CN204679622U - Three-phase smart energy meter communication interface load capacity test device with communication module - Google Patents

Abstract

A three-phase smart energy meter communication interface loading capacity testing device with a communication module, including a MOSFET circuit, resistors R1 and R2, a three-phase power supply, a voltage detection module, a current detection module, a high-speed sampling circuit, and an A/D conversion unit , MCU circuit, serial port communication, keyboard, DC voltage measurement and display circuit, D/A conversion unit and PWM control circuit. The utility model adopts a device that uses an electronic load composed of a MOSFET circuit as a main circuit as a test load. The electronic load can simulate the load conditions of constant current, constant voltage, and constant resistance, and the initial value can be set; when detecting the drain current of the MOSFET circuit Based on the drain-source voltage and the drain-source voltage, the MOSFET circuit is adjusted through the MCU circuit and the PWM control circuit to obtain a load whose resistance and precision meet the measurement requirements; the high-speed sampling circuit is used to effectively measure the accuracy of the measured DC voltage. The utility model is suitable for the load capacity test of the communication interface of the three-phase intelligent electric energy meter with the communication module.

Description

Three-phase smart energy meter communication interface load capacity test device with communication module

                   

The utility model relates to a device for testing the load capacity of the communication interface of a three-phase intelligent electric energy meter with a communication module, which belongs to the field of electric measurement technology.

Background technique

The communication module is an equipment unit for local communication and mutual data transmission between the master station and the collection terminal, the collector and the terminal, and the collection terminal and the smart energy meter of the electric power user information collection system. The smart energy meter is equipped with a communication module interface, which can perform data interaction with the communication module, and uses power line carrier communication or micro-power wireless communication to realize communication with the collector/acquisition terminal.

During the on-site operation, it was found that there are more and more matching and compatibility problems between the smart energy meter and the communication module. For example, the load capacity of the communication interface of the energy meter exceeds the allowable range, which makes the dynamic power consumption of the module communication larger, and the power supply of the energy meter is pulled down, resulting in The energy meter does not work; the load capacity of the communication interface of the energy meter is insufficient to drive the communication module to work normally, which affects the data reading of the electricity information collection system. For this reason, the State Grid Enterprise Standard "Q/GDW 1827-2013 Three-phase Smart Meter Technical Specifications" puts forward corresponding requirements for the load capacity of the communication interface of the three-phase smart energy meter. It stipulates: V _CC voltage +12V±1V, load current 0mA～400mA.

The traditional communication interface load capacity test method is to remove the communication module of the three-phase smart meter, and connect a pure resistive load between the analog power interface (Vcc) pin of the energy meter communication module and the ground according to the definition of the communication interface pins of the meter. , the load resistance is 30Ω (±5% accuracy), use a multimeter to measure whether the Vcc voltage and the ground pin voltage are within the range of 12V±1V. This test method needs to manually search for the power interface wiring, which is tedious, time-consuming, and error-prone. Moreover, the use of a purely resistive load is affected by environmental factors, resulting in low accuracy and poor reliability of the load capacity test.

Invention Contents

The purpose of the utility model is to solve the problems of cumbersome, error-prone and low accuracy of the existing manual method for testing the carrying capacity of the communication interface, to meet the needs of field testing; to overcome the deficiencies of the prior art, and to provide a communication module The three-phase smart energy meter communication interface load capacity test device.

In order to solve the above-mentioned technical problems, the utility model is realized through the following technical solutions: The utility model has a communication module three-phase intelligent electric energy meter communication interface loading capacity testing device comprising: MOSFET circuit, resistor R1 and resistor R2, three-phase power supply , voltage detection module, current detection module, high-speed sampling circuit, A/D conversion unit, MCU circuit, serial communication, keyboard, DC voltage measurement and display circuit, D/A conversion unit and PWM control circuit.

The load capacity test device for the communication interface of the three-phase smart energy meter uses an electronic load composed of a MOSFET circuit as the main circuit as the test load.

In the device of the utility model, the drain of the MOSFET circuit is connected to the Vcc pin of the analog power supply interface of the communication module of the electric energy meter under test, and its source is connected to the ground of the communication interface of the electric meter through the current detection module; Provide power supply; resistor R1 and resistor R2 are connected in series, and connected between the analog power interface Vcc pin of the energy meter communication module and the ground; the input terminal of the voltage detection module is connected to both ends of the resistor R2, and the output terminal of the voltage detection module passes The sampling circuit transmits the test data to the MCU circuit after conversion and calculation; the current detection module is responsible for detecting the drain current of the MOSFET circuit, and its output terminal passes through the A/D conversion unit to simulate the detected drain current of the MOSFET circuit The signal is converted into a digital signal and transmitted to the MCU circuit; the other output terminal of the MCU circuit is connected to the PWM control circuit through the D/A conversion unit, and the PWM control circuit is connected to the gate of the MOSFET circuit; the output terminal of the MCU circuit is connected to the DC voltage measurement display circuit; the keyboard output is connected to the MCU circuit; the serial port circuit is interconnected with the MCU circuit.

The MCU circuit is responsible for analyzing the collected drain current signal and drain-source voltage signal of the MOSFET circuit, comparing with the preset value and outputting a voltage control signal of a certain size, which is output to the D/A conversion unit for D/A conversion The output terminal of the unit is connected to the input terminal of the PWM control circuit, and the output terminal of the PWM control circuit is connected to the gate of the MOSFET circuit; the human-computer interaction is realized through the keyboard and the DC voltage measurement and display circuit, and the two-way communication with the MCU circuit is realized through the serial port communication. It is used to select different working modes and set related parameters.

Compared with the prior art, the beneficial effect of the utility model is that the utility model adopts an electronic load composed of a MOSFET circuit as the main circuit as a test load, and the electronic load can simulate the load conditions of constant current, constant voltage and constant resistance, and can Set the initial value; on the basis of detecting the drain current and drain-source voltage of the MOSFET circuit, adjust the MOSFET circuit through the MCU circuit and the PWM control circuit to obtain a load whose resistance and accuracy meet the measurement requirements; use high-speed sampling The circuit effectively measures the accuracy of the measured DC voltage.

The utility model is suitable for the load capacity test of the communication interface of the three-phase intelligent electric energy meter with the communication module.

  Description of the drawings 

Figure 1 is a schematic diagram of the structure of the main circuit of the utility model;

Fig. 2 is a flow chart of testing the load capacity of the communication interface of the three-phase smart energy meter of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments and with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of the main circuit of the present invention.

The device in this embodiment includes: MOSFET circuit, resistor R1 and resistor R2, three-phase power supply, voltage detection module, current detection module, high-speed sampling circuit, A/D conversion unit, MCU circuit, serial port communication, keyboard, DC voltage measurement and display circuit , D/A conversion unit and PWM control circuit.

The MCU circuit of this embodiment adopts TMS320LF2812 chip.

The three-phase smart energy meter under test in the device is powered by a three-phase power supply; resistor R1 and resistor R2 are connected in series and connected between the analog power interface (Vcc) pin of the meter under test and the ground; the device mainly uses a MOSFET circuit The electronic load composed of the circuit is used as the test load; the current detection module detects the drain current of the MOSFET circuit, and converts it into a corresponding current digital signal through the A/D conversion unit and transmits it to TMS320LF2812; the voltage detection module detects the voltage at both ends of the resistor R2, and uses high-speed The sampling circuit performs high-speed sampling of the measured voltage, uses the built-in data processor to convert and calculate the test data, effectively measures the measured DC ripple voltage, and then transmits it to TMS320LF2812. According to the obtained voltage and current signals, TMS320LF2812 combines the resistance values of resistor R1 and resistor R2 to obtain the equivalent resistance value of the circuit between V _CC and the ground terminal at this time, compare and analyze with the preset value, and use it as TMS320LF2812 to adjust the control voltage The basis is to control the turn-on and turn-off of the MOS transistor of the power circuit to obtain the actual required working voltage and current, so that the equivalent resistance value between the meter communication analog power interface (Vcc) pin and the ground is 30Ω (accuracy meet ±5%). In this case, the output voltage, output current, output ripple, etc. between the V _CC terminal of the module interface in the meter and the ground are measured to realize the automatic test of the load capacity of the communication interface of the three-phase smart energy meter.

According to the State Grid Enterprise Standard "Q/GDW 1827-2013 Three-phase Smart Meter Technical Specifications", the requirements for the load capacity of the communication interface of the three-phase smart energy meter: VCC voltage + 12V ± 1V, load current 0mA ~ 400mA. The human-computer interaction is realized through the keyboard and the DC voltage measurement and display circuit, which is convenient for the recording of detection data; the serial port communication realizes the two-way communication with the TMS320LF2812 MCU circuit, which is used to select different working modes and set relevant initial parameters.

Fig. 2 is a flow chart of testing the load capacity of the communication interface of the three-phase smart energy meter of the present invention.

The steps to detect the load capacity of the single-phase carrier smart meter communication interface are as follows:

Step 1: Turn on the three-phase power supply and start the test;

Step 2: Set the initial resistance value of 30Ω through the keyboard and serial port communication;

Step 3: the current detection module detects the drain current of the MOSFET circuit;

Step 4: The voltage detection module detects the voltage value at both ends of R2;

Step 5: DSP obtains the drain current and the drain-source voltage of the MOSFET circuit;

Step 6: Calculate the resistance value of the equivalent resistance between Vcc and ground;

Step 7: The DSP outputs a negative feedback voltage signal to control the gate-source voltage of the MOSFET circuit;

Step 8: Repeat steps 3 to 7 until the resistance value of the equivalent resistance between Vcc and ground calculated by the DSP meets the measurement requirements, the resistance value is 30Ω, and the accuracy meets ±5%;

Step 9: DSP records the drain-source voltage of the MOSFET circuit at this time, and transmits it to the DC voltage measurement and display circuit;

Step 10: The test is over.

The utility model realizes the automatic test of the load capacity of the communication interface of the three-phase intelligent electric energy meter through the test device for the load capacity of the communication interface of the three-phase intelligent electric energy meter with the communication module.

The unexplained parts involved in the utility model are the same as the prior art or implemented by adopting the prior art.

Claims (3)

1. the three-phase intelligent electric-energy meter communication interface load capacity proving installation with communication module, comprises A/D converting unit, D/A converting unit, three-phase supply, keyboard, resistance R1 and resistance R2, it is characterized in that,

Described device also comprises MOSFET circuit, voltage detection module, current detection module, high speed sampling circuit, MCU circuit, serial communication, DC voltage measurement display circuit and pwm control circuit;

The drain electrode of described MOSFET circuit connects tested electric energy meter communication module analog power interface Vcc pin, and its source electrode connects the ground of ammeter communication interface by current detection module; Tested three-phase intelligent electric-energy meter provides power supply by three-phase supply; Resistance R1 and resistance R2 connects, and is attempted by between electric energy meter communication module analog power interface Vcc pin and ground; The input end of voltage detection module is connected on the two ends of resistance R2, and the output terminal of voltage detection module, through high speed sampling circuit, after the conversion carrying out test data and computing, is transferred to MCU circuit; Current detection module is responsible for the drain current detecting MOSFET circuit, and its output terminal, through A/D converting unit, converts the drain current simulating signal of the MOSFET circuit detected to digital signal, and is transferred to MCU circuit; Another output terminal of MCU circuit connects pwm control circuit by D/A converting unit, and pwm control circuit connects the grid of MOSFET circuit; The output terminal of MCU circuit connects DC voltage measurement display circuit; Keyboard exports and connects MCU circuit; Serial port circuit and MCU circuit interconnection.

2. the three-phase intelligent electric-energy meter communication interface load capacity proving installation of band communication module according to claim 1, is characterized in that, described device adopts the electronic load formed for main circuit using MOSFET circuit as test load.

3. the three-phase intelligent electric-energy meter communication interface load capacity proving installation of band communication module according to claim 1, is characterized in that, described MCU circuit adopts TMS320LF2812 chip.