A miniature circuit breaker electric energy metering system based on external power supply and signal bus
By using an external power supply and communication module and signal bus, a centralized power supply and signal are provided to the miniature circuit breaker, which solves the problems of large internal space occupation, low safety and high cost of miniature circuit breakers, and realizes efficient power metering and simple installation.
Patent Information
- Application Number
- CN202610792810.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-03
- Publication Date
- 2026-08-25
AI Technical Summary
In existing technologies, each miniature circuit breaker requires an independent connection to the live and neutral wires for voltage sampling, resulting in problems such as large space occupation, low safety, high cost, and difficult layout.
The miniature circuit breaker energy metering system, which adopts external power supply and signal bus, provides low-voltage DC operating voltage and low-voltage AC voltage signal through an external power supply and communication module. The signal bus is used to transmit the signal in series to each miniature circuit breaker, eliminating the internal neutral wire and realizing centralized voltage sampling and signal distribution.
It saves internal space, improves safety, reduces costs, simplifies wiring, enhances reliability, and enables high-precision power metering.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of low-voltage power distribution and smart meter technology, specifically to a modular device and connection system that provides centralized safe power and voltage sampling signals for multiple miniature circuit breakers. Background Technology
[0002] In smart grids and energy management, metering modules need to be integrated into each miniature circuit breaker in a household or building distribution box to achieve branch power metering and monitoring. The current mainstream solution is to set up an independent metering circuit board inside each miniature circuit breaker. This circuit board needs to be connected to both the live wire and the neutral wire to obtain voltage and current signals for metering. This approach has significant drawbacks: First, within the extremely limited internal space of a miniature circuit breaker, simultaneously arranging the live and neutral wires of high-voltage electricity and maintaining the necessary electrical safety creepage distance between them occupies most of the circuit board space, leading to crowded component layout, poor heat dissipation, decreased reliability, and limiting the functional expansion of the metering chip. Second, each circuit breaker requires separate handling of high voltage, resulting in repeated insulation and protection costs and high overall costs. Third, the installation and wiring are complex, requiring two power lines to be connected to each circuit breaker, leading to low construction efficiency. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art, which require each miniature circuit breaker to be independently introduced with live and neutral wires for voltage sampling, resulting in large space occupation, low safety, high cost and difficult layout. The present invention provides a new system with centralized external processing and serial distribution through a safety signal bus. To achieve the above objectives, the present invention adopts the following technical solution: A miniature circuit breaker energy metering system based on an external power supply and signal bus includes: an external power supply and communication module and at least one miniature circuit breaker with metering function; The external power supply and communication module integrates a switching power supply circuit and a voltage sampling isolation circuit. The input of the switching power supply circuit is connected to the live and neutral wires of the mains power supply, and the output provides a low-voltage DC operating voltage. The voltage sampling isolation circuit includes a voltage transformer, whose primary side is connected in parallel between the live and neutral wires of the mains power supply, and whose secondary side is connected in sequence to a signal conditioning circuit and a first-stage operational amplifier buffer circuit, for outputting a low-voltage AC voltage signal that is in phase and frequency with the mains power supply. The external power supply and communication module is provided with an output interface, which simultaneously outputs the low-voltage DC operating voltage and the low-voltage AC voltage signal. The miniature circuit breaker with metering function has a metering circuit board inside, on which an energy metering chip is integrated; the miniature circuit breaker has mutually cooperating input interfaces and cascaded output interfaces, which are electrically connected inside the miniature circuit breaker to the power input terminal of the metering circuit board and the voltage sampling channel of the energy metering chip. The output interface of the external power supply and communication module is plugged into the input interface of the first miniature circuit breaker; multiple miniature circuit breakers are connected in sequence through adjacent cascaded output interfaces and input interfaces to form a series bus, so as to transmit the low-voltage DC working voltage and low-voltage AC voltage signals to each miniature circuit breaker. The energy metering chip obtains the low-voltage AC voltage signal through its voltage sampling channel and combines it with the current sampling signal flowing through the miniature circuit breaker to complete the energy metering. Preferably, the operational amplifier buffer circuit is a voltage follower or a non-inverting amplifier with low output impedance, used to drive the series bus and ensure that the low-voltage AC signal does not attenuate significantly as the transmission distance increases. Preferably, the low-voltage AC signal output by the external power supply and communication module is an AC signal with an effective value of 10mV to 100mV. Preferably, in the voltage sampling isolation circuit of the external power supply communication module, the signal conditioning circuit is a resistor voltage divider circuit. This invention also provides an energy metering method applicable to the above-mentioned system, characterized in that: The external power supply and communication module draws power from the mains to generate a low-voltage DC working voltage, and at the same time generates a low-voltage AC voltage signal with the same frequency and phase as the mains voltage through isolation sampling via a voltage transformer. The low-voltage DC operating voltage and low-voltage AC voltage signals are transmitted to each miniature circuit breaker through the output interface and serial bus. Each miniature circuit breaker's internal energy metering chip receives the low-voltage AC voltage signal through its voltage sampling channel, and simultaneously acquires the current signal flowing through the circuit breaker, thereby calculating the energy parameters. The beneficial effects of this invention are: Saving internal space in miniature circuit breakers: The need for a neutral wire inside each miniature circuit breaker is completely eliminated, thus removing the encroachment of high-voltage neutral wires and their safety clearances on circuit board space. The miniature circuit breaker only needs to handle its own low-voltage current signal and externally introduced low-voltage signals, making the circuit board layout extremely flexible. This allows for the integration of more functions or the use of smaller PCBs to reduce costs. Fundamental improvement in safety: The introduction and conversion of 220V AC mains power, as well as high-precision voltage signal sampling, are all completed in a single, external module with sufficient protection. Only low-voltage DC safety voltage and low-voltage AC voltage signals are transmitted to each miniature circuit breaker, which are extra-low safety voltages. This fundamentally eliminates the risk of high-voltage electricity entering the densely packed area of circuit breakers, thus improving the electrical safety level of the entire distribution box. Achieving high-precision serial bus signal distribution: Through a built-in operational amplifier buffer circuit, weak voltage signals are converted into low-impedance outputs, enabling stable and attenuated transmission to multiple series-connected miniature circuit breakers via a serial bus. The wiring is extremely simple; only the module needs to be connected to the first circuit breaker, and subsequent circuit breakers are connected in series sequentially. This significantly reduces the number of overhead wires inside the enclosure, making installation convenient and highly reliable. Significantly reduces total system cost: A single external module can provide a shared power supply and accurate voltage reference for all miniature circuit breakers on a branch, avoiding the need to repeatedly set up AC / DC power supplies and voltage sampling circuits inside each circuit breaker, resulting in a significant reduction in component costs, installation costs, and maintenance costs. Attached Figure Description
[0004] Figure 1 This is a block diagram illustrating the electrical connection principle of the system of the present invention. Figure 2 This is a block diagram of the internal circuit principle of the external power supply and communication module. Detailed Implementation
[0005] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. See Figure 1 This embodiment provides a miniature circuit breaker energy metering system based on an external power supply and signal bus, including an external power supply communication module (1) and three miniature circuit breakers (2-1, 2-2, 2-3) with metering functions. The input terminal of the external power supply communication module (1) is connected to the live wire L and the neutral wire N of the mains power. The output interface of the external power supply communication module (1) is plugged into the input interface of the first miniature circuit breaker (2-1); the cascaded output interface of the miniature circuit breaker (2-1) is plugged into the input interface of the miniature circuit breaker (2-2); the cascaded output interface of the miniature circuit breaker (2-2) is plugged into the input interface of the miniature circuit breaker (2-3), thereby forming a series bus. Two signals are transmitted in this series bus: one is the low-voltage DC working voltage VCC and ground GND, and the other is the low-voltage AC voltage signal V_signal. Each miniature circuit breaker (MCB) contains a metering circuit board with an integrated energy metering chip. The MCB housing has matching input interfaces and cascaded output interfaces on both sides. These interfaces are electrically connected internally to the power input terminal of the metering circuit board and the voltage sampling channel of the energy metering chip via wires. VCC and V_signal on the serial bus enter the MCB through the input interface for the metering circuit board's operation; simultaneously, VCC, GND, and V_signal are transmitted to the cascaded output interface via internal through-connections, continuing transmission to subsequent MCBs. The energy metering chip within each MCB obtains V_signal as a voltage reference signal through the voltage sampling channel, while the current sampling channel connects to a current sampling device (such as a manganese-copper shunt or current transformer) flowing through the circuit breaker's live wire to obtain the current signal. Based on these two signals, the energy parameters are calculated. See Figure 2 The internal circuit of the external power supply communication module (1) includes a switching power supply circuit (11) and a voltage sampling isolation circuit. One end of the primary side of the voltage transformer T1 is connected to the live wire L, and the other end is connected to the neutral wire N through five 20kΩ resistors R3 to R7 connected in series. This resistor network is used to meet the withstand voltage requirements and power limits of the primary side to the mains voltage, ensuring that the voltage transformer works safely and stably. The secondary side of the voltage transformer T1 is connected to the signal conditioning circuit (12), which uses a resistor voltage divider network. Its circuit structure is configured according to the recommended design of the selected power metering chip to accurately divide the voltage signal output by the transformer and output an AC voltage signal with an amplitude in the millivolt range. This AC voltage signal is in phase and frequency with the mains power, but the amplitude has been reduced to a safe range. This signal is then sent to a buffer circuit (13) composed of an operational amplifier U1A. In this embodiment, U1A is configured as a voltage follower. The voltage follower has extremely high input impedance and extremely low output impedance, which can effectively isolate the influence of load changes on the subsequent series bus on the voltage division accuracy of the preceding stage, and significantly enhance the signal driving capability, ensuring that the signal has no significant attenuation during long-distance series transmission. Finally, the 12V DC output from the switching power supply circuit (11) and the low-voltage AC voltage signal (e.g., effective value 50mV) output from the buffer circuit (13) are jointly led out from the output port (14). The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A miniature circuit breaker energy metering system based on an external power supply and signal bus, characterized in that, include: An external power supply and communication module and at least one miniature circuit breaker with metering function; The external power supply and communication module has an input terminal for connecting to the live and neutral wires of the mains power supply, and internally integrates a switching power supply circuit and a voltage sampling isolation circuit. The switching power supply circuit is used to convert the mains power supply into a low-voltage DC operating voltage. The voltage sampling isolation circuit is used to extract a low-voltage AC voltage signal that is in phase and frequency with the mains power supply. The external power supply and communication module is provided with an output interface for simultaneously outputting the low-voltage DC operating voltage and the low-voltage AC voltage signal. The miniature circuit breaker with metering function has an internal metering circuit board with an integrated power metering chip. The metering circuit board is used to connect to the live wire to obtain a current sampling signal. The miniature circuit breaker is provided with a bus interface for receiving the low-voltage DC operating voltage and low-voltage AC voltage signals from the outside and introducing them into the power supply terminal of the metering circuit board and the voltage sampling channel of the power metering chip, respectively. The output interface of the external power supply and communication module is electrically connected to the bus interface of each miniature circuit breaker via a signal bus to transmit the low-voltage DC operating voltage and low-voltage AC voltage signals to each miniature circuit breaker. This allows each miniature circuit breaker to perform energy metering based on the low-voltage AC voltage signal and the current sampling signal received by the voltage sampling channel, without being directly connected to the neutral wire.
2. The miniature circuit breaker energy metering system according to claim 1, characterized in that: The voltage sampling isolation circuit includes a voltage transformer, the primary side of which is connected in parallel between the live wire and the neutral wire, and the secondary side is connected in sequence with a series of step-down and current-limiting resistors, a sampling resistor, and a buffer amplifier circuit. The voltage signal across the sampling resistor is impedance transformed and amplified by the buffer amplifier circuit to output the low-voltage AC voltage signal.
3. The miniature circuit breaker energy metering system according to claim 2, characterized in that: The buffer amplifier circuit is a voltage follower or a non-inverting proportional amplifier, used to reduce the output impedance and ensure that the low-voltage AC voltage signal does not undergo significant attenuation when transmitted to multiple miniature circuit breakers through the signal bus.
4. The miniature circuit breaker energy metering system according to claim 2, characterized in that: The step-down current-limiting resistor string is composed of multiple resistors connected in series, and the resistance value of the sampling resistor is much smaller than the total resistance value of the step-down current-limiting resistor string.
5. The miniature circuit breaker energy metering system according to claim 4, characterized in that: The step-down current-limiting resistor string consists of five 390kΩ resistors connected in series, and the sampling resistor has a resistance of 510Ω.
6. The miniature circuit breaker energy metering system according to claim 1, characterized in that: The low-voltage AC signal output by the external power supply and communication module is an AC signal with an effective value of 10mV to 100mV.
7. The miniature circuit breaker energy metering system according to claim 1, characterized in that: The external power supply and communication module outputs a low-voltage DC operating voltage of 12V DC safety voltage.
8. A method for metering the energy of a miniature circuit breaker based on an external power supply and signal bus, applied to the system described in any one of claims 1 to 7, characterized in that, Includes the following steps: The external power supply and communication module draws power from the mains power supply and generates a low-voltage DC working voltage through the switching power supply circuit. At the same time, it extracts a low-voltage AC voltage signal with the same frequency and phase as the mains power through the voltage sampling isolation circuit. The low-voltage DC operating voltage and low-voltage AC voltage signals are transmitted to each miniature circuit breaker through the output interface and signal bus. Each miniature circuit breaker's internal metering circuit board obtains the low-voltage DC operating voltage from the signal bus as its operating power supply. The energy metering chip receives the low-voltage AC voltage signal through its voltage sampling channel and simultaneously obtains the current sampling signal flowing through the live wire of the miniature circuit breaker, thereby calculating the energy parameters.