Three-phase power analysis circuit

Abstract

The utility model relates to the technical field of circuit design, in particular to a three-phase electric power analysis circuit, which adopts an ATT7022E three-phase electric energy dedicated chip to sample all parameters and measure three-phase voltage, current, active power, reactive power, apparent power, power factor and frequency parameters. The circuit specifically comprises an MCU control circuit, a liquid crystal display interface circuit, a power supply circuit, a 485 communication circuit, a switching value output circuit, an analog quantity output circuit, a buzzer drive circuit, an LED drive circuit, an ATT7022E core circuit and a sampling circuit. According to the utility model, signals converted by the mutual inductor are sampled through the ADC, the waveform of the whole period is sampled, parameters such as three-phase voltage, current, active power, reactive power, apparent power, power factor, frequency, voltage angle, current angle, harmonic wave and the like are calculated through an algorithm, the sampling precision is high, and the price is low.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit design, in particular to a three-phase power analysis circuit. Background Art

[0002] With the continuous improvement of the automation level of modern power systems and the in-depth promotion of smart grid construction, smart meters, as important terminal equipment of power systems, have the ability to effectively monitor the basic parameters of three-phase electricity, including but not limited to real-time measurement of conventional electrical parameters such as three-phase voltage, current, active power, reactive power, apparent power and electric energy. However, for deeper power quality analysis and precise load characteristics research, the functions of existing smart meters still need to be improved and perfected.

[0003] In actual three-phase power systems, the phase difference (i.e., angle) between phase voltages and between phase current and voltage is a key indicator reflecting the operating status of the power grid and the degree of load imbalance. This information is of great significance for power grid dispatching, power quality assessment, and equipment maintenance. For example, the phase difference between the three-phase voltages can help identify whether there is an asymmetric fault in the power grid, while the angle between the phase current and voltage is the basis for calculating the power factor and reactive power compensation.

[0004] In addition, the concept of vector sum is mainly used in power systems for voltage and current vector operations expressed in complex form. It can intuitively reflect the instantaneous power balance of three-phase electricity and has high practical value for dynamic load regulation, harmonic analysis, and formulation of control strategies for motor drive systems. Utility Model Content

[0005] The purpose of the utility model is to provide a three-phase power analysis circuit to solve the problem that the smart meter proposed in the above background technology realizes the measurement of some conventional parameters such as three-phase voltage, current, power, electric energy, etc., but lacks the angle between the phase voltages, the angle between the phase current and the voltage, the vector sum, and the A, B, C single-phase active, reactive, and apparent electric energy.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A three-phase power analysis circuit adopts ATT7022E three-phase power dedicated chip to sample all parameters, measures three-phase voltage, current, active power, reactive power, apparent power, power factor and frequency parameters, and specifically includes MCU control circuit, liquid crystal display interface circuit, power supply circuit, 485 communication circuit, switch output circuit, analog output circuit, buzzer drive circuit, LED drive circuit, ATT7022E core circuit and sampling circuit.

[0008] Preferably, the MCU control circuit adopts STMicroelectronics microcontroller STM32F103RCT6, Cortex-M3 core.

[0009] Preferably, the power supply circuit uses 220V AC input to convert into 12V, and then converts into 3.3V through DC-DC for powering the entire system.

[0010] Preferably, the built-in chip of the 485 communication circuit is SP3485, including RS485 and RS422 transceivers, with a built-in 5.0V logic voltage conversion, and data transmission and reception are achieved by controlling the levels of the DE and RE pins.

[0011] Preferably, the switch output circuit has a built-in amplifier, and when the power is added to the base of the transistor through the resistor R1 and the capacitor C1, the transistor changes its conduction state according to the state of the input signal.

[0012] Preferably, the analog output circuit uses an LM358 operational amplifier, which is configured in follower mode to amplify the signal from DACOUT1. Resistors R5 and R6 form a voltage divider circuit to reduce the VCC_12V voltage to a value suitable for the LM358 input range. The resistance values ​​are 10K and 43K respectively, so that R5 / R6 is 1 / 5, and thus the output voltage is 5 times the input voltage.

[0013] Preferably, the buzzer driving circuit adopts a transistor Q3, a resistor R19 and a buzzer BEEPER. The transistor Q3 adopts an NPN transistor S8550 for switch control. The base is connected to VCC 3V3 through a resistor R19, the emitter is grounded (GND), and the collector is connected to the buzzer BEEPER. When the transistor Q3 is turned on, the current flows from VCC 3V3 through R19, Q3, and BEEPER to GND, causing the buzzer to sound.

[0014] Preferably, the LED driving circuit includes D5, D7, D8, R33, R41, R44 and a power supply VCC_3V3, R33, R41, R44 are all 1KΩ current limiting resistors, respectively connected between the corresponding LED cathode and GND.

[0015] Preferably, the ATT7022E core circuit is based on the core of the ATT7022E chip, including power supply, crystal oscillator circuit, reset circuit and some IO ports.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] This three-phase power analysis circuit samples the signal converted by the mutual inductor through ADC, samples the entire cycle waveform, and calculates the three-phase voltage, current, active power, reactive power, apparent power, power factor, frequency, voltage angle, current angle, harmonics and other parameters through the algorithm. It also has the following effects:

[0018] High-precision measurement: Through the ATT7022E three-phase power dedicated chip, the circuit can achieve high-precision power parameter measurement. This is very important for power system monitoring, energy management and fault analysis, and can provide accurate data support.

[0019] Multifunctional integration: The circuit integrates multiple functions, such as the measurement of multiple parameters such as voltage, current, power, and the calculation of frequency and power factor, etc. This enables the circuit to complete multiple tasks in a compact module, improving the integration and efficiency of the system.

[0020] Easy to expand and communicate: Through the 485 communication circuit, the circuit can easily communicate with other devices or systems to achieve remote transmission and monitoring of data. In addition, the circuit also has switch output and analog output functions, which can be easily connected and expanded with other devices or systems.

[0021] Stability and reliability: The MCU control circuit uses STMicroelectronics' STM32F103RCT6 microcontroller, which has high performance and stability. At the same time, the power supply circuit uses 220V AC input to convert it into 12V, and then converts it into 3.3V through DC-DC to provide a stable power supply for the entire system. These designs help improve the stability and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, further detailed explanation is provided, but the accompanying drawings do not constitute a limitation to the present invention.

[0023] Figure 1 This is the schematic diagram of the MCU control circuit of the utility model;

[0024] Figure 2 It is a circuit schematic diagram of the liquid crystal display interface circuit in the utility model;

[0025] Figure 3 It is a circuit schematic diagram of the power supply circuit in the utility model;

[0026] Figure 4 It is the circuit principle diagram of the 485 communication circuit in the utility model;

[0027] Figure 5 It is the circuit principle diagram of the switch output circuit in the utility model;

[0028] Figure 6 It is a circuit principle diagram of the analog output circuit in the utility model;

[0029] Figure 7 This is a circuit schematic diagram of the buzzer driving circuit in the utility model;

[0030] Figure 8 This is a circuit schematic diagram of the LED driving circuit in the utility model;

[0031] Fig. 9 This is the circuit schematic diagram of the ATT7022E core circuit in the utility model;

[0032] Fig.10 It is a circuit principle diagram of the power supply circuit in the utility model. DETAILED DESCRIPTION

[0033] The following will combine the embodiments of the utility model and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] A three-phase power analysis circuit, such as Figure 1-Figure 10 As shown, the ATT7022E three-phase power dedicated chip is used to sample all parameters, and measure the three-phase voltage, current, active power, reactive power, apparent power, power factor, and frequency parameters. Specifically, it includes MCU control circuit, LCD display interface circuit, power supply circuit, 485 communication circuit, switch output circuit, analog output circuit, buzzer drive circuit, LED drive circuit, ATT7022E core circuit and sampling circuit. It can measure three-phase voltage, current, active power, reactive power, apparent power, power factor, frequency and other electrical parameters, and can record the maximum and minimum values ​​of three-phase voltage, three-phase current and active power. It can measure the 2-31 harmonic content rate of voltage and current in the power network, total harmonic distortion rate (THD), odd total harmonic distortion rate (TOHD), even total harmonic distortion rate (TEHD), and total harmonic factor (THF). It can display harmonic bar graphs, measure phase angles, and display vector diagrams. It can measure the grid quality parameters such as voltage and current positive sequence, negative sequence, zero sequence, and imbalance in the power network.

[0035] Furthermore, the MCU control circuit adopts STMicroelectronics microcontroller STM32F103RCT6, Cortex-M3 core, the power supply circuit adopts 220V AC input to convert into 12V, and then converts into 3.3V through DC-DC for powering the entire system, the built-in chip of the 485 communication circuit is SP3485, including RS485 and RS422 transceivers, built-in 5.0V logic voltage conversion, and data sending and receiving are achieved by controlling the levels of DE and RE pins, and the switch output circuit has a built-in amplifier. When it is added to the base of the transistor through resistor R1 and capacitor C1, the transistor will change its conduction state according to the state of the input signal.

[0036] The analog output circuit uses the LM358 operational amplifier, which is configured in follower mode to amplify the signal from DACOUT1. The resistors R5 and R6 form a voltage divider circuit to reduce the VCC_12V voltage to a value suitable for the LM358 input range. The resistance values ​​are 10K and 43K respectively, making R5 / R6 1 / 5, so the output voltage is 5 times the input voltage.

[0037] LM358: This is a dual op amp, only one of which (U3A) is used here. It is configured in follower mode to amplify the signal from DACOUT1.

[0038] R5 and R6: These two resistors form a voltage divider circuit to reduce the VCC_12V voltage to a value suitable for the LM358 input range. Their resistance values ​​are 10K and 43K respectively, making R5 / R6 approximately 1 / 5, so the output voltage is approximately 5 times the input voltage.

[0039] R7: is a 1K ohm resistor connected between the output of LM358 and ground as a load resistor.

[0040] C10: is a 100 microfarad electrolytic capacitor connected between the output of LM358 and ground to filter out high frequency noise.

[0041] R8 and R9: Two resistors form a voltage divider circuit to adjust the output voltage range. Their resistance values ​​are 10K and 43K respectively, making R8 / R9 about 1 / 5, so the output voltage is about 5 times the input voltage.

[0042] C12: is a 100 microfarad electrolytic capacitor connected between the power pin of LM358 and ground to filter out power supply noise.

[0043] VOUT: is the output terminal of LM358, connected to ground through R7 and C10 to form a low-pass filter.

[0044] VS3: is an LED or other type of indicator connected between the output terminal of LM358 and ground to display the output voltage.

[0045] In general, the function of this circuit is to amplify and output the analog signal from DACOUT1. By adjusting the resistance values ​​of R5, R6, R8 and R9, the range of the output voltage can be changed. At the same time, through C10 and VS3, the output voltage can be filtered and displayed.

[0046] Among them, the buzzer driving circuit adopts transistor Q3, resistor R19 and buzzer BEEPER. Transistor Q3 adopts NPN transistor S8550 for switch control. The base is connected to VCC 3V3 through a resistor R19, the emitter is grounded (GND), and the collector is connected to the buzzer BEEPER. When the transistor Q3 is turned on, the current flows from VCC 3V3 through R19, Q3, and BEEPER to GND, making the buzzer sound.

[0047] VCC 3V3: This is the power input terminal, providing 3.3V operating voltage.

[0048] Q3: This is an NPN transistor S8550, used for switch control. Its base (B) is connected to VCC 3V3 through a resistor R19, the emitter (E) is grounded (GND), and the collector (C) is connected to the buzzer BEEPER.

[0049] R19: This is a 1K ohm current limiting resistor, which is used to limit the current flowing through the base of transistor Q3 and protect the transistor from being burned.

[0050] BEEPER: This is a buzzer. When transistor Q3 is turned on, current flows from VCC 3V3 through R19, Q3, BEEPER to GND, making the buzzer sound.

[0051] GND: This is the ground of the circuit, the common reference point for all circuits.

[0052] When VCC 3V3 is added to the circuit, current will flow through R19 to the base of Q3, turning Q3 on. At this time, the collector voltage of Q3 is close to 0V, causing a voltage difference across the BEEPER, thereby generating current and making the buzzer sound. When VCC 3V3 is disconnected, Q3 is cut off, there is no voltage difference across the BEEPER, the current stops, and the buzzer stops sounding.

[0053] It is worth mentioning that the LED driving circuit includes D5, D7, D8, R33, R41, R44 and power supply VCC_3V3. R33, R41 and R44 are all 1KΩ current limiting resistors, which are respectively connected between the corresponding LED cathode and GND.

[0054] VCC_3V3: This is the power input terminal, providing 3.3V operating voltage.

[0055] D5: This is a red LED with its positive terminal (longer leg) connected to VCC_3V3 and its negative terminal (shorter leg) connected to ground (GND) through resistor R33.

[0056] D7: This is a green LED with its positive terminal connected to VCC_3V3 and its negative terminal connected to ground through resistor R41.

[0057] D8: This is also a green LED, with its positive terminal connected to VCC_3V3 and its negative terminal connected to ground through resistor R44.

[0058] R33, R41, R44: These three are 1K ohm current limiting resistors, used to limit the current flowing through the LED and protect the LED from being burned. They are connected between the corresponding LED cathode and GND respectively.

[0059] When VCC_3V3 is added to the circuit, current will flow through R33, D5, R41, D7, R44, and D8 to GND, making the three LEDs light up. Due to the existence of resistors, the voltage drop on each LED is about 2V (the typical forward voltage drop of LEDs), so that the voltage provided by VCC_3V3 can be effectively distributed to the three LEDs. If the power supply is directly connected to the LED without using a current limiting resistor, the LED may burn out due to excessive current.

[0060] In addition, the ATT7022E core circuit is based on the core of the ATT7022E chip, including power supply, crystal oscillator circuit, reset circuit and some IO ports.

[0061] Power supply:

[0062] VCC_3V3: Power input terminal, providing 3.3V operating voltage.

[0063] AGND: Analog ground, separate from digital ground (DGND), used to ensure the purity of analog signals. DGND: Digital ground, the common reference point of the entire circuit.

[0064] VDD_3V3: Digital power supply, which provides power for the digital circuit inside the chip.

[0065] REFCAP: Reference voltage, used to provide a stable reference voltage.

[0066] VREFVP: positive reference voltage.

[0067] VREFVN: negative reference voltage.

[0068] Crystal oscillator circuit:

[0069] Y1: 5.5296MHz crystal oscillator, used to provide the clock frequency for the chip to work. C3: 100pF capacitor, together with the crystal oscillator, forms an oscillation circuit.

[0070] C4: A 15pF capacitor, which forms an oscillation circuit together with the crystal oscillator.

[0071] C5: 100pF capacitor, together with the crystal oscillator, forms an oscillation circuit.

[0072] Reset circuit:

[0073] R1: A 100kΩ resistor connected in series with capacitor C1 to form a power-on reset circuit.

[0074] C1: A 100μF capacitor, together with resistor R1, forms a power-on reset circuit.

[0075] R2: 1MΩ resistor, connected in series with capacitor C2, forms the reset circuit of the watchdog timer. C2: 100μF capacitor, together with resistor R2, forms the reset circuit of the watchdog timer. IO port connection method:

[0076] VCC 3V3: Power input terminal, providing 3.3V operating voltage.

[0077] GND: Ground, the common reference point for the entire circuit.

[0078] L2: 100nH inductor, used for filtering and anti-interference.

[0079] C6: 100μF capacitor, together with inductor L2, forms a power supply filter circuit.

[0080] C7: 100nF capacitor, together with inductor L2, forms a power supply filter circuit.

[0081] C8: 100nF capacitor, together with inductor L2, forms a power supply filter circuit.

[0082] C9: 100nF capacitor, together with inductor L2, forms a power supply filter circuit.

[0083] SEL: Select input signal, used to choose three-phase four-wire or three-phase three-wire mode.

[0084] GND: Ground, the common reference point for the entire circuit.

[0085] other:

[0086] J1: Connector, used to connect external devices or signals.

[0087] U2: ATT7022E chip, the core of the whole circuit.

[0088] VCC 3V3: Power input terminal, providing 3.3V operating voltage.

[0089] GND: Ground, the common reference point for the entire circuit.

[0090] VDD 3V3: Digital power supply, powers the digital circuit inside the chip.

[0091] REFCAP: Reference voltage, used to provide a stable reference voltage.

[0092] VREFVP: positive reference voltage.

[0093] VREFVN: negative reference voltage.

[0094] The three-phase power analysis circuit includes:

[0095] 1) Parameter sampling function:

[0096] It can collect three-phase voltage, current, power, power factor, active power, reactive power, apparent power, grid frequency, total reactive power, total active power, total apparent power, current and voltage angle, voltage and voltage angle, three-phase vector sum and other parameters

[0097] 2) Alarm function:

[0098] Overvoltage alarm, overcurrent alarm, power alarm, total power alarm, grid frequency alarm

[0099] 3) Analog output

[0100] Any sampled parameter can set the corresponding analog output.

[0101] This three-phase power analysis circuit samples the signal converted by the mutual inductor through ADC, samples the entire cycle waveform, and calculates the three-phase voltage, current, active power, reactive power, apparent power, power factor, frequency, voltage angle, current angle, harmonics and other parameters through the algorithm. It also has:

[0102] High-precision measurement: Through the ATT7022E three-phase power dedicated chip, the circuit can achieve high-precision power parameter measurement. This is very important for power system monitoring, energy management and fault analysis, and can provide accurate data support.

[0103] Multifunctional integration: The circuit integrates multiple functions, such as the measurement of multiple parameters such as voltage, current, power, and the calculation of frequency and power factor, etc. This enables the circuit to complete multiple tasks in a compact module, improving the integration and efficiency of the system.

[0104] Easy to expand and communicate: Through the 485 communication circuit, the circuit can easily communicate with other devices or systems to achieve remote transmission and monitoring of data. In addition, the circuit also has switch output and analog output functions, which can be easily connected and expanded with other devices or systems.

[0105] Stability and reliability: The MCU control circuit uses STMicroelectronics' STM32F103RCT6 microcontroller, which has high performance and stability. At the same time, the power supply circuit uses 220V AC input to convert it into 12V, and then converts it into 3.3V through DC-DC to provide a stable power supply for the entire system. These designs help improve the stability and reliability of the circuit.

[0106] Easy to use and maintain: Through the LCD display interface circuit, the circuit can intuitively display various power parameters and status information, which is convenient for users to monitor and operate. In addition, the circuit also has a buzzer drive circuit and an LED drive circuit, which can provide sound and visual prompts, which is convenient for users to troubleshoot and maintain.

[0107] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the utility model and are not used to limit the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. A three-phase power analysis circuit, characterized in that: The ATT7022E three-phase power dedicated chip is used to sample all parameters and measure the three-phase voltage, current, active power, reactive power, apparent power, power factor, and frequency parameters. Specifically, it includes MCU control circuit, LCD display interface circuit, power supply circuit, 485 communication circuit, switch output circuit, analog output circuit, buzzer drive circuit, LED drive circuit, ATT7022E core circuit and sampling circuit.

2. The three-phase power analysis circuit according to claim 1, characterized in that: The MCU control circuit adopts STMicroelectronics microcontroller STM32F103RCT6, Cortex-M3 core.

3. The three-phase power analysis circuit according to claim 1, characterized in that: The power supply circuit uses 220V AC input to convert into 12V, and then converts into 3.3V through DC-DC to power the entire system.

4. The three-phase power analysis circuit according to claim 1, characterized in that: The built-in chip of the 485 communication circuit is SP3485, which includes RS485 and RS422 transceivers, and has a built-in 5.0V logic voltage conversion, and realizes data sending and receiving by controlling the levels of DE and RE pins.

5. The three-phase power analysis circuit according to claim 1, characterized in that: The switch output circuit has a built-in amplifier. When the amplifier is added to the base of the transistor through the resistor R1 and the capacitor C1, the transistor will change its conduction state according to the state of the input signal.

6. The three-phase power analysis circuit according to claim 1, characterized in that: The analog output circuit uses an LM358 operational amplifier, which is configured in follower mode to amplify the signal from DACOUT1. The resistors R5 and R6 form a voltage divider circuit to reduce the VCC_12V voltage to a value suitable for the LM358 input range. The resistance values ​​are 10K and 43K respectively, making R5 / R6 1 / 5, so the output voltage is 5 times the input voltage.

7. The three-phase power analysis circuit according to claim 1, characterized in that: The buzzer driving circuit adopts transistor Q3, resistor R19 and buzzer BEEPER. Transistor Q3 adopts NPN transistor S8550 for switch control. The base is connected to VCC 3V3 through a resistor R19, the emitter is grounded GND, and the collector is connected to the buzzer BEEPER. When the transistor Q3 is turned on, the current flows from VCC 3V3 through R19, Q3, and BEEPER to GND, making the buzzer sound.

8. The three-phase power analysis circuit according to claim 1, characterized in that: The LED driving circuit includes D5, D7, D8, R33, R41, R44 and a power supply VCC_3V3. R33, R41 and R44 are all 1KΩ current limiting resistors, which are respectively connected between the corresponding LED cathode and GND.

9. The three-phase power analysis circuit according to claim 1, characterized in that: The ATT7022E core circuit is based on the core of the ATT7022E chip, including power supply, crystal oscillator circuit, reset circuit and some IO ports.

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