Sampling circuit of circuit breaker and circuit breaker

Abstract

The utility model provides a sampling circuit of a circuit breaker and the circuit breaker. The sampling circuit of the circuit breaker comprises a first current transformer, a metering sampling conditioning circuit, a protection sampling conditioning circuit, a power supply and a controller, the first current transformer sleeves a power line, the output end of the first current transformer is electrically connected with the input end of the metering sampling conditioning circuit and the input end of the protection sampling conditioning circuit, the input end of the power supply is electrically connected with the power line, and the output end of the metering sampling conditioning circuit is electrically connected with the first sampling end of the controller; the output end of the protection sampling conditioning circuit is electrically connected with the second sampling end of the controller, and the output end of the power supply is electrically connected with the power supply end of the controller. Different sampling requirements are met by sharing one group of current transformers, the corresponding metering sampling conditioning circuit and the corresponding protection sampling conditioning circuit, so that the number of the transformers is reduced, the cost and the occupied volume are reduced, and additional investment in the aspect of insulation is not needed.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit breakers, in particular to a sampling circuit of a circuit breaker and a circuit breaker. Background Art

[0002] The circuit breaker has functions such as overload protection and metering. In order to realize the described functions, the traditional solution adopts a variety of transformers. The protection type transformer is used for protection sampling, and the high-precision transformer is used for metering sampling.

[0003] Using multiple sets of transformers will result in high costs and occupy a large internal volume; in addition, the processes involved are complex and the phase-to-phase insulation will increase additional investment. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides a sampling circuit of a circuit breaker and a circuit breaker.

[0005] In a first aspect, in one embodiment, the utility model provides a sampling circuit of a circuit breaker, the sampling circuit of the circuit breaker comprising:

[0006] A first current transformer, a metering sampling and conditioning circuit, a protection sampling and conditioning circuit, a power supply and a controller;

[0007] The first current transformer is sleeved on the power line, the output end of the first current transformer is electrically connected to the input end of the metering sampling and conditioning circuit and the input end of the protection sampling and conditioning circuit respectively, the input end of the power supply is electrically connected to the power line, the output end of the metering sampling and conditioning circuit is electrically connected to the first sampling end of the controller, the output end of the protection sampling and conditioning circuit is electrically connected to the second sampling end of the controller, and the output end of the power supply is electrically connected to the power supply end of the controller.

[0008] In one embodiment, the sampling circuit of the circuit breaker further includes a rectifier circuit, the metering sampling and conditioning circuit includes a first operational amplifier circuit, and the protection sampling and conditioning circuit includes a second operational amplifier circuit;

[0009] The input end of the rectifier circuit is electrically connected to the output end of the first current transformer, the output end of the rectifier circuit is electrically connected to the input end of the first operational amplifier circuit and the input end of the second operational amplifier circuit respectively, the output end of the first operational amplifier circuit is electrically connected to the first sampling end of the controller, and the output end of the second operational amplifier circuit is electrically connected to the second sampling end of the controller.

[0010] In one embodiment, the rectifier circuit includes a first rectifier diode, a second rectifier diode, a third rectifier diode and a fourth rectifier diode, the first operational amplifier circuit includes a first resistor, a second resistor, a first operational amplifier and a first feedback resistor, and the second operational amplifier circuit includes a third resistor, a fourth resistor, a second operational amplifier and a second feedback resistor;

[0011] The anode of the first rectifier diode and the cathode of the third rectifier diode are electrically connected to the positive output terminal of the first current transformer, the anode of the second rectifier diode and the cathode of the fourth rectifier diode are electrically connected to the negative output terminal of the first current transformer, and the anode of the third rectifier diode and the anode of the fourth rectifier diode are grounded.

[0012] The cathode of the first rectifier diode is electrically connected to the non-inverting input terminal of the first operational amplifier through the first resistor and is electrically connected to the non-inverting input terminal of the second operational amplifier through the third resistor, and the cathode of the second rectifier diode is electrically connected to the inverting input terminal of the first operational amplifier through the second resistor and is electrically connected to the inverting input terminal of the second operational amplifier through the fourth resistor;

[0013] The first end of the first feedback resistor is electrically connected to the inverting input terminal of the first operational amplifier, the second end of the first feedback resistor and the output terminal of the first operational amplifier are electrically connected to the first sampling terminal of the controller respectively, the first end of the second feedback resistor is electrically connected to the inverting input terminal of the second operational amplifier, and the second end of the second feedback resistor and the output terminal of the second operational amplifier are electrically connected to the second sampling terminal of the controller respectively.

[0014] In one embodiment, the rectifier circuit includes a rectifier bridge and a first sampling resistor, the first operational amplifier circuit includes a fifth resistor, a sixth resistor, a third operational amplifier and a third feedback resistor, and the second operational amplifier circuit includes a seventh resistor, an eighth resistor, a fourth operational amplifier and a fourth feedback resistor;

[0015] The positive input end of the rectifier bridge is electrically connected to the positive output end of the first current transformer, the negative input end of the rectifier bridge is electrically connected to the negative output end of the first current transformer, the positive output end of the rectifier bridge is electrically connected to the power load, and the negative output end of the rectifier bridge is grounded through the first sampling resistor;

[0016] The non-inverting input terminal of the third operational amplifier is grounded through a fifth resistor, the inverting input terminal of the third operational amplifier is electrically connected to the first sampling resistor and the negative output terminal of the rectifier bridge through a sixth resistor, the non-inverting input terminal of the fourth operational amplifier is grounded through a seventh resistor, and the inverting input terminal of the fourth operational amplifier is electrically connected to the first sampling resistor and the negative output terminal of the rectifier bridge through an eighth resistor;

[0017] The first end of the third feedback resistor is electrically connected to the inverting input terminal of the third operational amplifier, the second end of the third feedback resistor and the output terminal of the third operational amplifier are electrically connected to the first sampling terminal of the controller, the first end of the fourth feedback resistor is electrically connected to the inverting input terminal of the fourth operational amplifier, and the second end of the fourth feedback resistor and the output terminal of the fourth operational amplifier are electrically connected to the second sampling terminal of the controller.

[0018] In one embodiment, the sampling circuit of the circuit breaker further includes a second sampling resistor, a third sampling resistor, a fourth sampling resistor, a fifth sampling resistor and a first comparator;

[0019] The first end of the second sampling resistor is electrically connected to the positive output end of the first current transformer and the positive input end of the rectifier bridge respectively, and the second end of the second sampling resistor is electrically connected to the non-inverting input end of the first comparator and the first end of the third sampling resistor respectively;

[0020] The first end of the fourth sampling resistor is electrically connected to the negative output end of the first current transformer and the negative input end of the rectifier bridge respectively, and the second end of the fourth sampling resistor is electrically connected to the inverting input end of the first comparator and the first end of the fifth sampling resistor respectively;

[0021] The second end of the third sampling resistor and the second end of the fifth sampling resistor are grounded respectively, and the output end of the first comparator is electrically connected to the third sampling end of the controller.

[0022] In one embodiment, the sampling circuit of the circuit breaker further includes a transformer power supply circuit;

[0023] The input end of the transformer power supply circuit is electrically connected to the output end of the rectifier circuit, and the output end of the transformer power supply circuit is electrically connected to the power supply end of the controller.

[0024] In one embodiment, the transformer power supply circuit includes a MOS tube, an anti-reverse diode, a second comparator, a first voltage-dividing resistor and a second voltage-dividing resistor;

[0025] The drain of the MOS tube is electrically connected to the output end of the rectifier circuit and the anode of the anti-reverse diode respectively, the source of the MOS tube is grounded, and the gate of the MOS tube is electrically connected to the output end of the second comparator;

[0026] The first end of the first voltage-dividing resistor is electrically connected to the cathode of the anti-reverse diode, the output end of the power supply and the power supply end of the controller respectively, the second end of the first voltage-dividing resistor is electrically connected to the non-inverting input end of the second comparator and the first end of the second voltage-dividing resistor respectively, the second end of the second voltage-dividing resistor is grounded, and the inverting input end of the second comparator is connected to the reference voltage;

[0027] The output voltage of the transformer power supply circuit is less than the output voltage of the power supply.

[0028] In one embodiment, the transformer power supply circuit further includes a third voltage-dividing resistor and a fourth voltage-dividing resistor;

[0029] The first end of the third voltage-dividing resistor is electrically connected to the cathode of the anti-reverse diode and the first end of the first voltage-dividing resistor respectively, the second end of the third voltage-dividing resistor is electrically connected to the output end of the second comparator, the gate of the MOS tube and the first end of the fourth voltage-dividing resistor respectively, and the second end of the fourth voltage-dividing resistor is grounded.

[0030] In one embodiment, the sampling circuit of the circuit breaker further includes a second current transformer and a residual current sampling and conditioning circuit;

[0031] The second current transformer is sleeved on the power line, the output end of the second current transformer is electrically connected to the input end of the residual current sampling and conditioning circuit, and the output end of the residual current sampling and conditioning circuit is electrically connected to the fourth sampling end of the controller.

[0032] In a second aspect, in one embodiment, the utility model provides a circuit breaker, comprising the sampling circuit of the circuit breaker in any one of the above embodiments.

[0033] The sampling circuit and circuit breaker of the above-mentioned circuit breaker, with respect to the protection and metering functions of the circuit breaker, realize different sampling requirements by sharing a set of current transformers and corresponding metering sampling conditioning circuits and protection sampling conditioning circuits, thereby reducing the number of transformers, reducing costs and occupied volume, and eliminating the need for additional investment in insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 This is a schematic diagram of the structure of a sampling circuit of a circuit breaker in one embodiment of the utility model;

[0036] Figure 2 It is a schematic diagram of the structure of a transformer power supply circuit, a metering sampling conditioning circuit and a protection sampling conditioning circuit under full-wave sampling in one embodiment of the utility model;

[0037] Figure 3 It is a schematic diagram of the structure of a transformer power supply circuit, a metering sampling conditioning circuit and a protection sampling conditioning circuit under half-wave sampling in one embodiment of the utility model;

[0038] Figure 4 The figure is a schematic diagram of the assembly of the first current transformer and the second current transformer in one embodiment of the utility model. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0040] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used 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 utility model, the following description is given. In the following description, details are listed for the purpose of explanation. It should be understood that one of ordinary skill in the art can recognize that the utility model 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 utility model obscure. Therefore, the utility model is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in this application.

[0041] First, as Figure 1 As shown, in one embodiment, the utility model provides a sampling circuit of a circuit breaker, the sampling circuit of the circuit breaker includes a first current transformer, a metering sampling conditioning circuit, a protection sampling conditioning circuit, a power supply (in Figure 1 In the embodiment, the power supply is specifically a switching power supply. In other embodiments, the power supply may also be other types of power supplies) and a controller.

[0042] Among them, Figure 1 In the example, the controller is MCU.

[0043] The first current transformer is sleeved on the power line, the output end of the first current transformer is electrically connected to the input end of the metering sampling and conditioning circuit and the input end of the protection sampling and conditioning circuit respectively, the input end of the switching power supply is electrically connected to the power line, the output end of the metering sampling and conditioning circuit is electrically connected to the first sampling end of the MCU, the output end of the protection sampling and conditioning circuit is electrically connected to the second sampling end of the MCU, and the output end of the switching power supply is electrically connected to the power supply end of the MCU.

[0044] The first current transformer outputs the required current signal according to the winding turns ratio.

[0045] The metering sampling and conditioning circuit performs small-scale conditioning on the output current of the first current transformer according to the corresponding sampling range, that is, the amplification factor of the signal is relatively large, and then outputs the corresponding analog voltage to the MCU for metering.

[0046] Among them, the protection sampling and conditioning circuit performs a large-scale conditioning on the output current of the first current transformer according to the corresponding sampling range, that is, the amplification factor of the signal is relatively small, and then outputs the corresponding analog voltage to the MCU for protection.

[0047] The sampling circuit of the above-mentioned circuit breaker realizes different sampling requirements for the protection and metering functions of the circuit breaker by sharing a set of current transformers and corresponding metering sampling conditioning circuits and protection sampling conditioning circuits, thereby reducing the number of transformers, reducing costs and occupied volume, and eliminating the need for additional investment in insulation.

[0048] In one embodiment, the sampling circuit of the circuit breaker further includes a rectifier circuit, the metering sampling and conditioning circuit includes a first operational amplifier circuit, and the protection sampling and conditioning circuit includes a second operational amplifier circuit.

[0049] The input end of the rectifier circuit is electrically connected to the output end of the first current transformer, the output end of the rectifier circuit is electrically connected to the input end of the first operational amplifier circuit and the input end of the second operational amplifier circuit respectively, the output end of the first operational amplifier circuit is electrically connected to the first sampling end of the controller, and the output end of the second operational amplifier circuit is electrically connected to the second sampling end of the controller.

[0050] Among them, the operational amplifier circuit is a typical circuit for realizing signal amplification. Therefore, in this embodiment, the signal conditioning can be realized in the form of an operational amplifier.

[0051] Among them, since the current signal output by the first current transformer is alternating current, it needs to be rectified by a rectifier circuit before being conditioned by the operational amplifier circuit, so as to meet the input requirements of the operational amplifier circuit.

[0052] like Figure 2As shown, in one embodiment, the rectifier circuit includes a first rectifier diode D5, a second rectifier diode D4, a third rectifier diode D6 and a fourth rectifier diode D7, the first operational amplifier circuit includes a first resistor R15, a second resistor R13, a first operational amplifier U2A and a first feedback resistor R10, and the second operational amplifier circuit includes a third resistor R8, a fourth resistor R2, a second operational amplifier U1A and a second feedback resistor R7.

[0053] For ease of understanding, Figure 2 In FIG. 5 , the first current transformer is represented as a current source of 800 mA / 50 Hz.

[0054] The anode of the first rectifier diode D5 and the cathode of the third rectifier diode D6 are electrically connected to the positive output terminal of the current source respectively, the anode of the second rectifier diode D4 and the cathode of the fourth rectifier diode D7 are electrically connected to the negative output terminal of the current source respectively, and the anode of the third rectifier diode D6 and the anode of the fourth rectifier diode D7 are grounded respectively.

[0055] The cathode of the first rectifier diode D5 is electrically connected to the non-inverting input terminal of the first operational amplifier U2A through the first resistor R15 and is electrically connected to the non-inverting input terminal of the second operational amplifier U1A through the third resistor R8. The cathode of the second rectifier diode D4 is electrically connected to the inverting input terminal of the first operational amplifier U2A through the second resistor R13 and is electrically connected to the inverting input terminal of the second operational amplifier U1A through the fourth resistor R2.

[0056] A first end of the first feedback resistor R10 is electrically connected to the inverting input terminal of the first operational amplifier U2A, a second end of the first feedback resistor R10 and an output terminal of the first operational amplifier U2A are electrically connected to a first sampling terminal of the controller, a first end of the second feedback resistor R7 is electrically connected to the inverting input terminal of the second operational amplifier U1A, and a second end of the second feedback resistor R7 and an output terminal of the second operational amplifier U1A are electrically connected to a second sampling terminal of the controller.

[0057] The ratio of the first feedback resistor R10 to the second resistor R13 determines the gain of the first operational amplifier U2A, and the ratio of the second feedback resistor R7 to the fourth resistor R2 determines the gain of the second operational amplifier U1A. Figure 2 As shown, it can be seen that the amplification factor of the first operational amplifier U2A is obviously greater than that of the second operational amplifier U1A. Therefore, the first operational amplifier U2A corresponds to the measurement sampling, and the second operational amplifier U1A corresponds to the protection sampling.

[0058] Among them, whether it is the first operational amplifier U2A or the second operational amplifier U1A, its in-phase input terminal is electrically connected to the positive output terminal of the current source through the first rectifier diode D5, and its inverting input terminal is electrically connected to the negative output terminal of the current source through the second rectifier diode D4, so it can realize full-wave sampling.

[0059] like Figure 3 As shown, in one embodiment, the rectifier circuit includes a rectifier bridge BR1 and a first sampling resistor R25, the first operational amplifier circuit includes a fifth resistor R27, a sixth resistor R28, a third operational amplifier U3A and a third feedback resistor R31, and the second operational amplifier circuit includes a seventh resistor R29, an eighth resistor R30, a fourth operational amplifier U4A and a fourth feedback resistor R32.

[0060] For ease of understanding, Figure 3 In FIG. 5 , the first current transformer is represented as a current source of 800 mA / 50 Hz.

[0061] The positive input terminal of the rectifier bridge BR1 is electrically connected to the positive output terminal of the current source, the negative input terminal of the rectifier bridge BR1 is electrically connected to the negative output terminal of the current source, the positive output terminal of the rectifier bridge BR1 is electrically connected to the power load, and the negative output terminal of the rectifier bridge BR1 is grounded through the first sampling resistor R25.

[0062] The non-inverting input terminal of the third operational amplifier U3A is grounded through the fifth resistor R27, the inverting input terminal of the third operational amplifier U3A is electrically connected to the first sampling resistor R25 and the negative output terminal of the rectifier bridge BR1 through the sixth resistor R28, the non-inverting input terminal of the fourth operational amplifier U4A is grounded through the seventh resistor R29, and the inverting input terminal of the fourth operational amplifier U4A is electrically connected to the first sampling resistor R25 and the negative output terminal of the rectifier bridge BR1 through the eighth resistor R30.

[0063] A first end of the third feedback resistor R31 is electrically connected to the inverting input terminal of the third operational amplifier U3A, a second end of the third feedback resistor R31 and an output terminal of the third operational amplifier U3A are electrically connected to the first sampling terminal of the controller, a first end of the fourth feedback resistor R32 is electrically connected to the inverting input terminal of the fourth operational amplifier U4A, a second end of the fourth feedback resistor R32 and an output terminal of the fourth operational amplifier U4A are electrically connected to the second sampling terminal of the controller.

[0064] The ratio of the third feedback resistor R31 to the sixth resistor R28 determines the gain of the third operational amplifier U3A, and the ratio of the fourth feedback resistor R32 to the eighth resistor R30 determines the gain of the fourth operational amplifier U4A. Figure 3 As shown, it can be seen that the amplification factor of the third operational amplifier U3A is obviously greater than that of the fourth operational amplifier U4A, so the third operational amplifier U3A corresponds to the measurement sampling, and the fourth operational amplifier U4A corresponds to the protection sampling.

[0065] Among them, whether it is the third operational amplifier U3A or the fourth operational amplifier U4A, its in-phase input terminal is grounded through the fifth resistor R27 and the seventh resistor R29 respectively, and its inverting input terminal is electrically connected to the first sampling resistor R25 through the sixth resistor R28 and the eighth resistor R30 respectively. Since the first sampling resistor R25 is grounded, it can be known from the current flowing through it that the voltage obtained by the sixth resistor R28 and the eighth resistor R30 is a negative value, and then the corresponding inverting input terminal is output, and the corresponding in-phase input terminal is grounded, so the conditioning function can be realized. It should be noted that the conditioning process is for the direct current rectified by the rectifier bridge BR1, so only half-wave sampling after rectification can be realized, and the sampling results include positive half-wave and negative half-wave, but based only on the circuit structure in this embodiment, it is impossible to determine the positive and negative of the half-wave.

[0066] like Figure 3 As shown, in one embodiment, the sampling circuit of the circuit breaker further includes a second sampling resistor R21, a third sampling resistor R22, a fourth sampling resistor R23, a fifth sampling resistor R24 ​​and a first comparator U1B.

[0067] For ease of understanding, Figure 3 In FIG. 5 , the first current transformer is represented as a current source of 800 mA / 50 Hz.

[0068] The first end of the second sampling resistor R21 is electrically connected to the positive output end of the current source and the positive input end of the rectifier bridge BR1 respectively, and the second end of the second sampling resistor R21 is electrically connected to the non-inverting input end of the first comparator U1B and the first end of the third sampling resistor R22 respectively.

[0069] The first end of the fourth sampling resistor R23 is electrically connected to the negative output end of the current source and the negative input end of the rectifier bridge BR1 respectively, and the second end of the fourth sampling resistor R23 is electrically connected to the inverting input end of the first comparator U1B and the first end of the fifth sampling resistor R24 ​​respectively.

[0070] The second end of the third sampling resistor R22 and the second end of the fifth sampling resistor R24 ​​are grounded respectively, and the output end of the first comparator U1B is electrically connected to the third sampling end of the controller.

[0071] Among them, the non-inverting input terminal of the first comparator U1B is electrically connected to the positive output terminal of the current source through the second sampling resistor R21 and the third sampling resistor R22, so the voltage division result of the second sampling resistor R21 and the third sampling resistor R22 corresponding to the positive output terminal of the current source can be connected, and the inverting input terminal of the first comparator U1B is electrically connected to the negative output terminal of the current source through the fourth sampling resistor R23 and the fifth sampling resistor R24, so the voltage division result of the fourth sampling resistor R23 and the fifth sampling resistor R24 ​​corresponding to the negative output terminal of the current source can be connected, so as to determine the positive or negative of the current half wave according to the comparison result of the first comparator U1B.

[0072] Among them, the controller can realize the combination of positive and negative half waves according to the comparison result of the first comparator U1B and the output value of the third operational amplifier U3A or the output value of the fourth operational amplifier U4A to obtain a complete full wave and realize full-wave sampling.

[0073] In one embodiment, the sampling circuit of the circuit breaker further includes a transformer power supply circuit.

[0074] The input end of the transformer power supply circuit is electrically connected to the output end of the rectifier circuit, and the output end of the transformer power supply circuit is electrically connected to the power supply end of the controller.

[0075] Among them, the above embodiments have mentioned that the controller can work through the power supply of the power supply. However, in actual situations, when the power supply fails to work properly, for example, due to the activation of the protection function, it causes an internal short circuit, and it can no longer output a voltage signal to the next stage. In this embodiment, since there is still current on the power line after the short circuit, the first current transformer can still output a current signal. Therefore, the direct current output by the rectifier circuit can be stabilized or regulated by the transformer power supply circuit to meet the power supply requirements of the controller, so that the controller can still work when the power supply fails to work properly, ensuring that it can reliably perform the tripping operation of the circuit breaker.

[0076] like Figure 2 or Figure 3 As shown, in one embodiment, the transformer power supply circuit includes a MOS tube Q1, an anti-reverse diode D2, a second comparator U2B, a first voltage-dividing resistor R4 and a second voltage-dividing resistor R3.

[0077] The drain of the MOS tube Q1 is electrically connected to the output end of the rectifier circuit and the anode of the anti-reverse diode D2 respectively, the source of the MOS tube Q1 is grounded, and the gate of the MOS tube Q1 is electrically connected to the output end of the second comparator U2B.

[0078] The first end of the first voltage-dividing resistor R4 is electrically connected to the cathode of the anti-reverse diode D2, the output end of the power supply and the power end of the controller respectively, the second end of the first voltage-dividing resistor R4 is electrically connected to the in-phase input end of the second comparator U2B and the first end of the second voltage-dividing resistor R3 respectively, the second end of the second voltage-dividing resistor R3 is grounded, and the inverting input end of the second comparator U2B is connected to the reference voltage.

[0079] Among them, Figure 2 or Figure 3 In the example, the power supply outputs 12V, so the first end of the first voltage-dividing resistor R4 is electrically connected to the output end of the power supply, which can be represented as access to 12V.

[0080] Among them, when the output voltage of the transformer power supply circuit is too high, the voltage divided on the second voltage-dividing resistor R3 will be greater than the reference voltage, so that the second comparator U2B outputs a high level, thereby turning on the MOS tube Q1 and pulling down the voltage of the anode of the anti-reverse diode D2 until it is the same as the ground terminal. Correspondingly, the voltage of the cathode of the anti-reverse diode D2 is also pulled down, thereby lowering the output voltage of the transformer power supply circuit and realizing the voltage stabilization function.

[0081] When the MOS tube Q1 is turned on, the anti-reverse diode D2 can prevent the signal at the output end from being reversed to the ground through the MOS tube Q1.

[0082] The output voltage of the transformer power supply circuit is less than the output voltage of the power supply. Figure 2 or Figure 3 As shown, according to the resistance of the first voltage-dividing resistor R4, the resistance of the second voltage-dividing resistor R3 and the voltage value of the reference voltage, when the voltage at the first end of the first voltage-dividing resistor R4 exceeds 11.55V ((3 / 20)*(57+20)=11.55), the second comparator U2B outputs a high level to turn on the MOS tube Q1. The output voltage of the power supply is 12V, so the output voltage of the transformer power supply circuit is less than the output voltage of the power supply. This difference will cause the output voltage of the power supply to force the transformer power supply circuit to stop outputting when the transformer power supply circuit and the power supply are both working normally, so as to realize that the switching power supply is the priority power supply mode.

[0083] like Figure 2 or Figure 3 As shown, in one embodiment, the transformer power supply circuit further includes a third voltage-dividing resistor R11 and a fourth voltage-dividing resistor R12.

[0084] The first end of the third voltage-dividing resistor R11 is electrically connected to the cathode of the anti-reverse diode D2 and the first end of the first voltage-dividing resistor R4, respectively; the second end of the third voltage-dividing resistor R11 is electrically connected to the output end of the second comparator U2B, the gate of the MOS tube Q1 and the first end of the fourth voltage-dividing resistor R12, respectively; the second end of the fourth voltage-dividing resistor R12 is grounded.

[0085] The voltage-dividing function of the third voltage-dividing resistor R11 and the fourth voltage-dividing resistor R12 can increase the switching speed of the MOS tube Q1.

[0086] like Figure 2 or Figure 3 As shown, in one embodiment, the transformer power supply circuit further includes a voltage regulator tube D1.

[0087] The cathode of the voltage regulator tube D1 is electrically connected to the anode of the anti-reverse diode D2, and the anode of the voltage regulator tube D1 is grounded. When the voltage of the anode of the anti-reverse diode D2 is too high, the voltage regulator tube D1 is turned on and short-circuited, thereby protecting the subsequent stage.

[0088] like Figure 2 or Figure 3 As shown, in one embodiment, the transformer power supply circuit further includes a filter capacitor CE1.

[0089] The positive electrode of the filter capacitor CE1 is electrically connected to the cathode of the anti-reverse diode D2, and the negative electrode of the filter capacitor CE1 is grounded. The filter capacitor CE1 realizes the smoothing of the voltage signal through charging and discharging, thereby improving the smoothness of the direct current.

[0090] like Figure 1 As shown, in one embodiment, the sampling circuit of the circuit breaker further includes a second current transformer and a residual current sampling and conditioning circuit.

[0091] The second current transformer is sleeved on the power line, the output end of the second current transformer is electrically connected to the input end of the residual current sampling and conditioning circuit, and the output end of the residual current sampling and conditioning circuit is electrically connected to the fourth sampling end of the controller.

[0092] The second current transformer outputs a current signal, which is conditioned by the residual current sampling and conditioning circuit and then outputs an analog voltage signal to the MCU for leakage protection.

[0093] like Figure 4 As shown, in one embodiment, the first current transformer 3 and the second current transformer 4 are respectively arranged on the fixing column 2 in the transformer housing 1 .

[0094] In a second aspect, in one embodiment, the utility model provides a circuit breaker, comprising the sampling circuit of the circuit breaker in any one of the above embodiments.

[0095] Through the above-mentioned circuit breaker, a group of current transformers is shared for the protection and metering functions of the circuit breaker, and different sampling requirements are met through corresponding metering sampling conditioning circuits and protection sampling conditioning circuits, thereby reducing the number of transformers, reducing costs and occupied volume, and eliminating the need for additional investment in insulation.

[0096] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the detailed description of other embodiments above, and will not be repeated here.

[0097] The sampling circuit and circuit breaker of a circuit breaker provided by the utility model are introduced in detail above. The principle and implementation mode of the utility model are explained in this article by using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the utility model. At the same time, for technicians in this field, according to the idea of ​​the utility model, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the utility model.

[0098] 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. A sampling circuit for a circuit breaker, characterized in that: The sampling circuit of the circuit breaker comprises: A first current transformer, a metering sampling and conditioning circuit, a protection sampling and conditioning circuit, a power supply and a controller; The first current transformer is sleeved on the power line, the output end of the first current transformer is electrically connected to the input end of the metering sampling and conditioning circuit and the input end of the protection sampling and conditioning circuit respectively, the input end of the power supply is electrically connected to the power line, the output end of the metering sampling and conditioning circuit is electrically connected to the first sampling end of the controller, the output end of the protection sampling and conditioning circuit is electrically connected to the second sampling end of the controller, and the output end of the power supply is electrically connected to the power supply end of the controller.

2. The sampling circuit of the circuit breaker according to claim 1, characterized in that: The sampling circuit of the circuit breaker further comprises a rectifier circuit, the metering sampling and conditioning circuit comprises a first operational amplifier circuit, and the protection sampling and conditioning circuit comprises a second operational amplifier circuit; The input end of the rectifier circuit is electrically connected to the output end of the first current transformer, the output end of the rectifier circuit is electrically connected to the input end of the first operational amplifier circuit and the input end of the second operational amplifier circuit respectively, the output end of the first operational amplifier circuit is electrically connected to the first sampling end of the controller, and the output end of the second operational amplifier circuit is electrically connected to the second sampling end of the controller.

3. The sampling circuit of the circuit breaker according to claim 2, characterized in that: The rectifier circuit includes a first rectifier diode, a second rectifier diode, a third rectifier diode and a fourth rectifier diode, the first operational amplifier circuit includes a first resistor, a second resistor, a first operational amplifier and a first feedback resistor, and the second operational amplifier circuit includes a third resistor, a fourth resistor, a second operational amplifier and a second feedback resistor; The anode of the first rectifier diode and the cathode of the third rectifier diode are electrically connected to the positive output terminal of the first current transformer, the anode of the second rectifier diode and the cathode of the fourth rectifier diode are electrically connected to the negative output terminal of the first current transformer, and the anode of the third rectifier diode and the anode of the fourth rectifier diode are grounded. The cathode of the first rectifier diode is electrically connected to the non-inverting input terminal of the first operational amplifier through the first resistor and is electrically connected to the non-inverting input terminal of the second operational amplifier through the third resistor, and the cathode of the second rectifier diode is electrically connected to the inverting input terminal of the first operational amplifier through the second resistor and is electrically connected to the inverting input terminal of the second operational amplifier through the fourth resistor; The first end of the first feedback resistor is electrically connected to the inverting input terminal of the first operational amplifier, the second end of the first feedback resistor and the output terminal of the first operational amplifier are electrically connected to the first sampling terminal of the controller, the first end of the second feedback resistor is electrically connected to the inverting input terminal of the second operational amplifier, and the second end of the second feedback resistor and the output terminal of the second operational amplifier are electrically connected to the second sampling terminal of the controller.

4. The sampling circuit of the circuit breaker according to claim 2, characterized in that: The rectifier circuit includes a rectifier bridge and a first sampling resistor, the first operational amplifier circuit includes a fifth resistor, a sixth resistor, a third operational amplifier and a third feedback resistor, and the second operational amplifier circuit includes a seventh resistor, an eighth resistor, a fourth operational amplifier and a fourth feedback resistor; The positive input end of the rectifier bridge is electrically connected to the positive output end of the first current transformer, the negative input end of the rectifier bridge is electrically connected to the negative output end of the first current transformer, the positive output end of the rectifier bridge is electrically connected to the power load, and the negative output end of the rectifier bridge is grounded through the first sampling resistor; The non-inverting input terminal of the third operational amplifier is grounded through the fifth resistor, the inverting input terminal of the third operational amplifier is electrically connected to the first sampling resistor and the negative output terminal of the rectifier bridge through the sixth resistor, the non-inverting input terminal of the fourth operational amplifier is grounded through the seventh resistor, and the inverting input terminal of the fourth operational amplifier is electrically connected to the first sampling resistor and the negative output terminal of the rectifier bridge through the eighth resistor; The first end of the third feedback resistor is electrically connected to the inverting input terminal of the third operational amplifier, the second end of the third feedback resistor and the output terminal of the third operational amplifier are electrically connected to the first sampling terminal of the controller, the first end of the fourth feedback resistor is electrically connected to the inverting input terminal of the fourth operational amplifier, and the second end of the fourth feedback resistor and the output terminal of the fourth operational amplifier are electrically connected to the second sampling terminal of the controller.

5. The sampling circuit of the circuit breaker according to claim 4, characterized in that: The sampling circuit of the circuit breaker further includes a second sampling resistor, a third sampling resistor, a fourth sampling resistor, a fifth sampling resistor and a first comparator; The first end of the second sampling resistor is electrically connected to the positive output end of the first current transformer and the positive input end of the rectifier bridge respectively, and the second end of the second sampling resistor is electrically connected to the non-inverting input end of the first comparator and the first end of the third sampling resistor respectively; The first end of the fourth sampling resistor is electrically connected to the negative output end of the first current transformer and the negative input end of the rectifier bridge respectively, and the second end of the fourth sampling resistor is electrically connected to the inverting input end of the first comparator and the first end of the fifth sampling resistor respectively; The second end of the third sampling resistor and the second end of the fifth sampling resistor are grounded respectively, and the output end of the first comparator is electrically connected to the third sampling end of the controller.

6. The sampling circuit of the circuit breaker according to claim 2, characterized in that: The sampling circuit of the circuit breaker also includes a transformer power supply circuit; The input end of the transformer power supply circuit is electrically connected to the output end of the rectifier circuit, and the output end of the transformer power supply circuit is electrically connected to the power supply end of the controller.

7. The sampling circuit of the circuit breaker according to claim 6, characterized in that: The mutual inductor power supply circuit includes a MOS tube, an anti-reverse diode, a second comparator, a first voltage-dividing resistor and a second voltage-dividing resistor; The drain of the MOS tube is electrically connected to the output end of the rectifier circuit and the anode of the anti-reverse diode respectively, the source of the MOS tube is grounded, and the gate of the MOS tube is electrically connected to the output end of the second comparator; The first end of the first voltage-dividing resistor is electrically connected to the cathode of the anti-reverse diode, the output end of the power supply and the power supply end of the controller respectively, the second end of the first voltage-dividing resistor is electrically connected to the non-inverting input end of the second comparator and the first end of the second voltage-dividing resistor respectively, the second end of the second voltage-dividing resistor is grounded, and the inverting input end of the second comparator is connected to the reference voltage; Wherein, the output voltage of the transformer power supply circuit is less than the output voltage of the power supply.

8. The sampling circuit of the circuit breaker according to claim 7, characterized in that: The transformer power supply circuit also includes a third voltage-dividing resistor and a fourth voltage-dividing resistor; The first end of the third voltage-dividing resistor is electrically connected to the cathode of the anti-reverse diode and the first end of the first voltage-dividing resistor respectively, the second end of the third voltage-dividing resistor is electrically connected to the output end of the second comparator, the gate of the MOS tube and the first end of the fourth voltage-dividing resistor respectively, and the second end of the fourth voltage-dividing resistor is grounded.

9. The sampling circuit of the circuit breaker according to claim 1, characterized in that: The sampling circuit of the circuit breaker also includes a second current transformer and a residual current sampling and conditioning circuit; The second current transformer is sleeved on the power line, the output end of the second current transformer is electrically connected to the input end of the residual current sampling and conditioning circuit, and the output end of the residual current sampling and conditioning circuit is electrically connected to the fourth sampling end of the controller.

10. A circuit breaker, characterized in that: A sampling circuit for a circuit breaker comprising any one of claims 1 to 9.

Images