A multi-loop smart energy meter based on WiFi HaLow network

Abstract

The application discloses a kind of multi-loop intelligent electric energy meter based on WiFi HaLow network, to solve the problems of short communication distance, high networking cost, weak anti-interference ability, multi-loop metering synchronism and insufficient metering accuracy of existing intelligent electric energy meter.The application includes power supply module, wireless communication module and sampling measurement module;Power supply module adopts isolated transformer double-way independent output architecture, cooperates with optocoupler feedback circuit, provides multi-way isolated voltage stabilizing power supply for RS485 communication unit and wireless communication module;Wireless communication module adopts WiFi HaLow communication chip, communicates with MCU through digital isolation chip, and cooperates with external storage chip to store communication protocol stack, firmware and configuration parameters;Sampling measurement module adopts double measurement chip and differential sampling circuit, realizes double three-phase multi-loop synchronous measurement.The application realizes kilometer-level low-power wireless communication, and improves anti-interference and measurement accuracy through full-link isolation design, which meets the needs of remote measurement and high-density deployment in smart grid, distributed energy storage and other scenarios.

Description

Technical Field

[0001] This invention relates to the field of electricity metering technology, and more specifically, to a multi-loop smart electricity meter based on a WiFi HaLow network. Background Technology

[0002] With the rapid development of smart grids and distributed energy storage systems, electricity metering equipment needs to have the ability to conduct long-distance wireless communication and multi-loop metering.

[0003] Existing smart meters mainly use communication methods such as RS485, wired Ethernet, 2G / 4G cellular communication, or LoRa. Among them, wired communication is complex to install and has high maintenance costs; cellular communication modules have high power consumption and there are ongoing communication tariff issues; although LoRa communication has low power consumption and long distance, its bandwidth is low and it is difficult to meet the requirements of high-frequency data real-time reporting and transmission.

[0004] WiFi HaLow technology is a low-power, long-range wireless communication technology operating in the Sub-1GHz band, offering advantages such as ultra-long coverage, low power consumption, high bandwidth, and support for large-scale node access. However, integrating WiFi HaLow modules into multi-loop energy meters faces two major technical challenges: first, high-frequency noise from the switching power supply can interfere with radio frequency performance through the power supply lines, leading to a shortened communication distance; second, the high-frequency signals transmitted by the wireless module can couple to the metering circuit through the ground or power lines, affecting metering accuracy. Furthermore, multi-loop metering inherently suffers from crosstalk between signals, and RS485 communication and wireless communication require different power quality standards.

[0005] Therefore, existing products cannot meet the core needs of multiple scenarios, and there is an urgent need to develop a power metering solution that optimizes the entire chain from the dimensions of power supply isolation, wireless communication, and multi-circuit metering to solve the pain points of existing technologies. Summary of the Invention

[0006] The core objective of this invention is to overcome the aforementioned deficiencies of the prior art and provide a multi-loop smart energy meter based on a WiFi HaLow network. This addresses the problems of short communication distance, high networking cost, poor anti-interference capability, insufficient metering accuracy, and weak multi-loop scalability in traditional energy meters, enabling long-distance low-power wireless communication, high-precision metering with a fully isolated architecture, centralized multi-loop data acquisition, and highly reliable and stable operation.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a multi-loop smart energy meter based on a WiFi HaLow network, comprising: The power supply module includes a power management chip IC3 and an isolation transformer T1. The power management chip IC3 is connected to the primary side of the isolation transformer T1 and is used to achieve high-frequency switching conversion and closed-loop voltage regulation control. It chops the input constant high-voltage DC into a high-frequency alternating pulse current, which is input to the primary winding of the isolation transformer T1 to drive the isolation transformer T1 to complete energy transfer and electrical isolation, providing stable and reliable multi-channel isolated power supply for subsequent functional modules. The secondary side of the isolation transformer T1 is connected to the RS485 communication unit through the first winding output circuit and to the wireless communication module through the second winding output circuit. The second winding output circuit is also electrically connected to the enable pin of the power management chip IC3 through an optocoupler feedback circuit for feedback adjustment of the output voltage of the second output winding. The wireless communication module includes a wireless communication chip U9. The power input pin of the wireless communication chip U9 is electrically connected to a linear voltage regulator unit, the antenna pin is connected to an external radio frequency antenna through a radio frequency connector J10, and the communication interface is connected to the MCU chip UP1 through an isolation chip U4. The sampling and metering module includes an energy metering unit, a current sampling unit, and a voltage sampling unit connected to the energy metering unit; wherein the energy metering unit is connected to the MCU chip UP1 via an SPI serial interface or a parallel interface.

[0008] Furthermore, the power output pin of the isolation chip U4 is connected to the power input terminal of the MCU chip UP1 and the power input terminal of the energy metering unit, respectively, to provide a stable working power supply with electrical isolation for the MCU chip and the energy metering unit, and to block the conduction path of interference to the metering circuit.

[0009] Furthermore, the first winding output circuit includes a diode D1, capacitors C6, C7, and C11, as well as a voltage regulator chip IC1; the anode of the diode D1 is electrically connected to one end of the first output winding of the isolation transformer T1, and the cathode is electrically connected to the input terminal (Vi) of the voltage regulator chip IC1; the capacitors C6 and C7 are connected in parallel with each other, and are also connected in parallel between the cathode of the diode D1 and the other end of the first output winding; the output terminal of the voltage regulator chip IC1 is grounded through capacitor C11.

[0010] Furthermore, the second winding output circuit includes a diode D8, an electrolytic capacitor C8, an electrolytic capacitor C9, a capacitor C10, and an inductor L2; the anode of the diode D8 is electrically connected to one end of the second output winding of the isolation transformer T1, and the cathode is connected to the positive terminal of the electrolytic capacitor C8 and one end of the inductor L2; the second end of the inductor L2 is electrically connected to the positive terminal of the electrolytic capacitor C9 and one end of the capacitor C10; the negative terminals of the capacitors C8 and C9 and the other end of the capacitor C10 are grounded.

[0011] Furthermore, the optocoupler feedback circuit includes an optocoupler U1, a reference voltage regulator chip IC5, resistors R6, R7, R8, and R13, and a capacitor C14. The second winding of the secondary side of the isolation transformer T1 is rectified by diode D8 and divided by resistor R6, and electrically connected to the anode of the LED inside the optocoupler U1. Resistor R8 connects the anode and cathode of the LED. The cathode of the LED is electrically connected to the cathode of the reference voltage regulator chip IC5. The anode of the reference voltage regulator chip IC5 is grounded, and the reference electrode is electrically connected to the output terminal of the second winding output circuit via voltage divider resistor R7. Resistor R13 is also connected in series between the reference electrode and anode of the reference voltage regulator chip IC5. The connection point of resistors R7 and R13 is shared with one end of capacitor C14, and the other end of capacitor C14 is connected to the cathode of the LED. The collector of the phototransistor inside the optocoupler U1 is electrically connected to the feedback pin of the power management chip IC3, and the emitter is grounded.

[0012] The optocoupler feedback circuit provides closed-loop voltage regulation control for the isolated flyback switching power supply. Its core uses optocoupler U1 to achieve electrical isolation between the primary high-voltage circuit and the secondary low-voltage circuit, while simultaneously performing feedback regulation of the output voltage. Resistors R7 and R13 are connected in series to form an output voltage sampling divider network, which samples the output voltage after rectification and filtering on the secondary side. The sampled voltage is output to the reference pin of the reference voltage regulator IC5 and compared in real time with the reference voltage inside the IC5. When the input voltage fluctuates, the reference voltage regulator IC5 adjusts its conduction level in real time according to the difference between the sampled voltage and the reference voltage, cooperating with the rectifier... The current-limiting resistor R6 at the cathode of diode D8 precisely controls the operating current and luminous intensity of the LED inside optocoupler U1, thereby changing the conduction level of the phototransistor inside U1. This dynamically adjusts the potential of the enable pin of power management chip IC3, causing power management chip IC3 to adjust the duty cycle of its internal power switch accordingly, changing the energy transfer of isolation transformer T1, and ultimately pulling the output voltage back and stabilizing it at the rated value. Among these measures, resistor R8 is used to stabilize the operating state of the LED and avoid voltage drift under light load conditions, while compensation capacitor C14 provides phase compensation for the voltage regulation loop, eliminating loop self-oscillation and ensuring the stability and anti-interference capability of the voltage regulation control.

[0013] Furthermore, the power supply module also includes a clamping circuit, which consists of a TVS diode D2, a diode D5, and a capacitor C4. The anode of the diode D5 is connected to the drain pin of the power management chip IC3 and one end of the primary winding of the transformer, and the cathode of the diode D5 is electrically connected to the cathode of the TVS diode D2. The anode of the TVS diode D2 and one end of the capacitor C4 are connected to the other end of the primary winding of the transformer, and the other end of the capacitor C4 is grounded.

[0014] Furthermore, the wireless communication chip U9 is electrically connected to an external storage chip U10 via pins IOA0~IOA3, ensuring that the wireless communication chip U9 can directly read the protocol stack and firmware program from the external storage chip U10 for startup and operation. When it is necessary to upgrade the communication protocol or fix firmware vulnerabilities, only the contents of the external storage chip U10 need to be updated, without replacing the wireless chip hardware, thus reducing maintenance costs.

[0015] Specifically, the wireless communication chip U9 establishes a communication connection with the external memory chip U10 through its general purpose input / output pins IOA0, IOA1, IOA2, and IOA3. This connection typically uses a four-wire SPI bus, where IOA0 serves as the chip select signal, IOA1 as the clock signal, IOA2 as the master-output / slave-in signal, and IOA3 as the master-in / slave-output signal, enabling the wireless communication chip U9 to control the read and write operations of the memory chip.

[0016] The external storage chip U10 is used to store the following three types of core data: First, the wireless communication protocol stack, namely the underlying driver and network layer protocol code of the WiFi HaLow protocol, to ensure that the wireless chip can correctly parse and process data frames of the IEEE 802.11ah standard; Second, the firmware program, namely the dedicated program embedded in the non-volatile memory inside the hardware device, including RF front-end control parameters, power calibration data, and MAC layer management program; Third, parameter configuration data, including user-configurable operating parameters such as device operating mode, network name, encryption password, IP address allocation method, and sampling reporting cycle; The device operating mode includes STA mode or AP mode.

[0017] Furthermore, the power metering unit includes a first metering chip IC7 and a second metering chip IC8, both of which are dedicated multi-channel power metering chips.

[0018] Furthermore, the current sampling unit includes six sets of current sampling circuits connected to the current differential input pins of the first metering chip IC7 and the second metering chip IC8, respectively. Among them, three sets of current sampling circuits correspond to ID, IE, and IF of the first three-phase circuit and are connected to the current differential input pin of the first metering chip IC7; the other three sets of current sampling circuits correspond to IA, IB, and IC of the second three-phase circuit and are connected to the current differential input pin of the second metering chip IC8. Each set of current sampling circuits consists of a current transformer interface, a sampling resistor, a bidirectional transient suppression diode, and a differential filter network, used to convert the primary current into a differential voltage signal that can be received by the metering chip.

[0019] The voltage sampling unit includes three sets of voltage sampling circuits, all of which are electrically connected to the voltage differential input pins of the first metering chip IC7 and the second metering chip IC8.

[0020] Specifically, the three sets of voltage sampling circuits correspond to the voltages of phase A, phase B, and phase C, respectively. The output terminals of these three sets of voltage sampling circuits are simultaneously connected to the voltage differential input pins of the first metering chip IC7 and the second metering chip IC8. That is, the three sets of voltage sampling circuits are shared by the two metering chips. On the one hand, this ensures that the voltage signals acquired by the two chips are completely consistent in phase and amplitude, providing an accurate phase reference for energy calculation. On the other hand, it reduces the number of voltage sampling circuits, simplifies the circuit layout, saves space, and is conducive to the miniaturization of the whole machine.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: High-reliability power supply design: The power supply module adopts a dual-output independent design with isolation transformer T1, providing power to the RS485 unit and wireless module as needed, ensuring a stable power supply suitable for different loads. Combined with clamping circuits and optocoupler feedback circuits, it achieves precise voltage regulation and multiple circuit protections under wide input voltage ranges, significantly improving the overall reliability of the device in complex power grid environments.

[0022] High-precision metering and anti-interference design: This invention adopts an architecture in which dual metering chips and differential sampling circuits work together, effectively improving the synchronization and anti-crosstalk capability of multi-loop energy metering. Simultaneously, an isolation chip is placed between the wireless communication chip and the MCU chip, along with an independent linear regulated power supply, fundamentally blocking conducted interference from radio frequency transmission to the metering circuit, achieving electromagnetic compatibility coexistence of high-precision metering and long-distance communication.

[0023] Flexible Wireless Communication Design: This invention employs WiFi HaLow wireless communication technology to achieve kilometer-level long-distance communication. An external storage chip supports STA / AP dual-mode software configuration, enabling both remote automatic meter reading and on-site direct connection debugging. The external chip independently stores communication protocols, firmware, and configuration parameters, facilitating firmware upgrades, production adaptation, and reliable data storage, significantly improving deployment convenience and maintenance flexibility. Attached Figure Description

[0024] Figure 1 This is a circuit structure block diagram of the multi-loop smart energy meter of the present invention; Figure 2 This is a circuit schematic diagram of the power supply module of the present invention; Figure 3 This is a circuit diagram of the linear voltage regulator circuit of the present invention; Figure 4 This is a circuit schematic diagram of the wireless communication chip U9 of the present invention; Figure 5 This is a circuit schematic diagram of the external storage chip of the present invention; Figure 6 This is a circuit schematic diagram of the isolation chip of the present invention; Figure 7 This is a circuit schematic diagram of the MCU chip of the present invention; Figure 8 This is a circuit diagram of the power metering unit of the present invention; Figure 9 This is a circuit schematic diagram of the current sampling unit of the present invention; Figure 10 This is a circuit diagram of the voltage sampling unit of the present invention. Detailed Implementation

[0025] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0026] like Figure 1 As shown, this embodiment provides a multi-loop smart energy meter based on a WiFi HaLow network, including a power supply module, a wireless communication module, and a sampling and metering module; like Figure 2 As shown, the power supply module includes a power management chip IC3 and an isolation transformer T1 connected in sequence. The power management chip is connected to the primary side of the isolation transformer T1 and is used to realize high-frequency switching conversion and closed-loop voltage regulation control. It chops the input constant high-voltage DC into a high-frequency alternating pulse current and inputs it to the primary winding of the isolation transformer T1 to drive the isolation transformer T1 to complete energy transfer and electrical isolation, providing a stable and reliable multi-channel isolated power supply for the subsequent functional modules. The secondary side of the isolation transformer T1 is connected to the RS485 communication unit via the first winding output circuit and to the wireless communication module via the second winding output circuit. The first winding output circuit provides an independent electrically isolated regulated power supply for the RS485 communication unit, blocking the conduction of 485 bus interference to the system side. The second winding output circuit provides a low-noise isolated power supply for the wireless communication module to filter out high-frequency ripple and ensure the stability of radio frequency communication. The power supply module also includes an input protection unit. A varistor RTV1 is connected in parallel to the input of the input protection circuit to suppress grid surge voltage and lightning overvoltage. When the input voltage exceeds the varistor's threshold, the varistor quickly conducts to discharge energy, protecting the downstream circuitry. The input protection unit also includes a rectifier bridge and an LC filter circuit connected sequentially after the varistor RTV1. The LC filter circuit includes an inductor L1 and an electrolytic capacitor C5. The positive terminal of the electrolytic capacitor C5 is connected to the inductor L1, and the negative terminal is grounded. The input AC power first passes through the varistor RTV1 to suppress grid surge voltage, then is rectified by the rectifier bridge DB1 to convert it into pulsating DC power. After smoothing and filtering by the LC filter circuit, a stable DC voltage is obtained and input to the drain pin of the power management chip IC3.

[0027] The power management chip IC3 is preferably TNY286PG, a switching power management chip IC3 integrating a 700V power MOSFET. It has overvoltage, overcurrent, and overheat protection functions and is used to realize high-frequency switching control. The stable DC voltage output from the front-end input protection unit is chopped into high-frequency alternating pulse voltage by the internally integrated high-frequency power switching transistor and input to the primary winding of the isolation transformer T1 to achieve energy transfer and electrical isolation from the high-voltage side of the power grid. At the same time, it receives the voltage feedback signal output from the optocoupler feedback circuit and dynamically adjusts the on / off cycle and switching enable state of the internal switching transistor. It adopts ON / OFF control mode to realize high-precision closed-loop voltage regulation control of the output voltage. It can achieve high-precision closed-loop voltage regulation control of the output voltage when the grid voltage fluctuates and the load current changes. The chip has built-in overvoltage, overcurrent, overheat, and undervoltage lockout protection functions, which can shut down the output under abnormal conditions, improving the operational reliability and electrical safety of the power supply module.

[0028] Preferably, in this embodiment, the voltage output from the first output winding on the secondary side of the isolation transformer T1 is rectified by diode D1, filtered by capacitors C6 and C7, and then input to a voltage regulator chip IC1. After step-down and regulation, and filtered by capacitor C11, it powers the RS485 communication unit, achieving independent isolated power supply for the RS485 interface and preventing bus interference from entering the system. The voltage output from the second output winding on the secondary side of the isolation transformer T1 is rectified by diode D8, filtered by a filter network consisting of capacitors C8 and C9 and inductor L2, and then powers the wireless communication module. The wireless module experiences a large transient current during transmission; electrolytic capacitors C8 and C9 provide instantaneous energy reserves, and inductor L2 suppresses high-frequency noise, preventing power consumption fluctuations of the wireless module from affecting other circuits.

[0029] like Figure 3 , Figure 4 As shown, the wireless communication module includes a wireless communication chip U9, whose power input pin is electrically connected to a linear voltage regulator unit; the linear voltage regulator unit includes a linear voltage regulator chip IC4 and its peripheral circuitry; the antenna pin of the wireless communication chip U9 is connected to an external radio frequency antenna via a radio frequency connector J10, for transmitting and receiving WiFi HaLow radio frequency signals in the Sub-1GHz band, realizing long-distance, low-power wireless data interaction at the kilometer level; the radio frequency connector J10 facilitates antenna selection and on-site replacement. like Figure 6 As shown, the communication interface of the wireless communication chip U9 is connected to the MCU chip UP1 via the isolation chip U4. This isolation chip U4 enables electrical isolation and bidirectional data communication between the wireless communication chip U9 and the MCU chip UP1, blocking the transmission path of radio frequency interference and power supply noise to the metering system, thereby improving the system's anti-interference capability and metering accuracy. Simultaneously, it transmits the energy metering data processed by the MCU chip UP1 to the wireless communication chip U9, and forwards external downlink control commands received by the wireless communication chip U9 to the MCU chip UP1 for execution. In this embodiment, the MCU chip UP1 is preferably an AT32F423CCT7, used to execute energy metering data processing, communication protocol processing, and system control programs. The MCU chip UP1 is also connected to a clock circuit, which consists of a crystal oscillator X1 and capacitors C24 and C25, providing a stable system clock signal for the MCU chip UP1.

[0030] Specifically, pin IOA10 of the wireless communication chip U9 is connected to pin VO4 of the isolation chip U4, pin IOA11 is connected to pin VIN2 of the isolation chip U4, pin IOA12 is connected to pin VO3 of the isolation chip U4, and pin IOA13 is connected to pin VIN1 of the isolation chip U4; pin VO1 of the isolation chip U4 is connected to pin PB6 of the MCU chip UP1, pin VO2 is connected to pin PB3 of the MCU chip UP1, pin VIN3 is connected to pin BOOT0 of the MCU chip UP1, and pin VIN4 is connected to pin PA15 of the MCU chip UP1.

[0031] In this embodiment, the wireless communication chip U9 is preferably TX-AH-R900PNR-860M, used to implement WiFi HaLow wireless communication function based on the IEEE 802.11ah standard. The transmit power of the wireless communication chip U9 is adjustable, supports STA / AP dual-mode, and low-power standby. The wireless communication chip U9 supports access to the WiFi HaLow gateway in STA mode to realize large-scale node networking, supporting more than 1000 nodes to access; it also supports acting as an access point in AP mode, allowing up to 8 STA nodes to access, realizing point-to-point and point-to-multipoint communication without the need for an additional gateway, adapting to distributed scenarios without public network coverage.

[0032] like Figure 6 As shown, the isolation chip U4 is a dual-channel digital isolation chip with an isolation withstand voltage of not less than AC2500V. It is used to achieve electrical isolation of the communication interface between the wireless communication chip U9 and the MCU chip UP1, blocking radio frequency interference and bus interference from entering the metering system. At the same time, the isolation chip U4 integrates a high-efficiency, low-radiation DC-DC converter. Its power output pin VISO is electrically connected to the power input pin VDD of the MCU module and the power input pin VCC of the energy metering unit via inductor L8. The power output of the isolation chip U4 is filtered by an LC filter circuit composed of capacitor C64, capacitor C77, and inductor L8, providing a clean and stable isolated power supply for the MCU module and the energy metering unit, effectively suppressing power ripple and high-frequency noise, and ensuring the reliable operation of the metering and control loop.

[0033] like Figures 8-10 As shown, the sampling and metering module includes an energy metering unit and a current sampling unit and a voltage sampling unit connected to the energy metering unit; wherein, the energy metering unit is communicatively connected to the MCU chip UP1.

[0034] Based on the above embodiments, the power supply module in this embodiment further includes an optocoupler feedback circuit; Preferred, such as Figure 2As shown, the optocoupler feedback circuit includes an optocoupler U1, a reference voltage regulator IC5, resistors R6, R7, R8, and R13, and a compensation capacitor C14; the resistor R7 is connected between the rectified and filtered output terminal of the second output winding and the reference pin of the reference voltage regulator IC5 to perform voltage division sampling of the output voltage. In this embodiment, IC5 is preferably a TL431, and the internal reference of the TL431 voltage regulator IC5 is 2.5V. When the output voltage increases, its reference pin voltage exceeds 2.5V, the cathode of the TL431 conducts, the current flowing through the internal LED of the optocoupler U1 increases, and the luminous intensity increases. The collector of the phototransistor is connected to the enable pin of the power management chip IC3, and the emitter is grounded. When the luminous intensity increases, the conduction degree of the phototransistor deepens, pulling down the enable pin voltage of the power management chip IC3, thereby controlling the power management chip IC3 to reduce the switching transistor's on-cycle and reduce energy transfer. Conversely, when the output voltage decreases, the reference terminal voltage of the TL431 is below 2.5V, the cathode is cut off, the current of the optocoupler's LED decreases, the conduction degree of the phototransistor decreases, the enable pin voltage of the power management chip IC3 increases, the switching transistor's on-cycle increases, energy transfer is improved, and the output voltage recovers.

[0035] The compensation capacitor C14 is connected between the cathode and reference pin of the TL431 for loop frequency compensation, preventing oscillation and ensuring feedback loop stability. Resistor R13 provides bias current to the TL431. Resistor R8 is connected in parallel across the LED to provide a small shunt current, improving linearity under small signal conditions.

[0036] In another embodiment, the power supply module further includes a clamping circuit composed of a TVS diode D2, a diode D5, and a capacitor C4. When the switching transistor inside the power management chip IC3 is turned off, the transformer leakage inductance generates an extremely high spike voltage, which, if not suppressed, will break down the switching transistor. The operation is as follows: at the instant the switching transistor is turned off, the primary voltage of the transformer reverses, and current flows through D5 to charge C4. The TVS diode D2 clamps the spike voltage within a safe range, and the energy is stored in C4, subsequently dissipated through a resistor or in subsequent cycles. Compared to simple RC absorption, this TVS-equipped RCD clamping has the advantages of faster response and better absorption effect.

[0037] like Figure 5As shown, in another embodiment, the wireless communication chip U9 is electrically connected to an external storage chip U10 via pins IOA0~IOA3. The external storage chip U10 is used to store the wireless communication protocol stack, firmware program, and parameter configuration data. The wireless communication protocol stack is the protocol software of WiFi HaLow, and the firmware program is the running firmware of the wireless communication chip U9. Through external storage, the wireless module can support different communication protocols and configurations through software upgrades without replacing the chip, improving the flexibility of the product.

[0038] like Figure 8 As shown, in another embodiment, the energy metering unit uses two multi-channel metering chips to jointly complete multi-loop metering; the metering chip is preferably HT7034L, used to synchronously sample multiple voltage and current signals and calculate parameters such as active energy, reactive energy, voltage, current and power factor; the current sampling unit includes six sets of current sampling circuits respectively connected to the current differential input pins of the first metering chip IC7 and the second metering chip IC8; the voltage sampling unit includes three sets of voltage sampling circuits, all of which are electrically connected to the voltage differential input pins of the first metering chip IC7 and the second metering chip IC8.

[0039] The first metering chip IC7 is responsible for current sampling and three-phase voltage sampling of the first group of three-phase circuits; the second metering chip IC8 is responsible for current sampling of the second group of three-phase circuits, and its voltage sampling input shares the three-phase voltage signal with the first metering chip IC7; the two groups of metering chips process the three currents respectively, realizing physical isolation between the two three-phase metering circuits and avoiding crosstalk between the sampling signals of different outgoing circuits.

[0040] like Figure 9 As shown, in this embodiment, the current sampling unit includes six sets of current sampling circuits, which are respectively connected to the current differential input pins of the first metering chip IC7 and the second metering chip IC8. Each set of current sampling circuits consists of current transformer input interfaces IA, IB, IC, ID, IE, IF and corresponding transient suppression diodes VD1~VD6, resistor network R24~R47 and capacitors C57~C68. The current transformer isolates and transforms the primary large current into a secondary small current. The secondary current flows through the sampling resistor and is converted into a differential voltage signal according to Ohm's law, and then input to the metering chip.

[0041] like Figure 10As shown, in this embodiment, the voltage sampling unit includes three sets of voltage sampling circuits, corresponding to phase A, phase B, and phase C voltages respectively. The three sets of voltage sampling circuits are composed of resistor voltage divider networks RA2~RA6, RB1~RB3, RC1~RC3, filter inductors L3~L5, resistors R48~R53, and capacitors C69~C74, which are used to convert single-phase or three-phase high-voltage grid voltage into low-voltage signals acceptable to the metering chip.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-loop smart energy meter based on a WiFi HaLow network, characterized in that, include: The power supply module includes a power management chip IC3 and an isolation transformer T1. The power management chip IC3 is connected to the primary side of the isolation transformer T1. The secondary side of the isolation transformer T1 is connected to the RS485 communication unit through a first winding output circuit and to the wireless communication module through a second winding output circuit. The second winding output circuit is also electrically connected to the enable pin of the power management chip IC3 through an optocoupler feedback circuit. The wireless communication module includes a wireless communication chip U9. The power input pin of the wireless communication chip U9 is electrically connected to a linear voltage regulator unit. The antenna pin (ANT) is connected to an external radio frequency antenna through a radio frequency connector J10. The communication interface is connected to the MCU chip UP1 through an isolation chip U4. The sampling and metering module includes an energy metering unit, a current sampling unit, and a voltage sampling unit connected to the energy metering unit; wherein the energy metering unit is connected to the MCU chip UP1 via an SPI serial interface or a parallel interface.

2. The multi-circuit smart energy meter according to claim 1, characterized in that, The power output pin (VISO) of the isolation chip U4 is connected to the power input terminal of the MCU chip UP1 and the power input terminal of the power metering unit, respectively.

3. The multi-circuit smart energy meter according to claim 1, characterized in that, The first winding output circuit includes a diode D1, capacitors C6, C7, and C11, and a voltage regulator chip IC1; the anode of the diode D1 is electrically connected to one end of the first output winding of the isolation transformer T1, and the cathode is electrically connected to the input terminal (Vi) of the voltage regulator chip IC1; the capacitors C6 and C7 are connected in parallel between each other and between the cathode of the diode D1 and the other end of the first output winding; the output terminal (Vo) of the voltage regulator chip IC1 is grounded through capacitor C11.

4. The multi-circuit smart energy meter according to claim 1, characterized in that, The second winding output circuit includes a diode D8, an electrolytic capacitor C8, an electrolytic capacitor C9, a capacitor C10, and an inductor L2; the anode of the diode D8 is electrically connected to one end of the second output winding of the isolation transformer T1, and the cathode is connected to the positive terminal of the electrolytic capacitor C8 and one end of the inductor L2; the second end of the inductor L2 is electrically connected to the positive terminal of the electrolytic capacitor C9 and one end of the capacitor C10; the negative terminals of capacitors C8 and C9 and the other end of capacitor C10 are grounded.

5. The multi-circuit smart energy meter according to claim 4, characterized in that, The optocoupler feedback circuit includes an optocoupler U1, a reference voltage regulator chip IC5, resistors R6, R7, R8, and R13, and a capacitor C14. The second winding of the secondary side of the isolation transformer T1 is rectified by diode D8 and divided by resistor R6, and electrically connected to the anode of the LED inside the optocoupler U1. Resistor R8 connects the anode and cathode of the LED. The cathode of the LED is electrically connected to the cathode of the reference voltage regulator chip IC5. The anode of the reference voltage regulator chip IC5 is grounded, and the reference electrode is electrically connected to the output terminal of the second winding output circuit via voltage divider resistor R7. Resistor R13 is also connected in series between the reference electrode and anode of the reference voltage regulator chip IC5. The connection point of resistors R7 and R13 is shared with one end of capacitor C14, and the other end of capacitor C14 is connected to the cathode of the LED. The collector of the phototransistor inside the optocoupler U1 is electrically connected to the feedback pin of the power management chip IC3, and the emitter is grounded.

6. The multi-circuit smart energy meter according to claim 1, characterized in that, The power supply module also includes a clamping circuit, which consists of a TVS diode D2, a diode D5, and a capacitor C4. The anode of the diode D5 is connected to the drain pin of the power management chip IC3 and one end of the primary winding of the transformer. The cathode of the diode D5 is electrically connected to the cathode of the TVS diode D2. The anode of the TVS diode D2 and one end of the capacitor C4 are connected to the other end of the primary winding of the transformer. The other end of the capacitor C4 is grounded.

7. The multi-circuit smart energy meter according to claim 1, characterized in that, The wireless communication chip U9 is electrically connected to an external storage chip U10 via pins IOA0~IOA3. The external storage chip U10 is used to store the wireless communication protocol stack, firmware program, and parameter configuration data.

8. The multi-circuit smart energy meter according to claim 1, characterized in that, The power metering unit includes a first metering chip IC7 and a second metering chip IC8, both of which are dedicated multi-channel power metering chips.

9. The multi-circuit smart energy meter according to claim 8, characterized in that, The current sampling unit includes six sets of current sampling circuits respectively connected to the current differential input pins of the first metering chip IC7 and the second metering chip IC8; the voltage sampling unit includes three sets of voltage sampling circuits, all of which are electrically connected to the voltage differential input pins of the first metering chip IC7 and the second metering chip IC8.

Images