CN110702976A

CN110702976A - Wide-range high-precision current sensor/ammeter

Info

Publication number: CN110702976A
Application number: CN201911057671.0A
Authority: CN
Inventors: 徐伟专; 庞林
Original assignee: HUNAN YINHE ELECTRIC CO Ltd
Current assignee: HUNAN YINHE ELECTRIC CO Ltd
Priority date: 2019-11-01
Filing date: 2019-11-01
Publication date: 2020-01-17

Abstract

The invention relates to a wide-range high-precision current sensor/ammeter, which comprises a current sensing element for sensing current to be measured, an MCU module and a plurality of signal sampling and conditioning modules, wherein the AD input amplitudes of the signal sampling and conditioning modules are different, the signal sampling and conditioning modules simultaneously acquire secondary signals of the current sensing element, the MCU module processes signals output by the signal sampling and conditioning modules, judges and selects proper analog quantity data according to different input amplitudes and transmits the selected analog quantity data to a signal conversion module, and the signal conversion module outputs digital quantity signals after processing. The invention can keep the output signal of the product in a certain amplitude range all the time through the configuration of the sampling module, and is not limited by the range configuration of external measuring equipment.

Description

Wide-range high-precision current sensor/ammeter

Technical Field

The invention relates to a current sensor/ammeter, in particular to a wide-range high-precision current sensor/ammeter.

Background

The range covered by the nominal accuracy of the traditional current sensor or ammeter is narrow due to the linearity problem of a sensing device or the resolution capability problem of a back-end sampling device. For example, a 1000A current sensor with nominal 0.5% accuracy reduces the accuracy to 1% when measuring 500A current, and when the amplitude of a test object is smaller, the measurement accuracy is reduced sharply, which cannot meet the accuracy requirement of wide-amplitude dynamic range test. In the prior art, some users adopt a mode of shifting gears by an external switch of a sensor, and realize measurement in a wide-amplitude range by a mode of switching a plurality of groups of sensors with different ranges, wherein the mode has the following defects: 1. the transfer switch has large volume (especially under the working conditions of high voltage/heavy current and the like), occupies the space of a laboratory, and has complex system design; 2. the design cost increases; 3. the conversion process is physical switching, and data loss can be caused in the conversion process, so that the important information is incompletely acquired; 4. misoperation is easy to occur, so that test results are wrong or test equipment is damaged beyond the range.

At present, no device for automatically switching measuring ranges at a sensor end exists for a current sensor, and measuring range switching is generally carried out at an analyzer part. At present, the digital quantity transmission current meter/sensor only has an optical fiber current sensor, the Faraday magneto-optical effect principle is adopted, and the nominal precision of the sensors is full-scale precision. The corresponding complex tool needs to be customized according to the actual situation of the field when the test is finished, the test precision can reach the optimal precision only when the signal near the full range is tested, but the precision is reduced quickly once the signal is reduced to be below the half range. The IT series sensor of LEM company adopts closed loop Hall principle, and test accuracy and linearity are very high, but because IT is when measuring the small signal, the measuring device does not have the measuring range that matches with IT, for example 1000A sensor exports 100mA when full range, exports 10mA when testing 100A, and some analysis appearance current measurement channel minimum measurement range is 500mA, can't satisfy the measurement requirement far away. In addition, the existing sensing element is a feed-through coil and a coil closed loop, and cannot be opened during measurement, so that the application has certain limitation on occasions where a circuit cannot be opened or cut.

Disclosure of Invention

Aiming at the technical problems, the invention provides a wide-range high-precision current sensor/ammeter which can synchronously sample and ensure the test precision of a wide-range value.

The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides a wide range high accuracy current sensor/ampere meter, is including the current sensing element of response electric current that awaits measuring, still includes MCU module and several signal sampling conditioning module, and this several signal sampling conditioning module's AD input amplitude is different, the secondary signal of current sensing element is gathered simultaneously to several signal sampling conditioning module, the MCU module is handled the signal of several signal sampling conditioning module output to judge according to different input amplitudes and select suitable analog quantity data to carry to signal conversion module, output digital quantity signal after being handled by this signal conversion module again.

Preferably, each of the signal sampling and conditioning modules includes a sampling circuit for collecting the secondary signal and LPF low-pass filters connected to the sampling circuit, the LPF low-pass filters transmit the correspondingly filtered signals to a multi-channel high-precision high-speed AD sampling circuit, and the multi-channel high-precision high-speed AD sampling circuit transmits the signals with different amplitudes to the MCU module.

Preferably, the digital signal is transmitted to other devices through an optical fiber, an ethernet or other digital interface.

Preferably, the current sensing element is a zero-flux current sensing element having high linearity.

Preferably, the zero-flux current sensor element has a linearity of 1ppm and a dynamic response time of less than 1 μ s.

Preferably, each signal sampling and conditioning module adopts a sampling circuit and a conditioning circuit.

Compared with the prior art, the invention has the following advantages:

1. through the configuration of the sampling module, the output signal of the product can be always kept within a certain amplitude range and is not limited by the range configuration of external measuring equipment.

2. The existing optical fiber current sensor needs to manufacture a complex test tool, and the tool and configuration are very complex, the measurement precision is poor and the measurement real-time performance is poor aiming at different test objects; the device only needs to adjust the sampling and conditioning circuit part, the measurement precision can reach more than 10ppm, and the dynamic response time is less than 1 mu s.

3. And a plurality of modules synchronously sample at the same time, so that the continuity and the real-time performance of data testing are ensured.

4. The uploading signal is automatically judged through the MCU, manual intervention is not needed, and the efficiency is greatly improved.

5. The digital quantity signal output product has extremely strong isolation performance, and the safety of users is ensured.

6. And the medium such as optical fiber is used as a transmission carrier, so that electromagnetic interference is avoided, signal attenuation is reduced, and the electromagnetic compatibility of the product is enhanced.

Drawings

Fig. 1 is a block diagram of the present invention.

Detailed Description

The invention will now be described in detail with reference to fig. 1 and examples, wherein the exemplary embodiments and descriptions of the invention are provided to explain the invention, but not to limit the invention.

The invention provides a wide-range high-precision current sensor/ammeter, which comprises a current sensing element 1 for sensing current to be measured, an MCU module 2 and a plurality of signal sampling and conditioning modules, wherein the AD input amplitudes of the signal sampling and conditioning modules are different, the signal sampling and conditioning modules simultaneously acquire secondary signals of the current sensing element, the MCU module processes the signals output by the signal sampling and conditioning modules, judges and selects proper analog quantity data according to different input amplitudes and transmits the selected analog quantity data to a signal conversion module 4, and the signal conversion module processes the analog quantity data and outputs digital quantity signals. In the implementation process, the current sensing element is a zero-flux current sensing element with high linearity, when a current to be measured flows, the current sensing element outputs a secondary signal (generally a current signal), when a primary signal is near a full-scale range, the amplitude of the secondary output signal is also large, and at the moment, the signal sampling conditioning module needs to be configured according to a large signal and an AD input upper limit and an AD input lower limit. When the primary signal is reduced to half or less of full scale, the original signal sampling and conditioning module may no longer meet the AD input requirements, and therefore additional signal sampling and conditioning modules must be modified to meet the signal test below 1/2. And by analogy, when the setting range is more, the more the signal sampling conditioning module configuration is adopted.

Specifically, each of the signal sampling and conditioning modules includes a sampling circuit 31 for collecting the secondary signal and an LPF low-pass filter 32 connected to the sampling circuit, and each sampling circuit has a different input amplitude and a different power of its corresponding filter, so as to meet the requirements of different ranges of the primary signal of the current sensing element. Meanwhile, the plurality of LPF low-pass filters transmit the correspondingly filtered signals to a multi-channel high-precision high-speed AD sampling circuit 33, and the multi-channel high-precision high-speed AD sampling circuit transmits the signals with different amplitudes to the MCU module respectively, so that the MCU module judges and selects proper analog quantity data to transmit the analog quantity data to the signal conversion module.

All the signal sampling conditioning modules are simultaneously accessed for testing, so that the sampling process is not interrupted, the loss of sampling data is not caused, and the continuity and the integrity of the data are ensured. The invention adopts a novel zero-flux current sensing element, the linearity of the zero-flux current sensing element can reach 1ppm, the dynamic response time is less than 1 mu s, the accuracy and the real-time property of secondary signal output are ensured, and the problem of inaccurate secondary output when a non-full-scale signal is generated due to insufficient linearity of the sensing element is solved. The MCU module is arranged in the invention, so that the adopted and uploaded secondary signal data can be automatically judged and selected, manual intervention is not needed, and the problem of measurement limitation caused by insufficient range setting of external equipment is solved.

According to the invention, the digital quantity signal is converted and output through the signal conversion module, the traditional analog quantity transmission mode is changed, the interference introduced in the transmission link is avoided, the signal attenuation generated by the remote transmission of the analog quantity small signal is reduced, and the product measurement precision is greatly improved. The digital quantity signal is transmitted to other equipment through optical fiber, Ethernet or other digital quantity interfaces so as to enhance the electromagnetic compatibility of the product.

Claims

1. The utility model provides a wide range high accuracy current sensor/ampere meter, includes the current sensing element of response current to be measured, its characterized in that: the current sensor comprises a plurality of signal sampling and conditioning modules, and is characterized by further comprising an MCU module and a plurality of signal sampling and conditioning modules, wherein AD input amplitudes of the plurality of signal sampling and conditioning modules are different, secondary signals of the current sensing element are simultaneously acquired by the plurality of signal sampling and conditioning modules, the MCU module processes signals output by the plurality of signal sampling and conditioning modules, judges and selects proper analog quantity data according to different input amplitudes and transmits the selected analog quantity data to the signal conversion module, and then the signal conversion module processes the signals and outputs digital quantity signals.

2. The wide range high accuracy current sensor/ammeter of claim 1 wherein: each signal sampling and conditioning module comprises a sampling circuit for collecting the secondary signals and LPF low-pass filters connected with the sampling circuit, the LPF low-pass filters transmit the correspondingly filtered signals to a multi-channel high-precision high-speed AD sampling circuit, and the multi-channel high-precision high-speed AD sampling circuit transmits the signals with different amplitudes to the MCU module respectively.

3. The wide range high accuracy current sensor/ammeter of claim 1 or 2 wherein: the digital quantity signal is transmitted to other equipment through optical fiber or Ethernet.

4. The wide range high accuracy current sensor/ammeter of claim 1 or 2 wherein: the current sensing element is a zero-flux current sensing element with high linearity.

5. The wide range high accuracy current sensor/ammeter of claim 4 wherein: the linearity of the zero magnetic flux type current sensing element is 1ppm, and the dynamic response time is less than 1 mu s.