel connection, such as R3 / / R4 represents the resistance after resistors R3 and R4 are connected in parallel. It can be seen that when the insulation performance of the first insulator circuit and the second insulator circuit are normal, the resistance of resistor R3 and the resistance of resistor R4 are infinite, and the voltage division can be approximated as follows:

[0070] V1=230*(R2 / (R2+R1)) (2)

[0071] In formula (2), since the resistance values ​​of resistors R1 and R2 do not change, the voltage V1 divided by resistor R2 is always a fixed value. In this embodiment, the voltage V1 can be directly output to the controller as the target voltage, or the voltage V1 can be subjected to relevant voltage reduction processing and the voltage after voltage reduction is output to the controller as the target voltage. It can be clearly seen that regardless of whether the voltage V1 is subjected to voltage reduction processing, as long as the insulation performance of the first insulator circuit and the second insulator circuit are normal, the controller can receive a fixed target voltage based on formula (2).

[0072] Based on formula (1), when the insulation performance of any one of the first insulator circuit and the second insulator circuit is abnormal, the corresponding resistance of the resistor R3 and the resistor R4 decreases from infinity to a certain range, such as several thousand ohms, thereby lowering the resistance of the resistor R2, the resistor R3 and the resistor R4 in parallel, and reducing the voltage V1 divided by the resistor R2.

[0073] It can be seen that the size of the target voltage obtained by the controller is linearly related to the target impedance corresponding to the first insulator circuit and the second insulator circuit as a whole. The controller can determine the corresponding target impedance based on the linear change relationship and the target voltage obtained in real time, and then determine the corresponding insulation fault state.

[0074] Among them, when only the first insulator circuit or the second insulator circuit is subjected to insulation detection, if the resistance value of the corresponding resistor R3 or resistor R4 is greater than or equal to the first preset resistance value (such as 16KΩ), the target voltage obtained by the controller is greater than or equal to the first preset voltage, and it is determined that the insulation performance of the first insulator circuit or the second insulator circuit is normal, and the insulation fault state of the first insulator circuit or the second insulator circuit is determined to be that there is no insulation fault; if the resistance value of the corresponding resistor R3 or resistor R4 is less than the first preset resistance value, the target voltage obtained by the controller is less than the first preset voltage, and it is determined that the insulation performance of the first insulator circuit or the second insulator circuit is abnormal, and the insulation fault state of the first insulator circuit or the second insulator circuit is determined to be that there is an insulation fault.

[0075] Among them, when the first insulator loop and the second insulator loop exist at the same time, the target voltage obtained by the controller reflects the parallel resistance of resistors R3 and R4, but the parallel resistance will be lower than the single resistance. For example, the actual resistances R3 and R4 are 16KΩ respectively, and the corresponding target voltage actually reflects a parallel resistance of 8KΩ. According to the above example, the actual insulation performance of the first insulator loop corresponding to resistor R3 and the actual insulation performance of the second insulator loop corresponding to resistor R4 are both normal, but the insulation performance determined based on the target voltage is performance, so in this case, it is necessary to further set the comparison logic. Specifically, if the target voltage received by the controller is greater than or equal to the first preset voltage, it is determined that the insulation performance is normal, and the insulation fault state is that there is no insulation fault. At this time, the parallel resistance is greater than or equal to the first preset resistance, and the resistance of any one of the resistors R3 and R4 must be greater than the first preset resistance; if the target voltage received by the controller is less than the second preset voltage, it is determined that the insulation performance is abnormal, and the insulation fault state is that there is an insulation fault. At this time, the parallel resistance is less than the second preset resistance (such as 7KΩ), and the resistance of at least one of the resistors R3 and R4 must be less than the first preset resistance.

[0076] It should be noted that, in the above-mentioned case where the first insulator circuit and the second insulator circuit exist at the same time, two preset thresholds are used to achieve the normal operation of the comparison logic, but this method will result in the situation between the two preset thresholds being unable to directly make a result judgment. In other embodiments, other data or means can be further combined to clarify the situation between the two preset thresholds, which will not be explained in this application.

[0077] In other embodiments, the anode of the first diode D4 is electrically connected to the second end of the resistor R1 and the first end of the resistor R2 respectively, and the cathode of the first diode D4 is electrically connected to the first end of the resistor R3 through the detection terminal TEST-1.

[0078] Wherein, based on the connection mode of the first diode D4, the resistor R3 corresponding to the first insulator loop is effective only in the positive half axis of the AC power supply.

[0079] In other embodiments, the anode of the second diode D5 is electrically connected to the second end of the resistor R1 and the first end of the resistor R2 respectively, and the cathode of the second diode D5 is electrically connected to the first end of the resistor R4 through the detection terminal TEST-2.

[0080] Wherein, based on the connection mode of the second diode D5, the resistor R4 corresponding to the second insulator loop is effective only in the positive half axis of the AC power supply.

[0081] like Figure 3 As shown, in one embodiment, the detection circuit includes a first voltage-dividing resistor R9 and a second voltage-dividing resistor R8, and the voltage-dividing module includes a thermistor RT2 and a third voltage-dividing resistor (such as Figure 3 The resistors R10 and R11 in FIG.

[0082] Among them, the first end of the first voltage-dividing resistor R9 is electrically connected to the second end of the resistor R10, and the second end of the first voltage-dividing resistor R9 is electrically connected to the first end of the second voltage-dividing resistor R8 and the controller respectively to output the target voltage MCU_ADC after voltage reduction processing, and the second end of the second voltage-dividing resistor R8 is electrically connected to the center point N of the three-phase output winding.

[0083] The first voltage-dividing resistor R9 and the second voltage-dividing resistor R8 are used to divide the voltage output by the voltage-dividing module. The voltage divided by the second voltage-dividing resistor R8 is clamped by the resistor R5 and the diode D7 to output the corresponding target voltage MCU_ADC to the controller.

[0084] like Figure 3 As shown, in one embodiment, the detection circuit further includes a first TVS tube D10 and a second TVS tube D11.

[0085] Among them, the anode of the first TVS tube D10 is electrically connected to the first end of the first voltage-dividing resistor R9 and the second end of the resistor R10 respectively, the cathode of the first TVS tube D10 is electrically connected to the cathode of the second TVS tube D11, and the anode of the second TVS tube D11 is electrically connected to the center point N of the three-phase output winding.

[0086] The first TVS tube D10 and the second TVS tube D11 constitute a shaping circuit, which is used to limit the amplitude of the sinusoidal signal output by the resistor R10 and then shape it into a square wave signal.

[0087] like Figure 3 As shown, in one embodiment, the detection loop further includes a third diode D6 and a fourth diode D8.

[0088] Among them, the cathode of the third diode D6 is electrically connected to the second end of the first voltage-dividing resistor R9 and the anode of the fourth diode D8, respectively, the anode of the third diode D6 is electrically connected to the center point N of the three-phase output winding, and the cathode of the fourth diode D8 is electrically connected to the first end of the second voltage-dividing resistor R8 and the controller, respectively, to output the target voltage MCU_ADC.

[0089] Among them, the fourth diode D8 is used to shape the square wave signal output by the first TVS tube D10 and the second TVS tube D11 into a DC signal of the positive half axis; the third diode D6 is used to clamp the negative half axis of the square wave signal output by the first TVS tube D10 and the second TVS tube D11 to a smaller value, such as the forward conduction voltage of the third diode D6, which can prevent the reverse voltage of the negative half axis from damaging other related devices.

[0090] It can be seen that the third diode D6 and the fourth diode D8 are used together to shape the AC signal into a DC signal to output to the controller.

[0091] Among them, in other embodiments, the third diode D6 and the fourth diode D8 can also be replaced by a rectifier bridge. When the rectifier bridge is used, the positive input terminal of the rectifier bridge is electrically connected to the first end of the first voltage-dividing resistor R9, the negative input terminal of the rectifier bridge is electrically connected to the center point N of the three-phase output winding, the positive output terminal of the rectifier bridge is electrically connected to the first end of the second voltage-dividing resistor R8, and the second end of the second voltage-dividing resistor R8 is used to be grounded together with the negative output terminal of the rectifier bridge, and is no longer electrically connected to the center point N of the three-phase output winding.

[0092] like Figure 3 As shown, in one embodiment, the detection circuit further includes a first capacitor C4 and a second capacitor C5.

[0093] Among them, the first end of the first capacitor C4 is electrically connected to the second end of the first voltage-dividing resistor R9, and the second end of the first capacitor C4 is electrically connected to the cathode of the third diode D6 and the anode of the fourth diode D8 respectively; the first end of the second capacitor C5 is electrically connected to the cathode of the fourth diode D8 and the first end of the second voltage-dividing resistor R8 respectively, and the second end of the second capacitor C5 is electrically connected to the second end of the second voltage-dividing resistor R8 and the center point N of the three-phase output winding respectively.

[0094] The first capacitor C4 is connected in series between the first voltage-dividing resistor R9 and the fourth diode D8 to filter out DC noise signals.

[0095] The second capacitor C5 is connected in parallel to both ends of the second voltage-dividing resistor R8 to filter out AC noise signals.

[0096] like Figure 3 As shown, in one embodiment, the detection circuit further includes a transistor Q1.

[0097] Among them, the base of the transistor Q1 is electrically connected to the second end of the first voltage-dividing resistor R9 and the first end of the second voltage-dividing resistor R8 through the resistor R6, the collector of the transistor Q1 is used to access the working voltage (such as a 5V working voltage) and is electrically connected to the controller to output the working status signal MCU, and the emitter of the transistor Q1 is electrically connected to the center point N of the three-phase output winding.

[0098] The controller is also used to determine the working state of the AC power supply according to the collector voltage of the transistor Q1.

[0099] Among them, when the AC power supply has power input, the base of the transistor Q1 is at a high level, the transistor Q1 is turned on, the connected working voltage is pulled down, and the collector voltage of the transistor Q1 is at a low level; when the AC power supply has no power input, the base of the transistor Q1 is at a low level, the transistor Q1 is turned off, the connected working voltage is not pulled down, and the collector voltage of the transistor Q1 is at a high level.

[0100] In one embodiment, the insulation detection circuit further includes a switch module, such as Figure 3 As shown, the switch module includes a relay K1. In other embodiments, other switch devices other than the relay K1 may be used as the switch module in this embodiment.

[0101] Among them, the first access end of the relay K1 is electrically connected to the second end of the resistor R10 and the first end of the first voltage-dividing resistor R9 respectively, the second access end of the relay K1 is electrically connected to the cathode of the first diode D4 and the cathode of the second diode D5 respectively, and the controlled end of the relay K1 is electrically connected to the controller.

[0102] The controller is used to control the relay K1 to be in the on state when entering the insulation detection process.

[0103] Among them, when the insulation detection process is not entered, the controller can control the relay K1 to be in a disconnected state to reduce related power consumption.

[0104] In a second aspect, in one embodiment, the present invention provides a circuit breaker system, comprising a circuit breaker and the insulation detection circuit in any one of the above embodiments;

[0105] The first end of the AC power supply is electrically connected to the first end of the voltage dividing module and the first access end of the circuit breaker respectively, the second access end of the circuit breaker is electrically connected to the second end of the unidirectional conduction module and is used to be electrically connected to the first end of the equivalent insulation circuit, and the controlled end of the circuit breaker is electrically connected to the controller;

[0106] The controller is used to control the reclosing of the circuit breaker according to the insulation fault state of the equivalent insulation circuit after the circuit breaker is opened.

[0107] When the detected insulation fault state is that there is no insulation fault, the controller controls the circuit breaker to reclose, and when the detected insulation fault state is that there is an insulation fault, the controller controls the circuit breaker not to reclose.

[0108] Through the above-mentioned circuit breaker system, a detection circuit is set in parallel with the equivalent insulation circuit. Due to the existence of the voltage divider module, the impedance of the equivalent insulation circuit will affect the voltage division of the detection circuit, so that the controller can determine the target impedance of the equivalent insulation circuit according to the target voltage obtained by the detection circuit, and thus determine the insulation fault state of the equivalent insulation circuit according to the target impedance, thereby realizing automated insulation detection, improving detection efficiency and reducing costs; in addition, the set unidirectional conduction module can make the impedance of the equivalent insulation circuit affect the voltage division of the detection circuit only on a certain half axis of the AC power supply, so that the target voltage obtained by the controller can be kept within a relatively small range, reducing the range requirements of the controller and ensuring the reliability of voltage acquisition.

[0109] like Figure 3 As shown, in one embodiment, the insulation detection circuit further includes a micro switch SW1.

[0110] The first access end of the micro switch SW1 is electrically connected to the second end of the resistor R10 and the first end of the first voltage-dividing resistor R9 through the relay K1, and the second access end of the micro switch SW1 is electrically connected to the cathode of the first diode D4 and the cathode of the second diode D5.

[0111] The micro switch SW1 is used to be closed due to the corresponding mechanical operation when the circuit breaker is switched to the automatic closing state.

[0112] Among them, the circuit breaker usually has two closing states, one is the manual closing state, and the other is the automatic closing state. Only in the automatic closing state, it is necessary to test the insulation performance of the equivalent insulation circuit before reclosing. The switching between the two closing states of the circuit breaker is usually achieved through a corresponding mechanical trigger device, such as a knob, button, etc., so as to feedback the corresponding trigger signal to the controller.

[0113] In this embodiment, when the operator operates the mechanical trigger device to switch the closing state, the switch state of the micro switch SW1 can be changed synchronously.

[0114] The above is a detailed introduction to an insulation detection circuit and a circuit breaker system provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

[0115] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. An insulation detection circuit, characterized in that: The insulation detection circuit includes an AC power supply, a voltage dividing module, a detection loop, a unidirectional conduction module, and a controller; The first end of the AC power supply is electrically connected to the first end of the one-way conducting module and the first end of the detection circuit respectively through a voltage divider module, the second end of the one-way conducting module is used to be electrically connected to the first end of the equivalent insulation circuit, the second end of the detection circuit is electrically connected to the second end of the AC power supply, the second end of the AC power supply is also used to be electrically connected to the second end of the equivalent insulation circuit, and the controller is electrically connected to the detection circuit; The unidirectional conduction module is used to control the unidirectional flow of current between the equivalent insulation loop and the voltage dividing module; The controller is used to obtain the target voltage divided by the detection circuit and the voltage divider module, determine the target impedance of the equivalent insulation circuit according to the target voltage, and determine the insulation fault state of the equivalent insulation circuit according to the target impedance.

2. The insulation detection circuit according to claim 1, characterized in that: The one-way conducting module comprises a diode unit; The cathode of the diode unit is electrically connected to the second end of the voltage divider module, and the anode of the diode unit is used to be electrically connected to the equivalent insulating loop; or, the anode of the diode unit is electrically connected to the second end of the voltage divider module, and the cathode of the diode unit is used to be electrically connected to the equivalent insulating loop.

3. The insulation detection circuit according to claim 2, characterized in that: The equivalent insulation circuit includes a first insulator circuit and a second insulator circuit, and the diode unit includes a first diode and a second diode; The cathode of the first diode is electrically connected to the second end of the voltage divider module, and the anode of the first diode is electrically connected to the first end of the first insulator loop; or, the anode of the first diode is electrically connected to the second end of the voltage divider module, and the cathode of the first diode is electrically connected to the first end of the first insulator loop; The cathode of the second diode is electrically connected to the second end of the voltage divider module, and the anode of the second diode is electrically connected to the first end of the second insulator loop; or, the anode of the second diode is electrically connected to the second end of the voltage divider module, and the cathode of the first diode is electrically connected to the first end of the first insulator loop; The second end of the AC power supply is used to be electrically connected to the second end of the first insulator loop and the second end of the second insulator loop respectively.

4. The insulation detection circuit according to any one of claims 1 to 3, characterized in that: The detection circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor; The first end of the first voltage-dividing resistor is electrically connected to the second end of the voltage-dividing module, the second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor and the controller respectively, and the second end of the second voltage-dividing resistor is electrically connected to the second end of the AC power supply.

5. The insulation detection circuit according to claim 4, characterized in that: The detection circuit also includes a first TVS tube and a second TVS tube; The anode of the first TVS tube is electrically connected to the first end of the first voltage-dividing resistor and the second end of the voltage-dividing module respectively, the cathode of the first TVS tube is electrically connected to the cathode of the second TVS tube, and the anode of the second TVS tube is electrically connected to the second end of the AC power supply.

6. The insulation detection circuit according to claim 4, characterized in that: The detection circuit also includes a third diode and a fourth diode; The cathode of the third diode is electrically connected to the second end of the first voltage-dividing resistor and the anode of the fourth diode, the anode of the third diode is electrically connected to the second end of the AC power supply, and the cathode of the fourth diode is electrically connected to the first end of the second voltage-dividing resistor and the controller.

7. The insulation detection circuit according to claim 6, characterized in that: The detection circuit also includes a first capacitor and a second capacitor; The first end of the first capacitor is electrically connected to the second end of the first voltage-dividing resistor, and the second end of the first capacitor is electrically connected to the cathode of the third diode and the anode of the fourth diode respectively; The first end of the second capacitor is electrically connected to the cathode of the fourth diode, the first end of the second voltage-dividing resistor and the controller respectively, and the second end of the second capacitor is electrically connected to the second end of the second voltage-dividing resistor and the second end of the AC power supply respectively.

8. The insulation detection circuit according to claim 4, characterized in that: The detection circuit also includes a triode; The base of the transistor is electrically connected to the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor respectively, the collector of the transistor is used to access the working voltage and is electrically connected to the controller, and the emitter of the transistor is electrically connected to the second end of the AC power supply; The controller is also used to determine the working state of the AC power supply according to the collector voltage of the transistor.

9. The insulation detection circuit according to any one of claims 1 to 3, characterized in that: The voltage dividing module includes a thermistor and a third voltage dividing resistor; The first end of the thermistor is electrically connected to the first end of the AC power supply, the second end of the thermistor is electrically connected to the first end of the third voltage-dividing resistor, and the second end of the third voltage-dividing resistor is electrically connected to the first end of the unidirectional conduction module and the first end of the detection circuit respectively.

10. The insulation detection circuit according to any one of claims 1 to 3, characterized in that: The insulation detection circuit also includes a switch module; The first access end of the switch module is electrically connected to the second end of the voltage dividing module and the first end of the detection loop respectively, the second access end of the switch module is electrically connected to the first end of the unidirectional conduction module, and the controlled end of the switch module is electrically connected to the controller; The controller is used to control the switch module to be in a conducting state when entering the insulation detection process.

11. The insulation detection circuit according to any one of claims 1 to 3, characterized in that: The insulation detection circuit also includes a three-phase transformer, and the three-phase transformer includes a three-phase output winding; The output end of at least one phase output winding of the three-phase output winding serves as the first end of the AC power source, and the center point of the three-phase output winding serves as the second end of the AC power source.

12. A circuit breaker system, characterized in that: A circuit breaker comprising an insulation detection circuit according to any one of claims 1 to 10; The first end of the AC power supply is electrically connected to the first end of the voltage dividing module and the first access end of the circuit breaker respectively, the second access end of the circuit breaker is electrically connected to the second end of the unidirectional conduction module and is used to be electrically connected to the first end of the equivalent insulation circuit, and the controlled end of the circuit breaker is electrically connected to the controller; The controller is used to control the reclosing of the circuit breaker according to the insulation fault state of the equivalent insulation circuit after the circuit breaker is opened.

13. The circuit breaker system according to claim 12, characterized in that The insulation detection circuit also includes a micro switch; The first access end of the micro switch is electrically connected to the second end of the voltage dividing module and the first end of the detection circuit respectively, and the second access end of the micro switch is electrically connected to the first end of the unidirectional conduction module; The micro switch is used to be closed due to the corresponding mechanical operation when the circuit breaker is switched to the automatic closing state.

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