CN203054072U - Corona current acquisition card based on USB bus - Google Patents

Abstract

The utility model provides a corona current acquisition card based on a USB bus. The corona current acquisition card based on the USB bus comprises a signal conditioning unit, an A/D conversion unit and a USB control unit which are connected in order, wherein the USB control unit is connected with the signal conditioning unit. The corona current acquisition card realizes safe, stable and reliable acquisition of corona current at a low voltage side of a super high voltage direct current corona cage, can realize stable and high-speed data transmission through USB2.0 protocol and carries out fast and timely acquired waveform display and large-capacity timing data storage on a host computer. The corona current acquisition card can realize control of signal acquisition and parameter storage of corona current through the A/D conversion unit and the USB control unit. The corona current acquisition card can realize reliable acquisition, safe storage and high-speed transmission of corona current signals under a super high voltage complex electromagnetic environment.

Description

A kind of corona current capture card based on usb bus

Technical field

The utility model belongs to field of power, is specifically related to a kind of corona current capture card based on usb bus.

Background technology

Along with the raising of Chinese transmission line of electricity electric pressure and putting into operation of extra-high voltage direct-current transmission engineering, the corona loss problem of transmission line of electricity becomes increasingly conspicuous.The research of corona loss, significant for the operation of transmission line of electricity economic stability.

At present the corona current measuring system is made up of goods shelf products mostly, and employed data collector is varied, and data precision, sampling rate, storage depth are uneven, can't satisfy the stable needs that reliably transmit of gathering of corona current.The data collector that some is developed voluntarily, also only limit to carry out simple experiment in the comparatively ideal environment such as laboratory, in case be operated in the actual transmission line of electricity, generation equipment punctures or disturbs and causes data situation accurately inadequately more greatly easily, can not carry out the practical application on the engineering reliably.

Advantages such as that USB (the Universal Serial BUS) interface of widespread use at present has is easy for installation, bandwidth is high, cost is low, reliability is high and the peripheral hardware capacity is big.The high transmission speed that USB2.0 supports can reach 480Mb/s, can satisfy complicated day by day senior peripheral hardware and the high-performance connection requirement between the computing machine substantially, becomes one of trend of modern data transmission development just gradually.So the utility model has now on the basis of achievement in research at home and abroad, based on low-power consumption, Anti-Jamming Technique and USB transfer bus, develop the corona current data collecting card of low-frequency range, can measure extra-high voltage direct-current corona cage low-pressure side corona current signal accurately and reliably, and realize waveform show in real time fast and the big capacity of data is stored automatically.

The utility model content

At the deficiencies in the prior art, the utility model provides a kind of corona current capture card based on usb bus, has realized that in extra-high voltage direct-current corona cage low-pressure side corona current being carried out safety and stability gathers reliably.

A kind of corona current capture card based on usb bus that the utility model provides is characterized in that, described corona current capture card comprises signal condition unit, A/D converting unit and the USB control module that connects successively; Described USB control module is connected with described signal condition unit.

Wherein, described signal condition unit comprises limiter protection circuit, programmable amplifying circuit, antialiasing filtering circuit and the emitter follower circuit that connects successively.

Wherein, described A/D converting unit comprises the signals collecting chip, and it adopts the A/D converter AD7864 of 500kHZ acquisition rate, 12 bit resolutions.Its analog signal conversion that is used for the output of described signal condition unit is digital signal.

Wherein, described USB control module comprises 8051 microcontrollers, general programmable interface GPIF, serial interface engine and USB transceiver;

Described 8051 micro controller I/O mouth is connected with described signal conditioning circuit;

Described general programmable interface is connected with described A/D converting unit by data bus;

Described serial interface engine is communicated by letter with PC respectively with described USB transceiver.

Wherein, described limiter protection circuit comprises Transient Suppression Diode TVS and ceramic discharge diode in parallel.It is used for the collection signal of A/D modular converter is carried out the amplitude restriction.

Wherein, described emitter follower circuit comprises operational amplifier A D817, and it is used for improving input impedance and signal is isolated.

Wherein, described programmable amplifying circuit comprises integrated gain-programmed amplifier;

Described integrated gain-programmed amplifier is selected the PGA202 programme-controlled instrument amplifier of BURR.BROWN company for use.

Wherein, described antialiasing filtering circuit adopts and is integrated with source filter;

Describedly be integrated with the monolithic integrated filter chip MAX27 that source filter is selected MAXIM company for use.

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

The design of limiter protection circuit has strengthened the safe and reliable of capture card in the utility model signal condition unit, has avoided that capture card suffers the risk of voltage breakdown under the extra-high voltage environment; Pre-amplification circuit and filtering circuit have guaranteed the true and reliable of data under the forceful electric power magnetic environment.The A/D conversion chip has 12 bit resolutions, has guaranteed the precision of corona current signal.Adopt usb bus, can realize that the high speed of corona current signal is reliably transmitted.

The utility model satisfies the requirement of extra-high voltage direct-current corona current reliable measuring data high-speed transfer, can reliable and stable work under extra-high voltage forceful electric power magnetic environment.

The utility model data acquisition program flow process has realized that slave computer sends the process of data automatically to host computer under the control waveform of GPIF design.

The utility model host computer acquisition applications program circuit has realized receiving at a high speed the slave computer data by multithreading, the function that fast real-time display waveform and big capacity are regularly stored.

Description of drawings

Fig. 1 is the corona current data collecting card system chart in the utility model;

Fig. 2 is the signal condition cellular construction figure in the utility model;

Fig. 3 is the USB control module structural drawing in the utility model;

Fig. 4 is the A/D converting unit translation data process in the utility model and reads data time sequence figure;

Fig. 5 reads data time sequence figure after the converting in the utility model;

Fig. 6 is A/D converting unit AD7864 in the utility model and the employing data bus communication synoptic diagram of USB control module CY7C68013A;

Fig. 7 is the data acquisition program process flow diagram in the utility model;

Fig. 8 is the host computer acquisition applications program flow diagram in the utility model.

Fig. 9 is the application synoptic diagram of the corona current data collecting card in the utility model.

Embodiment

Below in conjunction with accompanying drawing embodiment of the present utility model is described in further detail.

The utility model is a kind of extra-high voltage direct-current corona current data collecting card based on the USB transmission, and its system chart is made of signal condition unit, A/D converting unit and the USB control module of connecting successively as shown in Figure 1.

Be illustrated in figure 2 as signal condition module of the present utility model, constituted by the limiter protection circuit, programmable amplifying circuit, antialiasing filtering circuit and the emitter follower circuit that connect successively.

Described limiter protection circuit comprises Transient Suppression Diode TVS and ceramic discharge diode in parallel, and the collection signal that is used for the A/D modular converter carries out amplitude and limits, and prevents high-voltage breakdown A/D module.Limiter protection circuit plays the effect of clamping down on voltage and a large amount of electric energy of abrupt release, but can guarantee that capture card passage both end voltage is in tolerance range; Corona current signal itself is fainter, and comprises various interference, and programmable amplifying circuit can increase the corona current signal to the driving force of subsequent conditioning circuit.

May contain the high frequency noise composition in the corona current signal, occur aliasing during for fear of collection, must design antialiasing filtering circuit.For improving input impedance and realizing the signal isolation, adopt emitter follower circuit as the input buffering of AD.Described emitter follower circuit is realized that by low cost, low-power consumption, high speed operation amplifier AD817 it is used for improving input impedance and realizes the signal isolation.

Described programmable amplifying circuit comprises integrated gain-programmed amplifier, and integrated gain-programmed amplifier is selected the PGA202 programme-controlled instrument amplifier of BURR.BROWN company for use.This chip need not to connect peripheral chip, and is easy to use, performance good.The gain control input of PGA202 and TTL, CMOS level compatibility can be directly and Microprocessor Interface.Numerical control input end A1, A0 can directly link to each other with the I/O mouth of USB control module.4 kinds of logic states according to A1, A0 during use can be selected 4 kinds of gains.

Described antialiasing filtering circuit is selected for use and is integrated with source filter.Be integrated with the monolithic integrated filter chip MAX27 that source filter selects for use MAXIM company to release, according to designing requirement, each filter unit only needs external 4 programming resistors, can realize low pass, bandpass filtering from 100Hz to 300KHz; MAXIM company's site provides free special designs software, need not complicated calculating; This chip is type continuous time, and lower than switching mode wave filter noise, dynamic perfromance is good, and clock when not required, has avoided clocking noise.

Corona signal after the A/D converting unit receiving signal reason processing of circuit of the present utility model is reliable and stable digital signal with the analog signal conversion that is subject to disturb.The A/D converting unit is mainly selected a high precision, high frequency acquisition, low power consumption for signal acquisition chip for use, can satisfy multichannel synchronousing collection.

That described signals collecting chip is selected for use is the A/D converter AD7864 of 500kHZ acquisition rate, 12 bit resolutions.AD7864 is a high precision, high frequency acquisition, the low power consumption for signal acquisition chip that ADI produces, and can realize that 4 passages gather simultaneously.Be 1.65us single channel switching time of AD7864, and the collection retention time is 0.35us, and the highest frequency acquisition of single channel is 500kSPS.If four-way is gathered simultaneously, the highest frequency acquisition of every passage can reach 130kSPS.12 high-speed parallel radix-minus-one complement data output formats are adopted in signal output, have made things convenient for follow-up PC to handle.4 analog input channels of AD7864 start the AD conversion by CONVST.AD7864 can select arbitrarily to select less than the input of 4 passages, and selecteed passage is changed with the order of ascending order, and its selection can adopt the hardware pattern also can adopt software pattern.The clock of AD7864 can be provided by internal clocking or external clock.

Be illustrated in figure 3 as USB control module of the present utility model, constituted by USB transceiver, SIE serial interface engine, 8051 microcontrollers and general programmable interface GPIF.USB control module and A/D converting unit common data bus, under the read-write control command that the USB control module sends, the digital signal after the collection of A/D converting unit transforms is stored in the inner buffer of USB control module.Carry out data communication between USB control module and the local side computing machine and drive by bottom hardware, firmware program and host computer application software realize.The USB driver is between application program and the equipment end firmware, makes operating system identification USB device, and sets up the communication between host side and the equipment end.Firmware program is mainly finished usb protocol processing, exchanges data and other logic control function.Enumerating with re-enumeration is a very important mechanism of USB device, only finishes this two processes, and USB device is just set up the communication relation with main frame, otherwise main frame can't identification equipment.Application program realizes alternating interface between man and computer, and reading, show and function such as storage of the transmission that realizes control command, image data is provided.The EZUSB FX2 (CY7C68013A) that the USB control module adopts Cypress company to produce has comprised USB 2.0 transceivers, SIE (serial interface engine), 8051 microcontrollers, 4KB FIFO storer and programmable peripheral interface GPIF.Its intelligent SIE serial interface engine that carries can hardware handles USB 2.0 agreements, and the general programmable interface and the master/slave end points FIFO that have simultaneously provide the seamless link interface for microprocessor operation.Chip CY7C68013A has following principal character: four end points able to programme can be double buffering, three buffer zones or four buffer zones, can adjust width and the degree of depth of buffer zone according to the reading rate of external data.GPIF allows to be directly connected to 8 of most of parallel interfaces or 16, defines waveform by waveform descriptor able to programme and configuration register; Support a plurality of Ready(RDY) input and Control(CTL) output.+ 3.3V power voltage supply conveniently is connected with other element, and has reduced the power consumption of controller.Enhancement mode industrial standard 8051 microcontrollers, clock frequency have improved its travelling speed largely up to 48MHz, and each instruction cycle only comprises four clock period.

In the utility model capture card is dropped into application, it uses synoptic diagram as shown in Figure 9.The corona current signal at first is converted into voltage signal through the noninductive resistance sensor, pass through amplitude limit, amplification, filtering and the buffer action of signal condition unit again after, be converted into A/D converting unit acceptable signal; Then the A/D converting unit is carried out data sampling.At first AD control parameter is configured, the USB control module is by the initialization of interrupt mode realization to the A/D conversion chip, begin to start data acquisition for the first time afterwards, gathered signal and delivered to the A/D conversion chip through behind the signal condition of input channel, the A/D conversion chip is changed signal under the clock that logic control circuit produces drives, and the stored digital after the conversion is in the inner terminal buffer memory of USB control module.The firmware program of USB control module through enumerating with re-enumeration after, with GPIF holotype control data acquisition with read, and the Waveform Control AD sequential by GPIF, the A/D conversion chip is changed signal under the clock that logic control circuit produces drives, and the data after the conversion are stored in the inner terminal buffer memory of USB control module.When collection count reach the storage depth that USB control module inside sets after, steering logic can produce automatically and realize that data block is to the transmission of host computer.In this process, host computer can dispose in real time to acquisition channel, enlargement factor, storage depth, sampling rate etc., and can preserve data and display waveform in real time.

For A/D converting unit translation data process in the utility model with read data time sequence figure, read transformation result during every passage EOC as Fig. 4, namely when EOC becomes low level, carry out a read operation.Reading by CS and RD control of data.When CS=RD=0, DB11～DB0 triple gate is opened, and allows data output.Under this control sequential, AD7864 can reach the highest conversion and acquisition rate.

Read data time sequence figure as Fig. 5 after converting in the utility model, data just are read out after passages all in the conversion sequence converts.It is the transformation result that BUSY reads all passages when becoming low level.During each read operation, increase output data register pointer, when reading last transformation result, will export the data register pointer and reset.

Be the communication scheme of A/D conversion chip AD7864 and USB control module CY7C68013A in the utility model as Fig. 6, adopt the mode that reads data after the conversion here.When conversion start signal CONVST is effective (rising edge), all retainers enter hold mode, begin the passage collection to selecting.The BUSY output signal is triggered high level when conversion start signal CONVST rising edge, and remains height in transfer process always, behind the passage EOC, becomes low level.All effective during each passage EOC of EOC signal EOC, the data after each passage conversion are kept in the inner corresponding latch of AD7864.Behind all passage EOCs, when read signal RD and chip selection signal CS are effective, just can read data from data bus concurrently.During data read, read according to conversion sequence, read the back at every turn and revise internal lock storage pointer automatically.After all channel datas all read, internal lock storage pointer automatically reset.DB0 ~ DB15 is data bus, and CY7C68013A is by CONVERT, RD and the WR pin of CTL0, CTL1 and CTL2 control AD7864, and the EOC leg signal of gathering AD7864 by RDY0.

The implementation of GPIF mono-recordable waveform is in the utility model: after CY7C68013A powered on, system carried out initialization, simultaneously AD is resetted.System enters 0 state, and CONVERT signal step-down starts the AD conversion, and the simulated data of gathering is converted into digital signal, and according to the duration that AD arranges state 0 switching time be 42ns; Then, system enters 1 state, and it is decision point, begins to gather eoc signal, and EOC represents whether conversion is finished, and then enters idle condition if finish, and finishes this waveform, otherwise waits for always, finishes conversion up to it.

FIFO reads the implementation of waveform and is in the utility model: state 0, during RD signal step-down, AD can read, state 1, data are effective, read in data, because FIFO can arrange the number of times that waveform is read, so state 3 is determination points, whether the number of times according to the setting of TCXpire signal deciding runs through, if run through, enter dummy status and finish this waveform, read otherwise proceed FIFO.

Be illustrated in figure 7 as data acquisition program process flow diagram in the utility model.When program begins, principal function is called TD_Init () initialization global variable, call the initialize routine GpifInit () of GPIF then, initialization GPIF register, and by two automatic pointer registers the GPIF waveform program that generates is called in the RAM of chip, then state machine brings into operation, and produces designed control waveform.

The Waveform Control program is carried out in the state machine circulation, and what therefore data acquisition did not also stop is performed.After if the AD7864 data converted is effective, in TD_Poll () function, carry out and read data distributing program, and at first judge whether full scale will of buffer zone, if it is discontented, then begin to read 12 bit data, the data of AD7864 just, and the address pointer of buffer zone added 1, guarantee that data can not covered by data afterwards, and be kept in the next address.After running through 512 data, buffer zone is full, and the request according to host computer at this moment transmits data automatically.

CY7C68013A has two automatic pointer register AUTOPTR1 and AUTOPTR2, by these two pointers, data can be transmitted quickly and without the need for the participation of CPU, they are by after disposing, and point to data source address and data destination address respectively, after a byte has transmitted, increase the value of pointer automatically and begin the transmission of next byte.

Be illustrated in figure 8 as host computer acquisition applications program flow diagram in the utility model, at first obtain the capture card tabulation after system's operation, select acquisition system (anodal measuring system still is the negative pole measuring system), acquisition channel is set opens collection afterwards with other control parameters.Image data selects whether to want the real-time monitored data at first, and real-time monitored is just opened new thread collection and shown data if desired, also shows otherwise only need gather once.After data acquisition finishes, can select whether to preserve data and image.When setting chip is storage automatically, need to set the time interval of timer, finish automatic hold function.When realizing wave shape playback, need read wave file earlier, be written into waveform and characteristic parameter (comprising current maxima, current minimum, current average and current peak peak value etc.) and finish wave shape playback.The host computer major function is as follows:

(1) multisystem selection function.When a plurality of measuring systems were worked simultaneously, program was given their automatic numberings, can select the capture card of appointment to carry out data acquisition.Owing to need measure the positive-negative polarity corona current simultaneously, therefore need this application program can identify two cover measuring systems in the native system, avoid image data to cause confusion.

(2) measurement pattern is selected.Data acquisition scheme can continuous working under unattended situation, can select whether to preserve data, image and mean value, and the preservation of data and image at interval, preservation length and the mean value in each file of data counts and can arrange respectively.The virtual oscilloscope pattern only is used for real-time monitored corona current waveform.

(3) parameter setting and hold function.It mainly is the setting of capture card for convenience, because the duty basically identical of capture card in most cases, can preserve the capture card parameter of frequent use get off like this, and in program start, be written into, only need to select corresponding capture card duty just can finish the parameter setting.

(4) current data, image hold function.The preservation form of data is the txt type, and current measuring system configuration parameter, Measuring Time is saved in file, conveniently carries out follow-up data and handles, and the preservation form of picture is the bmp type, convenient directly observation.The storing path of data and image can be distinguished independent setting.

(5) wave shape playback function.The data of in the past preserving be can be written into, its mean value, maximal value and minimum value observed.

(6) subsidiary function.Comprise the selection of zoom mode, the setting of decay gear, zoom mode can be observed interested that part of image, the decay gear refer to capture card probe can be set to * 1 or * 10 decay.

Should be noted that at last: above embodiment is only in order to illustrate that the technical solution of the utility model is not intended to limit, although with reference to above-described embodiment the utility model is had been described in detail, those of ordinary skill in the field are to be understood that: still can make amendment or be equal to replacement embodiment of the present utility model, and do not break away from any modification of the utility model spirit and scope or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present utility model.

Claims (8)

1. the corona current capture card based on usb bus is characterized in that, described corona current capture card comprises signal condition unit, A/D converting unit and the USB control module that connects successively; Described USB control module is connected with described signal condition unit.

2. corona current capture card as claimed in claim 1 is characterized in that, described signal condition unit comprises limiter protection circuit, programmable amplifying circuit, antialiasing filtering circuit and the emitter follower circuit that connects successively.

3. corona current capture card as claimed in claim 1 is characterized in that, described A/D converting unit comprises the signals collecting chip, and it adopts the A/D converter AD7864 of 500kHZ acquisition rate, 12 bit resolutions.

4. corona current capture card as claimed in claim 1 is characterized in that, described USB control module comprises 8051 microcontrollers, general programmable interface GPIF, serial interface engine and USB transceiver;

Described 8051 micro controller I/O mouth is connected with described signal conditioning circuit;

Described general programmable interface is connected with described A/D converting unit by data bus;

Described serial interface engine is communicated by letter with PC respectively with described USB transceiver.

5. corona current capture card as claimed in claim 2 is characterized in that, described limiter protection circuit comprises Transient Suppression Diode TVS and ceramic discharge diode in parallel.

6. corona current capture card as claimed in claim 2 is characterized in that, described emitter follower circuit comprises operational amplifier A D817.

7. corona current capture card as claimed in claim 2 is characterized in that, described programmable amplifying circuit comprises integrated gain-programmed amplifier;

Described integrated gain-programmed amplifier is selected the PGA202 programme-controlled instrument amplifier of BURR.BROWN company for use.

8. corona current capture card as claimed in claim 2 is characterized in that, described antialiasing filtering circuit adopts and is integrated with source filter;

Describedly be integrated with the monolithic integrated filter chip MAX27 that source filter is selected MAXIM company for use.

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