CN205501431U - Aluminium cell positive pole distribution electric current precision measurement appearance with self calibration function - Google Patents

Abstract

The utility model provides an aluminium cell positive pole distribution electric current precision measurement appearance with self calibration function belongs to the distribution of aluminium electroloysis anode current and detects technical field. Does this measuring apparatu include microprocessor, self calibration module, AD conversion module, temperature acquisition module, RS back voltage and the further analytical calculation of temperature signal will be handled to 485 communication module, data storage module, power module and isolation protective film piece, microprocessor, convert the conversion module 0 signal into, again through industrial grade RS 485 the mode of bus conveys to the host computer. This measuring apparatu has signal self calibration function and DCDC keeps apart power module, keeps apart the chip through the numeral and keeps apart all data signal and microprocessor, can realize the real -time accurate monitoring of antianode distribution electric current, and measurement accuracy height, good reliability, data management convenience can finally obtain each anode rod electric current of aluminium cell, can finally obtain the electrolysis trough anode current distribution change circumstances.

Description

There is the aluminium cell anode distributed current accurate measurement instrument of self-calibration function

Technical field

This utility model relates to aluminium electrolysis anode CURRENT DISTRIBUTION detection technique field, particularly relates to one Plant the aluminium cell anode distributed current accurate measurement instrument with self-calibration function.

Background technology

Aluminium electroloysis is a complicated electrochemical reaction process, by electric field, magnetic field, thermal field, The coupling of multiple physical field such as flow field.The complexity of aluminum electrolysis condition and production environment Badly cause lack the method and apparatus to aluminium electrolysis process on-line monitoring, and anode current is Highly important data in aluminum electrolysis, it and the multiple situation in aluminum electrolysis There are close ties.Current distribution in anode changes, and can cause the change of current efficiency, can cause Liquid aluminum is unstable, can produce effect, can affect anode service life, energy consumption can be caused to increase.

At present, aluminium electrolytic industry scene still uses the method for artificial off-line to measure anode current, i.e. The most hand-held drill rod being tied with circuit tester, one by one detection anode rod pressure drop, according to test data Judge that anode rod is the best with contacting of anode large bus bar.This traditional detection method work People's labor intensity is big, it is impossible to measure all anode rods, inefficiency simultaneously, number According to delayed seriously, be difficult to react in time the change of Current distribution in anode.Tested in industry spot Cheng Zhong, owing in producing, production process is had great importance by the test data of various parameters, Therefore various data testing accuracy are required higher.And for traditional sensor, the one of output As be the faint analogue signal of millivolt level, temperature characterisitic is poor, and signal to noise ratio in transmitting procedure Substantially reduce.Whenever ambient temperature and running voltage change, or the duty of device Change (as input channel switches), gain or the variation of digital filter trap frequency, signal input When range etc. occur, the precision of DATA REASONING can produce large effect, it is therefore desirable to right The analogue signal of input is calibrated, thus eliminates biasing and gain error.

The domestic on-line measurement to aluminium electrolysis anode guide rod electric current has been also carried out substantial amounts of research, CN201220251734.3 uses the mode directly equidistant voltage to anode rod of coding and decoding Signal is transmitted, and data are shown over the display by the process of central processing element.But DATA REASONING precision is low, and the data of transmission only have four significance bits, and not temperature compensated device； CN105242098A has invented a kind of constant-current source aluminium electrolysis anode electric current based on differential amplification Measuring instrument, because its differential amplification module can make the voltage signal collected become apparent from, but The temperature drift caused for site environment change does not carry out error correction, does not reaches requirement Certainty of measurement；CN204714919U has invented the online prison of a kind of aluminum cell anodic current distribution Survey device, although the analogue signal collected is amplified Filtering Processing, but not for The calibration function of null offset, precision cannot ensure.

In sum, require further improvement the level monitoring of aluminum cell anodic current distribution, Thus improve the control level of electrolysis production further.

Utility model content

The technical problems to be solved in the utility model is to provide a kind of aluminum with self-calibration function Anode electrolytic cell distributed current accurate measurement instrument, with solve existing metering system can not school automatically Just measuring the problem such as signal and certainty of measurement difference.

This measuring instrument includes self calibration module, A/D modular converter, microprocessor, temperature acquisition Module, RS-485 communication module, data memory module, power module and insulation blocking module, Wherein, self calibration module electrically connects with A/D modular converter, A/D modular converter and micro-process Device electrically connects, and arranges insulation blocking module between A/D modular converter and microprocessor, and temperature is adopted Collection module electrically connects with microprocessor, arranges isolation and protect between temperature collect module and microprocessor Protecting module, RS-485 communication module electrically connects with microprocessor, RS-485 communication module and micro- Arranging insulation blocking module between processor, data memory module electrically connects with microprocessor, number According to arranging insulation blocking module between memory module and microprocessor, power module is self-correcting quasi-mode Block, A/D modular converter, microprocessor, temperature collect module, RS-485 communication module and Data memory module is powered.

Self calibration module mainly includes self-calibration circuit, amplifying circuit and filter circuit, can be effective Calibration input signal, and suppress common-mode signal to disturb, reduce input noise, it is ensured that certainty of measurement. The wherein MAX4932 Port Multiplier switch of self-calibration circuit selection Maxim Integrated company IC, this variable connector is triple channel, microprocessor directly controlled logical by two digits signal Road selects, and wherein 01,10,11 control passage one, passage two, passage three respectively.Power on It is defaulted as 00, i.e. high-impedance state, to prevent overcurrent from equipment is caused damage.Specifically calibrated Cheng Wei: first carry out zero degree demarcation, i.e. selects a passage to make it be shorted to ground, with obtain in order to Determine the scale zero point of calibration factor, equation one, be scale zero input value and output the most respectively Value, a is function coefficients, and b is constant；Then carry out full scale demarcation, i.e. select second and lead to Road accesses standard signal source, obtains equation two, is full scale input value and output the most respectively Value, the 10mV that standard signal source is provided by the ADR4525 chip of Analog Devices company Standard source；According to linear approximation theory between above-mentioned two range, calculate coefficient a with often The value of amount b, selecting the 3rd passage is actual measure analog signals so that it is quickly reasonably enter Row revises zero offset error and gain error automatically.

The equidistant pressure drop signal theoretical assessment of anode rod is 0.761mV～2.173mV, for The least voltage signal is amplified to the appreciable level of A/D, it is necessary to use and amplify It is processed by circuit.Selecting the INA129 precision instrument amplifier of TI company, this amplifier is adopted Use differential type structure, three amplifiers are integrated in a chip, it is ensured that the knot of difference amplifier Full symmetric property on structure, has low maladjustment voltage, ultralow Low-bias Current, ultra low temperature drift The advantages such as shifting, high cmrr.Only need an i.e. scalable amplification of gain resistor R Scope, from 1～10000 changes, uses high-precision metal membrane resistance as the gain-adjusted of amplifier Resistance.

In order to prevent aliasing effect and effective filter out high-frequency noise, the design amplifying circuit with Anti-aliased low pass filter (LPF) is set between A/D converter.According to documents and materials and Field experience is introduced, and the change frequency of anode current is about 0.5Hz, in order to preferably filter High-frequency Interference and more complete reproduction anode current signal, the cut-off frequency arranging wave filter is 10Hz.Design two grades of three rank Butterworth (Butterworth) active low-pass filter circuit, and Connect increase shunt capacitance at power supply when circuit design, isolate the AC noise of power supply.

The analogue signal of filter circuit output is input to A/D modular converter through amplitude limiter circuit, by Height is required, by 0.5 class precision in equidistant pressure drop signal relatively low (about 2mV), certainty of measurement Calculate, then the resolution of the A/D conversion module needed is at least 12, it is contemplated that system Redundancy and cost performance, the design uses the A/D conversion chip of 16.Comprehensive each side because of Element, selects the AD7705 chip of Analog Devices company.This chip is high speed, low merit Consumption, successive approximation A/D converter, can meet the sampling rate requirement of 20Hz, uses ∑-Δ Technology can realize 16 without error performance.Number is used between A/D modular converter and microprocessor Word isolator is isolated.

For site environment variations in temperature, this utility model passes through AD7705 to skew and gain Drift is calibrated.The design is in self-calibration mode, and analog-digital converter determines internal calibration point. The depositor that arranges of AD7705 is an eight bit register, and which kind of calibration specifically chosen can be by MD1 and the MD0 position arranging depositor programs.When making MD1MD0=01, chip enters Row self calibration.It is to exist with the input of Differential Input pair for determining the scale zero point of calibration factor Device inside short circuit, i.e. AIN1 (+)=AIN1 (-)=internal bias voltage V2；Full scale standard Conversion is to complete under the standard signal source 2.5V voltage provided by ADR4525 chip.At this In calibration mode, determine when conversion terminates and simulate input by chip logic output pin Conversion data can use.Calibration is high level when initializing, until the conversion of external analog input Low level is just become when result can use.

The High performance industrial level microprocessor STM32F103 of ST company selected by microprocessor, should Chip core is 32 Cortex-M3 processors of ARM company.Microprocessor is the completeest Become the collection of related data, process and the communication function with host computer.By software design, Can realize host computer it is initialized, school time, parameter setting, parameter query, control The sequence of operations such as order.Microprocessor can be by many with time, electric current, guide rod numbering etc. The packet of the information of kind sends host computer to.

Temperature collect module mainly includes temperature sensor and processes temperature signal module, the design Use PT100 temperature sensor as temperature-measuring element.PT100 temperature sensor is pacified Being contained on fixture and be close to anode rod surface, its signal gathered is through processes temperature signal module Be converted to the digital signal input as microprocessor, for the calculating to anode rod resistance value Carry out temperature-compensating.Temperature Treatment module selects MAX31865 chip, is internally integrated 15 ADC, the resistance signal of RTD directly can be converted to what microprocessor can identify by it Digital signal.

RS-485 communication module is data transmission module, in order to will with time, electric current, lead The packet of the much informations such as bar numbering is real-time transmitted to host computer, and the control sent by host computer System is ordered and is arranged parameter and is sent to microprocessor.Data communication uses daisy chain bus mode Technical grade RS-485 transmission.It is Transistor-Transistor Logic level from the signal of microprocessor output, needs logical Over level conversion chip is converted into the differential signal meeting 485 communication standards, and the design selects With the ADM2687E chip of AnalogDevices company, data rate is up to 16Mbps.

In order to ensure the safety of data, this utility model devises data memory module, in order to The various information datas of temporary microprocessor output, it is to avoid the loss of data during communication failure.Deposit The SST25VF032B chip that storage chip uses memory capacity to be 32Mb, the clock of this chip Frequency reaches as high as 80MHz, and storage speed is fast；Convenient erasing, optional sector erasing, Four kinds of erasing modes are wiped in the erasing of 32kB or 64kB block, full wafer；Memory capacity is big, for adopting The sample cycle is the collection data of 0.05s, can Coutinuous store about 9 hours.

Power supply is the properly functioning key of whole system, and therefore, the quality of Power Management Design is directly Affect performance and the stability thereof of system.Owing to system required voltage grade is more, and system To the performance requirement of power supply compared with high and want cube little, lightweight, therefore, use high-performance The form of Switching Power Supply, according to the environmental factors that power demands and consideration are on-the-spot, adds gold The DC/DC insulating power supply module (internal 1500V isolation) that yang invigorating Science and Technology Ltd. produces, Safety and the reliability of system can be improved, improve EMC (Electro magnetic Compatibility Electro Magnetic Compatibility) characteristic and protect secondary side.This utility model devises The power supply circuits of three kinds of grades, every grade all through insulating power supply module.The program can well expire The demand of foot low-voltage circuit.

In order to microcontroller is protected, adopt with A/D modular converter, temperature in micro-process Collection devises insulation blocking module between module, data memory module, RS-485 communication module, The main digital isolating chip using Si8662 model.The work temperature of Si86622 digital isolator Degree scope is wide, can bear the high temperature of on-the-spot about 80 DEG C of aluminium electroloysis；Message transmission rate 150Mbps, is current industry rs most level；Comparing with like product, jitter performance is minimum, Can ensure that there is minimum data transmission fault and the bit error rate；Capacity of resisting disturbance is the strongest, anti-electric field Interference performance is 300V/m, and diamagnetic field interference performance is 1000A/m.

Having the beneficial effect that of technique scheme of the present utility model:

(1) the design uses equidistant pressure decline method to measure anode current, and with self-calibration function, Biasing and gain error can be eliminated, utilize software filtering algorithm and the ratio of microprocessor simultaneously Measurement data is processed by regression algorithm, and certainty of measurement is up to 0.32%.

(2) the design uses 485 bus transfer technology, supports infinite expanding, signal communication Stable.By host computer, measuring instrument can be initialized, school time, parameter arrange, parameter The sequence of operations such as inquiry, control command, it is achieved the real-time monitoring to all anode currents, pass Deliver to the data delay of host computer less than 48 seconds.

(3) the design uses AD7705 data calibration function, when on-the-spot test environment occurs During change, data calibration can be realized by automatically calibration, with the internal error of abatement device, partially Move and gain and sensor drift error.

(4) the anode distribution all modules of electric current accurate measurement instrument of the design and microprocessor it Between be equipped with numeral isolation module, microprocessor can be effectively protected and maintain the stability of signal.

(5) the anode distribution electric current accurate measurement instrument simple in construction of the design, reliable, Certainty of measurement is high, and low cost is suitable in industry spot large-area applications.

Accompanying drawing explanation

Fig. 1 is the aluminium cell anode distributed current with self-calibration function of the present utility model The structural representation of accurate measurement instrument；

Fig. 2 is the self calibration module circuit diagram of this measuring instrument；

Fig. 3 is the self calibration flow chart of this measuring instrument；

Fig. 4 is the A/D modular converter circuit diagram of this measuring instrument；

Fig. 5 is the AD7705 reading data flow journey figure that this measuring instrument uses；

Fig. 6 is the power module structure figure of this measuring instrument；

Fig. 7 is the insulation blocking module circuit diagram of this measuring instrument；

Fig. 8 is the distributed architecture schematic diagram during application of this measuring instrument.

Wherein: 1-self calibration module；2-A/D modular converter；3-microprocessor；4-temperature is adopted Collection module；5-RS-485 communication module；6-data memory module；7-power module；8-isolates Protection module；1-1-self-calibration circuit；1-2-amplifying circuit；1-3-filter circuit；9-anode divides Cloth electric current accurate measurement instrument；10-anode rod；11-electrolysis bath；12-hub；13-is upper Machine.

Detailed description of the invention

For making the technical problems to be solved in the utility model, technical scheme and advantage clearer, It is described in detail below in conjunction with the accompanying drawings and the specific embodiments.

This utility model can not measure signal and survey from dynamic(al) correction for existing metering system The problems such as accuracy of measurement difference, it is provided that a kind of aluminium cell anode distributed current with self-calibration function Accurate measurement instrument.

As it is shown in figure 1, this measuring instrument includes self calibration module 1, A/D modular converter 2, micro- Processor 3, temperature collect module 4, RS-485 communication module 5, data memory module 6, Power module 7 and insulation blocking module 8, wherein, self calibration module 1 and A/D modular converter 2 electrical connections, A/D modular converter 2 electrically connects with microprocessor 3, A/D modular converter 2 He Insulation blocking module 8, temperature collect module 4 and microprocessor 3 are set between microprocessor 3 Electrical connection, arranges insulation blocking module 8 between temperature collect module 4 and microprocessor 3, RS-485 communication module 5 electrically connects with microprocessor 3, RS-485 communication module 5 and Wei Chu Arranging insulation blocking module 8 between reason device 3, data memory module 6 is electrically connected with microprocessor 3 Connect, insulation blocking module 8, power supply mould are set between data memory module 6 and microprocessor 3 Block 7 be self calibration module 1, A/D modular converter 2, microprocessor 3, temperature collect module 4, RS-485 communication module 5 and data memory module 6 are powered.

As in figure 2 it is shown, the self calibration module 1 of this measuring instrument includes self-calibration circuit 1-1, puts Big circuit 1-2 and filter circuit 1-3, self-calibration circuit 1-1, amplifying circuit 1-2 and filtered electrical Road 1-3 is sequentially connected in series, and filter circuit 1-3 and A/D modular converter 2 is connected, amplifying circuit 1-2 Use high-precision metal membrane resistance as gain setting resistor, the cut-off frequency of filter circuit 1-3 For 10Hz；Self-calibration circuit 1-1 uses the MAX4932 of Maxim Integrated company many Road device switch IC, amplifying circuit 1-2 use the INA129 precision instrument of TI company, filtering Circuit 1-3 uses anti-aliased low pass filter.

Self calibration module carries out self calibration according to flow process shown in Fig. 3.

As shown in Figure 4, the AD7705 of A/D modular converter selection Analog Devices company Chip.This chip is high speed, low-power consumption, successive approximation A/D converter, can meet 20Hz Sampling rate requirement, use ∑-Δ technology can realize 16 without error performance.

For site environment variations in temperature, skew and gain are floated by this measuring instrument by AD7705 Shift-in row calibration.AD7705 reading data flow journey figure is as shown in Figure 5.

As shown in Figure 6, power module uses the form of high performance switch power supply, according to power supply need Seek and consider the environmental factors at scene, add what gold yang invigorating Science and Technology Ltd. produced DC/DC insulating power supply module (internal 1500V isolation), can improve system safety and Reliability, improves the spy of EMC (Electro magnetic compatibility Electro Magnetic Compatibility) Property also protects secondary side.This utility model devises the power supply circuits of three kinds of grades, every grade of all warp Cross insulating power supply module.The program is well positioned to meet the demand of low-voltage circuit.Power supply in figure Object be self calibration module 1, A/D modular converter 2, microprocessor 3, temperature collect module 4, RS-485 communication module 5 and data memory module 6.

Insulation blocking module mainly uses the digital isolating chip of Si8662 model, and circuit diagram is such as Shown in Fig. 7.

Additionally, microprocessor 3 uses the High performance industrial level microprocessor of ST company STM32F103.Temperature collect module 4 includes temperature sensor and processes temperature signal module, Temperature sensor is PT100 temperature sensor.

This measuring instrument the most as shown in Figure 8, anode distribution electric current of the present utility model Accurate measurement instrument 9 is directly installed in measured material, and measured material is arranged on anode rod 10 On, every anode rod of electrolysis bath 11 is mounted on an anode distribution electric current and accurately surveys Amount instrument 9.In order to reduce the space of measured material as far as possible, two distances measured between head set For 10cm～15cm, the equidistant pressure drop signal theoretical assessment of anode rod 10 is 0.761mV～2.173mV, in order to the least voltage signal is amplified to appreciable level, Amplifying circuit 1-2 must be used.Amplify from equidistant drop measurement head extraction voltage signal process, It is connected with A/D modular converter 2 through amplitude limiter circuit after filtering, it is contemplated that redundancy and sexual valence The AD7705 conversion chip of 16 is used than this utility model.A/D modular converter 2 is with micro- Insulation blocking module 8 is used to isolate, through A/D modular converter 2 between processor 3 Digital voltage signal after conversion is input to microprocessor 3 after flowing through insulation blocking module 8.

When using equidistant pressure decline method to measure guide rod electric current, what microprocessor 3 received is voltage signal, Need to calculate corresponding anode rod 10 resistance value measured between head, work at electrolysis bath 11 Time anode rod 10 temperature be up to about 100 degree, can to anode rod 10 resistance value produce shadow Ring, be therefore provided with guide rod surface temperature acquisition module 4, in order to anode rod 10 resistance Value does temperature-compensating.Temperature acquisition front end uses PT100 temperature sensor, by temperature sensing The temperature signal of device collection is sent to the temperature acquisition mould of anode distribution electric current accurate measurement instrument 9 Block 4, is input to microprocessor 3 after data process.

The outfan of microprocessor 3 is RS-485 communication module 5 and data memory module 6. Each electrolysis bath 11 is designed with a hub 12, and the data of microprocessor 3 output first pass through RS-485 communication module 5 is sent to the hub 12 of this electrolysis bath 11, through hub 12 Process, concentrate after be sent to host computer 13.Can be by host computer 13 to anode distribution electricity Stream accurate measurement instrument 9 carry out various operation, including initialize, school time, parameter arrange, parameter Inquiry, control command etc..When having sampled, microprocessor 3 will be with time, terminal every time The data of the information such as address, anode current send hub 12 to, and store data to number According in memory module 6.

Whole anode distribution electric current accurate measurement instrument 9 electricity consumption uses power frequency 220V, through switch Power supply and voltage conversion circuit are powered into different components after changing, and 220V voltage is directly from manipulation Electromechanical source is drawn, and power taking is convenient, it is not necessary to often change battery.

The above is preferred implementation of the present utility model, it is noted that for this technology For the those of ordinary skill in field, on the premise of without departing from principle described in the utility model, Can also make some improvements and modifications, these improvements and modifications also should be regarded as of the present utility model Protection domain.

Claims (8)

1. there is an aluminium cell anode distributed current accurate measurement instrument for self-calibration function, It is characterized in that: include self calibration module (1), A/D modular converter (2), microprocessor (3), Temperature collect module (4), RS-485 communication module (5), data memory module (6), electricity Source module (7) and insulation blocking module (8), wherein, self calibration module (1) and A/D Modular converter (2) electrically connects, and A/D modular converter (2) electrically connects with microprocessor (3), Insulation blocking module (8) is set between A/D modular converter (2) and microprocessor (3), temperature Degree acquisition module (4) electrically connects with microprocessor (3), temperature collect module (4) and micro- Insulation blocking module (8) is set between processor (3), RS-485 communication module (5) with Microprocessor (3) electrically connects, between RS-485 communication module (5) and microprocessor (3) Arranging insulation blocking module (8), data memory module (6) electrically connects with microprocessor (3), Insulation blocking module (8) is set between data memory module (6) and microprocessor (3), electricity Source module (7) be self calibration module (1), A/D modular converter (2), microprocessor (3), Temperature collect module (4), RS-485 communication module (5) and data memory module (6) supply Electricity.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: described self calibration module (1) includes self calibration electricity Road (1-1), amplifying circuit (1-2) and filter circuit (1-3), self-calibration circuit (1-1), Amplifying circuit (1-2) and filter circuit (1-3) are sequentially connected in series, filter circuit (1-3) with A/D modular converter (2) is connected, and amplifying circuit (1-2) uses high-precision metal membrane resistance to make For gain setting resistor, the cut-off frequency of filter circuit (1-3) is 10Hz.

The aluminium cell anode with self-calibration function the most according to claim 1 and 2 Distributed current accurate measurement instrument, it is characterised in that: described self-calibration circuit (1-1) uses Maxim The MAX4932 Port Multiplier switch IC of Integrated company, described amplifying circuit (1-2) is adopted With the INA129 precision instrument of TI company, described filter circuit (1-3) uses anti-aliased low Bandpass filter.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: the resolution of described A/D modular converter (2) is not Less than 12.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: described microprocessor (3) uses ST company High performance industrial level microprocessor STM32F103.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: described temperature collect module (4) includes that temperature passes Sensor and processes temperature signal module, temperature sensor is PT100 temperature sensor.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: described power module (7) is DC/DC isolation electricity Source module.

The aluminium cell anode distribution with self-calibration function the most according to claim 1 Electric current accurate measurement instrument, it is characterised in that: described insulation blocking module (8) uses Si8662 The digital isolating chip of model.