CN203643502U - Full-automatic microcurrent detection device - Google Patents
Full-automatic microcurrent detection device Download PDFInfo
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- CN203643502U CN203643502U CN201420006527.0U CN201420006527U CN203643502U CN 203643502 U CN203643502 U CN 203643502U CN 201420006527 U CN201420006527 U CN 201420006527U CN 203643502 U CN203643502 U CN 203643502U
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Abstract
The utility model relates to an full-automatic microcurrent detection device. The device comprises a current sampling module, a filtering module, an AD conversion module and a FPGA module. A power supply is connected with the current sampling module. The current sampling module is connected with the AD conversion module through the filtering module. An output terminal of the FPGA module is connected with the current sampling module. A load to be measured is connected to the current sampling module. The full-automatic microcurrent detection device which adopts the above structure uses a plurality of sampling gears. When different measurement gears are switched, a load outage situation is not generated. A condition that power supply of the load is insufficient due to a current limiting effect of sampling resistors is avoided. The sampling resistors with different units convert current signals into voltage signals in a same scope. A controllable gain amplifier does not need to be used so that the circuit is simplified and errors are reduced. A resolution ratio of the AD conversion module is used appropriately. Through the FPGA, rapid current detection with a wide range and over-current detection can be realized.
Description
Technical field
The utility model relates to a kind of current sensing means, specifically refers to a kind of full-automatic micro-current sensing means.
Background technology
At present, the current detecting scope of the micro-current detecting equipment of low-voltage is generally less, or detection speed is slower, thereby or go in order to obtain the measured value of relative accuracy that the different gear of manual switchover cannot be continuous read current curent change etc., to such an extent as to have certain use restriction.
Although some current detecting equipments have wider current detecting scope, can realize the current measurement from several milliamperes to several thousand milliamperes, use many grades of sample resistances or carry out current and voltage signals conversion and amplification with one grade of sample resistance and controllable gain amplifier (PGA) but these equipments are general, and the former generally can not realize full automatic measurement, the latter can become and be difficult to process at the lower limit that approaches measurement range about the offset voltage of amplifier, processes the accuracy of owing can affect at that time measurement result.
In micro-current detecting equipment, the offset voltage of amplifier can produce larger impact to measurement result, and the words of dealing with improperly can make to measure and lose efficacy.There are at present a lot of methods can realize the zeroing of amplifier, for example use chopper amplifier etc., in the zero blanking float method of micro current instrument that the Tang Wengang of Zhejiang University is CN1080726 at publication number and the patent of device thereof, mentioned and a kind ofly reduced the impact of offset voltage on measurement result through getting the method for difference after utilizing microcomputer sampling, but this method there is very large use restriction.First will repeatedly sample offset voltage signal, then input is repeatedly sampled, and then get difference, this intermittent sampling for the electric current of measuring smooth change is perhaps desirable, but just shows comparatively bothersome for the current detecting of wide region.
Utility model content
The purpose of this utility model is to have overcome above-mentioned shortcoming of the prior art, and full-automatic micro-current sensing means that a kind of circuit structure is simple, can realize current detecting, load fast and can not produce powering-off state is provided.
For realizing above-mentioned object, full-automatic micro-current sensing means of the present utility model by the following technical solutions:
This full-automatic micro-current sensing means, its principal feature is, comprise current sampling module, filtration module, AD modular converter and FPGA module, power supply is connected with described current sampling module, described current sampling module is connected with described AD modular converter by described filtration module, the output terminal of described FPGA module is connected with described current sampling module, and load to be measured is connected in described current sampling module.
Current sampling module in this full-automatic micro-current sensing means comprises the sample resistance that a plurality of resistances are different, and each described sample resistance is connected with a change-over switch respectively, and described FPGA module is connected with each described change-over switch.
Filtration module in this full-automatic micro-current sensing means comprises voltage amplifier, and the output terminal of described current sampling module is connected with this voltage amplifier.
Filtration module in this full-automatic micro-current sensing means also comprises filtering circuit, the output terminal of described voltage amplifier is connected with this filtering circuit, this filtering circuit is connected with amplifying circuit, the output terminal of described amplifying circuit is connected with one-level voltage follower, and described one-level voltage follower is connected with low-pass filter.
Compensating circuit in this full-automatic micro-current sensing means is in parallel with described amplifying circuit.
Adopt full-automatic micro-current sensing means of this structure, used multiple sampling gears, and can realize the situation that there will not be load power-off while switching different measuring gear, avoided because of the metering function of sample resistance but load supplying deficiency; The sample resistance of commensurate is not converted to current signal the voltage signal of same scope, has avoided use controllable gain amplifier, has simplified circuit, has also reduced and has made mistakes, and the resolution of AD modular converter obtains most suitable utilization; Help realize wide region, fast current detecting and over-current detection by FPGA.
Accompanying drawing explanation
Fig. 1 is the circuit theory diagrams of micro-current sensing means of the present utility model.
Fig. 2 is the schematic diagram of current sampling module of the present utility model.
Fig. 3 is the schematic diagram of filtration module of the present utility model.
Fig. 4 is voltage amplification schematic diagram of the present utility model.
Fig. 5 is the data plot that micro-current sensing means of the present utility model carries out temperature experiment.
Embodiment
In order more clearly to understand technology contents of the present utility model, describe in detail especially exemplified by following examples.
Refer to Fig. 1 to Fig. 5, full-automatic micro-current sensing means, comprise current sampling module, filtration module, AD modular converter and FPGA module, power supply is connected with current sampling module, current sampling module is connected with AD modular converter by filtration module, the output terminal of FPGA module is connected with current sampling module, load to be measured is connected in current sampling module, power supply is connected with external power source, after connecting device under test, can obtain corresponding measurement data, power supply is generally below 3.3V, part is measured can arrive 5V, but conventionally below 5.5V, can choose according to the maximum power supply voltage in power supply the chip of the amplifier in current sampling module, general chip is included as 3.3V power supply and is two kinds of specifications of 5V power supply.
Current sampling module comprises at least one sample resistance, and each sample resistance is connected with a change-over switch respectively, and FPGA module is connected with each change-over switch.Resistance precision in current sampling module, on-off effect is rapid, FPGA chooses suitable sampling scope, sample resistance handle converts corresponding voltage signal to the current value of each grade, the change-over switch corresponding to sample resistance has rapid discharge, low on-resistance, high feature of turn-offing internal resistance, order that can quick corresponding FPGA, shelves load required for electric current hour, the sample resistance larger by resistance samples, and the pressure drop very little (can ignore compared with supply voltage) on sample resistance, in the time that load current sports higher value by smaller value, change-over switch switches to the sample resistance of less resistance, to avoid causing load supplying deficiency because of the metering function of sample resistance.
Filtration module comprises voltage amplifier, and the output terminal of sampling module is connected with this voltage amplifier.This voltage amplifier has the circuit of automatic zero set (AZS) or has zeroing circuit, or use wave chopping technology that voltage signal is chopped into AC signal, through being ac-coupled to post-amplifier, after amplifying, be averaging and also can obtain more stable voltage signal by low pass circuit more again
Vin(1) the output voltage signal Vo(3 that signal is Fig. 3), through R(1), R(2), CL(1), Cl(2) filtering circuit of composition, this filtering circuit can appropriately adjust according to the sampling rate of AD modular converter in the scope that is less than 1KHz, filtration module also comprises filtering circuit, the output terminal of voltage amplifier is connected with this wave filter, this wave filter and Rb(5) and Rb(6) composition amplifying circuit be connected, this enlargement factor can be selected, the adjustment and the compensation that are generally used for for the amplifying circuit in Fig. 3, the output terminal of amplifying circuit is connected with one-level voltage follower, this one-level voltage follower is connected with low-pass filter, output signal is voltage Vo(4).Wave filter, voltage follower and low-pass filter in filtration module guaranteed AD modular converter sampling voltage steadily, protection AD modular converter can not damage because of input too high voltages.AD modular converter is mainly a high-resolution position AD with multichannel configurable sampling rate and gain, uses the reference source of outside high precision, high-temperature degree of stability as a reference, reads the voltage signal after amplification filtering of being exported by filtration module.
Preferably, if any need especially can be at Rf(6) corrective network of a upper resistance in parallel and electric capacity, to improve the decay of high frequency noise.
Fig. 5 is the temperature experiment that adopts micro-current sensing means of the present utility model, experiment condition carries out 1 hour at 1～25 degree, 25～50 degree carry out 1 hour, 50～25 degree carry out one hour, and record at set intervals a secondary data by software, then curve shown in data favour city Fig. 5, wherein often indulge lattice 0.1 μ A, from figure, can obviously find out, temperature characterisitic is good.
Fundamental measurement flow process is: electric current to be detected flows into sampling module, obtain current signal, transfer voltage signal to through amplifier, device after filtering again, after filtering, the signal of voltage is sampled via AD modular converter, the data obtained transfers to FPGA to process, and FPGA generates and the communication data of miscellaneous equipment and the signal of control sampling module according to the current data of gained.
Adopt full-automatic micro-current sensing means of this structure, used multiple sampling gears, and can realize the situation that there will not be load power-off while switching different measuring gear, avoided because of the metering function of sample resistance but load supplying deficiency; The sample resistance of commensurate is not converted to current signal the voltage signal of same scope, has avoided use controllable gain amplifier, has simplified circuit, has also reduced and has made mistakes, and the resolution of AD modular converter obtains most suitable utilization; Help realize wide region, fast current detecting and over-current detection by FPGA.
In this instructions, the utility model is described with reference to its specific embodiment.But, still can make various modifications and conversion obviously and not deviate from spirit and scope of the present utility model.Therefore, instructions and accompanying drawing are regarded in an illustrative, rather than a restrictive.
Claims (5)
1. a full-automatic micro-current sensing means, it is characterized in that, comprise current sampling module, filtration module, AD modular converter and FPGA module, power supply is connected with described current sampling module, described current sampling module is connected with described AD modular converter by described filtration module, the output terminal of described FPGA module is connected with described current sampling module, and load to be measured is connected in described current sampling module.
2. full-automatic micro-current sensing means according to claim 1, it is characterized in that, described current sampling module comprises the sample resistance that a plurality of resistances are different, each described sample resistance is connected with a change-over switch respectively, and described FPGA module is connected with each described change-over switch.
3. full-automatic micro-current sensing means according to claim 1, is characterized in that, described filtration module comprises voltage amplifier, and the output terminal of described current sampling module is connected with this voltage amplifier.
4. full-automatic micro-current sensing means according to claim 3, it is characterized in that, described filtration module also comprises filtering circuit, the output terminal of described voltage amplifier is connected with this filtering circuit, this filtering circuit is connected with amplifying circuit, the output terminal of described amplifying circuit is connected with one-level voltage follower, and described one-level voltage follower is connected with low-pass filter.
5. full-automatic micro-current sensing means according to claim 4, is characterized in that, compensating circuit is in parallel with described amplifying circuit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420006527.0U CN203643502U (en) | 2014-01-06 | 2014-01-06 | Full-automatic microcurrent detection device |
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| CN201420006527.0U CN203643502U (en) | 2014-01-06 | 2014-01-06 | Full-automatic microcurrent detection device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107800395A (en) * | 2017-11-14 | 2018-03-13 | 江西怡杉环保股份有限公司 | A kind of filter circuit in micro-current detection |
| CN111965413A (en) * | 2020-09-03 | 2020-11-20 | 南方电网数字电网研究院有限公司 | Current measuring method |
-
2014
- 2014-01-06 CN CN201420006527.0U patent/CN203643502U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107800395A (en) * | 2017-11-14 | 2018-03-13 | 江西怡杉环保股份有限公司 | A kind of filter circuit in micro-current detection |
| CN111965413A (en) * | 2020-09-03 | 2020-11-20 | 南方电网数字电网研究院有限公司 | Current measuring method |
| CN111965413B (en) * | 2020-09-03 | 2023-11-03 | 南方电网数字电网研究院有限公司 | Current measuring method |
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