CN101201365A - System and method for measuring and analyzing voltage frequency - Google Patents

Abstract

The invention provides a measurement and analysis system of the voltage and frequency and its analysis method. The invention can be applied in the fields of the detection, data acquisition and analysis, and the frequency conversion technology. The device can measure the voltage signal and the frequency signal, and the precision can reach as high as 10<-6>. The invention provides a calculation and analysis method of the linearity of the voltage-frequency curve Alpha out, the ratio of the voltage and frequency Kout and the base point of the voltage and frequency V50Hz, coordinates with the drawing and analysis method of the voltage-time, the frequency-time and the voltage-frequency curve, to provide the effective auxiliary analysis method for the operation condition of the variable frequency equipment, thereby realizing the function of low cost, high precise, wide-range measurement on the voltage and frequency and intelligent analysis function of the measurement results.

Description

Electric voltage frequency measuring and analysis system and analytical approach

Technical field

The present invention proposes a kind of electric voltage frequency measuring and analysis system and analytical approach, can be applied to fields such as detection, data collection and analysis, converter technique.

Background technology

At present, the device of measuring voltage is modal to be multimeter, signals such as multimeter can measuring voltage, electric current and resistance, but lack measurement function to frequency signal; The device of survey frequency is modal to be frequency meter, and its precision is high but lack measurement, the particularly measurement of forceful electric power signal to various voltage signals.Oscillograph has the function of multimeter and frequency meter concurrently, can measure simultaneously voltage and frequency, and can draw each waveform constantly out, but it lacks the measurement to continuous time section voltage, frequency sequence, the voltage surveyed, frequency sequence can't be drawn that to become with time be voltage-time, frequency-time curve and the voltage-frequency curve of transverse axis, be used for the professional and analyze use, and single the oscillograph too high and complex operation of cost often, volume is difficult for portable greatly.

Summary of the invention

Two purposes of the present invention are to overcome oscillographic above-mentioned defective, and a kind of electric voltage frequency measuring and analysis system and analytical approach are provided.Native system can be measured voltage, the frequency of various waveforms, and can draw out voltage-time, frequency-time and voltage-frequency curve, carry out the curve eigenvalue calculation, for the electric voltage frequency curve is applied to actual engineering, particularly to the Application of frequency conversion technique field, provide assistant analysis that effective help is provided, better meet the demand of practical application.

To achieve these goals, the present invention has taked following technical scheme.Native system mainly includes signal processing circuit 1, frequency measurement circuit 2, A/D change-over circuit 3, cpu control circuit 4, keyboard-display circuit 5 and power circuit 8; Wherein:

Signal processing circuit 1 includes light current place in circuit 1.1, forceful electric power place in circuit 1.2, reduction voltage circuit 1.3, voltage stabilizing follow circuit 1.4, TTL normalization circuit 1.5, peak holding circuit 1.6;

The input end of light current place in circuit 1.1 is one and is used for and 0～5V measured signal IN _LowThe analog signal interface that is connected, the output terminal of light current place in circuit 1.1 is connected with voltage stabilizing follow circuit 1.4;

The input end of forceful electric power place in circuit 1.2 is one and is used for and 5～300V measured signal IN _HighThe analog signal interface that is connected, the output of forceful electric power place in circuit 1.2 are connected on reduction voltage circuit 1.3 and are connected; 5～300V measured signal IN that reduction voltage circuit 1.3 is sent the forceful electric power place in circuit here _HighExport to voltage stabilizing follow circuit 1.4 after reducing to 0～5V light current measured signal according to the linear geometric ratio of step-down multiplying power;

The output signal IN of voltage stabilizing follow circuit 1.4 _StdEnd is connected with peak holding circuit 1.6 with TTL normalization circuit 1.5 respectively; TTL normalization circuit 1.5 becomes ac square wave with the output signal of voltage follower circuit 1.4, removes shake by the hysteresis comparator circuit again, by having obtained the TTL frequency measured signal IN of standard behind the stabilivolt _TTL, export to frequency measurement circuit 2; The maximal value that the output signal voltage of voltage follower circuit 1.6 appearred in peak holding circuit 1.6 is with the signal IN of dc constant voltage _PeakExport to A/D change-over circuit 3;

The output terminal of frequency measurement circuit 2 is connected with cpu control circuit 4 by data bus, address bus and control bus, frequency measurement circuit 2 is measured the frequency values of TTL reference waveform, and the frequency values that records outputed to cpu control circuit 4 with the form of digital quantity, and deliver to keyboard-display circuit 5 and show;

The input of A/D change-over circuit 3 is connected with the output terminal of signal processing circuit 1 voltage peak circuit 1.6, and output terminal is connected with cpu control circuit 4 with control bus by data bus, address bus; The magnitude of voltage that A/D change-over circuit 3 is exported voltage peak circuit 1.6 converts digital quantity to and outputs to cpu control circuit 4, and delivers to keyboard-display circuit 5 demonstrations;

Cpu control circuit 4 is connected with the output terminal of frequency measurement circuit 2, the frequency values that the receive frequency metering circuit records; Cpu control circuit 4 is connected with A/D change-over circuit 3, receives the magnitude of voltage of the digital quantity after changing; If the forceful electric power signal, magnitude of voltage and the step-down multiplying power of cpu control circuit 4 after according to the step-down of reduction voltage circuit 1.3 calculates actual magnitude of voltage, and among the RAM of storage cpu control circuit 4, and the display part of delivering in the keyboard-display circuit 5 shows;

Keyboard-display circuit 5 is connected with cpu control circuit 4 by data bus, address bus and control bus, and the display part in the keyboard-display circuit 5 is used for the result of display frequency metering circuit 2 and the 3 real-time conversions of A/D change-over circuit; Keyboard in the keyboard-display circuit 5 is connected with cpu control circuit 4 by the keyboard display control chip;

Power circuit 8 provides power supply for above each circuit.

Also be provided with the communicating circuit 6 that is used for upper machine communication, communicating circuit 6 is connected with cpu control circuit 4.Communicating circuit 6 is connected by data line with computing machine, its transmitting terminal, receiving terminal, data terminal, address end and control end are received respectively on transmitting terminal, receiving terminal, data bus, address bus and the control bus of line programmable cpu control circuit 4, communicating circuit.

Also be provided with self calibration positive circuit 7, the data terminal of self calibration positive circuit 7, address end and control end are received respectively on data bus, address bus and the control bus of cpu control circuit 4, and self calibration positive circuit 7 output terminals are connected with signal processing circuit 3 light current places in circuit 1.1 interfaces.Cpu control circuit 4 formation voltages, frequency signal input to the self calibration positive circuit and produce the self check waveform by self calibration positive circuit 7, the self check waveform inputs to light current place in circuit 1.1, and the self check voltage of the voltage that cpu controller collects light current place in circuit 1.1, frequency measurement and its generation, frequency compare to judge whether system is normal.

Described frequency measurement circuit 2 comprises that the counter group of the series connection of two relays, 4 74F161 register formations, 1 74F161 register are as logic controller and 2 74LS245 bus transceivers, four each registers of counter have 4 outputs, 8 outputs of per two registers are connected in the input of bus transceiver 74LS245, and the output of bus transceiver 74LS245 is connected with cpu control circuit 4 by data bus, address bus and control bus;

Often the opening of first relay, the frequency that normal-closed end connects high frequency are respectively treated side signal IN _TTLOutput pin IN with the known standard crystal oscillator _Cry, public output terminal is connected on the counting input end of first counter in the counter chip group; Often the opening of second relay, the CPU pin IN that normal-closed end is practiced midwifery living timing pip respectively _TimerTreat side signal IN with the frequency of low frequency _TTLBe connected, the Enable Pin of four counting chips is received in public output, and often the opening of first relay and second relay, normally closed switching controls end link to each other with cpu control circuit 4 control buss and fetch two relay normally opens of control, normally closed switching;

CLK end as the 74F161 counter of logic controller meets low frequency signal IN all the time _TTL, its CLR end links to each other by an anti-door with its 2nd counting output P1, the latching circuit that realization only allows the one-period waveform to pass through, and reset signal CLR links to each other for control end by control bus and CPU's;

CLK as the 74F161 counter of logic controller meets low frequency signal IN all the time _TTL, its CLR end links to each other by an anti-door with its 2nd counting output P1, the latching circuit that realization only allows the one-period waveform to pass through, and reset signal CLR links to each other for control end by control bus and CPU's.

Four each registers of counter have 4 outputs, and 8 outputs of per two registers are connected in the input of bus transceiver, and the output of bus transceiver links to each other with CPU with control bus by data bus, address bus;

2. device workflow:

Signal flow diagram during device work is seen the weak electric signal IN of accompanying drawing 15,0～5V _LowBy the light current place in circuit 1.1 of signal processing circuit 1, or the forceful electric power signal IN of 5～380V _HighAfter the forceful electric power place in circuit 1.2 and reduction voltage circuit 1.3 step-downs by signal processing circuit 1, after voltage follower circuit 1.4 impedance matchings, obtain standard measured signal IN _Std, IN _StdObtain crest voltage IN through peak holding circuit 1.6 _Peak, obtain measured signal frequency measurement OUT through the A/D change-over circuit _U, for the situation that is input as the weakness signal, OUT _UBe measured signal voltage actual value U (t), for the situation that is input as the strong point signal, OUT _UNeed multiply by the step-down multiplying power and obtain measured signal voltage actual value U (t); IN _StdObtain the frequency measured signal IN of the TTL form of standard through TTL normalization circuit 1.5 _TTL, high frequency measured signal IN _TTLThe high level pulse IN of the known duration that sends with cpu control circuit 4 _TimerBy frequency measurement circuit, obtain exporting OUT _FAnd low frequency measured signal IN _TTLOutput waveform IN with the given frequency crystal oscillator _CryBy frequency measurement circuit, obtain measured signal frequency measurement OUT _F, frequency measurement and voltage measuring value input to cpu control circuit, and deliver to keyboard-display circuit 5 demonstrations simultaneously.

Utilize above-mentioned electric voltage frequency measuring and analysis system, acquisition time sequence voltage, frequency and analytical approach thereof is characterized in that, mainly may further comprise the steps: data acquisition, data pre-service, three line analysises and voltage-frequency eigenvalue calculation are analyzed:

1) data acquisition: by system acquisition time series voltage, the time series frequency described in the claim 1, concrete acquisition method is as follows:

The 1st step: the acquisition time interval T is set by the keyboard in the keyboard-display circuit (5) _SampleWith continuous acquisition number of times t to voltage, frequency _Sample, put current times of collection t _Once=1, above-mentioned parameter is deposited among the RAM of cpu control circuit (4), cpu control circuit (4) is carried out the continuous acquisition subroutine;

The 2nd step: cpu control circuit (4) obtains the collection value OUT of current access signal voltage by A/D change-over circuit (3) _V, multiply by the actual value U (t that the step-down multiplying power draws current voltage _Once) leave among its RAM;

The 3rd step: cpu control circuit (4) obtains the collection value OUT of current access signal frequency by frequency measurement circuit (2) _F, calculate the actual value F (t of current voltage _Once) leave among its RAM;

The 4th step: current times of collection t _OnceFrom increasing 1, if t _Once≤ t _SampleThen repeated execution of steps 2,3, and 4;

The 5th step: gather and finish;

So produced in time the sequence magnitude of voltage (U (t), t) and the time series frequency values (F (t), t), wherein t is the sampling time, t=1,2 ..., t _Sample, t _SampleBe positive integer, the final value in expression sampling time, U (t), F (t) represent t magnitude of voltage and frequency values constantly respectively;

2) data pre-service:

The 1st step: from the RAM of cpu control circuit 4, read continuous acquisition number of times t _Sample, put current calculation times t _Prc=n+1 calculates comparison and finishes number of times t _Prcend=t _Sample-n, wherein n is and U (t _Sample) and F (t _Sample) number of magnitude of voltage of contrast, the span of n is generally 3≤n≤10;

To (the U (t) that collected in the last step, t), (F (t), t) carry out correcting process, promptly the value deletion that obviously departs from adjacent data, the correction principle is: if t magnitude of voltage U (t) constantly with before or after the absolute value of difference of n moment magnitude of voltage mean value, greater than t constantly before or after n the mean value of absolute difference between the magnitude of voltage constantly, need correction, promptly

$|U\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}U(t-i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|U(t-i)-U(t-i-1)|}{n-1}---\left(1\right)$

Or

$|U\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}U(t+i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|U(t+i)-U(t+i+1)|}{n-1}---\left(2\right)$

In the formula (1), t-i represents constantly before the t i constantly, the magnitude of voltage during U (t-i) expression sampling instant t-i then, and U (t) is a t magnitude of voltage constantly, the magnitude of voltage in U (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), U (t) is a t magnitude of voltage constantly, the magnitude of voltage when then U (t+i) represents sampling instant t+i, and U (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage U (t) constantly satisfies (1) formula or (2) formula, then be modified to:

$U\left(t\right)=\frac{U(t-1)+U(t+1)}{2};$ Wherein, U (t-1) is a t-1 magnitude of voltage constantly, and U (t+1) is a t+1 magnitude of voltage constantly;

The correction principle of frequency value F (t) is identical with the correction principle of U (t): if t frequency value F (t) constantly with before or after the absolute value of difference of n moment magnitude of voltage mean value, greater than t constantly before or after the mean value of absolute difference between n moment magnitude of voltage, need to revise, promptly

$|F\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}F(t-i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|F(t-i)-F(t-i-1)|}{n-1}---\left(3\right)$

Or

$|F\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}F(t+i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|F(t+i)-F(t+i+1)|}{n-1}---\left(4\right)$

In the formula (3), t-i represents constantly before the t i constantly, the magnitude of voltage during F (t-i) expression sampling instant t-i then, and F (t) is a t magnitude of voltage constantly, the magnitude of voltage in F (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), F (t) is a t magnitude of voltage constantly, the magnitude of voltage when then F (t+i) represents sampling instant t+i, and F (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage F (t) constantly satisfies (3) formula or (4) formula, then be modified to:

$F\left(t\right)=\frac{F(t-1)+F(t+1)}{2};$ Wherein, F (t-1) is a t-1 magnitude of voltage constantly, and F (t+1) is a t+1 magnitude of voltage constantly;

The 2nd step: preceding calculation times t _PrcFrom increasing 1, if t _Prc≤ t _PrcendThen repeated execution of steps 1;

The 3rd step: the data pre-service is finished;

3) three line analysis and eigenvalue calculation:

The 1st step, the voltage-frequency curve match:

1) uses least square method the point in the U-F curve is fitted to a straight line, and calculate fitting parameter a, b and voltage-frequency eigenwert: voltage-frequency curve linearity α _Out, voltage-frequency compares K _OutWith voltage-frequency basic point V _50Hz

In order to represent conveniently U (t) to be designated as u _t, F (t) is designated as f _t, with t _SampleBe designated as n, concrete steps are as follows:

If the voltage-frequency linear function is f=au+b, wherein a, b are undetermined constants;

Note ε _t=f _t-(au _t+ b), it has reflected with straight line f=au+b and has described u=u _t, f=f _tThe time, calculated value f and actual value f _tThe deviation that produces; With

Measure total departure;

Determine constant a and b among the f=au+b, make $F(a,b)=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="A20071011875200323.png,A20071011875200324.png"\; state="\{\{state\}\}">t</figure-callout>}}^2=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{(f_t-{\mathrm{au}}_t-b)}^2$ Be minimum;

Get by extremum principle $\frac{\&PartialD;F}{\&PartialD;a}=\frac{\&PartialD;F}{\&PartialD;b}=0,$ Promptly $\left\{\begin{array}{c}\frac{\&PartialD;F}{\&PartialD;a}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t(f_t-{\mathrm{au}}_t-b)=0\\ \frac{\&PartialD;F}{\&PartialD;b}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_t-{\mathrm{au}}_t-b)=0\end{array}\right.$

Separating these simultaneous equations gets: $\left\{\begin{array}{c}a=\frac{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t{f}_t-\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t}{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u_t}^2-{\left(\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\right)}^2}\\ b=\frac{1}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t-\frac{a}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\end{array}\right.$

In the 2nd step, voltage, frequecy characteristic value are calculated:

Voltage-frequency compares K _Out=a: voltage-frequency is than the linear relationship that is used for representing voltage and frequency values;

The voltage-frequency curve linearity $L_{\mathrm{out}}=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_t^2:$ The voltage-frequency curve linearity is used for weighing point on the voltage-frequency curve and departs from the come out degree of straight line of match;

Voltage-frequency basic point V _50Hz=50a+b: the operating voltage when the voltage-frequency basic point is used for weighing frequency of operation 50Hz;

In the 3rd step, draw three curves:

Drawing voltage time is the U-t curve: with revised time series (U (t), t) each t and corresponding voltage value U (t) are plotted in the U-t coordinate system voltage time U-t curve that obtains constantly;

Draw frequency time F-t curve: with revised time series (F (t), t) each t and frequency value corresponding F (t) are plotted in the F-t coordinate system frequency time F-t curve that obtains constantly;

Draw electric voltage frequency U-F curve: with revised time series variable (U (t), t) and (F (t), t), the formation tlv triple (U (t), F (t), t), each constantly the U (t), two values of F (t) of t correspondence as the (U of a point, F) coordinate is plotted in the U-F coordinate system, obtains the U-F curve;

The 4th step, Performance Analysis:

According to three curves and three eigenwerts of the above-mentioned drafting of item, the slip-stick artist draws the requirement whether measured electric voltage frequency value satisfies engineering actual items index, and satisfaction degree.

Beneficial effect of the present invention:

1) equipment of the present invention has volume and urinates in carrying, and cost is low, has voltage, frequency signal measuring accuracy height, and measurement range is wide; Particularly the system of the present invention's formation has the time series continuous acquisition, data processing, the characteristics of visual analyzing function;

2) the time series electric voltage frequency analytical approach of the present invention's proposition, by to three kinds of curves that pass through eigenvalue calculation and drafting of proposing among the present invention with to the curve fitting analysis method of electric voltage frequency scatter diagram, can provide quick, convenient, reference intuitively for the performance index that the slip-stick artist analyzes Devices to test, the present invention has directly provided some evaluation indexes, these evaluation indexes come from the actual engineering practice of experienced slip-stick artist, but are not proposed by the form of official of academia as yet.

3) the present invention particularly to development in recent years rapidly Application of frequency conversion technique give and very big help, for the PWM waveform of frequency-variable controller output, this equipment not only can be measured, and can also analyze, and has remedied the technical blank of frequency converter output PWM waveform measurement.

Description of drawings

Accompanying drawing 1 electric voltage frequency measuring and analysing meter circuit module connection layout

Accompanying drawing 1.1 signal processing circuit module connection layout

Accompanying drawing 2CPU control circuit figure

Accompanying drawing 3LEM module circuit diagram

Accompanying drawing 4 analog signal processing channel circuits

Accompanying drawing 5 voltage peak sampling hold circuits

Accompanying drawing 6A/D change-over circuit figure

7 low-frequency cycles of accompanying drawing are caught sequential chart

Accompanying drawing 8 high frequency frequency measurement sequential charts

9 low-frequency cycle of accompanying drawing catching circuits

Accompanying drawing 10 frequency meter modules

Accompanying drawing 11 high-frequency/low-frequency are measured multiplex circuit figure

Accompanying drawing 12CH451 and CPU, LED show connecting circuit figure

The connection layout of accompanying drawing 13 chips and usb bus

Accompanying drawing 14AD7008 and microcomputer interface circuit figure

Accompanying drawing 15 multiplexing type electric voltage frequency Measurement and analysis method signal flow diagrams

Accompanying drawing 16 capture program software flow patterns

Embodiment

Present embodiment at first is described in detail (referring to accompanying drawing 1-14) to the process that electric voltage frequency measurement analysis device hardware circuit, annexation and concrete principle of work and measured signal are transmitted, changed and handle in device, next master routine being described, is time series electric voltage frequency analytical approach to the detailed step (referring to accompanying drawing 14-15) of the computational analysis of the drafting of the data characteristics curve of above-mentioned collection and eigenwert at last.

1. hardware circuit annexation, principle of work and signal Processing:

The hardware circuit of present embodiment is shown in Fig. 1～14, mainly include signal processing circuit 1, frequency measurement circuit 2, A/D change-over circuit 3, cpu control circuit 4, keyboard-display circuit 5, communicating circuit 6, self calibration positive circuit 7,8 eight cores compositions of power circuit, see accompanying drawing 1.

Signal processing circuit 1 is seen accompanying drawing 1.1, and effect is that input signal is inserted, and is treated as frequency measurement circuit 2 and A/D change-over circuit 3 manageable signal forms.Signal processing circuit 1 has a multiplexing analog input interface, both can be used as the input (inserting 0～5V measured signal) of light current place in circuit 1.1, can be used as the input (inserting 5～300V measured signal) of forceful electric power place in circuit 1.2 again.Signal processing circuit 1 has two output interfaces, and one is that to export to 2, one of frequency measurement circuits be that voltage peak circuit 1.6 is exported to A/D change-over circuit 3 to TTL normalization circuit 1.5.

Light current place in circuit 1.1 has an analog signal interface, with 0～5V measured signal IN _LowBe connected, output is connected in the input of voltage stabilizing follow circuit 1.4, i.e. the input pin of back step voltage follower operational amplifier.

Forceful electric power place in circuit 1.2 has an analog signal interface, with 5～300V measured signal IN _HighBe connected, output be connected in the input of reduction voltage circuit 1.3, be about to press chip input high pressure pin (+HT);

5～300V measured signal IN that reduction voltage circuit 1.3 is sent the forceful electric power place in circuit here _High, keep the waveform shape of its input signal constant, amplify or dwindle the circuit of its amplitude by equal proportion, the signal that obtains, its scope is at 0 ~ 5V.Because IN _HighVoltage magnitude is up to ± 300V about, so we need with the line drop of being tested become amplitude at 10V with interior weak electric signal, what it should be noted that our required measurement is waveform, this just requires in the process of transformation, waveform can not distortion.And our common used transformer is designed for the 50Hz cycle, is not suitable for our test.Therefore, we have selected state-of-the-art technology---magnetic compensation is former---the LEM current/voltage sensor assembly of Switzerland LEM company for use.

The circuit of LEM module connects, and sees accompanying drawing 3.

Wherein+HT ,-HT is the forceful electric power input end ,+,-be power supply, M is an output terminal

Need to measure PWM width modulation wave voltage peak-peak: generally at ± 300V

Power available: ± 15V (± 5%)

Step-down ratio can make when amplitude be that the PWM pulse width modulated wave step-down of 300V is that amplitude is the PWM pulse width modulated wave of 6.25V, that is to say, when the transformation ratio that adopts LV28 transformation module gained is 300: 6.25 promptly 48: 1.By the signal of step-down, in cpu control circuit 4 computation processes,, obtain the actual value of forceful electric power measured signal voltage by multiply by the mode of above-mentioned step-down multiplying power.

Reduction voltage circuit 1.3 output IN _LEMBe connected in the input of voltage stabilizing follow circuit 1.4.

Voltage stabilizing follow circuit 1.4 is with input signal IN _Low, IN _LEMBy the 5V mu balanced circuit, the voltage amplitude limit between 0～5V, is carried out output signal IN after the impedance matching by voltage follow _Std, be connected on respectively in the input of TTL normalization circuit 1.5 and peak holding circuit 1.6.

TTL normalization circuit 1.5 is with input signal IN _StdWaveform one-level one-level is handled, and promptly the simulating signal in the test macro is handled, and until the form that the voltage that becomes test macro, frequency measurement circuit can be accepted, sees accompanying drawing 4.At first input signal is earlier through a voltage stabilizing, and purpose is to prevent the excessive late-class circuit that burns of input signal, and then it is carried out voltage follower, and the level impedance is isolated before and after making, and output is delivered to the voltage peak holding circuit when sending next stage to handle.Then through an open loop integrated operational amplifier, (wherein 1M resistance and the 10K resistance in the positive potential input is when being TTL for input signal, is not ac square wave through not existing negative potential also can be infinitely enlarged after the voltage stabilizing).And then, remove the upset shake through hysteresis loop comparator, be Transistor-Transistor Logic level after the voltage stabilizing.Passing through homophase door (74LS07) at last again makes it become the TTL signal IN of standard _TTLIN _TTLBe connected with the input end of frequency measurement circuit 2.

Peak holding circuit 1.6 is with input signal IN _StdFeed the input end of peak holding circuit 1.6, the reset terminal of peak holding circuit 1.6 is connected with the control bus of cpu control circuit 4, and physical circuit figure sees accompanying drawing 5.The crest voltage sampling hold circuit is made of a slice sampling holder chip LF398 and a voltage comparator LM311.Output voltage and the input voltage of LF398 compare by LM311, and when Vi＞V0, LM311 exports high level, delivers to logic control end 8 pin of LF398, makes LF398 be in sample states; When Vi reaches peak value and descends, Vi＜V0, voltage comparator LM311 output low level, the logic control end of LF398 is put low level, makes LF398 be in hold mode.Because LM311 adopts open collector output, draws resistance so need connect.The conducting of the pulse control circuit switch of sending here by the overvoltage detection circuit output terminal, sampling capacitance discharge when having electricity, otherwise sample circuit is followed the tracks of the variation of peak value always.

Be that peak holding circuit is zero IN through the back output voltage that resets _Peak=0, IN _StdBehind the input peak holding circuit, compare IN _StdAnd IN _PeakIf: IN _Std＞IN _Peak, IN then _Peak=IN _StdAnd locking IN _PeakMagnitude of voltage; If IN _Std＜IN _Peak, IN then _PeakOutput voltage values remains unchanged; Obtain IN _Peak=IN _StdPeak I N _PeakSimulation output; The output IN of peak holding circuit _PeakBe connected in the input of A/D change-over circuit (3).

The output IN of the input of frequency measurement circuit 2 and signal processing circuit 1TTL normalization circuit 1.5 _TTLBe connected, as the input of frequency signal to be measured; Measurement result output OUT _F(t) be connected with cpu control circuit 3 with control bus by data bus, address bus.

The low frequency measurement principle:

Frequency signal IN _TTLMeasurement adopted pure hard-wired method, the quick 74F161 of level Four series connection forms 74F161 counter group, Measurement Resolution is up to 2 ¹⁶For low frequency signal below the 1KHz and the medium-high frequency signal more than the 1KHz, adopted diverse method: when measuring low frequency signal, catch the length of one-period, with the active crystal oscillator of the 1MHz of standard as series connection counting chip group CLK input signal, just in input measured signal one-period, measure the number of the 1MHz high-frequency signal that feeds 74F161 counter group.

Accompanying drawing 7 is for being the sequential chart of low frequency measurement circuit imagination:

Catching circuits is only when trigger pulse comes, catch two adjacent rising edges of measured signal, export high level during this period, make 74F161 counter group feed the 1MHz high-frequency signal, all keep low level At All Other Times, unless the triggering level input is arranged again, catches two adjacent rising edges of measured signal again

Skilful use 74F161 realizes above-mentioned logic, sees accompanying drawing 9.It is signal source that 74F161 imports CLK all the time, when the zero clearing of CLR low level, counter time low level P1 is 0, counter can be worked, so ensuing rising edge of signal source, counter low level P0 is uprised by low, and this moment is because counter time low level P1 still is 0, so counter can work on; So the ensuing rising edge of signal source, by high step-down, this hour counter time low level P1 is 1 with counter low level P0, the counter self-locking, it is low that P0 keeps, and finished the seizure of signal source one-period length, just repeats above-mentioned capture-process when CLR signal arrival next time.

With respect to the input signal below the 1KHz, use the high-frequency signal measurement of 1MHz to have very high accuracy and precision.Suppose that in the one-period of input signal the periodicity of the given frequency signal of process counter is N, then the frequency values of low frequency signal to be measured is: $f=\frac{{10}^6\mathrm{\&mu;s}}{1\mathrm{\&mu;s}\&times;N}.$

The circuit diagram that accompanying drawing 10 is organized and is connected with data bus for 74F161, counting unit has 4 74F161 fast counter serial connections to constitute, every 74F161 can count 4, therefore can realize totally 16 countings, least-significant byte meets a 75LS245 respectively with most-significant byte and links to each other with data bus, every 74LS245 has oneself independently chip select address, thereby realizes and the cpu data exchange.

The high frequency measurement principle:

For the medium-high frequency signal more than the 1KHz, adopted distinct measuring method---interior signal source umber of pulse during the measurement timing: four fast counter 74F161 are joined end to end according to the way of the carry end TC of the preceding a slice counter of clock CLK end connection of back a slice counter, the a certain pin of 89C51 single-chip microcomputer produces a fixing timing signal (being divided into several retainings), be connected on the Enable Pin of counter 74F161, high-frequency signal be connected on the clock end of first counter.The counting output of counter is delivered to data bus by bus transceiver 74F245 upload back single-chip microcomputer.Like this, the single-chip microcomputer timing signal is between high period, and counter can gather the data of four counters with the high-frequency signal umber of pulse of meter, and just can know has how many high-frequency signals cycle through counter between the timing signal high period.

Fig. 8 is the sequential chart of high frequency measurement circuit:

The cycle of supposing timing pip is T, and the high-frequency signal periodicity by counter during pulse high level is N, and the frequency that then can obtain high-frequency signal is: $\frac{\mathrm{<figure-callout\; id="10"\; label="f"\; filenames="A20071011875200313.png,A20071011875200324.png"\; state="\{\{state\}\}">f</figure-callout>}}{{10}^6\mathrm{\&mu;s}}=\frac{N}{T}$ $f=\frac{{10}^6\&times;N}{T}\left(\mathrm{Hz}\right)$

Because the frequency band of circuit working is only by the frequency of operation decision of four counters that participate in counting, and irrelevant with single-chip microcomputer and bus buffer, therefore as long as select the counter of bandwidth, just can realize the counting of high-frequency signal fully.The nominal operation frequency of the 74F161 that we select for use is 143MHz, so our circuit can reach more than 100,000,000 to the measurement of high-frequency signal in theory, but because the restriction of experiment condition, our measured value can only reach the frequency of 50MHz, and (upper limiting frequency that signal source produces only has 15MHz, we serve as signal source with the active crystal oscillator of 50MHz), measure normal fully at this high-frequency signal below frequency.When following table has provided the measurement different frequency, the best regularly length of timer:

Frequency range	Timing length	Single-chip microcomputer timer initial value	This frequency range counter peak value
				10K-1MHz	50ms	3CB0H	50000＜65535
1MHz-10MHz	5ms	0EC78H	50000＜65535

10MHz-100MHz

0.5ms

0FE0CH

50000＜65535

High-frequency/low-frequency is measured multiplex circuit:

In order to make frequency measurement more accurate, frequency band is wideer, and the input signal of high and low frequency range has been taked different measurement ways, and two kinds of ways set the overlapping region between the frequency range that can measure, to guarantee the integrality of system, do not make frequency measurement zone out of stock occur.

For high-frequency signal metering circuit and low frequency signal metering circuit, the counter group of series connection is identical, the clock signal that counter connect in different just two kinds of schemes different with enable signal.Clock signal is the input measured signal during high frequency measurement, and is the output waveform of given frequency crystal oscillator during low frequency measurement; Enable signal is the single-chip microcomputer timing pip during high frequency measurement, is the waveform after input signal process waveform transformation and the frequency transformation during low frequency measurement.

Do not influence signal quality for guaranteeing that signal path switches, do not select analog switch (for example CD4051) for use, and use two relays, often the opening of first relay, normal-closed end meet high-frequency input signal IN respectively _TTLOutput pin IN with crystal oscillator _Cry, public output terminal is connected on the counting input end of counting chip group, by the height control magnetic sheet adhesive end of one-bit digital signal, thus the switching of realization two paths of signals; Often the opening of another relay, the single-chip microcomputer pin IN that normal-closed end is practiced midwifery living timing pip respectively _TimerWith low frequency input IN _TTLSignal is through the waveform after the signal Processing, and the Enable Pin of four counting chips is received in public output.By identical its switching of one-bit digital signal controlling.Control by digital signal like this (this control signal can from certain pin of single-chip microcomputer) just can realize the switching of frequency measurement medium-high frequency passage and low channel, and save design cost significantly.Through our practice, it has good stable.But notice that the reliable adhesive magnetic sheet of relay needs enough operating currents (add draw realizations on the small resistor with 74LS07), also will guarantee pickup time (in the program with the time-delay assurance) simultaneously, Figure 11 is the circuit diagram of frequency channel.

The MAX153 simulating signal input pin of A/D change-over circuit 3 keeps output pin to be connected with the LF398 sampling of signal processing circuit 1 voltage peak circuit 1.6, as the input of voltage signal to be measured; Measurement result OUT _U(t) output is connected with cpu control circuit 3 with control bus by data bus, address bus.

Owing to use the AT89C51 single-chip microcomputer to control, use the crystal oscillator of 12M, then therefore every instruction of single-chip microcomputer can be adopted and read-WriteMode (MODE=1) with 1 μ s, utilizes the conversion of WR signal enabling, and the RD signal reads transformation result.Article two, command interval 1 μ s satisfies the control requirement.

Select the high-speed a/d MAX153 chip of Maxim company for use.With the output resistance RM200 Ω of LEM module, replace with two precision resistance 100 Ω, form dividing potential drop.Therefore need select for use resistance to guarantee the accurate dividing potential drop of device.Circuit diagram is referring to accompanying drawing 6.

The effect of cpu control circuit 4 is the work of all circuit of control, the processing of data, mobile and storage; The CPU external bus is made of data bus and address bus; Realize other each circuit working of control by data bus, address bus and control bus.Flash links to each other extender, address space with RAM with CPU with address bus by data bus.

CPU selects the AT89C51 single-chip microcomputer for use in device, and address allocation plan is: taked the P0 mouth to connect data bus, be specifically designed to the transmission of chip chamber data; P2 mouth ground connection location bus, be specifically designed to and distribute the address, this connection greatly abbreviation classical P0 mouth connect the mode that 74LS373 latchs by ALE, circuit stability improves, but addressing range reduces, but the address realm that the P2 mouth is provided has fully satisfied our demand;

Distribute the address according to following three principles:

(1) choose the CH371 chip with P2.7, connect the GA Enable Pin of 74LS138 simultaneously: CH371 is selected during P2.7=0, and 74LS138 closes (be that CH371 carries out the USB communication, other equipment are all not selected); And CH371 is idle when P2.7=1, and 74LS138 just can choose other equipment; In other words, P2.7 has determined test macro to select one in CH371 and 74LS138 (being other chip).Such design has realized the control strategy of the priority functional module above all (slave computer) of USB communication (order of host computer);

The Y5 of (2) the 1st 74LS138～Y7 as with the interface of keyboard display chip communication, by the cooperation of LOAD, DIN, three data lines of DCLK, realize the communication of keyboard display chip and CPU;

(3) the P2 mouth works in dual mode, and a kind of is the read-write operation that common P2 mouth cooperates RD, WR; A kind of is to utilize the P2 mouth characteristics of the input/output port of depositing with lock at ordinary times own, realizes choosing for a long time the mode of operation of a slice chip.

Address assignment such as following table:

The address

8000H

8100-8105H

8200H

8300H

＜8000H

Chip

AD

Reserve

The frequency module high eight-bit

Low eight of frequency module

USB(CH371)

Accompanying drawing 2 is seen in the decoding scheme wiring.

In test macro, 8 pins of P1 mouth have also been sent important purposes, and are as shown in the table:

Keyboard interface in the keyboard-display circuit 5 is connected with the 4X4 keyboard, and real interface is connected by the real data line with real device.Its data terminal, address end and control end are received respectively on data bus, address bus and the control bus of line cpu control circuit 4.

Select CH451 keyboard display driver chip for use, it is a multifunction peripheral chip of having integrated charactron display driver and keyboard scan control and μ P monitoring.The built-in RC oscillatory circuit of CH451 can 8 charactrons of dynamic driving or 64 LED, have functions such as BCD decoding, flicker, displacement; Simultaneously can also carry out the keyboard scan of 64 keys; Serial line interface and the swap data such as single-chip microcomputer of CH451 by can cascade; And provide monitoring functions such as electrification reset and house dog.Fig. 3-14 connects block diagram for circuit, and single-chip microcomputer has 3 position datawires to be connected with 1 interrupt line with CH451:

CH451 and keyboard LED electrical equipment connection layout be as shown in figure 12:

Communicating circuit 6 is connected by data line with computing machine, and its data terminal, address end and control end are received respectively on data bus, address bus and the control bus of line programmable cpu control circuit 4, communicating circuit.

CH371 intelligence USB communication chip is selected in the USB communication for use.CH371 is the common interface chip of a usb bus.At local side, CH371 has 8 bit data bus and reading and writing, sheet select control line and interrupt output, can be articulated on the system bus of controllers such as single-chip microcomputer, DSP, MCU easily; In computer system, the software kit of CH371 provides succinct easy-to-use operation-interface, with the microcontroller communication of local side just as the file in the reading writing harddisk.CH371 has shielded the institute's protocols having in the USB communication, provides end-to-end being connected between computer utility layer and local side controller.Based on CH371, do not need to understand any usb protocol or firmware program even driver, just can realize the USB communication.Relation between single-chip microcomputer, CH371 interface chip, the computing machine such as Fig. 3-19.CH371 is connected with the data bus that passes through between the CPU, and by the address decoding gating, cooperates RD#, WR# to read, write data to CH371, and CPU, CH371 are connected as shown in figure 13 with usb bus.

Self calibration positive circuit 7 data terminals, address end and control end are received respectively on data bus, address bus and the control bus of line programmable cpu control circuit 4.The self check waveform output pin that AD7008 produces is connected with signal processing circuit 3 light current places in circuit 1.1 output interfaces, promptly directly is connected in voltage stabilizing and follows on the input pin of operational amplifier.Referring to Figure 14.

In equipment self-inspection, often need frequency, amplitude can both be by the self-regulating signal source of test macro.Adopt Direct Digital synthesis chip AD7008 and add the controllable signal source that D/A conversion chip AD7520 constitutes, can produce sine wave, frequency-modulated wave, amplitude modulation and involve square wave etc., and the frequency of its signal and amplitude can accurately be controlled by microcomputer, regulate very convenient.

The effect of power circuit 8 be for each module provide 5V and ± 12V power supply power supply; The input of power circuit 8 is connected with the 220V power supply, by rectification, filtering, amplitude limit, voltage stabilizing and overload protecting circuit, obtains normal voltage, by voltage bus, is connected with other 7 parts.

3. the realization of present embodiment analytical approach:

1) data acquisition: by system acquisition time series voltage, the time series frequency described in the claim 1, concrete acquisition method is as follows, sees accompanying drawing 17:

The 1st step: the acquisition time interval T is set by the keyboard in the keyboard-display circuit (5) _SampleWith continuous acquisition number of times t to voltage, frequency _Sample, put current times of collection t _Once=1, above-mentioned parameter is deposited among the RAM of cpu control circuit (4), cpu control circuit (4) is carried out the continuous acquisition subroutine;

The 2nd step: cpu control circuit (4) obtains the collection value OUT of current access signal voltage by A/D change-over circuit (3) _V, multiply by the actual value U (t that the step-down multiplying power draws current voltage _Once) leave among its RAM;

The 3rd step: cpu control circuit (4) obtains the collection value OUT of current access signal frequency by frequency measurement circuit (2) _F, calculate the actual value F (t of current voltage _Once) leave among its RAM;

The 4th step: current times of collection t _OnceFrom increasing 1, if t _Once≤ t _SampleThen repeated execution of steps 2,3, and 4;

The 5th step: gather and finish;

So produced in time the sequence magnitude of voltage (U (t), t) and the time series frequency values (F (t), t), wherein t is the sampling time, t=1,2 ..., t _Sample, t _SampleBe the final value that positive integer is represented the sampling time, U (t), F (t) represent t magnitude of voltage and frequency values constantly respectively;

2) data pre-service:

The 1st step: from the RAM of cpu control circuit 4, read continuous acquisition number of times t _Sample, put current calculation times t _Prc=6, calculate comparison and finish number of times t _Prcend=t _Sample-5, wherein with U (t _Sample) and F (t _Sample) number of magnitude of voltage of contrast is 5;

To (the U (t) that collected in the last step, t), (F (t), t) carry out correcting process, promptly the value deletion that obviously departs from adjacent data, the correction principle is: if t magnitude of voltage U (t) constantly with before or after 5 absolute values of the difference of magnitude of voltage mean values constantly, greater than t constantly before or after 5 mean values of absolute difference between the magnitude of voltage constantly, need to revise, promptly

$|U\left(t\right)-\frac{\underset{i=1}{\overset{5}{\mathrm{\&Sigma;}}}U(t-i)}{5}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}|U(t-i)-U(t-i-1)|}{4}---\left(1\right)$

Or

$|U\left(t\right)-\frac{\underset{i=1}{\overset{5}{\mathrm{\&Sigma;}}}U(t+i)}{5}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}|U(t+i)-U(t+i+1)|}{4}---\left(2\right)$

In the formula (1), t-i represents constantly before the t i constantly, the magnitude of voltage during U (t-i) expression sampling instant t-i then, and U (t) is a t magnitude of voltage constantly, the magnitude of voltage in U (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), U (t) is a t magnitude of voltage constantly, the magnitude of voltage when then U (t+i) represents sampling instant t+i, and U (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage U (t) constantly satisfies (1) formula or (2) formula, then be modified to:

$U\left(t\right)=\frac{U(t-1)+U(t+1)}{2};$ Wherein, U (t-1) is a t-1 magnitude of voltage constantly, and U (t+1) is a t+1 magnitude of voltage constantly;

The correction principle of frequency value F (t) is identical with the correction principle of U (t): if t frequency value F (t) constantly with before or after the absolute value of difference of n moment magnitude of voltage mean value, greater than t constantly before or after the mean value of absolute difference between n moment magnitude of voltage, need to revise, promptly

$|F\left(t\right)-\frac{\underset{i=1}{\overset{5}{\mathrm{\&Sigma;}}}F(t-i)}{5}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}|F(t-i)-F(t-i-1)|}{4}---\left(3\right)$

Or

$|F\left(t\right)-\frac{\underset{i=1}{\overset{5}{\mathrm{\&Sigma;}}}F(t+i)}{5}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{4}{\mathrm{\&Sigma;}}}|F(t+i)-F(t+i+1)|}{4}---\left(4\right)$

In the formula (3), t-i represents constantly before the t i constantly, the magnitude of voltage during F (t-i) expression sampling instant t-i then, and F (t) is a t magnitude of voltage constantly, the magnitude of voltage in F (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), F (t) is a t magnitude of voltage constantly, the magnitude of voltage when then F (t+i) represents sampling instant t+i, and F (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage F (t) constantly satisfies (3) formula or (4) formula, then be modified to:

$F\left(t\right)=\frac{F(t-1)+F(t+1)}{2};$ Wherein, F (t-1) is a t-1 magnitude of voltage constantly, and F (t+1) is a t+1 magnitude of voltage constantly;

The 2nd step: preceding calculation times t _PrcFrom increasing 1, if t _Prc≤ t _PrcendThen repeated execution of steps 1;

The 3rd step: the data pre-service is finished;

3) three line analysis and eigenvalue calculation:

The 1st step, the voltage-frequency curve match:

1) uses least square method the point in the U-F curve is fitted to a straight line, and calculate fitting parameter a, b and voltage-frequency eigenwert: voltage-frequency curve linearity α _Out, voltage-frequency compares K _OutWith voltage-frequency basic point V _50Hz

In order to represent conveniently U (t) to be designated as u _t, F (t) is designated as f _t, with t _SampleBe designated as n, concrete steps are as follows:

If the voltage-frequency linear function is f=au+b, wherein a, b are undetermined constants;

Note ε _t=f _t-(au _t+ b), it has reflected with straight line f=au+b and has described u=u _t, f=f _tThe time, calculated value f and actual value f _tThe deviation that produces; With Measure total departure;

Determine constant a and b among the f=au+b, make $F(a,b)=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="A20071011875200323.png,A20071011875200324.png"\; state="\{\{state\}\}">t</figure-callout>}}^2=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{(f_t-{\mathrm{au}}_t-b)}^2$ Be minimum;

Get by extremum principle $\frac{\&PartialD;F}{\&PartialD;a}=\frac{\&PartialD;F}{\&PartialD;b}=0,$ Promptly $\left\{\begin{array}{c}\frac{\&PartialD;F}{\&PartialD;a}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t(f_t-{\mathrm{au}}_t-b)=0\\ \frac{\&PartialD;F}{\&PartialD;b}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_t-{\mathrm{au}}_t-b)=0\end{array}\right.$

Separating these simultaneous equations gets $\left\{\begin{array}{c}a=\frac{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t{f}_t-\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t}{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u_t}^2-{\left(\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\right)}^2}\\ b=\frac{1}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t-\frac{a}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\end{array}\right.$

In the 2nd step, voltage, frequecy characteristic value are calculated:

Voltage-frequency compares K _Out=a: voltage-frequency is than the linear relationship that is used for representing voltage and frequency values;

The voltage-frequency curve linearity $L_{\mathrm{out}}=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_t^2:$ The voltage-frequency curve linearity is used for weighing point on the voltage-frequency curve and departs from the come out degree of straight line of match;

Voltage-frequency basic point V _50Hz=50a+b: the operating voltage when the voltage-frequency basic point is used for weighing frequency of operation 50Hz;

In the 3rd step, draw three curves:

Drawing voltage time is the U-t curve: with revised time series (U (t), t) each t and corresponding voltage value U (t) are plotted in the U-t coordinate system voltage time U-t curve that obtains constantly;

Draw frequency time F-t curve: with revised time series (F (t), t) each t and frequency value corresponding F (t) are plotted in the F-t coordinate system frequency time F-t curve that obtains constantly;

Draw electric voltage frequency U-F curve: with revised time series variable (U (t), t) and (F (t), t), the formation tlv triple (U (t), F (t), t), each constantly the U (t), two values of F (t) of t correspondence as the (U of a point, F) coordinate is plotted in the U-F coordinate system, obtains the U-F curve;

The 4th step, Performance Analysis:

According to three curves and three eigenwerts of the above-mentioned drafting of item, the slip-stick artist draws the requirement whether measured electric voltage frequency value satisfies engineering actual items index, and satisfaction degree.

Claims (5)

1. the electric voltage frequency measuring and analysis system is characterized in that: mainly include signal processing circuit (1), frequency measurement circuit (2), A/D change-over circuit (3), cpu control circuit (4), keyboard-display circuit (5) and power circuit (8); Wherein:

Signal processing circuit 1 includes light current place in circuit (1.1), forceful electric power place in circuit (1.2), reduction voltage circuit (1.3), voltage stabilizing follow circuit (1.4), TTL normalization circuit (1.5), peak holding circuit (1.6);

The input end of light current place in circuit (1.1) is one and is used for and 0～5V measured signal IN _LowThe analog signal interface that is connected, the output terminal of light current place in circuit (1.1) is connected with voltage stabilizing follow circuit 1.4;

The input end of forceful electric power place in circuit (1.2) is one and is used for and 5～300V measured signal IN _HighThe analog signal interface that is connected, the output of forceful electric power place in circuit (1.2) are connected on reduction voltage circuit (1.3) and are connected; 5～300V measured signal IN that reduction voltage circuit (1.3) is sent the forceful electric power place in circuit here _HighExport to voltage stabilizing follow circuit (1.4) after reducing to 0～5V light current measured signal according to the linear geometric ratio of step-down multiplying power;

The output signal IN of voltage stabilizing follow circuit (1.4) _StdEnd is connected with peak holding circuit (1.6) with TTL normalization circuit (1.5) respectively; TTL normalization circuit (1.5) becomes ac square wave with the output signal of voltage follower circuit (1.4), removes shake by the hysteresis comparator circuit again, by having obtained the TTL frequency measured signal IN of standard behind the stabilivolt _TTL, export to frequency measurement circuit (2); The maximal value that the output signal voltage of voltage follower circuit (1.6) appearred in peak holding circuit (1.6) is with the signal IN of dc constant voltage _PeakExport to A/D change-over circuit (3);

The output terminal of frequency measurement circuit (2) is connected with cpu control circuit (4) by data bus, address bus and control bus, frequency measurement circuit (2) is measured the frequency values of TTL reference waveform, and the frequency values that records outputed to cpu control circuit (4) with the form of digital quantity, deliver to display circuit (5) simultaneously and show;

The input of A/D change-over circuit (3) is connected with the output terminal of signal processing circuit (1) voltage peak circuit (1.6), and output terminal is connected with cpu control circuit (4) with control bus by data bus, address bus; The magnitude of voltage that A/D change-over circuit (3) is exported voltage peak circuit (1.6) converts digital quantity to and outputs to cpu control circuit (4), delivers to display circuit (5) simultaneously and shows;

Cpu control circuit (4) is connected the frequency values that the receive frequency metering circuit records with the output terminal of frequency measurement circuit (2); Cpu control circuit (4) is connected with A/D change-over circuit (3), receives the magnitude of voltage of the digital quantity after changing; If forceful electric power signal, magnitude of voltage and the step-down multiplying power of cpu control circuit (4) after according to the step-down of reduction voltage circuit (1.3), calculate actual magnitude of voltage, and among the RAM of storage cpu control circuit (4), and the display part of delivering in the keyboard-display circuit (5) shows;

Keyboard-display circuit (5) is connected with cpu control circuit (4) by data bus, address bus and control bus, and the display part in the keyboard-display circuit (5) is used for the result of display frequency metering circuit (2) and the real-time conversion of A/D change-over circuit (3); Keyboard in the keyboard-display circuit (5) is connected with cpu control circuit (4) by the keyboard display control chip;

Power circuit (8) provides power supply for above each circuit.

2. according to the electric voltage frequency measuring and analysis system described in the claim 1, it is characterized in that: also be provided with the communicating circuit (6) that is used for upper machine communication, communicating circuit (6) is connected with cpu control circuit (4).

3. according to the electric voltage frequency measuring and analysis system described in the claim 1, it is characterized in that: also be provided with self calibration positive circuit (7), the data terminal of self calibration positive circuit (7), address end and control end are received respectively on data bus, address bus and the control bus of cpu control circuit (4), and self calibration positive circuit (7) output terminal is connected with signal processing circuit (3) light current place in circuit (1.1) interface; Cpu control circuit (4) formation voltage, frequency signal input to self calibration positive circuit (7) and produce the self check waveform by self calibration positive circuit (7), the self check waveform inputs to light current place in circuit (1.1), and cpu controller compares to judge self check voltage, the frequency of voltage, frequency measurement and its generation that light current place in circuit (1.1) collects whether system is normal.

4. according to the electric voltage frequency measuring and analysis system described in the claim 1, it is characterized in that: described frequency measurement circuit (2) comprises that the counter group of the series connection of two relays, 4 74F161 register formations, 1 74F161 register are as logic controller and 2 74LS245 bus transceivers, four each registers of counter have 4 outputs, 8 outputs of per two registers are connected in the input of bus transceiver 74LS245, and the output of bus transceiver 74LS245 is connected with cpu control circuit (4) by data bus, address bus and control bus;

Often the opening of first relay, the frequency that normal-closed end connects high frequency are respectively treated side signal IN _TTLOutput pin IN with the known standard crystal oscillator _Cry, public output terminal is connected on the counting input end of first counter in the counter chip group; Often the opening of second relay, the CPU pin IN that normal-closed end is practiced midwifery living timing pip respectively _TimerTreat side signal IN with the frequency of low frequency _TTLBe connected, the Enable Pin of four counting chips is received in public output, and often the opening of first relay and second relay, normally closed switching controls end link to each other with cpu control circuit (4) control bus and fetch two relay normally opens of control, normally closed switching;

CLK end as the 74F161 counter of logic controller meets low frequency signal IN all the time _TTL, its CLR end links to each other by an anti-door with its 2nd counting output P1, the latching circuit that realization only allows the one-period waveform to pass through, and reset signal CLR links to each other for control end by control bus and CPU's.

5. utilize the described electric voltage frequency measuring and analysis system of claim 1, acquisition time sequence voltage, time series frequency and analytical approach thereof is characterized in that: mainly include data acquisition, data pre-service, three line analysises and the analysis of voltage-frequency eigenvalue calculation;

1) data acquisition: by system acquisition time series voltage, the time series frequency described in the claim 1, concrete acquisition method is as follows:

The 1st step: the acquisition time interval T is set by the keyboard in the keyboard-display circuit (5) _SampleWith continuous acquisition number of times t to voltage, frequency _Sample, put current times of collection t _Once=1, above-mentioned parameter is deposited among the RAM of cpu control circuit (4), cpu control circuit (4) is carried out the continuous acquisition subroutine;

The 2nd step: cpu control circuit (4) obtains the collection value OUT of current access signal voltage by A/D change-over circuit (3) _VLeave among the RAM of cpu controller;

The 3rd step: cpu control circuit (4) obtains the collection value OUT of current access signal frequency by frequency measurement circuit (2) _FLeave among the RAM of cpu controller;

The 4th step: current times of collection t _OnceFrom increasing 1, if t _Once≤ t _SampleThen repeated execution of steps 2,3, and 4;

The 5th step: gather and finish;

So produced the time series magnitude of voltage (U (t), t) and the time series frequency values (F (t), t), wherein t is the sampling time, t=1,2 ..., t _Sample, t _SampleBe positive integer, the final value in expression sampling time, U (t), F (t) represent t magnitude of voltage and frequency values constantly respectively;

2) data pre-service:

The 1st step: from the RAM of cpu control circuit (4), read continuous acquisition number of times t _Sample, put current calculation times t _Prc=n+1 calculates comparison and finishes number of times t _Prcend=t _Sample-n, wherein n is and U (t _Sample) and F (t _Sample) number of magnitude of voltage of contrast, the span of n is generally 3≤n≤10;

To (the U (t) that collected in the last step, t), (F (t), t) carry out correcting process, promptly the value deletion that obviously departs from adjacent data, the correction principle is: if t magnitude of voltage U (t) constantly with before or after the absolute value of difference of n moment magnitude of voltage mean value, greater than t constantly before or after n the mean value of absolute difference between the magnitude of voltage constantly, need correction, promptly

$|U\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}U(t-i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|U(t-i)-U(t-i-1)|}{n-1}---\left(1\right)$

Or

$|U\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}U(t+i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|U(t+i)-U(t+i+1)|}{n-1}---\left(2\right)$

In the formula (1), t-i represents constantly before the t i constantly, the magnitude of voltage during U (t-i) expression sampling instant t-i then, and U (t) is a t magnitude of voltage constantly, the magnitude of voltage in U (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), U (t) is a t magnitude of voltage constantly, the magnitude of voltage when then U (t+i) represents sampling instant t+i, and U (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage U (t) constantly satisfies (1) formula or (2) formula, then be modified to:

$U\left(t\right)=\frac{U(t-1)+U(t+1)}{2};$ Wherein, U (t-1) is a t-1 magnitude of voltage constantly, and U (t+1) is a t+1 magnitude of voltage constantly;

The correction principle of frequency value F (t) is identical with the correction principle of U (t): if t frequency value F (t) constantly with before or after the absolute value of difference of n moment magnitude of voltage mean value, greater than t constantly before or after the mean value of absolute difference between n moment magnitude of voltage, need to revise, promptly

$|F\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}F(t-i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|F(t-i)-F(t-i-1)|}{n-1}---\left(3\right)$

Or

$|F\left(t\right)-\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}F(t+i)}{n}|\&times;\mathrm{\&alpha;}>\frac{\underset{i=1}{\overset{n-1}{\mathrm{\&Sigma;}}}|F(t+i)-F(t+i+1)|}{n-1}---\left(4\right)$

In the formula (3), t-i represents constantly before the t i constantly, the magnitude of voltage during F (t-i) expression sampling instant t-i then, and F (t) is a t magnitude of voltage constantly, the magnitude of voltage in F (t-i-1) the expression t-i-1 moment; α defines intensity, and span is 0%～100%;

In the formula (2), F (t) is a t magnitude of voltage constantly, the magnitude of voltage when then F (t+i) represents sampling instant t+i, and F (t+i+1) expression t+i+1 magnitude of voltage constantly, α defines intensity, and span is 0%～100%;

If t magnitude of voltage F (t) constantly satisfies (3) formula or (4) formula, then be modified to:

$F\left(t\right)=\frac{F(t-1)+F(t+1)}{2};$ Wherein, F (t-1) is a t-1 magnitude of voltage constantly, and F (t+1) is a t+1 magnitude of voltage constantly;

The 2nd step: preceding calculation times t _PrcFrom increasing 1, if t _Prc≤ t _PrcendThen repeated execution of steps 1;

The 3rd step: the data pre-service is finished;

3) three line analysis and eigenvalue calculation:

The 1st step, the voltage-frequency curve match:

1) uses least square method the point in the U-F curve is fitted to a straight line, and calculate fitting parameter a, b and voltage-frequency eigenwert: voltage-frequency curve linearity α _Out, voltage-frequency compares K _OutWith voltage-frequency basic point V _50Hz

In order to represent conveniently U (t) to be designated as u _t, F (t) is designated as f _t, with t _SampleBe designated as n, concrete steps are as follows:

If the voltage-frequency linear function is f=au+b, wherein a, b are undetermined constants;

Note ε _t=f _t-(au _t+ b), it has reflected with straight line f=au+b and has described u=u _t, f=f _tThe time, calculated value f and actual value f _tThe deviation that produces; With Measure total departure;

Determine the constant among the f=au+b

With

Make $F(a,b)=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_t^2=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_t-{\mathrm{au}}_t-b{)}^2$ Be minimum;

Get by extremum principle $\frac{\&PartialD;F}{\&PartialD;a}=\frac{\&PartialD;F}{\&PartialD;b}=0,$ Promptly

$\left\{\begin{array}{c}\frac{\&PartialD;F}{\&PartialD;a}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t(f_t-{\mathrm{au}}_t-b)=0\\ \frac{\&PartialD;F}{\&PartialD;b}=-2\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_t-{\mathrm{au}}_t-b)=0\end{array}\right.$

Separating these simultaneous equations gets

$\left\{\begin{array}{c}a=\frac{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t{f}_t-\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t}{n\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t^2-{\left(\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\right)}^2}\\ b=\frac{1}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{f}_t-\frac{a}{n}\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{u}_t\end{array}\right.$

In the 2nd step, voltage, frequecy characteristic value are calculated:

Voltage-frequency compares K _Out=a: voltage-frequency is than the linear relationship that is used for representing voltage and frequency values;

The voltage-frequency curve linearity $L_{\mathrm{out}}=\underset{t=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&epsiv;}}_t^2:$ The voltage-frequency curve linearity is used for weighing point on the voltage-frequency curve and departs from the come out degree of straight line of match;

Voltage-frequency basic point V _50Hz=50a+b: the operating voltage when the voltage-frequency basic point is used for weighing frequency of operation 50Hz;

In the 3rd step, draw three curves:

Drawing voltage time is the U-t curve: with revised time series (U (t), t) each t and corresponding voltage value U (t) are plotted in the U-t coordinate system voltage time U-t curve that obtains constantly;

Draw frequency time F-t curve: with revised time series (F (t), t) each t and frequency value corresponding F (t) are plotted in the F-t coordinate system frequency time F-t curve that obtains constantly;

Draw electric voltage frequency U-F curve: with revised time series variable (U (t), t) and (F (t), t), the formation tlv triple (U (t), F (t), t), each constantly the U (t), two values of F (t) of t correspondence as the (U of a point, F) coordinate is plotted in the U-F coordinate system, obtains the U-F curve.

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