CN209182394U - A non-contact current signal detection device - Google Patents

Abstract

The utility model discloses a non-contact current signal detection device, which comprises a power supply module, a circular current detection coil, a low-noise signal amplifier module, an STM32 module, a TFT display module, an FPGA clock source module and an input module; the power supply modules are respectively low Noise signal amplifier module, STM32 module, display module and FPGA clock source module supply power; the wire to be detected passes through the center of the ring current detection coil, and the output end of the ring current detection coil is connected to the signal input end of the low noise signal amplifier module, and the low noise signal The amplifier module signal output terminal is connected to the STM32 module signal input terminal, the video signal output interface of the STM32 module is connected to the display module, the FPGA clock source module output terminal is connected to the external clock input terminal of the STM32 module, and the STM32 module is also connected to the input module; The device has a large current measurement range, high measurement accuracy of small currents, can accurately measure small signal currents, has strong anti-interference ability, is implemented in a modular manner, and has a simple structure.

Description

A non-contact current signal detection device

technical field

The utility model relates to the technical field of current detection, in particular to a non-contact current signal detection device.

Background technique

Current is very common in nature, and human beings have accumulated rich experience in measuring current in the exploration of the nature of electrical phenomena. Especially for the measurement method of DC current, but for the measurement of AC current, there are fewer schemes and devices than DC current. Use the law of electromagnetic induction to make a non-contact AC current transmission detection instrument, that is, the alternating current will periodically generate alternating magnetic flux, and the alternating magnetic flux will generate an alternating current on the closed conductor, which can be sampled by ADC Get the magnitude of the current.

The traditional AC current detection device has the following disadvantages: the accuracy is relatively accurate when detecting large currents, and there is a large error when measuring currents below 100mA, especially when measuring currents of 10mA level, it cannot even be detected, and it is easily affected by the surrounding electric field, resulting in measurement results mistake. The small current range and poor measurement accuracy of small currents have always been a problem for technical personnel.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art, to provide a non-contact current signal detection device with a large measurement current range, high measurement accuracy for small currents, strong anti-interference ability, simple structure, and modularization. Accurately measure small signal currents.

The technical scheme that realizes the utility model purpose is:

A non-contact current signal detection device, including a power module, a ring current detection coil, a low-noise signal amplifier module, an STM32 module, a TFT display module, an FPGA clock source module, and an input module; the power modules are respectively a low-noise signal amplifier module, STM32 module, display module and FPGA clock source module supply power; the wire to be detected passes through the center of the ring current detection coil, the output end of the ring current detection coil is connected to the signal input end of the low noise signal amplifier module, and the signal output end of the low noise signal amplifier module Connect the signal input end of the STM32 module, the video signal output interface of the STM32 module is connected to the display module, the output end of the FPGA clock source module is connected to the external clock input end of the STM32 module, and the STM32 module is also connected to the input module.

The annular current detection coil is a coil formed by winding a manganese core magnetic ring with 0.05mm enameled wire, the output end of the coil is connected to one end of the load resistor, the other end of the load resistor is grounded, and the resistance of the load resistor is 30 ohms , the output port of the coil is an SMA interface.

The power supply module is based on LM7805 and LM7905 power supply chips, and uses STMicroelectronics LM7805 and LM7905 series three-terminal voltage regulator circuits. Due to the limitation of internal current, as well as the protection of overheating protection and safe working area, the circuit makes it It will not be damaged basically, and can output +5V and -5V voltage stably.

The low-noise signal amplifier module is a low-noise signal amplifier module based on the chip OPA2227, and adopts the OPA2227 low-noise and high-precision instrument operational amplifier in the OPAX22X series of TI Company, which has characteristics such as low noise, wide bandwidth and high precision. Ideal for applications requiring both AC and precision DC performance, the OPA2227 is unity-gain stable with a high slew rate (2.3V/µs) and wide bandwidth (8MHz). OPA2227 is optimized for closed-loop gain of 5 times or more, and provides higher speed with 10V/µs slew rate and 33MHz bandwidth. This module can denoise, amplify, and uplift the signal.

The FPGA clock source module is an FPGA module based on the EP4CE22F17C6N chip, and uses Altera's EP4CE22F17C6N as the core 2Khz clock source, which has the characteristics of stable and accurate signal generation and is suitable for meeting current detection requirements.

The STM32 module uses ST's stm32f407zgt6 as the core system control processing module. The stm32f407zgt6 is a 90nm 32-bit high-performance microcontroller developed by STMicroelectronics, which integrates a dedicated DSP unit and ADC. The DSP The unit can perform high-speed FFT transformation, and its ADC has a 12-bit precision enough to meet the demand, and it has a very high cost performance compared with other solutions. Its own key input can select the working mode through key input. The module provides an interface to facilitate the connection of other modules.

The display module is a TFT thin film diode LCD display screen based on the IDT7204 chip, which has the advantages of low price and good color, and its response speed is sufficient to meet the function of displaying test current parameters.

Beneficial effects: a new type of non-contact current signal detection device provided by the utility model adopts a modular structure; the system structure is simple, the cost is cheap, and it is easy to debug and maintain. The work of each module complements each other and interferes, and the measurement current has high precision and a large range; The device can accurately measure the harmonic current components and the frequency components of each harmonic for non-sinusoidal waves, and is suitable for various occasions of measuring alternating current, which provides great convenience and help for measuring and researching non-sinusoidal currents , Can detect current frequency 10hz-1Khz amplitude 5mA-1A, each harmonic frequency 10hz-1Khz, the amplitude error is within 1.5%, and the frequency error is within 0.5%. According to the harmonic characteristics of non-sinusoidal waves, it can accurately analyze its waveforms, and can analyze sine waves, triangle waves, square waves, sawtooth waves and other waveforms.

Description of drawings

Fig. 1 is a structural block diagram of a non-contact current signal detection device;

Figure 2 is a block diagram of the STM32 module structure;

Fig. 3 is a schematic circuit diagram of the low noise signal amplifier module.

Detailed ways

The utility model will be further elaborated below in conjunction with the accompanying drawings and embodiments, but the utility model is not limited thereto.

Example:

As shown in Figure 1, a non-contact current signal detection device includes a power supply module, a ring current detection coil, a low-noise signal amplifier module, an STM32 module, a TFT display module, an FPGA clock source module, and an input module; the power supply modules are respectively Low noise signal amplifier module, STM32 module, display module and FPGA clock source module supply power; the wire to be detected passes through the center of the ring current detection coil, and the output end of the ring current detection coil is connected to the signal input end of the low noise signal amplifier module, low noise The signal amplifier module signal output terminal is connected to the STM32 module signal input terminal, the video signal output interface of the STM32 module is connected to the display module, the FPGA clock source module output terminal is connected to the external clock input terminal of the STM32 module, and the STM32 module is also connected to the input module.

The annular current detection coil is a coil formed by winding a manganese core magnetic ring with 0.05mm enameled wire, the output end of the coil is connected to one end of the load resistor, the other end of the load resistor is grounded, and the resistance of the load resistor is 30 ohms , the output port of the coil is an SMA interface.

The power supply module is based on LM7805 and LM7905 power supply chips, and uses STMicroelectronics LM7805 and LM7905 series three-terminal voltage regulator circuits. Due to the limitation of internal current, as well as the protection of overheating protection and safe working area, the circuit makes it It will not be damaged basically, and can output +5V and -5V voltage stably.

Described low-noise signal amplifier module, is the low-noise signal amplifier module based on chip OPA2227, adopts OPA2227 low-noise high-precision instrument operational amplifier in OPAX22X series of TI company, as shown in Figure 3, comprises two OPA2227 operational amplifiers, It uses all 4 operational amplifier units, the first operational amplifier unit forms a follower, the second operational amplifier unit forms a closed-loop fixed amplifier, and the last two form an inverse adder to raise the signal level; Combining low noise, wide bandwidth, and high precision, it is ideal for applications requiring both AC and precision DC performance. The OPA2227 is unity-gain stable with high slew rate (2.3V/µs) and wide bandwidth (8MHz). OPA2227 is optimized for closed-loop gain of 5 times or more, and provides higher speed with 10V/µs slew rate and 33MHz bandwidth. This module can denoise, amplify, and uplift the signal.

The FPGA clock source module is an FPGA module based on the EP4CE22F17C6N chip, and uses Altera's EP4CE22F17C6N as the core 2Khz clock source, which has the characteristics of stable and accurate signal generation and is suitable for meeting current detection requirements.

As shown in Figure 2, the STM32 module uses ST's stm32f407zgt6 as the core system control processing module. The stm32f407zgt6 is a 90nm 32-bit high-performance microcontroller developed by STMicroelectronics, which integrates a dedicated DSP Unit and ADC, its DSP unit can perform high-speed FFT transformation, its ADC has 12-bit precision enough to meet the demand, and has a very high cost performance compared to other solutions. Its own key input can select the working mode through key input. The module provides an interface to facilitate the connection of other modules; the working principle of the STM32 module is:

Use the external interrupt to start the ADC conversion, use the clock signal provided by the FPGA as the trigger signal of the external interrupt, and start the ADC conversion in the external interrupt. At the same time, the system stipulates the DMA channel that is triggered by the data change. When the ADC conversion is completed, the data transmission is started, and then the data is transferred to the DSP operation unit for processing. Finally, the FFT transformation with a sampling rate of 2048HZ and a sampling point of 4096 is realized. Accurately calculate results. At the same time, it has the function of judging the current type by participating in the current spectrum information.

The display module is a TFT thin film diode LCD display screen based on the IDT7204 chip, which has the advantages of low price and good color, and its response speed is sufficient to meet the function of displaying test current parameters.

The working process of the detection device is: the wire to be detected passes through the center of the ring current detection coil, and the signal passes around the ring current detection coil. According to Faraday's law of electromagnetic induction, the coil induces a signal with a reduced amplitude and a different frequency waveform than the original signal. The induction signal is changed, and the ring current detection coil inputs the induction signal into the low-noise signal amplifier module. The clock signal input by the clock source module is transformed by FFT, so as to accurately obtain the current information, and drive the TFT display module to display the various information of the current on it. After testing, the final device can test within the range of 10hz-1Khz, 5mA-1A Arbitrary current assignment and frequency, and test the harmonic information of the current, and calculate the current waveform based on the harmonic information of the current.

Claims (7)

1. A non-contact current signal detection device, is characterized in that, comprises power module, annular current detection coil, low-noise signal amplifier module, STM32 module, TFT display module, FPGA clock source module and input module; Power module is respectively Low noise signal amplifier module, STM32 module, display module and FPGA clock source module supply power; the wire to be detected passes through the center of the ring current detection coil, and the output end of the ring current detection coil is connected to the signal input end of the low noise signal amplifier module, low noise The signal amplifier module signal output terminal is connected to the STM32 module signal input terminal, the video signal output interface of the STM32 module is connected to the display module, the FPGA clock source module output terminal is connected to the external clock input terminal of the STM32 module, and the STM32 module is also connected to the input module. 2 . A non-contact current signal detection device according to claim 1 , wherein the annular current detection coil is a coil formed by winding an enameled wire on a manganese core magnetic ring. 3 . 3. A non-contact current signal detection device according to claim 1, characterized in that said power module is a power chip based on LM7805 and LM7905. 4. A non-contact current signal detection device according to claim 1, characterized in that the low-noise signal amplifier module is a low-noise signal amplifier module based on the chip OPA2227. 5. A kind of contactless current signal detection device according to claim 1, is characterized in that, described FPGA clock source module is the FPGA clock source module based on EP4CE22F17C6N chip. 6. A non-contact current signal detection device according to claim 1, characterized in that said STM32 module is a 32-bit high-performance microcontroller based on the stm32f407zgt6 chip. 7. A non-contact current signal detection device according to claim 1, characterized in that said display module is a TFT thin film diode LCD display screen based on IDT7204 chip.