Boost power supply module of electric energy metering box

Abstract

The utility model discloses a boost power supply module of an electric energy metering box. The boost power supply module comprises an integrated switch controller chip; the energy storage inductor is arranged between the input end and the switch node pin; a bootstrap capacitor; an input capacitor; the bleeder resistor is arranged between the input end and the ground; the first output capacitor is arranged between the output end and the ground and is positioned close to the integrated switch controller chip; the second output capacitor is arranged between the output end and the ground and is close to the load end; the soft start capacitor is arranged between the soft start pin and the ground; the compensation network is arranged between the compensation pin and the ground and comprises a compensation resistor and a compensation capacitor which are connected in series; and the feedback voltage-dividing network is arranged between the output end and the feedback pin and comprises a first voltage-dividing resistor and a second voltage-dividing resistor. The boost power supply module of the electric energy metering box has the characteristics of high stability, low interference, flexible working mode and convenience in mass production and maintenance.

Description

Technical Field

[0001] This utility model relates to a boost power supply module for an electricity metering box. Background Technology

[0002] With the rapid advancement of smart grid construction, electricity metering boxes, as a crucial infrastructure of smart grids, are increasingly equipped with richer control and communication functions, placing higher demands on auxiliary power supply systems. Modern electricity metering boxes typically require multiple voltage levels to power different circuit modules, such as communication modules, metering chips, relays, and display backlights. The power conversion requirement of boosting USB-VBUS (such as 5V bus or external adapter voltage) to 10V is particularly common in these applications.

[0003] Currently, the boost power modules for electricity metering boxes on the market mainly adopt three technical solutions: single-capacity output setting, fixed operating mode setting, and simple startup circuit setting. The single-capacity output setting typically uses only a large-capacity capacitor for filtering at the output end. Although the structure is simple, it cannot simultaneously ensure control loop stability and load-side transient response when facing sudden load changes such as those caused by relays, easily leading to output voltage fluctuations and overshoot. The fixed operating mode setting either uses a fixed-frequency PWM mode to reduce noise or a PFM power-saving mode to reduce standby power consumption, failing to dynamically adapt to the changing needs of the electricity metering box at different operating stages. The simple startup circuit setting lacks a robust soft-start and input discharge mechanism, easily generating spike currents and voltage overshoots during power-on and unplugging, causing interference or even damage to the electricity metering system.

[0004] These existing technologies have several problems in practical applications: First, the working environment of electricity metering boxes is complex, with numerous sources of electromagnetic interference, and the EMI suppression capability of traditional boost power modules is insufficient, with radiated and conducted noise affecting metering accuracy; second, the operation of relays and valve load switches in the metering box generates large current surges, and traditional single-capacity settings cannot simultaneously meet the requirements of near-end stability and far-end response; third, metering boxes usually need to operate stably for a long time, requiring both measurement accuracy and energy efficiency, and existing fixed-mode settings cannot meet these two contradictory needs; finally, maintenance safety and mass production consistency issues also plague existing technologies, with the lack of an effective power-off safety discharge mechanism increasing maintenance risks, while complex compensation and adjustment processes reduce production efficiency.

[0005] Therefore, there is an urgent need for a boost power supply module specifically designed for electricity metering boxes, which can provide low-noise and highly stable output voltage, has comprehensive protection and flexible operating modes, and is easy to mass-produce and maintain, so as to meet the requirements of smart grid development for electricity metering equipment. Utility Model Content

[0006] The purpose of this invention is to provide a boost power supply module for an electricity metering box. This boost power supply module features high stability, low interference, flexible operating modes, and ease of mass production and maintenance.

[0007] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0008] A power metering box booster power supply module includes: an integrated switch controller chip (U2) having a switch node pin (pin 1), a bootstrap pin (pin 13), a feedback pin, a compensation pin, a soft-start pin, an enable pin, a mode pin, and a ground pin; an energy storage inductor (L7) disposed between the input terminal and the switch node pin (pin 1); a bootstrap capacitor (C5) disposed between the bootstrap pin (pin 13) and the switch node pin (pin 1); an input capacitor (C3) disposed between the input terminal and ground; and a bleeder resistor (R2) disposed between the input terminal and ground. A first output capacitor (C7) is placed between the output terminal and ground and near the integrated switch controller chip; a second output capacitor (C11) is placed between the output terminal and ground and near the load terminal; a soft-start capacitor (C49) is placed between the soft-start pin and ground; a compensation network is placed between the compensation pin and ground, the compensation network including a compensation resistor (R4) and a compensation capacitor (C2) connected in series; a feedback voltage divider network is placed between the output terminal and the feedback pin, the feedback voltage divider network including a first voltage divider resistor (R9) and a second voltage divider resistor (R3).

[0009] The present invention is further configured such that the enable pin and the mode pin can be configured to select a fixed frequency PWM mode or a PFM power-saving mode.

[0010] The present invention is further configured such that: the integrated switch controller chip (U2) includes an analog ground pin (AGND) and a power ground pin (PGND), and the analog ground pin and the power ground pin are connected at a single point near the end of the integrated switch controller chip.

[0011] The present invention is further configured such that: the inductance value of the energy storage inductor (L7) is 2.2μH, and the capacitance value of the bootstrap capacitor (C5) is approximately 100nF.

[0012] The present invention is further configured such that: the capacitance value of the input capacitor (C3) is 22μF, and the capacitance values ​​of the first output capacitor (C7) and the second output capacitor (C11) are both 22μF.

[0013] The present invention is further configured such that: the resistance value of the bleeder resistor (R2) is 100kΩ, and the capacitance value of the soft-start capacitor (C49) is 10μF.

[0014] The present invention is further configured such that the resistance value of the compensation resistor (R4) is 6.8kΩ and the capacitance value of the compensation capacitor (C2) is 6.8nF, thus constituting Type-II compensation.

[0015] The present invention is further configured such that the resistance value of the first voltage divider resistor (R9) is 750kΩ and the resistance value of the second voltage divider resistor (R3) is 75kΩ, forming a voltage division ratio of 10:1.

[0016] The present invention is further configured to include a heat-dissipating copper sheet and heat-dissipating vias disposed in the areas of the integrated switch controller chip (U2), the energy storage inductor (L7), and the first output capacitor (C7).

[0017] The present invention is further configured such that the connection lines between the switching node pin (pin 1) and the energy storage inductor (L7) and the connection lines between the bootstrap pin (pin 13) and the bootstrap capacitor (C5) are both configured to be as short and thick as possible to reduce the area of ​​the high-frequency loop.

[0018] In summary, this utility model has the following beneficial effects:

[0019] Optimized Dual-Output Capacitor Distributed Layout: This invention employs two-stage output capacitors, C7 and C11, arranged in a distributed manner—C7 is placed close to the integrated switch controller chip U2, and C11 is placed close to the load. This distributed structure solves the current surge problem caused by relays and valve-type load switches in the energy metering box. C7 primarily serves the stability of the control loop, while C11 handles the transient current demands at the load end, jointly suppressing ripple and hot-swap overshoot. Compared to the traditional centralized capacitor layout, this arrangement significantly improves the stability of the output voltage, reduces output ripple, decreases electromagnetic interference and the probability of system false reset, and improves metering accuracy and system reliability.

[0020] Input bleedering + soft-start dual suppression protection mechanism: This invention achieves dual protection through bleedering resistor R2 (100kΩ) and soft-start capacitor C49 (10μF). R2 ensures that the input capacitor C3 can safely and quickly discharge after power failure, avoiding the risks of false power-on and residual voltage during maintenance; C49 controls the ramp-up slope of the output voltage during power-on, allowing the output voltage to rise smoothly within a few milliseconds to tens of milliseconds, avoiding current surges and output overshoot during startup. This dual suppression mechanism significantly improves the electromagnetic compatibility and reliability of the system, reduces interference to other modules on the same bus (such as 485 and PLC power supplies), and enhances maintenance safety, making it particularly suitable for multi-module integrated systems such as energy metering boxes.

[0021] Flexible and switchable operating mode settings: By configuring the enable and mode pins, this boost power supply module can flexibly switch between fixed-frequency PWM mode and PFM power-saving mode. During metering-sensitive periods, PWM mode can be selected to avoid interference from light-load whistling and low-frequency ripple on the metering ADC; during idle periods, it can switch to PFM mode to reduce standby power consumption. This dynamic switching strategy solves the contradictory needs of energy metering equipment—high-precision measurement requires a low-noise power supply, while long-term operation requires high energy efficiency, achieving the best balance between measurement friendliness and energy saving.

[0022] Minimizing high-frequency loops for low EMI: The connections between the switching node pin (pin 1) and the energy storage inductor L7, and between the bootstrap pin (pin 13) and the bootstrap capacitor C5, are designed with the shortest and thickest possible traces, significantly reducing the high-frequency loop area. Simultaneously, the single-point connection between the analog ground pin and the power ground pin near the chip prevents high-current interference from affecting sensitive feedback and compensation circuits in the power loop. This optimized layout significantly reduces radiated EMI and conducted noise, ensuring the accuracy of the metering circuit is unaffected by power supply interference in environments with high precision measurement requirements, such as energy metering boxes, thus improving the overall system's anti-interference capability and metering accuracy.

[0023] Easy-to-produce and maintain compensation network setup: This invention employs a Type-II compensation network consisting of a compensation resistor R4 (6.8kΩ) and a compensation capacitor C2 (6.8nF), which is simple and efficient to set up. This compensation setup facilitates mass production parameter tuning; simply replacing one resistor or capacitor is sufficient to adapt to varying loads or input ranges. Simultaneously, R9 (750kΩ) and R3 (75kΩ) in the feedback voltage divider network form a precise 10:1 voltage divider ratio, ensuring the accuracy of the output voltage. This flexible and convenient setup significantly reduces the complexity of mass production debugging and engineering applications, minimizes the cost and time of setup modifications and verification, and improves product adaptability and market competitiveness. Attached Figure Description

[0024] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0025] In the description of this utility model, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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 utility model.

[0026] like Figure 1As shown, this utility model provides a power metering box booster power supply module, which is suitable for boosting USB-VBUS (usually 5V) to a stable +10V voltage to power loads such as relays, analog drives or backlights.

[0027] The module is divided into five sections: input filtering and preload section, energy storage inductor and switching node section, main control and enable / mode section, loop compensation section, and output sampling and filtering section.

[0028] The input filtering and preload area includes an input capacitor (C3) and a bleed resistor (R2). The input capacitor (C3) has a capacitance of 22μF and is directly connected in parallel between the input terminal and ground. It filters out low-frequency pulsations in the input power supply and provides transient current. The bleed resistor (R2) has a resistance of 100kΩ and is connected in parallel between the input terminal and ground. It serves to bleed the input side and provide micro-preload. This resistor ensures that the input capacitor (C3) can safely discharge after power failure, avoiding the risks of false power-ups and residual voltage during maintenance. It also provides a minimal load on the input source under light load conditions, which is beneficial for stability.

[0029] The energy storage inductor and switching node area includes an energy storage inductor (L7) and a bootstrap capacitor (C5). The energy storage inductor (L7) has an inductance of 2.2μH and is connected between the input terminal and the switching node pin (pin 1) of the integrated switch controller chip (U2). The bootstrap capacitor (C5) has a capacitance of approximately 100nF and is connected between the bootstrap pin (pin 13) of the integrated switch controller chip (U2) and the switching node pin (pin 1), providing a drive voltage higher than the output voltage for the high-side MOSFET gate, achieving synchronous rectification and low-loss turn-on.

[0030] The core of the main control and enable / mode area is the integrated switch controller chip (U2), which is an MP3429GL-Z or similar model, integrating the main switch and high-side rectifier MOSFET. The chip has multiple functional pins, including a switch node pin (pin 1), a bootstrap pin (pin 13), a feedback pin (pin 5), a compensation pin (pin 4), a soft-start pin (pin 2), an enable pin, a mode pin, and a ground pin. The enable and mode pins can be configured to select either a fixed-frequency PWM mode or a PFM power-saving mode. The soft-start pin (pin 2) is connected to a soft-start capacitor (C49) with a capacitance of 10μF, which controls the output voltage ramp-up slope during power-up, preventing current surges and output overshoot during startup.

[0031] The integrated switch controller chip (U2) includes an analog ground pin (AGND) and a power ground pin (PGND). These two pins are connected at a single point near the chip end to form a ground plane partition, which prevents high current in the power loop from interfering with sensitive feedback and compensation circuits and improves the system's noise immunity.

[0032] The output sampling and filtering area includes a first output capacitor (C7), a second output capacitor (C11), and a feedback voltage divider network. Both the first output capacitor (C7) and the second output capacitor (C11) have a capacitance of 22μF and are connected in parallel between the output terminal and ground. However, they are physically arranged in a distributed layout—the first output capacitor (C7) is placed closer to the integrated switch controller chip (U2), and the second output capacitor (C11) is placed closer to the load terminal. This distributed layout allows the first output capacitor (C7) to primarily control the stability of the control loop, while the second output capacitor (C11) handles the transient current demands of the load terminal, jointly suppressing ripple and hot-plug overshoot.

[0033] The feedback voltage divider network consists of a first voltage divider resistor (R9) and a second voltage divider resistor (R3). The first voltage divider resistor (R9) has a resistance of 750kΩ, and the second voltage divider resistor (R3) has a resistance of 75kΩ, forming a 10:1 voltage division ratio. This proportionally reduces the output voltage before it is input to the feedback pin (pin 5) of the integrated switch controller chip (U2). The routing of the feedback voltage divider network is located away from the switching nodes to prevent high-frequency switching noise from coupling into the feedback path and to maintain the accuracy of the output voltage.

[0034] The loop compensation area consists of a compensation network, including a compensation resistor (R4) and a compensation capacitor (C2) connected in series. The compensation resistor (R4) has a resistance of 6.8kΩ, and the compensation capacitor (C2) has a capacitance of 6.8nF. Both are connected between the compensation pin (pin 4) of the integrated switch controller chip (U2) and ground, forming a Type-II compensation network. This compensation setting improves loop bandwidth with a phase margin greater than 45°, ensuring system stability under varying loads. It is also easy to mass-produce and adjust parameters; simply replacing one resistor or capacitor is sufficient to adapt to different load or input range requirements.

[0035] To reduce EMI radiation and conducted noise, the connection lines between the switching node pin (pin 1) and the energy storage inductor (L7), as well as the connection lines between the bootstrap pin (pin 13) and the bootstrap capacitor (C5), are designed to be as short and thick as possible to reduce the high-frequency loop area. Simultaneously, heat dissipation copper foil and heat dissipation vias can be provided in the areas of the integrated switch controller chip (U2), the energy storage inductor (L7), and the first output capacitor (C7) to achieve effective thermal management, reduce the impact of high temperatures on component lifespan, and improve long-term reliability.

[0036] The working principle of this invention is as follows: When the main switch inside the integrated switch controller chip (U2) is turned on, the current in the energy storage inductor (L7) rises linearly, storing energy; when the switch is turned off, the energy storage inductor (L7) releases energy, which is transferred to the output capacitor and load through the high-side synchronous rectifier MOSFET inside the integrated switch controller chip (U2). The output voltage is sent back to the feedback pin (pin 5) of the chip through the feedback voltage divider network (R9 / R3), and compared with the internal reference voltage to form a closed-loop control. The compensation network (R4 / C2) ensures the stability of the loop and an appropriate response speed.

[0037] In practical applications, this boost power supply module is installed on the control / communication board of the power metering box, providing a stable 10V power supply to various loads. By configuring the enable and mode pins, PWM mode can be selected during metering-sensitive periods to avoid interference, while PFM mode can be selected during idle periods to save energy. The distributed layout of the dual output capacitors effectively addresses the current surges from loads such as relays. The combination of a bleed resistor and a soft-start capacitor ensures smooth power-on and power-off processes. Minimizing the high-frequency loop area and ground plane partitioning significantly reduce EMI impact, while the simple and efficient compensation network setup facilitates mass production debugging and adaptability to changing application requirements.

[0038] In summary, this utility model achieves a boost power supply module with high stability, low interference, flexible working modes, and easy mass production and maintenance. It is particularly suitable for application scenarios such as power metering boxes that have high requirements for accuracy, reliability, and stability, and has significant application prospects.

[0039] This application uses the following experiments to verify the technical effectiveness of the power metering box booster module:

[0040] 1. A comparative experiment method was used to directly compare this utility model module with three settings on the market (single capacity output setting, fixed working mode setting, and simple start-up circuit setting). The test environment simulated the actual working environment of an electricity metering box, including relay load switching, electromagnetic interference injection, and long-term operation. Each test was repeated 50 times to ensure data reliability, and professional equipment such as a high-precision oscilloscope (bandwidth ≥200MHz), EMI analyzer, and electricity metering accuracy tester were used for parameter acquisition and analysis.

[0041] 2. Technical Effect Comparison Table

[0042]

[0043] 3. Verification Conclusion

[0044] Test results show that the boost power supply module of this invention is significantly superior to traditional technologies in terms of performance indicators.

[0045] The distributed layout of dual output capacitors improves voltage stability by 77% under load surges such as relay switching, reducing the fluctuation range from ±8% to ±1.8%, effectively preventing system reset errors caused by transient interference.

[0046] The input discharge + soft-start dual suppression protection mechanism reduces the power-on inrush current from 5.8A to 1.6A, a reduction of 72%; and the output voltage overshoot is reduced from 14% to less than 3%, an improvement of 79%. This improvement significantly enhances the system's EMC performance and long-term reliability. In actual testing, no system failures caused by power-on inrush were observed.

[0047] The flexible operating mode switching function achieves an optimal balance between low power consumption and low noise, reducing standby power consumption by 74% while ensuring EMC compliance. Long-term operation tests show that this setting can save 33.2 kWh of energy consumption over a 10-year service life, demonstrating significant energy-saving value.

[0048] EMI suppression settings reduce radiated interference by more than 10dB, decreasing the impact on metering accuracy from 0.15% to below 0.02%, an improvement of 87%. This ensures the metering accuracy of the energy metering box in complex electromagnetic environments, meeting the high-precision requirements of 0.2S class energy meters.

[0049] The Type-II compensation network setup reduced mass production debugging time from 20 minutes to 3 minutes, an improvement of 85%, while maintaining system stability under different operating conditions. This setup significantly improved the product's mass production efficiency and market competitiveness.

[0050] Comprehensive test results confirm that this utility model, through structural innovation and layout optimization, has successfully solved the technical problems faced by the power supply module of the power metering box, such as stability, EMC, power consumption and mass production adaptability, providing a more reliable and efficient power supply solution for power metering equipment, and has broad application prospects.

Claims

1. A boost power supply module for an electricity metering box, characterized in that, include: The integrated switch controller chip (U2) has a feedback pin (pin 5), a compensation pin (pin 4), a soft-start pin (pin 2), a bootstrap pin (pin 13), a switch node pin (pin 1), an enable pin, and a mode pin. An energy storage inductor (L7) is disposed between the input terminal and the switch node pin (pin 1); A bootstrap capacitor (C5) is disposed between the bootstrap pin (pin 13) and the switch node pin (pin 1); The input capacitor (C3) is placed between the input terminal and ground; A bleed resistor (R2) is placed between the input terminal and ground; The first output capacitor (C7) is located between the output terminal and ground, and close to the integrated switch controller chip; The second output capacitor (C11) is located between the output terminal and ground, and near the load terminal; A soft-start capacitor (C49) is provided between the soft-start pin and ground; A compensation network is provided between the compensation pin and ground, the compensation network including a compensation resistor (R4) and a compensation capacitor (C2) connected in series; A feedback voltage divider network is configured between the output terminal and the feedback pin, the feedback voltage divider network including a first voltage divider resistor (R9) and a second voltage divider resistor (R3).

2. The boost power supply module according to claim 1, characterized in that, The enable pin and the mode pin can be configured to select a fixed frequency PWM mode or a PFM power-saving mode.

3. The boost power supply module according to claim 1, characterized in that, The integrated switch controller chip (U2) includes an analog ground pin (AGND) and a power ground pin (PGND), which are connected at a single point near the integrated switch controller chip.

4. The boost power supply module according to claim 1, characterized in that, The inductance of the energy storage inductor (L7) is 2.2 μH, and the capacitance of the bootstrap capacitor (C5) is approximately 100 nF.

5. The boost power supply module according to claim 1, characterized in that, The input capacitor (C3) has a capacitance of 22μF, and the first output capacitor (C7) and the second output capacitor (C11) both have a capacitance of 22μF.

6. The boost power supply module according to claim 1, characterized in that, The bleeder resistor (R2) has a resistance of 100kΩ, and the soft-start capacitor (C49) has a capacitance of 10μF.

7. The boost power supply module according to claim 1, characterized in that, The compensation resistor (R4) has a resistance of 6.8kΩ and the compensation capacitor (C2) has a capacitance of 6.8nF, forming a Type-II compensation.

8. The boost power supply module according to claim 1, characterized in that, The first voltage divider resistor (R9) has a resistance of 750kΩ, and the second voltage divider resistor (R3) has a resistance of 75kΩ, forming a voltage division ratio of 10:1.

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