Control circuit of intelligent circuit breaker and intelligent circuit breaker

Abstract

The application provides a control circuit of an intelligent circuit breaker and the intelligent circuit breaker, and relates to the technical field of circuit breakers. The control circuit comprises an acquisition unit, a control unit and a driving unit. The acquisition unit comprises an air-core mutual inductor and a current acquisition unit. The current acquisition unit is an acquisition unit with a single-channel operational amplifier circuit. The air-core coil of the air-core mutual inductor is sleeved on a preset wiring end of the intelligent circuit breaker. The wiring end of the air-core mutual inductor is connected with the input end of the current acquisition unit. The output end of the current acquisition unit is connected with the control unit. The control unit is connected with the driving unit. The driving unit is used for connecting a release device in the intelligent circuit breaker. Thus, the application solves the technical problems of space limitation and measurement accuracy in the prior art.

Description

Technical Field

[0001] This application relates to the field of circuit breaker technology, and in particular to a control circuit for an intelligent circuit breaker and an intelligent circuit breaker. Background Technology

[0002] With the continuous advancement of intelligent upgrading of low-voltage power distribution systems, the market demand for intelligent miniature circuit breakers (MCBs) has grown rapidly, with the domestic annual market size exceeding 400 million yuan. However, existing intelligent miniature circuit breakers face a significant balance between functional integration and space and cost. On the one hand, they need to achieve complete protection functions such as overload, short-circuit short-delay, and instantaneous protection. On the other hand, they must adapt to the compact structure of miniature circuit breakers and strictly control hardware costs to meet the needs of large-scale applications.

[0003] To address the aforementioned contradictions, there are currently two types of solutions: one is the miniature circuit breaker (MCB) solution, which uses a core transformer to collect current and achieve long-delay overload protection, and uses a mechanical structure to achieve instantaneous protection; the other is the molded case circuit breaker (MCCB) solution, which uses a core transformer to supply power to the fast-saturating element, and uses an air-core transformer to collect current, or a single core transformer combined with dual operational amplifiers (such as large and small channels) to achieve three-stage protection function.

[0004] However, existing technologies still have some obvious problems. The miniature circuit breaker scheme is limited by space and usually cannot integrate short-circuit short-delay protection. Moreover, its iron core transformer is prone to waveform distortion when the current exceeds 80A, which affects the measurement and protection accuracy. The molded case circuit breaker scheme is too large to be compatible with the installation size of miniature circuit breakers. Utility Model Content

[0005] The purpose of this application is to provide a control circuit for an intelligent circuit breaker and an intelligent circuit breaker in order to solve the technical problems of space constraints and measurement accuracy in the prior art.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In a first aspect, embodiments of this application provide a control circuit for an intelligent circuit breaker, the control circuit comprising: a data acquisition unit, a control unit, and a drive unit; wherein, the data acquisition unit comprises: an air-core current transformer and a current acquisition unit, the current acquisition unit being a data acquisition unit having a single-channel operational amplifier circuit; The hollow coil of the air-core current transformer is sleeved on the preset terminal of the smart circuit breaker. The terminal of the air-core current transformer is connected to the input terminal of the current acquisition unit. The output terminal of the current acquisition unit is connected to the control unit. The control unit is connected to the drive unit. The drive unit is used to connect to the trip unit in the smart circuit breaker.

[0007] Optionally, the current acquisition unit includes: a first filter circuit, the single-channel operational amplifier circuit, and a second filter circuit; The first input terminal of the first filter circuit is the input terminal of the current acquisition unit. The second input terminal of the first filter circuit is used to connect to a preset power supply. The first output terminal and the second output terminal of the first filter circuit are respectively connected to the two input terminals of the single-channel operational amplifier circuit. The output terminal of the single-channel operational amplifier circuit is connected to the input terminal of the second filter circuit. The output terminal of the second filter circuit is the output terminal of the current acquisition unit.

[0008] Optionally, the first filter circuit includes: a first resistor, a second resistor, a first capacitor, and a second capacitor; one end of the first capacitor is connected to one end of the second capacitor through the first resistor, and the other end of the first capacitor is also connected to the other end of the second capacitor through the second resistor; one end and the other end of the first capacitor serve as the first input terminal and the second input terminal of the first filter circuit, respectively, and one end and the other end of the second capacitor serve as the first output terminal and the second output terminal of the first filter circuit, respectively.

[0009] Optionally, the single-channel operational amplifier circuit includes an operational amplifier and a third capacitor, wherein the negative input terminal and the positive input terminal of the operational amplifier are respectively used to connect to the first output terminal and the second output terminal of the first filter circuit; One end of the third capacitor is connected to the negative input terminal of the operational amplifier, and the other end of the third capacitor is connected to the output terminal of the operational amplifier.

[0010] Optionally, the single-channel operational amplifier circuit further includes a first open-circuit detection circuit, which is connected between the negative input terminal and the output terminal of the operational amplifier.

[0011] Optionally, the first open circuit detection circuit includes a third resistor connected between the negative input terminal and the output terminal of the operational amplifier.

[0012] Optionally, the current acquisition unit further includes a second disconnection detection circuit, which is connected between the first input terminal and the second input terminal of the first filter circuit.

[0013] Optionally, the second disconnection detection circuit includes a fourth resistor, which is connected between the first input terminal and the second input terminal of the first filter circuit, and one end of the fourth resistor is also grounded through a fifth resistor.

[0014] Optionally, the second filter circuit further includes a sixth resistor and a fourth capacitor. One end of the sixth resistor serves as the input terminal of the second filter circuit and is used to connect to the output terminal of the single-channel operational amplifier circuit. The other end of the sixth resistor is also grounded through the fourth capacitor, and the other end of the sixth resistor serves as the output terminal of the second filter circuit.

[0015] Secondly, embodiments of this application provide an intelligent circuit breaker, comprising at least: a control circuit as described in any of the first aspects above, and a circuit breaker body, wherein the hollow coil of the air-core current transformer in the control circuit is sleeved on a preset terminal of the circuit breaker body, and the drive unit in the control circuit is connected to the trip unit of the circuit breaker body.

[0016] Technical effects: This application provides a control circuit and an intelligent circuit breaker, relating to the field of circuit breaker technology. The control circuit comprises a data acquisition unit, a control unit, and a drive unit. The data acquisition unit consists of an air-core current transformer and a current acquisition unit with a single-channel operational amplifier circuit. This significantly reduces the overall circuit size, meeting the requirements for small circuit breaker installations and lowering production and debugging costs. The air-core coil of the current transformer is fitted onto the preset terminals of the intelligent circuit breaker. The terminals of the current transformer are connected to the input terminals of the current acquisition unit, and the output terminals of the current acquisition unit are connected to the control unit. The control unit is connected to the drive unit, which is used to connect to the trip unit in the intelligent circuit breaker. Therefore, by employing an air-core current transformer and a current acquisition unit, this application achieves three-stage protection—overload long-delay, short-circuit short-delay, and instantaneous protection—in a single-channel architecture, meeting the complete protection requirements of intelligent power distribution systems. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the control circuit of an intelligent circuit breaker provided in this application embodiment. Figure 1 ; Figure 2 This is a schematic diagram of the structure of a current acquisition unit provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of an intelligent circuit breaker provided in this application embodiment. Figure 1 ; Figure 4 A schematic diagram of the control circuit of an intelligent circuit breaker provided in this application embodiment. Figure 2 ; Figure 5 A schematic diagram of the structure of an intelligent circuit breaker provided in this application embodiment. Figure 2 . Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] To better understand the solutions provided in the embodiments of this application, the control circuit and the intelligent circuit breaker provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0027] Figure 1 A schematic diagram of the control circuit of an intelligent circuit breaker provided in this application embodiment. Figure 1 .like Figure 1 As shown, the control circuit 200 of the intelligent circuit breaker may include: a data acquisition unit 100, a control unit 210, and a drive unit 220.

[0028] The acquisition unit 100 includes: an air-core current transformer (CT) and a current acquisition unit 110.

[0029] Among them, the current acquisition unit 110 is an acquisition unit with a single-channel operational amplifier circuit; the single channel can significantly reduce the number of components such as operational amplifiers and capacitors, adapt to the compact space of miniature circuit breakers, and reduce circuit design and production debugging costs.

[0030] As a current sensing element, the air-core current transformer (CT) has its air-core coil mounted on a preset terminal of the intelligent circuit breaker. This preset terminal can be selected according to actual conditions; for example, it can be an incoming or outgoing terminal. When the air-core current transformer (CT) is in operation, the current at the preset terminal will induce a weak current signal proportional to the original current in the air-core coil, achieving contactless current acquisition and avoiding the problems of large size and waveform distortion under high current of iron-core current transformers.

[0031] The terminals of the air-core current transformer (CT) are connected to the input terminal of the current acquisition unit 110, and the output terminal of the current acquisition unit 110 is connected to the control unit 210. The control unit 210 amplifies the weak signal output by the air-core current transformer CT, eliminating the need to distinguish between large and small channels, and converts the amplified induced signal into a stable voltage signal, which is then sent to the control unit 210. The control unit 210 is connected to the drive unit 220, which is used to connect to the trip unit in the intelligent circuit breaker. The control unit 210 incorporates an algorithm to analyze the acquired current signal, enabling current measurement through multi-cycle sampling calculations, such as real-time current monitoring; or determining whether overload and / or short-circuit short-delay and / or instantaneous protection is triggered by calculating the effective current value using a single cycle, 0.5 cycles, or other numbers of cycles. For example, when the effective current value exceeds a preset threshold, the control unit 210 generates a trip command.

[0032] The type of control unit 210 can be selected according to the actual situation. For example, the type of control unit 210 can be a GD32 series controller.

[0033] The drive unit 220 is used to convert electrical signals into mechanical actions, ensuring that protection commands from the control unit 210 (such as overload tripping or short-circuit tripping) are accurately transmitted to the trip unit, ultimately realizing the opening and closing operations of the circuit breaker. The drive unit 220 can be divided into a tripping drive circuit and a closing drive circuit, depending on the actual situation. The corresponding trip unit may include a closing electromagnet and a tripping coil.

[0034] It should be noted that the control unit 210 can also be used to incorporate a Fourier transform algorithm to extract harmonic components, avoid protection malfunctions caused by high-order harmonics, and ensure the reliable operation of the circuit breaker in complex power grid environments.

[0035] Furthermore, it should be noted that the aforementioned acquisition unit 100 can be widely applied to different types of products, including single-stage, two-stage, and four-stage products. In single-stage and two-stage products, the intelligent circuit breaker only needs to be configured with one acquisition unit 100. The hollow coil of the air-core current transformer (CT) in this acquisition unit 100 is sleeved on the preset terminal connected to the corresponding phase line and works in conjunction with the current acquisition unit 110. In four-stage products, a separate acquisition unit 100 is set for each phase line, and the hollow coil of each air-core current transformer (CT) is sleeved on the preset terminal of the corresponding phase line.

[0036] The control circuit of the intelligent circuit breaker provided in this application can be composed of a data acquisition unit, a control unit, and a drive unit. The data acquisition unit can consist of an air-core current transformer and a current acquisition unit. The current acquisition unit is a data acquisition unit with a single-channel operational amplifier circuit. By using the air-core current transformer and the single-channel operational amplifier circuit, the overall circuit size is significantly reduced, conforming to the miniaturization design trend of intelligent circuit breakers and reducing production and debugging costs. The air-core coil of the air-core current transformer is fitted onto the preset terminals of the intelligent circuit breaker. The terminals of the air-core current transformer are connected to the input terminals of the current acquisition unit, and the output terminals of the current acquisition unit are connected to the control unit. The control unit is connected to the drive unit, which is used to connect to the trip unit in the intelligent circuit breaker. Therefore, by using an air-core current transformer and a current acquisition unit, this application achieves three-stage protection—overload long-delay, short-circuit short-delay, and instantaneous protection—in a single-channel architecture, meeting the complete protection requirements of intelligent power distribution systems.

[0037] Figure 2 This is a schematic diagram of a current acquisition unit provided in an embodiment of this application. Figure 2 As shown, the current acquisition unit 110 includes: a first filter circuit 111, a single-channel operational amplifier circuit 112, and a second filter circuit 113.

[0038] The first input terminal of the first filter circuit 111 is the input terminal of the current acquisition unit 110 to receive the raw current sensing signal output by the air-core transformer; the second input terminal of the first filter circuit 111 is used to connect to a preset power supply to provide DC bias or reference potential. The preset power supply can be selected according to actual conditions. For example, the preset power supply can be selected as 1.5V.

[0039] The first filter circuit 111 is used to initially filter out high-frequency interference (such as electromagnetic radiation) in the original current sensing signal, while providing stable input conditions for the subsequent single-channel operational amplifier circuit 112. A suitable DC bias (preset power supply) is superimposed on the original current sensing signal to ensure that the single-channel operational amplifier circuit 112 operates in the linear region. The first filter circuit 111 can be selected as a low-pass filter.

[0040] The first output terminal and the second output terminal of the first filter circuit 111 are respectively connected to the two input terminals of the single-channel operational amplifier circuit 112 to amplify the signal that has undergone preliminary filtering in a single channel.

[0041] The output of the single-channel operational amplifier circuit 112 is connected to the input of the second filter circuit 113. The second filter circuit 113 serves as a fine-filtering stage for the signal output, further filtering out operational amplifier noise or residual interference introduced during amplification. The output of the second filter circuit 113 is the output of the current acquisition unit 110, which transmits the amplified, clean voltage signal from the output to the control unit 210. The single-channel operational amplifier circuit 112 can be selected as an integrating circuit. The second filter circuit 113 can be selected as an RC filter circuit.

[0042] The first filter circuit 111 and the second filter circuit 113 form a front-to-back filter architecture. The front stage is used to filter out external interference (such as power grid harmonics or electromagnetic interference) in the original current sensing signal of the air-core transformer, and the back stage is used to filter out internal noise introduced by the operational amplifier amplification, so as to ensure the accuracy of the current information extracted by the control unit 210 and provide a basis for the accuracy of overload and short circuit protection.

[0043] The control circuit of the intelligent circuit breaker provided in this application includes a current acquisition unit comprising a first filter circuit, a single-channel operational amplifier circuit, and a second filter circuit. The first input terminal of the first filter circuit is the input terminal of the current acquisition unit, and the second input terminal of the first filter circuit is connected to a preset power supply. The first and second output terminals of the first filter circuit are respectively connected to the two input terminals of the single-channel operational amplifier circuit. The output terminal of the single-channel operational amplifier circuit is connected to the input terminal of the second filter circuit, and the output terminal of the second filter circuit is the output terminal of the current acquisition unit. Thus, the first filter circuit of this application, by setting a preset power supply, provides DC bias to superimpose the AC induced signal output from the air-core transformer onto the linear operating voltage range of the operational amplifier, ensuring that the signal amplification process has no cutoff or saturation, reducing acquisition linearity error, solving the problem of waveform distortion under high current in the iron-core transformer, and allowing the single-channel architecture to cover the complete protection current range.

[0044] Continue to refer to Figure 2 The first filter circuit 111 includes: a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2.

[0045] Wherein, one end of the first capacitor C1 is the first input terminal of the first filter circuit 111, which is connected to the original current sensing signal output by the air-core current transformer CT; the other end of the first capacitor C1 is the second input terminal of the first filter circuit 111, which is used to connect to a preset power supply to provide DC bias or reference potential.

[0046] One end of the first capacitor C1 is connected to one end of the second capacitor C2 through the first resistor R1, and the other end of the first capacitor C1 is also connected to the other end of the second capacitor C2 through the second resistor R2.

[0047] One end and the other end of the second capacitor C2 serve as the first output terminal and the second output terminal of the first filter circuit 111, respectively, and are directly connected to the two input terminals of the single-channel operational amplifier circuit 112 to form a differential input.

[0048] The first filter circuit 111 is a symmetrical RC filter network or a low-pass filter circuit.

[0049] In this circuit, the first capacitor C1 and the second capacitor C2 are filter capacitors, mainly used to filter out high-frequency interference in the signal (such as high-order harmonics of the power grid or glitches generated by electromagnetic radiation). The first resistor R1 and the second resistor R2 are current-limiting or voltage-dividing resistors, forming an RC filter network with the first capacitor C1 and the second capacitor C2. The symmetrical structure enables the first filter circuit 111 to have common-mode rejection capability against interference at its first input terminal (signal terminal) and second input terminal (reference power supply terminal). The two ends of the first capacitor C1 are used to handle external common-mode interference (such as spatial electromagnetic interference); the first resistor R1 and the second resistor R2 are used for symmetrical voltage division; and the second capacitor C2 is used to retain useful differential-mode signals (such as the current signal induced by the air-core current transformer CT).

[0050] The control circuit of the intelligent circuit breaker provided in this application includes a first filter circuit comprising: a first resistor, a second resistor, a first capacitor, and a second capacitor; one end of the first capacitor is connected to one end of the second capacitor through the first resistor, and the other end of the first capacitor is also connected to the other end of the second capacitor through the second resistor; one end and the other end of the first capacitor serve as the first input terminal and the second input terminal of the first filter circuit, respectively, and one end and the other end of the second capacitor serve as the first output terminal and the second output terminal of the first filter circuit, respectively. Therefore, the first filter circuit of this application is used to initially filter out high-frequency noise in the output signal of the air-core transformer, preventing high-frequency components from entering the subsequent single-channel operational amplifier circuit and causing signal distortion or full-scale bias. Simultaneously, it provides stable input conditions for the single-channel operational amplifier circuit.

[0051] Continue to refer to Figure 2 The single-channel operational amplifier circuit 112 includes: operational amplifier U1 and third capacitor C3.

[0052] The negative input terminal (inverting terminal) and positive input terminal (non-inverting terminal) of the operational amplifier U1 are respectively connected to the first output terminal and the second output terminal of the first filter circuit 111 to form a differential input to the output signal of the first filter circuit 111, that is, to receive the differential mode signal after primary filtering; one end of the third capacitor C3 is connected to the negative input terminal of the operational amplifier U1, and the other end of the third capacitor C3 is connected to the output terminal of the operational amplifier U1 to form a voltage parallel negative feedback loop, wherein the feedback signal returns from the output terminal of the operational amplifier U1 to the inverting input terminal.

[0053] Among them, the single-channel operational amplifier circuit 112 is an operational amplifier structure with a feedback capacitor.

[0054] Operational amplifier U1 is used for signal amplification, and the third capacitor C3 is a feedback capacitor used for phase compensation to extend the stable operating frequency range of operational amplifier U1 and avoid self-oscillation of the amplifier circuit (output signal distortion) caused by high-frequency signals (such as peak currents during short-circuit transients). This reduces the signal jitter amplitude caused by high-frequency interference, ensuring that the signal collected by control unit 210 accurately reflects the actual current state of the circuit and reduces protection malfunctions.

[0055] The control circuit of the intelligent circuit breaker provided in this application includes a single-channel operational amplifier circuit comprising an operational amplifier and a third capacitor. The negative and positive input terminals of the operational amplifier are respectively connected to the first and second output terminals of the first filter circuit. One end of the third capacitor is connected to the negative input terminal of the operational amplifier, and the other end of the third capacitor is connected to the output terminal of the operational amplifier. Thus, the single-channel operational amplifier circuit of this application receives the differential signal from the first filter circuit through its negative and positive input terminals. Combined with a negative feedback mechanism, it improves common-mode interference and achieves stable linear amplification. Compared with iron-core transformers, it reduces nonlinear distortion errors under high current, providing accurate raw signals for the three-stage protection algorithm of the control unit (overload long delay, short-circuit short delay, and instantaneous protection), and solving the signal distortion problem caused by the complex installation environment of miniature circuit breakers.

[0056] Continue to refer to Figure 2 The single-channel operational amplifier circuit 112 also includes: a first open circuit detection circuit.

[0057] The first open circuit detection circuit is connected between the negative input terminal and the output terminal of the operational amplifier U1. It is part of the operational amplifier feedback loop and is connected in parallel with the third capacitor C3 of the single-channel operational amplifier circuit 112 so as not to affect the amplification characteristics.

[0058] In one possible implementation, the first disconnection detection principle is as follows: When the control circuit 200 is working normally, there is a stable feedback relationship between the output signal of the operational amplifier U1 and the negative input signal. The voltage difference across the first disconnection detection circuit is the difference between the output signal and the negative input signal of the operational amplifier U1, which is within a stable range. When the air-core transformer CT disconnects, the first filter circuit 111 malfunctions (e.g., component damage) or the upstream signal transmission link is interrupted, the negative input signal of the operational amplifier U1 will become abnormal (e.g., approaching 0 or a fixed value), causing the voltage difference across the operational amplifier U1 to deviate from the normal range. This abnormal signal can be indirectly fed back to the control unit 210. This abnormal signal can also be used to deduce the signal change after passing through the second filter circuit.

[0059] The first open circuit detection circuit is used to identify open circuit faults by monitoring the voltage difference between the negative input terminal and the output terminal of the operational amplifier U1. The control unit 210 is used to immediately trigger an alarm (such as an indicator light or communication feedback) or safety protection (such as forced tripping) after receiving an abnormal signal, so as to solve the problem that signal link faults cannot be detected in the existing solution and improve the safety redundancy of the smart circuit breaker.

[0060] The control circuit of the intelligent circuit breaker provided in this application includes a first disconnection detection circuit connected between the negative input terminal and the output terminal of the operational amplifier. Therefore, this application can realize the signal link disconnection monitoring function of the miniature intelligent circuit breaker through the first disconnection detection circuit, thereby improving the reliability of the intelligent circuit breaker in complex power distribution environments.

[0061] Continue to refer to Figure 2 The first disconnection detection circuit includes: a third resistor R3.

[0062] The third resistor R3 is connected between the negative input terminal (inverting terminal) and the output terminal of the operational amplifier U1, and forms a parallel relationship with the third capacitor C3 (feedback capacitor) in the single-channel operational amplifier circuit 112, together forming the feedback loop of the single-channel operational amplifier circuit 112.

[0063] The resistance value of the third resistor R3 is designed to be much larger than the feedback resistor of the single-channel operational amplifier circuit 112.

[0064] The control circuit of the intelligent circuit breaker provided in this application includes a first disconnection detection circuit comprising a third resistor connected between the negative input terminal and the output terminal of an operational amplifier. Thus, this application utilizes the third resistor to achieve signal link disconnection monitoring in a miniature intelligent circuit breaker, thereby improving the reliability of the intelligent circuit breaker in complex power distribution environments.

[0065] Continue to refer to Figure 2 The current acquisition unit 110 also includes a second disconnection detection circuit 114.

[0066] The second disconnection detection circuit 114 is connected between the first input terminal and the second input terminal of the first filter circuit 111. The first input terminal of the first filter circuit 111 is connected to the output terminal of the air-core current transformer (CT) to receive the original current sensing signal; the second input terminal of the first filter circuit 111 is connected to a preset power supply to provide a DC bias or reference potential point, thus constituting direct monitoring of the signal link from the air-core current transformer (CT) to the front end of the first filter circuit.

[0067] In one possible implementation, the operating logic of the second disconnection detection circuit 114 is based on the sudden change in voltage difference between the normal signal and the disconnection state. During normal operation, the AC induction signal output by the air-core current transformer (CT) is superimposed with the DC bias of a preset power supply to form a stable alternating voltage difference between the two input terminals of the first filter circuit 111. The voltage across the second disconnection detection circuit 114 changes synchronously with this alternating voltage difference (the amplitude is determined by the signal strength). In the disconnection state, if the air-core current transformer (CT) lead is broken, the connection to the first filter circuit 111 is loose, or the CT itself is damaged, the first input terminal of the first filter circuit 111 will lose its induction signal. At this time, the voltage difference between the two input terminals will change abruptly, determined only by the DC bias of the preset power supply, without any alternating component. This abnormal signal is transmitted through the first filter circuit 111 to the subsequent single-channel operational amplifier circuit 112 and the control unit 210, which triggers the disconnection detection.

[0068] The control circuit of the intelligent circuit breaker provided in this application includes a current acquisition unit further comprising a second open-circuit detection circuit connected between the first and second input terminals of the first filter circuit. Thus, this application uses the second open-circuit detection circuit to directly monitor the front-end link from the air-core current transformer to the input terminal of the first filter circuit, while the first open-circuit detection circuit monitors the back-end link fault from the first filter circuit to the single-channel operational amplifier circuit. The combination of the two open-circuit detection circuits expands the coverage of open-circuit detection, improves the identification rate of signal link faults, avoids protection failures caused by undetected front-end open circuits, and thereby enhances the reliability of the equipment in complex power distribution environments.

[0069] Continue to refer to Figure 2 The second disconnection detection circuit 114 includes: a fourth resistor R4.

[0070] The fourth resistor R4 is connected between the first input terminal and the second input terminal of the first filter circuit 111. The first input terminal of the first filter circuit 111 is connected to the output terminal of the air-core current transformer (CT) to receive the original current sensing signal. The second input terminal of the first filter circuit 111 is connected to a preset power supply to provide DC bias or a reference potential point.

[0071] One end of the fourth resistor R4 is also grounded through the fifth resistor R5, and the other end of the fourth resistor R4 is connected to a preset power supply to form a series voltage divider and grounding monitoring loop between the fourth resistor R4 and the fifth resistor R5. This establishes a voltage anomaly monitoring point for the link from the air-core current transformer (CT) to the front end of the first filter circuit 111.

[0072] Among them, the fourth resistor R4 can be a pull-up resistor; the fifth resistor R5 is a pull-down resistor.

[0073] In one possible implementation, when the second open circuit detection circuit 114 is working normally, the AC induction signal output by the air-core current transformer (CT) (superimposed with the DC bias of the preset power supply) will form an alternating voltage across the fourth resistor R4. Since the fifth resistor R5 is connected in series with the fourth resistor R4, the voltage across the fifth resistor R5 changes synchronously with the alternating voltage. When the air-core current transformer CT is disconnected, the lead wire has poor contact, or the first input terminal connector is loose, the first input terminal of the first filter circuit 111 loses the induction signal and only retains the DC bias of the preset power supply, causing a sudden change in the voltage across the fourth resistor R4. The ground voltage across the fifth resistor R5 also becomes a fixed value. This abnormal signal is transmitted to the subsequent circuit through the first filter circuit 111, and the control unit 210 is used to identify the abnormal signal.

[0074] The control circuit of the intelligent circuit breaker provided in this application includes a second open-circuit detection circuit comprising a fourth resistor connected between the first and second input terminals of the first filter circuit, with one end of the fourth resistor grounded via a fifth resistor. Thus, this application achieves high-sensitivity open-circuit detection of the front-end signal link through the fourth and fifth resistors, forming a synergy with back-end detection. This is a key supplement to the minimalist architecture and high safety redundancy balance of miniature intelligent circuit breakers.

[0075] Continue to refer to Figure 2 The second filter circuit 113 also includes: a sixth resistor R6 and a fourth capacitor C4.

[0076] In this circuit, one end of the sixth resistor R6 serves as the input terminal of the second filter circuit 113, which is used to connect to the output terminal of the single-channel operational amplifier circuit U1. The other end of the sixth resistor R6 is also grounded through the fourth capacitor C4. The other end of the sixth resistor R6 serves as the output terminal of the second filter circuit 113, which is connected to the control unit 210, so as to form a complete link of the sixth resistor R6 series current limiting and the fourth capacitor C4 parallel ground filtering.

[0077] In one possible implementation, the second filter circuit 113 operates as follows: when the signal output by the operational amplifier (including the amplified useful current signal and a small amount of high-frequency noise) flows through the sixth resistor R6, the low-frequency useful signal, due to its low frequency and large capacitive reactance, is transmitted to the output terminal of the second filter circuit 113 by the sixth resistor R; while the high-frequency noise, due to its high frequency and small capacitive reactance, is absorbed by the fourth capacitor C4 by grounding, thus achieving the purification effect of retaining the low-frequency signal and filtering out the high-frequency noise.

[0078] It should be noted that the second filter circuit 113 and the first filter circuit 111 form a two-stage anti-interference system consisting of a pre-stage filter and a post-stage fine filter: the first filter circuit 111 is mainly used to filter out external high-frequency interference (such as power grid harmonics) introduced by the air-core current transformer (CT), while the second filter circuit 113 is used to specifically filter out internal noise generated during the operational amplifier amplification process. The two work together to improve the anti-interference capability of the control circuit. Even in complex electromagnetic environments (such as multiple devices working simultaneously in a distribution box), the purity of the current signal can still be maintained, solving the signal distortion problem caused by the complex installation environment of miniature circuit breakers.

[0079] The control circuit of the intelligent circuit breaker provided in this application includes a second filter circuit that further comprises a sixth resistor and a fourth capacitor. One end of the sixth resistor serves as the input terminal of the second filter circuit, connecting to the output terminal of the single-channel operational amplifier circuit. The other end of the sixth resistor is grounded through the fourth capacitor, and the other end of the sixth resistor serves as the output terminal of the second filter circuit. Therefore, the single-channel operational amplifier circuit of this application may introduce high-frequency noise from the operational amplifier itself when amplifying signals. If directly input to the control unit, this can cause fluctuations in the current sampling value, resulting in errors and affecting the accuracy of overload and short-circuit protection judgments. The second filter circuit, through its RC low-pass characteristic, improves the high-frequency noise attenuation rate and enhances the signal-to-noise ratio of the control unit, providing a reliable data foundation for the three-stage protection algorithm (overload long delay, short-circuit short delay, and instantaneous).

[0080] Figure 3 A schematic diagram of the structure of an intelligent circuit breaker provided in this application embodiment. Figure 1 .like Figure 3 As shown, the intelligent circuit breaker 300 includes at least: a control circuit 200 and a circuit breaker body 310.

[0081] In the control circuit 200, the air-core current transformer (CT) has its air-core coil mounted on a preset terminal of the circuit breaker body 310 to form a non-contact current acquisition. The drive unit 220 in the control circuit 200 is connected to the trip unit of the circuit breaker body 310 to trigger the trip unit to operate. For example, the tripping coil is used to generate magnetic force to push the tripping mechanism, or the closing electromagnet is used to achieve closing.

[0082] The control circuit 200 is responsible for current monitoring, logic judgment, and command output; the circuit breaker body 310 is responsible for the mechanical structure of the main circuit switching, including preset terminals, trip unit, moving and stationary contacts, etc. The two achieve electrical and mechanical coordination through two links from the air-core transformer signal acquisition and drive unit to the trip unit execution.

[0083] The trip unit includes actuators such as the tripping coil and the closing electromagnet.

[0084] The intelligent circuit breaker provided in this application consists of at least a control circuit and a circuit breaker body. The air-core coil of the air-core current transformer in the control circuit is fitted onto a preset terminal of the circuit breaker body to achieve electrical isolation between the control circuit and the main circuit (high voltage or high current). This prevents surges, overvoltages, and other interference from the main circuit from entering the control circuit, thus solving the safety hazard of mixed high and low voltage connections caused by electrical connections in traditional shunts (direct series connection). The drive unit in the control circuit is connected to the trip unit of the circuit breaker body, improving fault response speed. Therefore, this application, through non-contact current acquisition and direct drive, achieves multiple advantages such as safe isolation, rapid protection, and low-cost mass production while ensuring spatial compatibility of miniature circuit breakers. It overcomes the bottlenecks of high retrofit costs, limited installation, and slow response of traditional intelligent circuit breakers.

[0085] To facilitate understanding of the control circuit and the intelligent circuit breaker described above, this application also provides a structural example of the control circuit, which will be further described below with reference to the accompanying drawings. Figure 4 A schematic diagram of the control circuit of an intelligent circuit breaker provided in this application embodiment. Figure 2 .like Figure 4 As shown, the control circuit 200 of the intelligent circuit breaker may further include a voltage acquisition unit 230.

[0086] The input terminal of the voltage acquisition unit 230 is connected to the preset terminal of the smart circuit breaker, which is usually the phase line and neutral line of the incoming line. The output terminal of the voltage acquisition unit 230 is connected to the control unit 210 to process the acquired voltage signal, realize the digital acquisition of the voltage signal, and realize power level protection based on the voltage signal.

[0087] The control unit 210 is connected to the drive unit 220, which is used to connect to the trip unit in the intelligent circuit breaker so as to control the trip unit in the intelligent circuit breaker to open or close according to the voltage signal.

[0088] It should be noted that the voltage acquisition unit 230 described above can be applied to different types of products, such as single-pole, two-pole, and four-pole. In single-pole and two-pole products, the intelligent circuit breaker only needs to be equipped with one voltage acquisition unit 230 connected to the corresponding phase line; while in four-pole products, a separate voltage acquisition unit 230 needs to be configured for each phase line.

[0089] The control circuit of the intelligent circuit breaker provided in this application can also be composed of a voltage acquisition unit. The input terminal of the voltage acquisition unit is connected to the preset wiring terminal of the intelligent circuit breaker; the output terminal of the voltage acquisition unit is connected to the control unit. Thus, the addition of the voltage acquisition unit in this application upgrades the intelligent circuit breaker from single current protection to current-voltage coordinated monitoring, expanding the dimensions of protection functions and filling the gap in voltage fault monitoring. By monitoring the main circuit voltage in real time, the voltage acquisition unit, in conjunction with the voltage protection algorithm built into the control unit, can identify overvoltage or undervoltage faults and trigger tripping, solving the functional deficiency of traditional circuit breakers that only protect current and not voltage, and improving the comprehensiveness of protection for end appliances. Simultaneously, voltage and current acquisition work together to provide basic data for intelligent power distribution systems. Compared to traditional circuit breakers that can only disconnect circuits, this function gives the device dual attributes of metering and protection, making it suitable for energy management needs in smart homes and small industrial scenarios, expanding the product's application scenarios.

[0090] Figure 5 A schematic diagram of the structure of an intelligent circuit breaker provided in this application embodiment. Figure 2 .like Figure 5 As shown, the intelligent circuit breaker 300 may also include a communication unit 320 and a power supply 330.

[0091] The preset load unit is connected to the control unit 210 via the communication unit 320; the preset load unit can be selected according to actual conditions. For example, the preset load unit can be lighting or air conditioning in a smart home, or motors or sensors in industry.

[0092] The communication method of the communication unit 320 can be adapted to the scenario, and can adopt wired (such as RS485, CAN or Ethernet) or wireless (such as WiFi or 4G) technologies. For example, WiFi is commonly used in home scenarios to realize local load linkage, while RS485 is commonly used in industrial scenarios to realize remote monitoring.

[0093] It should be noted that the communication unit 320 breaks the information silo status of traditional circuit breakers. The control unit can be used to upload real-time electrical parameters (current, voltage, power) and fault information (overload, short circuit, open circuit) to the preset load unit or monitoring platform through the communication unit 320. At the same time, it can receive external control commands (such as remote tripping and adjustment of protection thresholds) to realize data interaction and remote management, thereby improving the level of intelligence.

[0094] The power supply 330 provides operating power to the control circuit 200 and the communication unit 320. The input terminal of the power supply 330 is typically connected to the preset wiring terminal of the main circuit of the smart circuit breaker (e.g., drawing 220V AC power from LN). If the power supply 330 is an AC power source, it also includes an AC-DC conversion module. This module converts the AC power signal into a low-voltage DC signal to power the control circuit (including the current or voltage acquisition unit, control unit, and drive unit) and the communication unit 320, ensuring stable operation of each module even when the mains voltage fluctuates.

[0095] The intelligent circuit breaker provided in this application can also consist of a communication unit and a power supply. The preset load unit is connected to the control unit via the communication unit; the power supply provides operating power to both the control circuit and the communication unit. Therefore, the power supply in this application ensures that the control circuit and communication unit can still operate normally under grid voltage fluctuations and harmonic interference, improving reliability and preventing protection function failure due to power outages.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A control circuit for an intelligent circuit breaker, characterized in that, The control circuit includes: a data acquisition unit, a control unit, and a drive unit; wherein, the data acquisition unit includes: an air-core current transformer and a current acquisition unit, and the current acquisition unit is a data acquisition unit with a single-channel operational amplifier circuit; The hollow coil of the air-core current transformer is sleeved on the preset terminal of the smart circuit breaker. The terminal of the air-core current transformer is connected to the input terminal of the current acquisition unit. The output terminal of the current acquisition unit is connected to the control unit. The control unit is connected to the drive unit. The drive unit is used to connect to the trip unit in the smart circuit breaker.

2. The control circuit of the intelligent circuit breaker according to claim 1, characterized in that, The current acquisition unit includes: a first filter circuit, the single-channel operational amplifier circuit, and a second filter circuit; The first input terminal of the first filter circuit is the input terminal of the current acquisition unit. The second input terminal of the first filter circuit is used to connect to a preset power supply. The first output terminal and the second output terminal of the first filter circuit are respectively connected to the two input terminals of the single-channel operational amplifier circuit. The output terminal of the single-channel operational amplifier circuit is connected to the input terminal of the second filter circuit. The output terminal of the second filter circuit is the output terminal of the current acquisition unit.

3. The control circuit of the intelligent circuit breaker according to claim 2, characterized in that, The first filter circuit includes: a first resistor, a second resistor, a first capacitor, and a second capacitor; one end of the first capacitor is connected to one end of the second capacitor through the first resistor, and the other end of the first capacitor is also connected to the other end of the second capacitor through the second resistor; one end and the other end of the first capacitor serve as the first input terminal and the second input terminal of the first filter circuit, respectively, and one end and the other end of the second capacitor serve as the first output terminal and the second output terminal of the first filter circuit, respectively.

4. The control circuit of the intelligent circuit breaker according to claim 2, characterized in that, The single-channel operational amplifier circuit includes an operational amplifier and a third capacitor. The negative input terminal and the positive input terminal of the operational amplifier are respectively used to connect to the first output terminal and the second output terminal of the first filter circuit. One end of the third capacitor is connected to the negative input terminal of the operational amplifier, and the other end of the third capacitor is connected to the output terminal of the operational amplifier.

5. The control circuit of the intelligent circuit breaker according to claim 4, characterized in that, The single-channel operational amplifier circuit further includes a first open-circuit detection circuit, which is connected between the negative input terminal and the output terminal of the operational amplifier.

6. The control circuit of the intelligent circuit breaker according to claim 5, characterized in that, The first open circuit detection circuit includes a third resistor connected between the negative input terminal and the output terminal of the operational amplifier.

7. The control circuit of the intelligent circuit breaker according to claim 2, characterized in that, The current acquisition unit further includes a second disconnection detection circuit, which is connected between the first input terminal and the second input terminal of the first filter circuit.

8. The control circuit of the intelligent circuit breaker according to claim 7, characterized in that, The second disconnection detection circuit includes a fourth resistor, which is connected between the first input terminal and the second input terminal of the first filter circuit, and one end of the fourth resistor is also grounded through a fifth resistor.

9. The control circuit of the intelligent circuit breaker according to claim 2, characterized in that, The second filter circuit further includes a sixth resistor and a fourth capacitor. One end of the sixth resistor serves as the input terminal of the second filter circuit and is used to connect to the output terminal of the single-channel operational amplifier circuit. The other end of the sixth resistor is grounded through the fourth capacitor, and the other end of the sixth resistor serves as the output terminal of the second filter circuit.

10. An intelligent circuit breaker, characterized in that, It includes at least: the control circuit as described in any one of claims 1 to 9 above, and the circuit breaker body, wherein the air core coil of the air core transformer in the control circuit is sleeved on the preset terminal of the circuit breaker body, and the drive unit in the control circuit is connected to the trip unit of the circuit breaker body.

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