Metering isolation power supply circuit suitable for manganin scheme electric energy meter

Abstract

The utility model relates to the technical field of electric energy meter power supply circuits, provides a metering isolation power supply circuit suitable for a manganin scheme electric energy meter, and aims to solve the influence of instability of a power supply on electric energy metering accuracy and normal work of a communication module. The circuit comprises an isolation power transformer driver UM1, a resistor, a magnetic bead, a double-series rectifier diode, an isolation transformer and a plurality of capacitors. Wherein the driver UM1 has a three-band frequency selection capability, a spread spectrum clock function is realized, and the anti-interference performance is improved. The circuit design effectively inhibits magnetic bias or saturation of the transformer, provides electrical isolation, reduces the influence of voltage fluctuation, and ensures the accuracy and consistency of voltage and current signal sampling. In addition, the integrated over-current and over-temperature detection and protection functions improve the safety and durability of the electric energy meter. The overall design improves the electromagnetic compatibility, and ensures the metering precision and the electric energy quality of the electric energy meter.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits of electric energy meters, and particularly relates to a metering isolation power supply circuit applicable to electric energy meters with a manganin scheme. Background Art

[0002] As an intelligent meter product, the metering accuracy and reliability of an electric energy meter should be effectively guaranteed. However, unstable metering power supply may cause interference to the signal processing and calculation processes inside the metering chip, thereby affecting the accuracy of key parameters such as electric energy metering and power factor calculation, resulting in errors in the electric energy metering results. Unstable metering power supply will also affect the normal operation of the communication module, causing problems such as data upload failure or data packet loss, thus affecting the product competitiveness.

[0003] The electric energy meter with a manganin scheme uses manganin alloy as the core material of the current transformer in the electric energy meter. Manganin is a high-permeability material with high magnetic permeability and low coercivity, which makes it very useful in the field of electric energy metering. The high magnetic permeability of the manganin alloy makes the current transformer very sensitive to small current changes, helping to improve the metering accuracy. Due to the low coercivity of the manganin alloy, the eddy current loss generated by the current transformer during operation is small, thus reducing the energy consumption. However, the electric energy meter with a manganin scheme mainly has the following problems in use:

[0004] Firstly, unstable power supply may cause interference to the signal processing and calculation processes inside the metering chip, affecting the accuracy of electric energy metering. Secondly, the noise caused by power supply fluctuations and ground loops may affect the normal operation of the communication module, resulting in data upload failure or data packet loss. In addition, power supply abnormalities such as high-voltage surges and transient spikes may damage the metering chip, affecting the long-term stability and reliability of the electric energy meter.

[0005] Therefore, it is of great significance to design a metering isolation power supply circuit applicable to electric energy meters with a manganin scheme to solve the above problems. Content of the Utility Model

[0006] To solve the problems in the background art, the utility model provides a metering isolation power supply circuit applicable to electric energy meters with a manganin scheme, which includes an isolation power transformer driver UM1; resistors RM1, RM2; beads LM1, LM2; double series rectifier diodes DM1, DM2; isolation transformer TM1; capacitors CM1, CM2, CM3, CM4, CM5, CM6.

[0007] Among them, pin 1 VDD of the driver UM1 is used as the power input pin, pin 2 GND is the ground of the internal analog circuit and drive circuit of the chip, pin 3 SEL is the frequency selection pin, pin 4 VB2 is the full-bridge drive stage output 2, and pin 5 VB1 is the full-bridge drive stage output 1.

[0008] A capacitor CM1 and a capacitor CM2 are connected in parallel between pin 1 and pin 2 of the driver UM1.

[0009] Pin 1 of the driver UM1 is connected to the circuit power supply VDDM, pin 2 of the driver UM1 is connected to a resistor RM2, the other end of the resistor RM2 is grounded, and pin 3 (frequency selection pin) of the driver UM1 is connected to VDDM, and the drive chip operates in the middle frequency band.

[0010] A capacitor CM5 is connected between pin 4 (full-bridge drive stage output 2) and pin 2 of the driver UM1, and a capacitor CM6 is connected between pin 5 (full-bridge drive stage output 1) and pin 2 of the driver UM1.

[0011] Pin 5 and pin 4 of the driver UM1 are respectively connected to pin 1 and pin 4 of the primary side of the transformer TM1, and the middle nodes of the rectifier diodes DM1 and DM2 are respectively connected to pin 8 and pin 5 of the secondary side of the transformer.

[0012] The anodes of the rectifier diodes DM1 and DM2 are connected together, a capacitor CM4 is connected between the anode of the rectifier diode DM1 and the cathode of the rectifier diode DM2, the cathodes of the rectifier diodes DM1 and DM2 are connected together and then connected to the analog ground.

[0013] The anode of the rectifier diode DM1 is connected to a capacitor CM3 and a resistor RM1 after passing through a magnetic bead LM1, the other ends of the capacitor CM3 and the resistor RM1 are grounded, the cathode of the rectifier diode DM2 is connected to a magnetic bead LM2, and the other end of the magnetic bead LM2 is connected to the grounded end of the capacitor CM3.

[0014] In a preferred solution, the capacitor CM2 is an input voltage stabilizing capacitor with a capacitance value greater than 1 μF, the capacitors CM5 and CM6 are EMI suppression capacitors with a capacitance value of 470 pF and a working voltage not lower than 10 V. The withstand voltage of the isolation transformer should be greater than 2.5 KV.

[0015] In a preferred solution, the rectifier diodes DM1 and DM2 are double-series Schottky barrier diodes with a maximum forward current of 200 mA and a withstand voltage of 30 V.

[0016] In a preferred solution, the magnetic beads LM1 and LM2 are filter inductance units, and also have good high-frequency attenuation characteristics, which are used to absorb and dissipate high-frequency noise and transient spike signals in the circuit.

[0017] In a preferred solution, the capacitor CM3 is an output voltage stabilizing capacitor, the capacitor CM4 is a voltage stabilizing capacitor, and the resistor RM1 is a dummy load resistor.

[0018] The beneficial effects achieved by the present utility model are:

[0019] First, the present utility model provides a metering isolation power supply circuit applicable to an electric energy meter using the manganese copper solution. The driver UM1 has the ability to select frequencies in three bands and realizes the spread spectrum clock function within each band. This design can dynamically adjust the operating frequency, effectively avoid electromagnetic interference that may occur at a single frequency, and thus improve the anti-interference performance of the circuit. At the same time, the design of the driver UM1 can prevent faults from spreading from one part to another, providing comprehensive protection for the entire system.

[0020] Second, through a specific circuit design, the driver UM1 can effectively suppress the bias magnetic or saturation phenomenon of the power transformer. This helps to maintain the stable operation of the transformer and prevent power instability caused by transformer problems.

[0021] Third, the isolation transformer in the circuit design provides electrical isolation, ensuring the stability of the power supply. Even in the case of external power fluctuations, it can provide a stable power supply for the electric energy meter, ensuring the continuity and reliability of the metering process.

[0022] Fourth, the design of the driver UM1 reduces the impact of voltage fluctuations on the metering module, ensuring the accuracy and consistency of voltage and current signal sampling. This is crucial for achieving accurate measurement of power consumption.

[0023] Fifth, the integrated overcurrent and over-temperature detection and protection functions enable the driver UM1 to provide protection in case of short circuit or over-temperature and have self-recovery ability. This greatly improves the safety and durability of the electric energy meter.

[0024] Sixth, improving the electromagnetic compatibility (EMC), the design of the driver UM1 reduces the noise and common mode interference caused by ground loops, effectively enhancing the electromagnetic compatibility of the system. This is crucial for ensuring the stability and accuracy of signal transmission, especially for the operation of electric energy meters in complex electromagnetic environments.

[0025] Seventh, the circuit ensures that the load end is not affected by input power fluctuations and can maintain stable output voltage and current. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the circuit diagram of the present utility model;

[0027] Figure 2 is the working flow chart of the present utility model. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solutions in the present utility model will be clearly and completely described below with reference to the accompanying drawings in the present utility model. In addition, the forms of the various structures described in the following embodiments are merely examples, and the present utility model is not limited to the various structures described in the following embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present utility model.

[0029] Referring to Figure 1 - Figure 2 , the present utility model provides a metering isolation power supply circuit applicable to an electric energy meter using a manganin scheme, which includes an isolation power transformer driver UM1, resistors RM1 and RM2, magnetic beads LM1 and LM2, double series rectifier diodes DM1 and DM2, an isolation transformer TM1, and capacitors CM1, CM2, CM3, CM4, CM5, and CM6.

[0030] Pin 1 (VDD) of the driver UM1 is the power input pin, pin 2 (GND) of the driver UM2 is the ground of the internal analog circuit and the driving circuit of the chip, pin 3 (SEL) of the driver UM1 is the frequency selection pin. When the SEL pin is floating, the driving chip operates in the low frequency band, and the spread spectrum range is 270 - 370 KHz. When the SEL pin is connected to VDD, the driving chip operates in the medium frequency band, and the spread spectrum range is 310 - 400 KHz. When the SEL pin is connected to GND, the driving chip operates in the high frequency band, and the spread spectrum range is 350 - 430 KHz. Pin 4 (VB2) of the driver UM1 is the full - bridge drive stage output 2, and pin 5 (VB1) of the driver UM1 is the full - bridge drive stage output 1.

[0031] Capacitors CM1 and CM2 are connected in parallel between pin 1 (power input pin) and pin 2 (internal ground of the chip) of the driver. Pin 1 of the driver is connected to the circuit power supply VDDM, pin 2 of the driver is connected to resistor RM2, and the other end of resistor RM2 is grounded. Pin 3 (frequency selection pin) of the driver is connected to VDDM, and the driving chip operates in the medium frequency band. Capacitor CM5 is connected between pin 4 (full - bridge drive stage output 2) and pin 2 of the driver, and capacitor CM6 is connected between pin 5 (full - bridge drive stage output 1) and pin 2 of the driver. Pin 5 and pin 4 of the driver are respectively connected to pin 1 and pin 4 of the primary side of the transformer TM1. Pin 8 and pin 5 of the secondary side of the transformer are respectively connected to the intermediate nodes of the rectifier diodes DM1 and DM2. The anodes of the rectifier diodes DM1 and DM2 are connected together. Capacitor CM4 is connected between the anode of the rectifier diode DM1 and the cathode of the rectifier diode DM2. The cathodes of the rectifier diodes DM1 and DM2 are connected together and then connected to the analog ground. The anode of the rectifier diode DM1 is connected to capacitor CM3 and resistor RM1 after passing through the magnetic bead LM1, and the other ends of capacitor CM3 and resistor RM1 are grounded. The cathode of the rectifier diode DM2 is connected to the magnetic bead LM2, and the other end of the magnetic bead LM2 is connected to the grounded end of capacitor CM3.

[0032] The capacitor CM2 is an input voltage stabilizing capacitor, and its capacitance value should be greater than 1 μF. The capacitors CM5 and CM6 are EMI suppression capacitors, with a capacitance value of 470 pF and a working voltage not lower than 10 V. The isolation transformer should have a withstand voltage capacity greater than 2.5 kV. Electrical isolation of the two windings is achieved through the isolation transformer. When an alternating current is applied to the primary winding, according to Faraday's law of electromagnetic induction, a corresponding alternating voltage will be induced in the secondary winding. There is no direct electrical connection between the primary winding and the secondary winding, and energy is transferred only through the magnetic core, thus achieving electrical isolation. The rectifier diodes DM1 and DM2 are double-series Schottky barrier diodes, with a maximum forward current of 200 mA and a withstand voltage of 30 V. The capacitor CM4 is a voltage stabilizing capacitor. The magnetic beads LM1 and LM2 are filter inductor units, and also have good high-frequency attenuation characteristics. They can absorb and dissipate high-frequency noise and transient spike signals in the circuit, effectively preventing these noises from spreading to other circuit parts through the power line, thereby improving the electromagnetic compatibility (EMC) of the system. The capacitor CM3 is an output voltage stabilizing capacitor, and the resistor RM1 is a dummy load resistor.

[0033] The power supply of this utility model is input through pin 1 VDD of the driver UM1. At the same time, the input voltage stabilizing capacitors CM1 and CM2 are connected in parallel between pin 1 and pin 2 GND to ensure power supply stability. Pin 3 SEL of the driver UM1 is used as the frequency selection pin. According to the level state of the SEL pin, the driving chip UM1 can work in the low-frequency band, medium-frequency band or high-frequency band to realize the spread-spectrum clock function and improve the anti-interference performance of the circuit. Pins 4 VB2 and 5 VB1 of the driver UM1 are used as the outputs of the full-bridge driving stage and are respectively connected to the primary side of the isolation transformer TM1 to realize isolated driving of the signal. The secondary side output of the isolation transformer TM1 is connected to the rectifier diodes DM1 and DM2 for rectification. The rectified signal is preliminarily filtered through the capacitor CM4. The anode of the rectifier diode DM1 is connected to the capacitor CM3 and the dummy load resistor RM1 through the magnetic bead LM1 for further filtering and voltage stabilization. The cathode of the rectifier diode DM2 is connected to the ground terminal of the capacitor CM3 through the magnetic bead LM2 to provide high-frequency noise attenuation. The capacitors CM5 and CM6 are used as EMI suppression capacitors and are connected in parallel with the corresponding pins of the driver UM1 to reduce electromagnetic interference. The capacitor CM3 is used as an output voltage stabilizing capacitor to ensure the stability of the output voltage. The driver UM1 integrates overcurrent and overtemperature detection and protection functions to ensure protection and self-recovery ability in abnormal situations. The overall circuit design reduces the noise and common-mode interference caused by the ground loop, improving the electromagnetic compatibility of the system. The circuit ensures that the load end is not affected by the input power supply fluctuation, maintaining stable output voltage and current, and ensuring the metering accuracy of the watt-hour meter.

[0034] As described above, it is only the preferred embodiment of the present invention, and it is not intended to limit the present invention in other forms. Any person skilled in the mechanical field may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A metering isolation power supply circuit suitable for a manganese copper scheme electric energy meter, characterized in that: It includes: Isolation power transformer driver UM1; Resistors RM1, RM2; magnetic beads LM1, LM2; dual series rectifier diodes DM1, DM2; isolation transformer TM1; capacitors CM1, CM2, CM3, CM4, CM5, CM6; Among them, the 1st pin VDD of the driver UM1 is used as the power input pin, the 2nd pin GND is the ground of the analog circuit and the driving circuit inside the chip, the 3rd pin SEL is the frequency selection pin, the 4th pin VB2 is the full-bridge driving stage output 2, and the 5th pin VB1 is the full-bridge driving stage output 1; Capacitors CM1 and CM2 are connected in parallel between pins 1 and 2 of driver UM1; Pin 1 of driver UM1 is connected to circuit power supply VDDM, pin 2 of driver UM1 is connected to resistor RM2, the other end of resistor RM2 is grounded, pin 3 of driver UM1 is connected to VDDM, and the driver chip works in the medium frequency band; Connect capacitor CM5 between pin 4 and pin 2 of driver UM1, and connect capacitor CM6 between pin 5 and pin 2 of driver UM1; Pins 5 and 4 of driver UM1 are connected to pins 1 and 4 of primary side of transformer TM1 respectively, and pins 8 and 5 of secondary side of transformer are connected to the middle nodes of rectifier diodes DM1 and DM2 respectively; The anodes of the rectifier diodes DM1 and DM2 are connected, the capacitor CM4 is connected between the anode of the rectifier diode DM1 and the cathode of the rectifier diode DM2, the cathodes of the rectifier diodes DM1 and DM2 are connected, and then connected to the analog ground; The anode of the rectifier diode DM1 is connected to the capacitor CM3 and the resistor RM1 via the magnetic bead LM1, and the other ends of the capacitor CM3 and the resistor RM1 are grounded. The cathode of the rectifier diode DM2 is connected to the magnetic bead LM2, and the other end of the magnetic bead LM2 is connected to the ground end of the capacitor CM3.

2. The metering isolation power supply circuit suitable for the manganese-copper scheme electric energy meter according to claim 1 is characterized in that: Capacitor CM2 is an input voltage stabilizing capacitor with a capacitance greater than 1μF. Capacitors CM5 and CM6 are EMI suppression capacitors with a capacitance of 470pF and an operating voltage of no less than 10V. The withstand voltage of the isolation transformer is greater than 2.5KV.

3. The metering isolation power supply circuit suitable for the manganese-copper scheme electric energy meter according to claim 1 is characterized in that: The rectifier diodes DM1 and DM2 are dual series Schottky barrier diodes, with a maximum forward current of 200 mA and a withstand voltage of 30 V.

4. The metering isolation power supply circuit suitable for the manganese-copper scheme electric energy meter according to claim 1 is characterized in that: The magnetic beads LM1 and LM2 are filter inductor units with high-frequency attenuation characteristics, and are used to absorb and dissipate high-frequency noise and transient spike signals in the circuit.

5. The metering isolation power supply circuit suitable for the manganese-copper scheme electric energy meter according to claim 1 is characterized in that: Capacitor CM3 is an output voltage stabilizing capacitor, capacitor CM4 is a voltage stabilizing capacitor, and resistor RM1 is a dummy load resistor.

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