A power supply circuit and system for an electric energy meter with a current doubling unit

Abstract

This invention relates to a power meter power supply circuit and system with a current multiplier unit, including an isolation step-down unit and a rectification and filtering unit, as well as a step-down output unit, a current multiplier-absorption multiplexing unit, and a switching selection unit. It adopts a dual-branch multiplexing power supply architecture, adaptable to the full operating conditions of relay engagement, steady-state holding, and disconnection. Relying on the current multiplier-absorption multiplexing unit, it can output transient high current to ensure reliable relay engagement, and can also store and recover reverse induced energy from the relay, improving energy utilization. The modular switching unit can isolate the path, eliminate circulating current and reverse current surges, and the front-end dual protection structure enhances the grid's anti-interference capability. The BUCK step-down circuit achieves low-power, low-ripple steady-state power supply. Combined with a controller, current sampling, and electronic load, it achieves adaptive adjustment under operating conditions, adapting to voltage fluctuation scenarios. Dual independent switches can simultaneously support transient high current for communication and provide regulated power supply for external devices, effectively improving circuit stability, energy efficiency, and scenario adaptability.

Description

Technical Field

[0001] This invention relates to the field of power supply driving technology, and more specifically, to a power supply circuit and system for an energy meter with a current multiplier unit. Background Technology

[0002] Relays are widely used actuators in industrial automation, electrical control, and intelligent equipment. Their coils are typical inductive loads, exhibiting three main electrical characteristics during operation: First, the instantaneous surge current, several times the steady-state current, is generated when the coil is energized, placing high demands on the short-term current-carrying capacity of the power supply circuit. Second, after the relay is energized, only a small holding current is needed to maintain its operating state; long-term full power supply will cause unnecessary power loss. Third, when the relay is de-energized, the inductive coil generates a reverse induced electromotive force with an amplitude much higher than the rated operating voltage, which can easily damage the front-end drive and control devices, while also generating electromagnetic interference.

[0003] Currently, the industry has developed multiple generations of relay power supply and drive technology solutions. Technological development has gradually evolved from basic drive to isolation protection and low power consumption. In current scenarios with wide-range AC power input, a DC voltage output signal is generally obtained first through a rectifier and filter unit. Among them, CN203456389U discloses a basic relay drive circuit. This solution uses an NPN transistor as the main switching device, connects a freewheeling diode in parallel across the coil to discharge the reverse electromotive force, and combines it with an RC snubber circuit to suppress switching arcing and adds a pull-down resistor to prevent circuit false triggering. It is the most widely used simple power supply drive architecture in the early days, mainly solving the basic on / off control and basic breakdown protection problems of relays. However, it is only suitable for simple control scenarios with low voltage, low power, and no strong interference. With increasing demands for electrical safety and anti-interference capabilities in industrial equipment, CN111555743A proposes an isolated electronic relay solution. This solution employs a composite isolation architecture combining optical and magnetic isolation to form an isolation step-down unit, integrating multi-level surge protection and status feedback circuits. This broadens the voltage adaptation range and overcomes the shortcomings of traditional basic circuits, such as lack of electrical isolation, direct connection between control and power terminals, and susceptibility to interference. It has become a mainstream isolation-enhanced power supply solution in industrial scenarios. To further reduce overall power consumption, the industry is moving towards energy storage-based low-power technologies. CN1737973A discloses a capacitor-based energy storage relay circuit. Utilizing the charging and discharging characteristics of capacitors, it relies on the instantaneous discharge of the capacitor to provide the inrush current required for relay engagement. In the steady-state phase, a micro-current maintains coil operation, optimizing standby and operating power consumption. Building upon this, CN101465636B further iterates and optimizes, proposing a hybrid low-power relay solution combining capacitor energy storage and resistor current limiting. This integrates electromagnetic and electronic control modes, extending its application to high-voltage, high-power contactor scenarios and further improving low-power performance and load adaptability.

[0004] The above four generations of technical solutions have successively solved the stage-specific problems of relay basic drive, electrical isolation, and high operating power consumption. However, due to the limitations of topology architecture and design concept, various existing power supply solutions still have many common defects and inherent shortcomings, and cannot simultaneously meet the modern usage requirements of high-power load, high energy efficiency, and multi-condition adaptability. The specific problems are reflected in the following aspects: First, the methods for handling reverse induced electromotive force are outdated, resulting in low energy utilization and significant issues with temperature rise and interference. All four existing technical documents employ passive discharge methods such as freewheeling diodes, TVS diodes, and RC snubber networks to handle the reverse high voltage generated when the relay disconnects. The magnetic field energy stored in the coil is entirely dissipated as heat, leading to energy waste and low overall energy efficiency. Furthermore, continuous heat loss accelerates device aging, resulting in significant heat dissipation pressure on the circuit during long-term continuous operation. Simultaneously, unsuppressed high-voltage spikes radiate electromagnetic interference, affecting the stable operation of peripheral control circuits and communication modules. Existing technologies lack a reverse energy recovery mechanism, making this problem unresolved.

[0005] Secondly, the instantaneous high current carrying capacity is insufficient, and the reliability of high-power relay engagement is poor. The CN203456389U uses a transistor as the switching device, which has limited current carrying capacity. When faced with the inrush current of relay engagement, it is prone to voltage drop on the power supply bus, leading to weak relay engagement or even relay failure. The CN111555743A focuses on optimizing electrical isolation and anti-interference performance but does not enhance the instantaneous current carrying capacity of the power circuit, and the risk of voltage drop still exists under high-power load scenarios. The CN1737973A relies on capacitor energy storage to provide inrush current, but the capacitance and charge / discharge rate of the capacitor have physical limits, making it unsuitable for high-current relays, resulting in a significant shortfall in inrush current support capability. Overall, existing solutions struggle to stably output large-value short-term inrush currents, limiting their application in high-power relays and multi-relay cluster devices.

[0006] Third, the adaptability to different operating conditions is limited and cannot match the multi-stage operating characteristics of relays. The complete working process of a relay consists of three operating conditions: pull-in, steady-state holding, and disconnection. The voltage and current requirements of different operating conditions vary significantly. Traditional basic drive circuits and isolation enhancement circuits have fixed topologies, outputting rated voltage and current throughout the entire process. They cannot dynamically adjust the output power according to the operating conditions, and the proportion of ineffective power consumption in the steady-state stage is high. Although capacitor energy storage and hybrid low-power circuits have optimized power consumption for the "pull-in" and "steady-state" stages, they only focus on current regulation and do not have a specific design for the relay disconnection condition. As a result, the failure rate increases when device parameters drift or age.

[0007] In summary, current relay drive circuits still have considerable room for improvement in circuit design and cannot cope with wide-range input scenarios while ensuring the relay's activation and deactivation effects and reducing power consumption. Summary of the Invention

[0008] To achieve the first objective of this invention, a power supply circuit for an energy meter with a current multiplier unit is provided, comprising an isolation step-down unit and a rectification and filtering unit, characterized in that: it further comprises a step-down output unit, a current multiplier-absorption multiplexing unit, and a switching selection unit; The step-down output unit is coupled to the output terminal of the rectifier filter unit and forms a sustaining voltage output terminal for outputting a sustaining voltage. The current multiplier-absorption multiplexing unit is coupled to the output terminal of the isolation step-down unit. The current multiplier-absorption multiplexing unit includes a current multiplier multiplexing sub-circuit, an energy storage sub-unit, and a multiplexing interface. The current multiplier-absorption multiplexing unit includes a current multiplier excitation state and an energy absorption state. The switching selection unit operates as follows: When the relay coil performs an engaging action, the switching selection unit activates the current multiplier-absorption multiplexing unit, which operates in a current multiplier excitation state. Its energy storage subunit outputs an engaging excitation current to the relay coil through the multiplexing interface. When the relay coil is in a steady-state holding state, the switching selection unit activates the buck output unit, which outputs a holding voltage to the relay coil through the holding voltage output terminal. When the relay coil performs an disconnecting operation, the switching selection unit disconnects the power supply path of the current multiplier-absorption multiplexing unit, which switches to an energy absorption state. The energy storage subunit receives and stores the reverse induced current generated by the relay coil through the multiplexing interface.

[0009] By setting up a dual-function branch with an independent step-down output unit and a current multiplier-absorption multiplexing unit, and coordinating with a switching selection unit to match the relay's operating logic under all operating conditions, the dual-operating-state multiplexing design of the current multiplier-absorption multiplexing unit allows for the output of excitation current when the relay is energized, ensuring reliable energization, and also allows for the reception and storage of reverse induced energy when the relay is de-energized. Furthermore, the switching selection unit ensures independent operation between circuits, especially preventing damage to front-end devices when reverse current is generated.

[0010] Furthermore, the switching selection unit includes a switching input execution switch, a bidirectional output power switch, and a sustaining output execution switch. The switching input execution switch is located between the isolation step-down unit and the current multiplier-absorption multiplexing unit. The bidirectional output power switch is located between the multiplexing interface and the relay's excitation interface. The sustaining output execution switch is located between the sustaining voltage output interface and the relay's excitation interface. The switching selection unit is modularly split into switches, with different functional switches controlling the current multiplier input path, power output path, and steady-state sustaining path respectively. Each switch operates independently and performs its specific function, accurately corresponding to different relay operating states to complete path switching. This avoids circuit anomalies caused by disordered conduction of multiple power supply paths, improving the accuracy of operating condition switching and circuit operational stability from a hardware structure perspective. Furthermore, the dual power switches ensure that the use of the multiplexing function does not affect unrelated components.

[0011] Furthermore, it also includes an input protection unit, which comprises a thermistor connected in series on the AC input side and a varistor connected in parallel on the AC input side. The thermistor and varistor are integrated on the AC input side to form the input protection unit. The thermistor can suppress abnormal inrush currents during circuit power-on and operation, while the varistor can clamp instantaneous high-voltage surges on the mains input side. These two types of protection devices work together to form a dual-protection system at the front end, effectively preventing damage to downstream circuits from abnormal mains voltage and current disturbances, and improving the overall input anti-interference capability and operational safety of the device.

[0012] Furthermore, the buck output unit is configured as a BUCK buck sub-circuit, which includes a BUCK control chip. The BUCK buck sub-circuit with a dedicated control chip serves as the core of the steady-state power supply. Based on the BUCK circuit's voltage regulation principle, it can achieve precise and stable control of the output voltage. It can provide a low-ripple, fluctuation-free holding voltage for the relay's steady-state holding phase, while reducing power consumption and avoiding overheating.

[0013] Furthermore, the current multiplier multiplexing sub-circuit includes a current multiplier branch and a clamping branch. The current multiplier branch includes a main power switch, a current multiplier capacitor, and a current multiplier resistor. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation buck unit through the current multiplier resistor. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The control electrode of the main power switch is grounded through a pull-down resistor. The clamping branch includes a TVS diode. The anode of the TVS diode is coupled to the positive output terminal of the multiplexing interface, and the cathode of the TVS diode is grounded. The RC switch architecture of the current multiplier branch realizes current gain, enhances the transient drive capability of the circuit, and meets the high current requirements of the relay's instantaneous pull-in. At the same time, combined with the TVS diode to form an independent clamping branch, it can quickly suppress various voltage spikes generated at the multiplexing interface, absorb transient high-voltage interference in the circuit, effectively protect the downstream relay load and power devices, and improve the circuit's anti-interference performance.

[0014] Furthermore, the energy storage subunit includes an energy storage inductor group and an energy storage capacitor group. The energy storage inductor group is coupled to the output terminal of the current multiplier multiplexing sub-circuit, and the energy storage capacitor group is connected in parallel to the multiplexing interface. The energy storage subunit is formed by combining the energy storage inductor group and the energy storage capacitor group. The energy storage inductor group can effectively smooth the output current, suppress current ripple, and optimize the output current quality. The energy storage capacitor group can cooperate to achieve positive transient energy replenishment, while simultaneously storing the reverse induced energy generated by the relay disconnection. Relying on the characteristics of passive components, it perfectly adapts to the core requirements of the dual operating modes of current multiplier unit excitation and energy storage.

[0015] A second objective of this invention is to provide a power meter system with a current multiplier unit, comprising the aforementioned power meter circuit with a current multiplier unit. The system is characterized by further including a controller, which is coupled to the switching selection unit and used to control the operation of the switching selection unit. The addition of a controller unifies the management of the switching selection units of multiple power circuits, abandoning the traditional passive control method with fixed timing. Through intelligent active control logic, the operating timing and switching logic of each circuit unit can be accurately matched, achieving coordinated and orderly operation of multiple circuits, significantly improving the automation level and overall operational coordination of the entire power system.

[0016] Furthermore, each current-multiplexing sub-circuit is also equipped with a current sampling resistor and an electronic load. The current sampling resistor is connected in series between the negative terminal of the relay coil and ground, and the electronic load is connected in parallel to the multiplexing interface. The controlled end of the electronic load is controlled by the controller. The relay operating current is collected in real time through the series current sampling resistor, providing accurate data for system condition judgment and parameter adjustment. The parallel-connected electronic load, controlled by the controller, can optimize the output state based on the sampled current characteristics, improving the operating point offset and output instability problems that easily occur when the circuit operates under light load and low voltage, and enhancing the circuit's dynamic adaptation capability when absorbing back electromotive force.

[0017] Further: The current multiplier multiplexing sub-circuit includes a current multiplier branch, which includes a main power switch, a current multiplier capacitor, and a current multiplier resistor. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation step-down unit through the current multiplier resistor. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The control electrode of the main power switch is grounded through a pull-down resistor. The clamping branch includes a TVS diode, the anode of which is coupled to the positive output terminal of the multiplexing interface. The controlled terminal of the main power switch of each current multiplier multiplexing sub-circuit is coupled to the controller. This ensures the core function of current amplification in the current multiplier circuit. Simultaneously, connecting the main power switch to the controller enables controllable adjustment, allowing precise control of the current multiplier branch's on / off state and operating mode according to different relay operating states. This adapts to the circuit's dual-mode switching requirements of forward excitation and reverse energy storage, ensuring the absorption efficiency of the reverse electromotive force based on the relay's operating current characteristics. It also ensures stable current output under different input voltage scenarios.

[0018] Furthermore, the switching selection unit also includes an external sustaining voltage switch and an external current multiplier voltage switch. The external sustaining voltage switch is coupled to the sustaining voltage output terminal, and the external current multiplier voltage switch is coupled to the multiplexing interface. By adding independent external sustaining voltage switches and external current multiplier voltage switches, the external paths of the steady-state power supply branch and the current multiplier excitation branch can be independently controlled. This allows the current multiplier excitation to provide current support for the communication module's transmission moment, while the regulated output interface can maintain the power supply operation of other peripheral modules.

[0019] The main technical advantages of this invention are reflected in the following aspects: It adopts a dual-branch multiplexing power supply architecture, adapting to the full operating requirements of relay engagement, steady-state holding, and disconnection. Relying on the current multiplier-absorption multiplexing unit, it can both output transient high current to ensure reliable relay engagement and store and recover reverse induced energy from the relay, improving energy utilization. The modular switching unit can isolate the path and eliminate circulating current and reverse current surges, while the front-end dual protection structure enhances the grid's anti-interference capability. The BUCK step-down circuit achieves low-power, low-ripple steady-state power supply. Combined with the controller, current sampling, and electronic load, it achieves adaptive adjustment under operating conditions, adapting to voltage fluctuation scenarios. The dual independent switches can simultaneously support transient high current for communication and provide regulated power supply for peripherals, effectively improving circuit stability, energy efficiency, and scenario adaptability. Attached Figure Description

[0020] Figure 1 : A schematic diagram of the working architecture of a power meter power supply circuit with a current multiplier unit according to the present invention; Figure 2 : A schematic diagram of the relay in the power supply circuit of an energy meter with a current multiplier unit according to the present invention in the activated state; Figure 3 : A schematic diagram of the power supply circuit relay of an energy meter with a current multiplier unit according to the present invention in the relay maintenance state; Figure 4 : A schematic diagram of the power supply circuit of an energy meter with a current multiplier unit in the relay-off state according to the present invention; Figure 5 The present invention provides a circuit diagram of a power meter power supply circuit with a current multiplier unit and a passive current multiplier relay. Figure 6 The present invention provides a circuit diagram of an active current multiplier relay power supply circuit for an energy meter with a current multiplier unit. Figure 7 : Schematic diagram of the controller pin distribution circuit of the present invention; Figure 8 : Schematic diagram of current waveform comparison in this invention; Figure 9 : Schematic diagram of voltage waveform comparison in this invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to make the technical solution of the present invention easier to understand and master. (Refer to...) Figure 1-4 As shown, a power supply circuit for an energy meter with a current multiplier unit includes an input protection unit, an isolation step-down unit, a rectifier and filter unit, a step-down output unit, a current multiplier-absorption multiplexing unit, and a switching selection unit. Referring to the illustrations, since this invention is specifically designed for the power supply circuit of an energy meter with a relay coil, Embodiment 1 mainly focuses on the three processes of relay activation, maintenance, and disconnection. Firstly, the AC power supply for a typical energy meter is a wide-range input scenario, so we will first refer to... Figure 1 As shown, the input protection unit is used to implement input-side overvoltage protection, surge protection, and burst pulse protection. The isolation step-down unit serves two purposes: stepping down the voltage and isolating the input and output sides to prevent reverse surges from affecting the input devices. The rectifier-filter unit rectifies and filters the AC power before inputting it to the step-down output unit, which provides a stable voltage output. It should be noted that the step-down output unit can not only provide the relay's holding current but also power other modules of the energy meter. In other words, this circuit is designed specifically for the overall energy meter power supply circuit considering the current characteristics of the relay coil at the moment of activation and deactivation. The following describes the circuit's working principle through the relay's activation state. Firstly, if the relay is in the instant of activation, a large activation current is required. Therefore... Figure 2 As shown, the bidirectional output power switch K1 is configured to be forward-biased, the input execution switch K3 is turned on, and the output execution switch K2 is kept off. The current multiplier-absorption multiplexing unit operates in the current multiplier excitation state. Current flows from the power supply side through the step-down isolation unit to the current multiplier-absorption multiplexing unit and is output through the multiplexing interface. (Refer to...) Figure 3 As shown, if the relay needs to maintain its engaged state after activation, a large current is not required. Therefore, a current-multiplier-absorption multiplexing unit can be selected. This unit can turn on the output sustaining switch K2, turn off the bidirectional output power switch K1, and switch the input switching switch K3. Current flows from the power supply side through the step-down isolation unit, rectifier filter unit, and step-down output unit to output a stable sustaining voltage. (Refer to...) Figure 4 As shown, if the relay needs to be disconnected, the output holding switch K2 can be turned off, the bidirectional output power switch K1 can be turned on in reverse, and the input switching switch K3 can be turned off. In this way, the reverse electromotive force generated by the relay being disconnected will charge the energy storage unit, ensuring that the reverse electromotive force does not impact other devices.

[0022] Reference Figure 5 As shown, the specific circuit composition of the invention is explained. First, there is an input protection unit, which includes a thermistor QT connected in series on the AC input side and a varistor RT1 connected in parallel on the AC input side. The varistor absorbs surge energy; the thermistor suppresses surge current. It also includes a protection element RT1, which can be configured as a fuse or other protective element, and can also provide additional functions such as current and voltage detection on the bus. This makes the power supply suitable for wide-range AC power supply scenarios.

[0023] The isolation step-down unit is connected to the input protection unit and is used to achieve AC high-voltage step-down and electrical isolation. The isolation step-down unit preferably adopts a power frequency transformer structure. The primary winding of the power frequency transformer is connected to the AC input, and the secondary winding outputs a low-voltage AC signal. Power frequency isolation effectively improves system safety and common-mode interference immunity. Furthermore, by rationally designing the transformer turns ratio, a wide input range adaptability can be achieved.

[0024] The filtering and rectifying unit is connected to the first branch after the isolation step-down unit. The filtering and rectifying unit includes a rectifier bridge and a filter capacitor. The rectifier bridge converts AC voltage into pulsating DC voltage; the filter capacitor reduces ripple and improves the stability of the subsequent BUCK input. After filtering and rectification, a stable DC bus voltage is formed.

[0025] It should be noted that the circuit configuration of the input protection unit, isolation step-down unit, and filter rectification unit is not limited to the above implementation method, and can be optimized and improved on this basis.

[0026] The buck output unit is coupled to the output of the rectifier-filter unit and forms a sustaining voltage output terminal for outputting a sustaining voltage. The buck output unit is configured as a BUCK buck sub-circuit, which includes a BUCK control chip. The BUCK buck unit is connected to the stage after the filter-rectifier unit. Referring to the diagram, the core components include a BUCK control chip U1, a power inductor L1, a bootstrap capacitor C1, feedback resistors R4 and R2, output filter capacitors C2, C3, and C7, and enable resistors R1 and R3. These components together form the BUCK buck circuit. The BUCK buck unit is used to further reduce the filtered and rectified DC voltage to a stable low-voltage output. In one embodiment, its output can be used for: MCU power supply, metering chip power supply, communication module power supply, LCD driver power supply, and memory power supply. Compared to traditional pure buck structures, this invention significantly reduces the power consumption of the subsequent stage through the BUCK pre-buck method. For example, when the input DC voltage is high, the BUCK unit first completes most of the voltage drop, reducing device heat generation. Therefore, it can effectively improve system efficiency and long-term operational stability.

[0027] The current multiplier-absorption multiplexing unit is coupled to the output terminal of the isolation step-down unit. The current multiplier-absorption multiplexing unit includes a current multiplier multiplexing sub-circuit, an energy storage sub-unit, and a multiplexing interface. The current multiplier-absorption multiplexing unit includes a current multiplier excitation state and an energy absorption state. In one embodiment, refer to Figure 5As shown, the current multiplier multiplexing sub-circuit includes a current multiplier branch, which includes a main power switch Q1, a current multiplier capacitor C12, and a current multiplier resistor R5. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation buck unit through the current multiplier resistor R5. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The main power switch can be configured as a switching transistor, and current multiplier diodes D6 / D8 are used to prevent reverse current conduction, and clamping diodes are used to limit the terminal voltage of current multiplier capacitors D1 / D2 and D9 / D10. The enhanced current multiplier unit enhances the output drive capability through capacitor charging and discharging and the current multiplier structure. Under low input voltage conditions: the enhanced current multiplier unit can improve the output current capability at the moment of relay energization. Simultaneously: it can provide transient high current support at the moment of communication module transmission or relay operation. (Refer to...) Figure 8 and Figure 9 As shown, the stability of current and voltage is significantly improved at the moment of pull-in.

[0028] To further verify the technical effectiveness of the circuit of the present invention under relay energizing conditions, this embodiment combines... Figure 8 and Figure 9 A comparative analysis was conducted on the output current and output voltage waveforms, as well as relevant typical values, between circuits with and without enhancement-type current multipliers. Figure 9 As shown, under typical test conditions of input AC 220V / 50Hz, output 12V relay power supply, relay pull-in current 80mA, and pull-in time 20ms, there are significant differences in voltage drop, recovery time, and power supply stability between the two: (1) Voltage sag and recovery characteristics analysis without the enhanced current multiplier circuit; Without the enhanced current multiplier circuit of this invention, when the relay starts to engage (at 20ms), the voltage of the power supply bus drops significantly due to the increased pull-in excitation current required by the coil. According to the voltage sag calculation formula: Among them, current gap 20mA, pull-in time 20ms, output capacitor 220 Calculations show that its theoretical voltage drop value is... (Typical test value is 1.8V), its waveform characteristics are as follows: large voltage drop, with the lowest bus voltage dropping to 10.2V; and a long recovery time after the drop, about 35ms to recover to steady state. This large voltage drop and slow recovery process may cause the relay to fail to release, resulting in poor overall system stability, with the voltage drop ratio (relative to 12V steady state voltage) as high as 15%.

[0029] (2) Voltage sag and recovery characteristics analysis with enhanced current multiplier circuit; When the enhanced current multiplier circuit proposed in this invention is used, relying on the transient large current support capability of the current multiplier-absorption multiplexing unit under the current multiplier excitation state, the current gap and voltage fluctuation during the pull-in process are greatly compensated. According to the voltage sag calculation formula: At this point, due to the intervention of the enhancement-type current multiplier circuit, the residual current gap... Reduced to 5mA, and equivalent energy storage capacitance Upgraded to 940 Calculations show that its theoretical voltage drop value is... (Typical test value is 0.11V), its waveform characteristics are as follows: the voltage drop is minimal, with the lowest voltage only slightly dropping to 11.8V; at the same time, the voltage has a fast recovery characteristic, and it only takes about 5ms to quickly recover to the steady-state voltage of 12.0V. The voltage drop rate is greatly reduced from 15% to 0.9%, which effectively ensures that the relay can reliably engage, and the system stability rating is improved from "poor" to "excellent".

[0030] The waveform comparison data (typical values) show that: voltage drop is 1.8V without the enhancement current multiplier circuit, and decreases to 0.11V with the enhancement current multiplier circuit; minimum voltage is 10.2V without the enhancement current multiplier circuit, and increases to 11.8V with the enhancement current multiplier circuit; recovery time is 35ms without the enhancement current multiplier circuit, and shortens to 5ms with the enhancement current multiplier circuit; voltage drop ratio is 15% without the enhancement current multiplier circuit, and is optimized to 0.9% with the enhancement current multiplier circuit; power supply stability is "poor" without the enhancement current multiplier circuit, and "excellent" with the enhancement current multiplier circuit.

[0031] Therefore, it can be seen that by adding a current multiplier-absorption multiplexing unit, this invention not only significantly improves the transient high current carrying and output capabilities (such as...) Figure 8 As shown, the peak current has been increased from 130mA to 150mA, which fundamentally suppresses the voltage drop of the power supply bus when the relay is energized, shortens the transient recovery time, and ensures the high stability and scenario adaptability of the power meter power supply circuit and system under complex full-operating conditions from the hardware topology.

[0032] Reference Figure 6As shown, in another embodiment, the current multiplier branch includes a main power switch Q1, a current multiplier capacitor C12, and a current multiplier resistor R5. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation buck unit through the current multiplier resistor R5. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The control electrode of the main power switch is grounded through a pull-down resistor R6. The controlled terminal of the main power switch of each current multiplier multiplexing sub-circuit is coupled to the controller. The main power switch is configured as a MOSFET, and its power is controlled by the controller, thereby controlling the corresponding current multiplier current. Its circuit configuration includes a pull-down resistor R6 with a conduction level and a cutoff diode D5, and the terminal voltage of the current multiplier capacitors D1 / D2 and D9 / D10 is limited by a clamping diode. Compared with the previous embodiment, this adds the function of adjusting the current multiplier current according to the power supply side current, improving the circuit adaptability.

[0033] In one embodiment, the clamping branch includes a TVS diode, the anode of which is coupled to the positive output of the multiplexing interface. The TVS device is used to absorb transient spike energy and improve noise immunity.

[0034] In one embodiment, the energy storage sub-unit includes an energy storage inductor group and an energy storage capacitor group, the energy storage inductor group being coupled to the output terminal of the current multiplier multiplexing sub-circuit, and the energy storage capacitor group being connected in parallel to the multiplexing interface.

[0035] The switching selection unit operates as follows: When the relay coil performs an engaging action, the switching selection unit activates the current multiplier-absorption multiplexing unit, which operates in a current multiplier excitation state. Its energy storage subunit outputs an engaging excitation current to the relay coil through the multiplexing interface. When the relay coil is in a steady-state holding state, the switching selection unit activates the buck output unit, which outputs a holding voltage to the relay coil through the holding voltage output terminal. When the relay coil performs an disconnecting operation, the switching selection unit disconnects the power supply path of the current multiplier-absorption multiplexing unit, which switches to an energy absorption state. The energy storage subunit receives and stores the reverse induced current generated by the relay coil through the multiplexing interface.

[0036] The switching selection unit includes a switching input execution switch, a bidirectional output power switch, and a sustain output execution switch. The switching input execution switch is located between the isolation step-down unit and the current multiplier-absorption multiplexing unit. The bidirectional output power switch is located between the multiplexing interface and the relay excitation interface. The sustain output execution switch is located between the sustain voltage output interface and the relay excitation interface. Specifically, the bidirectional output power switch is set to a bidirectional power thyristor D11, which forms a conduction loop controlled by the controller pins s-cr1 and s-cr2. When a pull-in current is required, s-cr1 is turned on and s-cr2 is turned off. When a reverse electromotive force is required, s-cr2 is turned on and s-cr1 is turned off, thus realizing the function of a unidirectional switch. Simultaneously, the loop can assist in discharge. V_rp12 is coupled to the relay coil. The switching input execution switch is configured as a switching input thyristor D15, controlled by the s-cr6 pin, while the sustain output execution switch is configured as a sustain output thyristor D12, controlled by the s-cr3 pin to form a loop.

[0037] In another embodiment, based on the previous embodiment, the switching selection unit further includes an external sustaining voltage switch and an external current multiplier voltage switch. The external sustaining voltage switch is coupled to the sustaining voltage output terminal, and the external current multiplier voltage switch is coupled to the multiplexing interface. Through the external sustaining voltage thyristor and the external current multiplier thyristor, the output is controlled so that when the circuit needs to power other modules, the corresponding circuit can be used for power supply. It should be noted that the circuit has a multiplexing relationship; to avoid reverse current directly acting on the external circuit, theoretically, D14 and D11 should have an interlocking relationship in their control signals.

[0038] A power supply system for an energy meter with a current multiplier unit includes the aforementioned power supply circuit for an energy meter with a current multiplier unit, and also includes a controller. The controller is coupled to the switching selection unit and is used to control the operation of the switching selection unit. The controller can be configured with corresponding data acquisition, analysis, and instruction generation functions, and controls the corresponding switching selection unit to control the corresponding switch to switch the circuit to different operating states to adapt to the overall operation. First, a single controller can control the power supply system of multiple circuits. If the number of pins is insufficient, a corresponding serial-to-parallel conversion unit can be configured for conversion. The controller's role is to capture information, thus configuring the corresponding absorption power and output current according to the actual scenario. Specifically, each current multiplier multiplexing sub-circuit is also configured with a current sampling resistor and an electronic load. The current sampling resistor is connected in series between the negative terminal of the relay coil and ground, and the electronic load is connected in parallel to the multiplexing interface. The controlled end of the electronic load is controlled by the controller. The current sampling resistor RS samples the current waveform through the rs1 port and obtains the supply voltage through the rs2 port. The controller analyzes the data and configures the impedance of the corresponding electronic load, thereby making adaptive adjustments.

[0039] Of course, the above are just typical examples of the present invention. In addition, the present invention may have many other specific embodiments. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. An electric energy meter power supply circuit having a current doubling unit, comprising an isolation voltage reduction unit and a rectification filter unit, characterized in that: It also includes a step-down output unit, a current multiplier-absorption multiplexing unit, and a switching selection unit; The step-down output unit is coupled to the output terminal of the rectifier filter unit and forms a sustaining voltage output terminal for outputting a sustaining voltage. The current multiplier-absorption multiplexing unit is coupled to the output terminal of the isolation step-down unit. The current multiplier-absorption multiplexing unit includes a current multiplier multiplexing sub-circuit, an energy storage sub-unit, and a multiplexing interface. The current multiplier-absorption multiplexing unit includes a current multiplier excitation state and an energy absorption state. The switching selection unit operates as follows: When the relay coil performs an engaging action, the switching selection unit activates the current multiplier-absorption multiplexing unit, which operates in a current multiplier excitation state. Its energy storage subunit outputs an engaging excitation current to the relay coil through the multiplexing interface. When the relay coil is in a steady-state holding state, the switching selection unit activates the buck output unit, which outputs a holding voltage to the relay coil through the holding voltage output terminal. When the relay coil performs an disconnecting operation, the switching selection unit disconnects the power supply path of the current multiplier-absorption multiplexing unit, which switches to an energy absorption state. The energy storage subunit receives and stores the reverse induced current generated by the relay coil through the multiplexing interface.

2. The power supply circuit for an energy meter with a current multiplier unit as described in claim 1, characterized in that: The switching selection unit includes a switching input execution switch, a bidirectional output power switch, and a sustain output execution switch. The switching input execution switch is located between the isolation step-down unit and the current multiplier-absorption multiplexing unit. The bidirectional output power switch is located between the multiplexing interface and the excitation interface of the relay. The sustain output execution switch is located between the sustain voltage output interface and the excitation interface of the relay.

3. The power supply circuit for an energy meter with a current multiplier unit as described in claim 1, characterized in that: It also includes an input protection unit, which includes a thermistor connected in series with the AC input side, and a varistor connected in parallel with the AC input side.

4. The power supply circuit of an energy meter with a current multiplier unit as described in claim 3, characterized in that: The step-down output unit is configured as a BUCK step-down sub-circuit, which includes a BUCK control chip.

5. The power supply circuit for an energy meter with a current multiplier unit as described in claim 1, characterized in that: The current multiplier multiplexing sub-circuit includes a current multiplier branch and a clamping branch. The current multiplier branch includes a main power switch, a current multiplier capacitor, and a current multiplier resistor. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation buck unit through the current multiplier resistor. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The control electrode of the main power switch is grounded through a pull-down resistor. The clamping branch includes a TVS diode. The anode of the TVS diode is coupled to the positive output terminal of the multiplexing interface, and the cathode of the TVS diode is grounded.

6. The power supply circuit for an energy meter with a current multiplier unit as described in claim 5, characterized in that: The energy storage sub-unit includes an energy storage inductor group and an energy storage capacitor group. The energy storage inductor group is coupled to the output terminal of the current multiplier multiplexing sub-circuit, and the energy storage capacitor group is connected in parallel to the multiplexing interface.

7. A power supply system for an energy meter with a current multiplier unit, comprising a plurality of power supply circuits for an energy meter with a current multiplier unit as described in any one of claims 1-6, characterized in that: It also includes a controller, which is coupled to the switching selection unit and is used to control the operation of the switching selection unit.

8. The power supply system for an energy meter with a current multiplier unit as described in claim 7, characterized in that: Each current multiplexing sub-circuit is also equipped with a current sampling resistor and an electronic load. The current sampling resistor is connected in series between the negative terminal of the relay coil and the ground terminal, and the electronic load is connected in parallel to the multiplexing interface. The controlled terminal of the electronic load is controlled by the controller.

9. A power supply system for an energy meter with a current multiplier unit as described in claim 8, characterized in that: The current multiplier multiplexing sub-circuit includes a current multiplier branch and a clamping branch. The current multiplier branch includes a main power switch, a current multiplier capacitor, and a current multiplier resistor. The ground electrode of the main power switch is coupled to the positive output terminal of the isolation buck unit through the current multiplier resistor. The output electrode of the main power switch is coupled to the positive output terminal of the multiplexing interface through the current multiplier capacitor. The control electrode of the main power switch is grounded through a pull-down resistor. The clamping branch includes a TVS diode. The anode of the TVS diode is coupled to the positive output terminal of the multiplexing interface. The controlled terminal of the main power switch of each current multiplier multiplexing sub-circuit is coupled to the controller.

10. A power supply system for an energy meter with a current multiplier unit as described in claim 9, characterized in that: The switching selection unit also includes an external sustaining voltage switch and an external current multiplier voltage switch. The external sustaining voltage switch is coupled to the sustaining voltage output terminal, and the external current multiplier voltage switch is coupled to the multiplexing interface.

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