CN101609116B - New method for detecting input phase failure - Google Patents

Abstract

The invention relates to a new method for detecting input phase failure, specifically comprising steps as follows: reducing the voltage of line voltage by using a line voltage detecting circuit, and sending the line voltage to an AD port for sampling after the line voltage passes through a signal conditioning circuit, obtaining a maximal value and a minimal value of the line voltage by comparison, taking the average value, and then obtaining line voltage bias; subtracting the line voltage bias from the line voltage sampled by the AD, and obtaining a line voltage momentary value according to an AD conversion formula and a linear relation of a line voltage sampling circuit; obtaining phase voltage momentary values of three phases from the line voltage momentary value according to a formula for converting the line voltage into phase voltage; and sampling phase voltage cycle to obtain the maximal value of the phase voltage three phases, sorting the phase voltage momentary values according to the greatness of the values; and judging the phase failure exists at an input end when the imbalance degree of the three phases exceeds a set threshold value. The method can directly detect input phase voltage and judges the existence of the phase failure; the method can detect the phase of the input voltage, which cannot be achieved by a traditional phase failure detecting method; and the method is reliable in application and can accurately detect whether the phase failure exists in a three-phase power supply.

Description

A kind of new detection method of phase shortage of importing

Technical field

The present invention relates to the three-phase consumer, particularly relate to a kind of lack detection circuit and detection method thereof of three-phase consumer.

Background technology

In the three-phase alternating current source power supply system,, and think phase shortage has taken place if wherein one when disconnecting mutually owing to fuse or the fault of air switch.Charge to electric capacity through rectification and through thereafter buffer resistance when three-phase electricity, when phase shortage not taking place, in a power frequency period, 6 wave heads will be arranged; And when open-phase fault takes place, have only 2 voltage wave heads in the power frequency period, and electric capacity will charge repeatedly on a large scale, and this situation is unallowed.

At present the phase shortage detection method generally is that ripple situation according to capacitive side voltage after the rectification judges whether phase shortage, and is bigger but this method is influenced by power network fluctuation, reduced reliability.

Summary of the invention

Technical matters to be solved by this invention is: a kind of economy, reliable and practical input phase shortage detection method are provided, and this method can be judged whether phase shortage of three-phase alternating current source power supply system in a kind of mode more intuitively.

The present invention solves its technical matters and adopts following technical scheme:

The new detection method of input phase shortage provided by the invention, it adopts the method that may further comprise the steps:

(1) step-down of line voltage warp voltage detecting circuit is handled, and send the sampling of AD mouth behind signal conditioning circuit, by relatively obtaining line voltage max and minimum value, gets its mean value, obtains the line voltage bias;

(2) the line voltage that is sampled by AD deducts the line voltage bias, and obtains the line instantaneous voltage by AD conversion formula and line voltage sampling circuit linear relationship;

(3) by the line instantaneous voltage, be converted into the phase voltage formula according to line voltage, obtain the three-phase phase voltage instantaneous value;

(4) sampling phase voltage cycle obtains the three-phase phase voltage maximal value, and carries out the size ordering, when tri-phase unbalance factor surpasses the threshold values of setting, then judges the input side phase shortage.

The new detection method of input phase shortage provided by the invention, it is judging during the three-phase alternating current source power supply system is to the load equipment power supply process the whether application of phase shortage.

The present invention compares with traditional phase shortage detection method has following major advantage:

One. can directly detect the input phase voltage, obtain phase voltage, directly judge phase shortage by line voltage, more directly perceived.

They are two years old. and can detect input voltage phase, this is that traditional phase shortage detection method is out of the question.

They are three years old. and testing circuit is simple, realize to be very easy in the system of digital signal processor spare is arranged, and to use reliably, can correctly detect whether phase shortage of input three-phase supply.

Description of drawings

Fig. 1 is the schematic diagram of line voltage uab testing circuit.

Fig. 2 is the schematic diagram of signal uab modulate circuit.

Embodiment

The invention will be further described below in conjunction with embodiment.

The new detection method of input phase shortage provided by the invention, it adopts the method that may further comprise the steps:

(1) step-down of line voltage warp voltage detecting circuit is handled, and send the sampling of AD mouth behind signal conditioning circuit, by relatively obtaining line voltage max and minimum value, gets its mean value, obtains the line voltage bias.

(2) the line voltage that is sampled by AD deducts the line voltage bias, and obtains the line instantaneous voltage by AD conversion formula and line voltage sampling circuit linear relationship.

(3) by the line instantaneous voltage, be converted into the phase voltage formula according to line voltage, obtain the three-phase phase voltage instantaneous value.

Described line voltage is converted into the phase voltage formula:

$\left\{\begin{array}{c}\mathrm{ua}=\frac{2\mathrm{uab}+\mathrm{ubc}}{3}\\ \mathrm{ub}=\frac{\mathrm{ubc}-\mathrm{uab}}{3}\\ \mathrm{uc}=-\frac{\mathrm{uab}+2\mathrm{ubc}}{3}\end{array}\right.$

In the formula: if

$\left\{\begin{array}{c}\mathrm{ua}=\sqrt{2}U\sin \left(\mathrm{\ωt}\right)\\ \mathrm{ub}=\sqrt{2}U\sin (\mathrm{\ωt}-\frac{2\mathrm{\π}}{3})\\ \mathrm{uc}=\sqrt{2}U\sin (\mathrm{\ωt}+\frac{2\mathrm{\π}}{3})\end{array}\right.$

Then

$\left\{\begin{array}{c}\mathrm{uab}=\sqrt{6}U\sin (\mathrm{\ωt}+\frac{\mathrm{\π}}{6})\\ \mathrm{ubc}=\sqrt{6}U\sin (\mathrm{\ωt}-\frac{\mathrm{\π}}{2})\end{array}\right.$

In the above-mentioned formula: ua, ub and uc uc are respectively a, b and c three-phase phase voltage, and uab is a and b phase line voltage, and ubc is b and c phase line voltage, and U is the effective value of three-phase alternating voltage phase voltage, and ω is the angular velocity of alternating voltage, and t is the time.

(4) sampling phase voltage cycle obtains the three-phase phase voltage maximal value, and carries out the size ordering, when tri-phase unbalance factor surpasses the threshold values of setting, then judges the input side phase shortage.

The new detection method of input phase shortage provided by the invention, it is used to judge whether phase shortage of three-phase AC electrical supply system.

For example, the frequency conversion speed-adjusting system that is used to judge TMS320F2812 DSP control phase shortage whether.Its step comprises:

(1) in a line voltage cycle, sample uab_AD, ubc_AD, and ordering reservation maximal value and minimum value to sampling, promptly obtain maximal value and minimum value in the line voltage cycle, ask for the mean value of maximal value and minimum value, thereby ask for the input line voltage biasing.

(2) value that DSP is sampled deducts input line voltage biasing, obtains uab and ubc value uab_DSP, the ubc_DSP in DSP, have just have negative,

And according to DSP AD formula, 3V correspondence 2 in the system ¹²-1 promptly $\frac{{\mathrm{uab}}^{\′}}{\mathrm{uab}\_\mathrm{DSP}}=\frac{3}{2^{12}-1}$ Ask for the analog voltage uab ' after input line voltage uab step-down is handled among Fig. 2;

In like manner can ask for the analog voltage of ubc '.

(3) by ${\mathrm{uab}}^{\′}=\frac{R2}{R1+R2}\mathrm{uab},$ Ask for line instantaneous voltage uab, in like manner ask for ubc;

(4) by the line instantaneous voltage, be converted into the phase voltage formula according to line voltage, obtain the three-phase phase voltage instantaneous value;

(5) in a phase voltage cycle, ask for the maximal value of three-phase phase voltage respectively, and ordering, when tri-phase unbalance factor surpasses the setting threshold values, judge its input side phase shortage.

Line voltage detecting circuit and signal conditioning circuit that the present invention adopts are prior art, and their circuit theory diagrams are respectively Fig. 1 and Fig. 2.Its hardware signal processing procedure is as follows:

Line voltage uab handles through line voltage detecting circuit step-down shown in Figure 1, that is:

${\mathrm{uab}}^{\′}=\frac{R2}{R1+R2}\mathrm{uab},$ As R1=3M Ω, during R2=10K Ω, $K=\frac{R2}{R1+R2}=\frac{1}{300},$ Through circuit shown in Figure 2 voltage signal is promoted again and be converted into the voltage range that DSP can accept, at this moment, $\mathrm{uab}\_\mathrm{AD}=\frac{{\mathrm{uab}}^{\′}+U}{2};$ In like manner also can obtain ubc_AD, uab_AD, ubc_AD;

To promote then when voltage signal after transforming send the DSPAD cause for gossip and detect.

Claims (4)

1. import the new detection method of phase shortage for one kind, it is characterized in that adopting the method that may further comprise the steps:

(1) step-down of line voltage warp voltage detecting circuit is handled, and send the sampling of AD mouth behind signal conditioning circuit, by relatively obtaining line voltage max and minimum value, gets its mean value, obtains the line voltage bias;

(2) the line voltage that is sampled by AD deducts the line voltage bias, and obtains the line instantaneous voltage by AD conversion formula and line voltage sampling circuit linear relationship;

(3) by the line instantaneous voltage, be converted into the phase voltage formula according to line voltage, obtain the three-phase phase voltage instantaneous value;

(4) sampling phase voltage cycle obtains the three-phase phase voltage maximal value, and carries out the size ordering, when tri-phase unbalance factor surpasses the threshold values of setting, then judges the input side phase shortage.

2. the new detection method of input phase shortage according to claim 1 is characterized in that line voltage is converted into the phase voltage formula and is:

$\left\{\begin{array}{c}\mathrm{ua}=\frac{2\mathrm{uab}+\mathrm{ubc}}{3}\\ \mathrm{ub}=\frac{\mathrm{ubc}-\mathrm{uab}}{3}\\ \mathrm{uc}=-\frac{\mathrm{uab}+2\mathrm{ubc}}{3}\end{array}\right.$

Wherein:

$\left\{\begin{array}{c}\mathrm{uab}=\sqrt{6}U\sin (\mathrm{\ωt}+\frac{\mathrm{\π}}{6})\\ \mathrm{ubc}=\sqrt{6}U\sin (\mathrm{\ωt}-\frac{\mathrm{\π}}{2})\end{array}\right.$

In the above-mentioned formula: ua, ub and uc are respectively a, b and c three-phase phase voltage, and uab is a and b phase line voltage, and ubc is b and c phase line voltage, and U is the effective value of three-phase alternating voltage phase voltage, and ω is the angular velocity of alternating voltage, and t is the time.

3. the purposes of the detection method that the described input phase shortage of arbitrary claim is new in the claim 1 to 2 is characterized in that this method judging whether phase shortage of three-phase AC electrical supply system.

4. purposes of importing the new detection method of phase shortage, the method that it is characterized in that adopting following steps is to whether phase shortage detects in the power supply process by the frequency conversion speed-adjusting system of TMS320F2812DSP control:

(1) in a line voltage cycle, sample uab_AD, ubc_AD, and the ordering to sampling, keep maximal value and minimum value, promptly obtain maximal value and minimum value in the line voltage cycle, ask for the mean value of maximal value and minimum value, thereby ask for the input line voltage biasing;

(2) digital quantity that DSP is sampled deducts the input line voltage biasing, obtain uab and the ubc digital quantity in DSP, having just has negatively, and the analog voltage uab ' after asking for input line voltage uab step-down and handle according to DSP AD formula in like manner asks for the analog voltage ubc ' after the ubc step-down is handled;

(3) by

Ask for line instantaneous voltage uab, in like manner ask for ubc,

In the formula:

R1 is the testing circuit input resistance, and R2 is a stake resistance;

(4) by the line instantaneous voltage, be converted into the phase voltage formula according to line voltage, obtain the three-phase phase voltage instantaneous value;

(5) in a phase voltage cycle, ask for the maximal value of three-phase phase voltage respectively, and ordering, when tri-phase unbalance factor surpasses the setting threshold values, judge its input side phase shortage.

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