CN101076053A - Method and circuit for multi-channel photoelectric isolated voltage - Google Patents

Abstract

The method comprises: in the first, according to the detected voltage reference signal point the measurement range is divided into several linear segments; measuring out the A/D value of the inputted voltage signals after passing through the linear photoelectric coupled circuit, and estimating the linear segment where the A/D value belongs; taking the voltage reference value at the both ends of said linear segment as an interpolation, and using a linear interpolation algorithm to convert the A/D value of the voltage signals to an accurate signal voltage value. The measuring circuit comprises an analog channel switching circuit, a linear photoelectric coupled circuit, a multi-segment voltage reference generating circuit, an A/D converter and a MPU.

Description

A kind of method of measurement and circuit thereof of multichannel photoelectricity isolation voltage

[technical field]

The present invention relates to the fields of measurement of telecommunications watch-dog, particularly a kind of method of measurement and circuit thereof of multichannel photoelectricity isolation voltage.

[background technology]

Existing linear photoconductor coupling measurement circuit has the following shortcoming that is not easy to overcome:

(1) only can in the particular measurement scope, keep higher measure linear degree, bigger deviation from linearity appears in complete some interval meeting of measuring in the range, this deviation from linearity can use specific compensating circuit to be remedied, but compensating circuit is comparatively complicated, need high-precision electric capacity resistance device, cost is higher, and debugging difficulty is bigger, if in addition software is not proofreaied and correct, fundamentally this shortcoming is difficult to eliminate.

(2) have intrinsic static measurement error (as the zero migration error) in the existing linear photoconductor coupling measurement circuit path; And existing linear photoconductor coupling measurement circuit is under the varying environment temperature conditions, and the measurement characteristics curve also can have greatly changed, need be in surveying work corrective action in addition in real time.

(3) existing linear photoconductor coupling measurement circuit is because of the otherness of optocoupler, and bigger difference will take place measured value, need to proofread and correct, but hardware corrected measure cost is higher, workload is bigger.

[summary of the invention]

The technical problem to be solved in the present invention provides a kind of method of measurement and circuit thereof of simple in structure, a kind of multichannel photoelectricity isolation voltage that can accurately measure signal voltage value.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is: a kind of method of measurement of multichannel photoelectricity isolation voltage, comprise the steps,

101, name a person for a particular job according to the voltage reference signal that measures and measure range and be divided into linear segments;

102, measure the A/D value of input voltage signal, judge the linear segments that this A/D value is affiliated by linear photoelectric coupled circuit;

103, with the both end voltage fiducial value of the linear segments under this as interpolation, use linear interpolation algorithm that the A/D value of input voltage signal is converted to signal voltage value accurately.

Wherein, described step 101 also comprises, measures the A/D value of described voltage reference signal by linear photoelectric coupled circuit, and corresponding to accurate known voltage fiducial value.

Wherein, the computing formula of linear interpolation algorithm described in the step 103 is,

${\mathrm{val}}_{\left(n\right)}={\mathrm{REF}}_{\left(n\right)}-\frac{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_{\mathrm{ai}}_{\left(n\right)})}{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_r_{(n+1)})}\×({\mathrm{REF}}_{\left(n\right)}-{\mathrm{REF}}_{(n+1)})$

Ad_r wherein _(n)≤ ad_ai _(n)≤ ad_r _(n), val _(n)Be the signal voltage value of conversion, REF _(n)Be the end-point voltage fiducial value of linear segments, ad_r _(n)Be the A/D value of voltage reference signal, ad_ai _(n)A/D value for input voltage signal.

Wherein, described reference signal point is described voltage reference signal A/D value and the corresponding points of voltage reference value in rectangular coordinate system.

A kind of multichannel photoelectricity isolation voltage measuring circuit comprises,

The analog channel commutation circuit, it selects multichannel input voltage signal and voltage reference signal to send into the input port of linear photoelectric coupled circuit;

Multi-segment voltage benchmark generation circuit, it provides the measuring basis of dividing linear segments;

Analog to digital converter, it will be converted to digital signal through the voltage signal of linear photoelectric coupled circuit, handle for microprocessor;

Microprocessor, its control analog channel commutation circuit, the signal of linear photoelectric coupled circuit is sent in selection, and the control analog to digital converter is converted to digital quantity with the voltage signal of linear photoelectric coupled circuit output, by linear interpolation algorithm this digital quantity is converted to signal voltage value.

Wherein, also comprise linear photoelectric coupled circuit, it is realized measured input voltage signal and measures the linear isolation of internal circuit photoelectricity;

Wherein, described linear interpolation algorithm solidifies in described microprocessor, and its computing formula is,

${\mathrm{val}}_{\left(n\right)}={\mathrm{REF}}_{\left(n\right)}-\frac{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_{\mathrm{ai}}_{\left(n\right)})}{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_r_{(n+1)})}\×({\mathrm{REF}}_{\left(n\right)}-{\mathrm{REF}}_{(n+1)})$

Ad_r wherein _(n)≤ ad_ai _(n)≤ ad_r _(n), val _(n)Be the signal voltage value of conversion, REF _(n)Be the end-point voltage fiducial value of linear segments, ad_r _(n)Be the A/D value of voltage reference signal, ad_ai _(n)A/D value for input voltage signal.

Adopt multichannel photoelectricity isolation voltage method of measurement of the present invention, utilize reference voltage signal point to form linear segments, utilize the two-end-point fiducial value of linear segments to adopt linear interpolation algorithm that the A/D value that measures is changed, make this method of measurement measurement voltage signal under the different measuring scope all have good measure linear precision, eliminate the intrinsic measured deviation of linear photoelectric coupled circuit; And with this photoelectricity isolation voltage measuring circuit, it is simple in structure, cost is also lower, has saved the offset peripheral circuit of complicated precision.

[description of drawings]

Fig. 1 is the schematic flow sheet of multichannel photoelectricity isolation voltage method of measurement of the present invention.

Fig. 2 is the matched curve and actual linear photoconductor coupling input-output characteristic curve schematic diagram that is formed by linear segments among the present invention.

Fig. 3 is a multichannel photoelectricity isolation voltage measuring circuit module map of the present invention.

Fig. 4 is the circuit diagram of linear photoelectric coupled circuit of the present invention.

Fig. 5 is the circuit diagram of analog channel commutation circuit of the present invention.

Fig. 6 is the circuit diagram of voltage reference generation circuit of the present invention.

[embodiment]

With specific embodiment the present invention is done to set forth further with reference to the accompanying drawings below.

Fig. 1 is the schematic flow sheet of multichannel photoelectricity isolation voltage method of measurement of the present invention, at first the analog channel commutation circuit switches to benchmark passage P_AREF, measure voltage reference signal P_AREF this moment successively, P_CHK1, P_CHK2, P_CHK3, P_CHK4, GND_DEV_AI is by the A/D value ad_r1 of linear photoelectric coupled circuit, ad_r2, ad_r3, ad_r4, ad_r5, ad_r6, it is corresponding to accurate known voltage fiducial value REF1, REF2, REF3, REF4, REF5, REF6, to measure range and be divided into 5 sections linear segments (A1), (A2), (A3), (A4), (A5), form matched curve linear interpolation table as shown in Figure 2, A/D value and voltage reference value be the corresponding reference signal point of forming in rectangular coordinate system, with linear segments (A1), (A2), (A3), (A4), (A5) can match reality the input-output characteristic curve of linear photoelectric coupled circuit.

Simulation switching phone switches to the measurement passage then, measure the A/D value ad_ai (n) of input voltage signal AI (n) again by linear photoelectric coupled circuit, judge which linear segments ad_ai (n) drops in (An), two ends fiducial value REF (n) with linear segments (An), REF (n+1) is as the fiducial value of interpolation calculation, use linear interpolation algorithm, ad_ai (n) value is converted to signal voltage value val (n) accurately, can calculate actual signal voltage value according to the matched curve table, the computing formula of linear interpolation algorithm is:

${\mathrm{val}}_{\left(n\right)}={\mathrm{REF}}_{\left(n\right)}-\frac{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_{\mathrm{ai}}_{\left(n\right)})}{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_r_{(n+1)})}\×({\mathrm{REF}}_{\left(n\right)}-{\mathrm{REF}}_{(n+1)})$

Wherein, ad_r _(n)≤ ad_ai _(n)≤ ad_r _(n)

It only is 6 that certain voltage reference signal is not limited to, and its many more signal voltage values that calculate at last are accurate more.

Corresponding multichannel photoelectricity isolation voltage measuring circuit as shown in Figure 3, it comprises,

A plurality of measured voltage signals 1, its from AI0 to AI15, (can increase and decrease the segmentation number) according to application need;

Multi-segment voltage benchmark generation circuit 2, it provides the measuring basis of dividing linear segments;

Analog channel commutation circuit (MUX) 3, it selects multichannel input voltage signal and voltage reference signal to send into the input port of linear photoelectric coupled circuit;

Linear photoelectric coupled circuit 4, it is realized measured input voltage signal and measures the linear isolation of internal circuit photoelectricity;

Analog to digital converter application circuit (A/D) 5, it will be converted to digital signal through the voltage signal AIN_E1 of linear photoelectric coupled circuit transmission, handle for the microprocessor (MCU) in the watch-dog, calculate actual voltage signal measured value.

It will be converted to digital signal through the voltage signal of linear photoelectric coupled circuit, handle for microprocessor;

Microprocessor (MCU) 6, the core control and the calculating unit of whole measuring circuit, its control analog channel commutation circuit, the signal of linear photoelectric coupled circuit is sent in selection, and control analog to digital converter (A/D) is converted to digital quantity with the voltage signal AIN_E1 of linear photoelectric coupled circuit output, by running on the linear interpolation algorithm that solidifies in inside, the converted measurement value is finished final measured value calculation task.

Wherein, the analog channel commutation circuit as shown in Figure 5, it mainly acts on is to select plurality of voltages input signal P_AI_MUX and voltage reference signal P_AREF, P_CHK1, P_CHK2, P_CHK3, P_CHK4, GND_DEV_AI to send into linear photoelectric coupled circuit input port P_AI_MUX.For preventing that interference signal from entering microprocessor (MCU), used optocoupler U2, U6, U8, U9, U12, U13 to isolate between control signal SEL_A, SEL_B, SEL_C, SEL_MUX1, SEL_MUX2, SEL_MUX3 and multiway analog switch U3, U7, the U11.

Multi-segment voltage benchmark generation circuit as shown in Figure 4, this partial circuit provides measuring basis for dividing linear segments formation matched curve, it is made of high-accuracy voltage parametric device U10 and precision resistance network, the measuring basis signal P_AREF of linear segments segmentation, P_CHK1, P_CHK2, P_CHK3, P_CHK4, GND_DEV_AI will measure range and be divided into 5 sections, the input port P_AI_MUX that process analog channel commutation circuit is sent into linear photoelectric coupled circuit sends into analog to digital converter (A/D) through the output port AIN_E1 of linear photoelectric coupled circuit.

Linear linear photoelectric coupled circuit as shown in Figure 6, this partial circuit is to realize measured signal and measure the linear Key Circuit of isolating of internal circuit photoelectricity, and it is to constitute linear photoelectric coupled circuit by linear optical coupling device U5, amplifier U1B, U4B and resistance, capacitor element; Amplifier U1A, the effect of U4A is to constitute the impedance influences that the positive follow circuit is eliminated input, output.

In sum, adopt multichannel photoelectricity isolation voltage method of measurement of the present invention, utilize reference voltage signal point to form linear segments, utilize the two-end-point fiducial value of linear segments to adopt linear interpolation algorithm that the A/D value that measures is changed, make this method of measurement measurement voltage signal under the different measuring scope all have good measure linear precision, eliminate the intrinsic measured deviation of linear photoelectric coupled circuit; And with this photoelectricity isolation voltage measuring circuit, it is simple in structure, cost is also lower, has saved the offset peripheral circuit of complicated precision.

Claims (7)

1, a kind of method of measurement of multichannel photoelectricity isolation voltage is characterized in that: may further comprise the steps,

101, name a person for a particular job according to the voltage reference signal that measures and measure range and be divided into some linear segments;

102, measure the A/D value of input voltage signal, judge the linear segments that this A/D value is affiliated by linear photoelectric coupled circuit;

103, with the both end voltage fiducial value of the linear segments under this as interpolation, use linear interpolation algorithm that the A/D value of input voltage signal is converted to signal voltage value accurately.

2, the method for measurement of multichannel photoelectricity isolation voltage according to claim 1, it is characterized in that: described step 101 also comprises, measure the A/D value of described voltage reference signal by linear photoelectric coupled circuit, and corresponding to accurate known voltage fiducial value.

3, the method for measurement of multichannel photoelectricity isolation voltage according to claim 1 and 2 is characterized in that: the computing formula of linear interpolation algorithm described in the step 103 is,

${\mathrm{val}}_{\left(n\right)}={\mathrm{REF}}_{\left(n\right)}-\frac{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_{\mathrm{ai}}_{\left(n\right)})}{(\mathrm{ad}\_r_n-\mathrm{ad}\_r_{(n+1)})}\×({\mathrm{REF}}_{\left(n\right)}-{\mathrm{REF}}_{(n+1)})$

Ad_r wherein _(n)≤ ad_ai _(n)≤ ad_r _(n+1), val _(n)Be the signal voltage value of conversion, REF _(n)Be the end-point voltage fiducial value of linear segments, ad_r _(n)Be the A/D value of voltage reference signal, ad_ai _(n)A/D value for input voltage signal.

4, according to the method for measurement of each described multichannel photoelectricity isolation voltage of claim 1 to 3, it is characterized in that: described reference signal point is described voltage reference signal A/D value and the corresponding points of voltage reference value in rectangular coordinate system.

5, a kind of measuring circuit of multichannel photoelectricity isolation voltage is characterized in that: comprises,

The analog channel commutation circuit, it selects multichannel input voltage signal and voltage reference signal to send into the input port of linear photoelectric coupled circuit;

Multi-segment voltage benchmark generation circuit, it provides the measuring basis of dividing linear segments;

Analog to digital converter, it will be converted to digital signal through the voltage signal of linear photoelectric coupled circuit, handle for microprocessor;

Microprocessor, its control analog channel commutation circuit, the signal of linear photoelectric coupled circuit is sent in selection, and the control analog to digital converter is converted to digital quantity with the voltage signal of linear photoelectric coupled circuit output, by linear interpolation algorithm this digital quantity is converted to signal voltage value.

6, the measuring circuit of multichannel photoelectricity isolation voltage according to claim 5 is characterized in that: also comprise linear photoelectric coupled circuit, it is realized measured input voltage signal and measures the linear isolation of internal circuit photoelectricity;

7, according to the measuring circuit of claim 5 or 6 described multichannel photoelectricity isolation voltages, it is characterized in that: described linear interpolation algorithm solidifies in described microprocessor, and its computing formula is,

${\mathrm{val}}_{\left(n\right)}={\mathrm{REF}}_{\left(n\right)}-\frac{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_{\mathrm{ai}}_{\left(n\right)})}{(\mathrm{ad}\_r_{\left(n\right)}-\mathrm{ad}\_r_{(n+1)})}\×({\mathrm{REF}}_{\left(n\right)}-{\mathrm{REF}}_{(n+1)})$

Ad_r wherein _(n)≤ ad_ai _(n)≤ ad_r _(n), val _(n)Be the signal voltage value of conversion, REF _(n)Be the end-point voltage fiducial value of linear segments, ad_r _(n)Be the A/D value of voltage reference signal, ad_ai _(n)A/D value for input voltage signal.

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