CN110007166A - A kind of method for fast measuring of frequency converter efficiency - Google Patents
A kind of method for fast measuring of frequency converter efficiency Download PDFInfo
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- CN110007166A CN110007166A CN201910232844.1A CN201910232844A CN110007166A CN 110007166 A CN110007166 A CN 110007166A CN 201910232844 A CN201910232844 A CN 201910232844A CN 110007166 A CN110007166 A CN 110007166A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The invention discloses a kind of method for fast measuring of frequency converter efficiency, carry out the acquisition of voltage and current signal in the input of frequency converter to be measured, output port first；Voltage signal and current signal are sampled using data collecting card, obtain voltage, the current signal of sampling；The voltage of sampling, current signal corresponding points are multiplied, the corresponding input of a single point, output power are obtained；According to the input of a single point, the input in the output power Y period of acquisition, output power；The time domain efficiency of frequency converter is acquired, and voltage and current signal is subjected to DFT transform according to input, output power, the frequency domain efficiency of frequency converter is calculated；It is then based on corresponding time domain efficiency and frequency domain energy valid value under a certain setting time node, obtains the efficiency of frequency converter to be measured.This method can accurately calculate frequency converter efficiency, and the selection of assessment and frequency converter to frequency converter efficiency provides reference.
Description
Technical field
The present invention relates to technical field of electrical measurement more particularly to a kind of method for fast measuring of frequency converter efficiency.
Background technique
Variable-frequency control technique is as energy-saving, improvement process flow, raising product quality and improves environment, promotion technology
A kind of progressive main means have been rooted in the hearts of the people.Currently, in the field low pressure (380V~690V), ac variable speed technology is
Through being widely applied, and in mesohigh (3kV, 6kV and 10kV voltage class) field, due to high voltage electric and electronic device system
The about influence of factor, using there are no widely have developed.The body dissipation of frequency converter mainly by device during the work time
Loss composition, including off-state loss (being caused by leakage current), on-state loss, turn-on consumption and cut-off loss four parts form,
The conducting of power device simultaneously and switching characteristic are again very sensitive to temperature.Due to skin effect, under different subharmonic, frequency conversion
The loss of device is different.By existing research shows that it is believed that flow through the electric current of insulated gate bipolar transistor (IGBT),
The voltage of IGBT emitter is the principal element for influencing device body loss.In a sense, the ontology damage of frequency converter
Consumption size is also the standard measuring a frequency converter sexual valence and comparing so as to see who is superior, so the measurement of frequency converter efficiency is particularly important.
It is in the prior art time domain approach mostly for the method for Measurement for Inverter efficiency, i.e. the sampling time takes input, defeated
The common multiple of signal period out is completed to obtain the efficiency of frequency converter to the calculating of input, output power in integer cycle.So
And according to the difference of industry spot electrical equipment, inverter output terminal signal frequency is different with the needs that equipment is run, and
Running frequency needed for one equipment is also likely to be variation, and since frequency converter input, output end frequency be not identical, is caused
Its period is not also identical, this brings great difficulty to the measurement of frequency converter efficiency.
Summary of the invention
The object of the present invention is to provide a kind of method for fast measuring of frequency converter efficiency, this method can be to frequency converter efficiency
It is accurately calculated, the selection of assessment and frequency converter to frequency converter efficiency provides reference.
The purpose of the present invention is what is be achieved through the following technical solutions:
A kind of method for fast measuring of frequency converter efficiency, which comprises
Step 1, the acquisition that voltage and current signal is carried out in the input of frequency converter to be measured, output port, obtain voltage signal U
With current signal I；
Step 2 samples voltage signal U and current signal I using data collecting card, to the every cycle of input end signal
Sample N number of point, the interception of t time span also carried out to output end signal, obtain corresponding sampled voltage, current signal U (n) and
I(n)；
The sampled voltage of acquisition, current signal U (n) are multiplied by step 3 with I (n) corresponding points, and it is corresponding to obtain a single point
Input, output power, are denoted as P respectivelyin(n) and Pout(n)；
Step 4, the input according to a single point, output power Pin(n) and Pout(n) input, the output in Y period are obtained
Power indicates are as follows:
Step 5, the input obtained according to step 4, output power PinAnd PoutAcquire the time domain efficiency of frequency converter are as follows:
Step 6 handles sampled voltage, current signal U (n) and I (n) with discrete Fourier transform DFT, obtains
Fundamental wave and each harmonic voltage, the frequency domain components U (k) of current signal, I (k) and phase difference θ (k)；
Wherein k (k=1,2,3 ...) is overtone order, then the frequency domain input power of frequency converter are as follows:
Step 7, the frequency domain output power P for similarly obtaining frequency converterout', and frequency converter is obtained according to the formula of step 5
Frequency domain efficiency is η ', records time domain efficiency η and frequency domain efficiency η ' value, and take Y=Y+1 period, repeats step 3-7；
Step 8 is then based on corresponding time domain efficiency and frequency domain energy valid value under a certain setting time node, obtains change to be measured
The efficiency of frequency device.
As seen from the above technical solution provided by the invention, the above method can accurately count frequency converter efficiency
It calculates, the selection of assessment and frequency converter to frequency converter efficiency provides reference, and provides for the efficiency measurement of other power equipments
It uses for reference.
Detailed description of the invention
In order to illustrate the technical solution of the embodiments of the present invention more clearly, required use in being described below to embodiment
Attached drawing be briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for this
For the those of ordinary skill in field, without creative efforts, it can also be obtained according to these attached drawings other
Attached drawing.
Fig. 1 is the method for fast measuring flow diagram of frequency converter efficiency provided in an embodiment of the present invention；
Fig. 2 is error function and input end signal periodicity e (Y)-Y relation schematic diagram in example of the present invention.
Specific embodiment
With reference to the attached drawing in the embodiment of the present invention, technical solution in the embodiment of the present invention carries out clear, complete
Ground description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based on this
The embodiment of invention, every other implementation obtained by those of ordinary skill in the art without making creative efforts
Example, belongs to protection scope of the present invention.
The embodiment of the present invention is described in further detail below in conjunction with attached drawing, is implemented as shown in Figure 1 for the present invention
The method for fast measuring flow diagram for the frequency converter efficiency that example provides, which comprises
Step 1, the acquisition that voltage and current signal is carried out in the input of frequency converter to be measured, output port, obtain voltage signal U
With current signal I；
Step 2 samples voltage signal U and current signal I using data collecting card, to the every cycle of input end signal
Sample N number of point, the interception of t time span also carried out to output end signal, obtain corresponding sampled voltage, current signal U (n) and
I(n)；
In this step, due to the frequency of input end signal (period T) be it is determining, to the input terminal of frequency converter to be measured
Signal carries out truncation complete cycle, and taking periodicity is Y (Y=1,2,3 ...), and corresponding time window length is t；
Voltage signal U and current signal I are sampled using data collecting card, analog quantity is converted into digital quantity, it is right
The every cycle of input end signal samples N number of point, and the interception of t time span is also carried out to output end signal, obtains corresponding voltage, electricity
Signal U (n) and I (n) are flowed, wherein n (n=1,2,3 ...) is sampled point, takes periodicity Y=1.
The sampled voltage of acquisition, current signal U (n) are multiplied by step 3 with I (n) corresponding points, and it is corresponding to obtain a single point
Input, output power, are denoted as P respectivelyin(n) and Pout(n)；
Step 4, the input according to a single point, output power Pin(n) and Pout(n) input, the output in Y period are obtained
Power indicates are as follows:
Step 5, the input obtained according to step 4, output power PinAnd PoutAcquire the time domain efficiency of frequency converter are as follows:
Step 6 handles sampled voltage, current signal U (n) and I (n) with discrete Fourier transform DFT, obtains
Fundamental wave and each harmonic voltage, the frequency domain components U (k) of current signal, I (k) and phase difference θ (k)；
Wherein k (k=1,2,3 ...) is overtone order, then the frequency domain input power of frequency converter are as follows:
In the specific implementation, the frequency domain components U (k) of obtained voltage, current signal, I (k) are indicated are as follows:
Step 7, the frequency domain output power P for similarly obtaining frequency converterout', and frequency converter is obtained according to the formula of step 5
Frequency domain efficiency is η ', records time domain efficiency η and frequency domain efficiency η ' value, then takes Y=Y+1 period, repeats step 3-7；
Step 8 is then based on corresponding time domain efficiency and frequency domain energy valid value under a certain setting time node, obtains change to be measured
The efficiency of frequency device.
The process of the step specifically:
Initially set up error function e (Y)=| η-η ' | (ε can be determined and be connect according to actual measured results with error threshold ε
It is bordering on zero), Y is input end signal periodicity；
Error function and input end signal periodicity e (Y)-Y relational graph are obtained, the minimum point of error threshold ε will be less than
It is denoted as Ej(j=1,2,3L)；
To ensure the accuracy and rapidity that calculate, E is taken2Corresponding timing node, when corresponding under the timing node
The average value of domain efficiency and frequency domain efficiency is the efficiency of frequency converter to be measured.
In addition, if can not find E in e (Y)-Y relational graph2Sampling time window length t can be then appropriately extended in timing node,
Re-start calculating.
Above-mentioned measurement method is described in detail with specific example below, numerical value employed in following examples is only
Citing, user can do corresponding change according to actual demand.In this example, certain industrial equipment supply voltage is 10kV/50Hz,
Equipment utilization voltage is 400V, and frequency is unknown, and wherein frequency conversion equipment uses uncontrollable diode rectifier circuit, via filter capacitor
Reach IGBT triggering control inverter circuit.When equipment works normally, respectively in the input of frequency converter, output end to voltage and current
Both signal is acquired, and is sampled at 256 points to the every cycle of input end signal, is calculated the electricity of frequency converter time domain, frequency domain, find out
Efficiency simultaneously compares as a result, when time-frequency domain efficiency differs minimum, and the efficiency of this frequency converter is the average value of time-frequency domain efficiency,
Its specific implementation step is as follows:
(1) signal picker is properly attached to input, the output end of frequency converter, it is right in the case where equipment works normally
Voltage and current signal measures, and time of measuring is 5 minutes；
(2) to input terminal voltage current signal described in step (1) carry out truncation complete cycle, time window length 1s, i.e.,
Periodicity Y=50, every cycle sample N=256 point, obtain discrete series；
(3) input end signal period Y=1 is taken, discrete voltage and current signal corresponding points are multiplied, it is corresponding to obtain a single point
Instantaneous power Pin(n) and Pout(n), it finds out the input in Y period, export general power PinAnd Pout, and then calculate frequency conversion
It inputted in device time domain, export total electricity and efficiency:
(4) DFT transform is carried out to step (3) discrete series and obtains its frequency domain components, obtain fundamental wave and each harmonic
Voltage, the amplitude (U (k) and I (k)) of current signal and phase difference (θ (k)), calculate the active-power P of fundamental wave and each harmonicin
(k) and Pout(k), input, the output general power P of frequency converter are found outin' and Pout', and then calculate in frequency converter frequency domain and input,
Export total electricity and efficiency:
(5) record η and η ' value, take input end signal period Y=Y+1, repeat step (3) and (4), draw error function and
Input end signal periodicity e (Y)-Y relational graph, is illustrated in figure 2 error function and input end signal in example of the present invention
Periodicity e (Y)-Y relation schematic diagram, with reference to Fig. 2: defining ε according to actual measured results is 0.1%, takes the minimum point less than ε
It is denoted as Ej(j=1,2,3L).
(6) timing node E is then determined according to step (5)2Corresponding period Y=46, does not consider rounding error, then frequency conversion
The efficiency of device is equal to
It is worth noting that, the content being not described in detail in the embodiment of the present invention belongs to professional and technical personnel in the field's public affairs
The prior art known.
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto,
Within the technical scope of the present disclosure, any changes or substitutions that can be easily thought of by anyone skilled in the art,
It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claims
Subject to enclosing.
Claims (5)
1. a kind of method for fast measuring of frequency converter efficiency, which is characterized in that the described method includes:
Step 1, the acquisition that voltage and current signal is carried out in the input of frequency converter to be measured, output port, obtain voltage signal U and electricity
Flow signal I；
Step 2 samples voltage signal U and current signal I using data collecting card, samples to the every cycle of input end signal
It is N number of, the interception of t time span is also carried out to output end signal, obtains corresponding sampled voltage, current signal U (n) and I
(n)；
The sampled voltage of acquisition, current signal U (n) are multiplied by step 3 with I (n) corresponding points, obtain a single point it is corresponding input,
Output power is denoted as P respectivelyin(n) and Pout(n)；
Step 4, the input according to a single point, output power Pin(n) and Pout(n) input in the Y period of acquisition, output power,
It indicates are as follows:
Step 5, the input obtained according to step 4, output power PinAnd PoutAcquire the time domain efficiency of frequency converter are as follows:
Step 6 handles sampled voltage, current signal U (n) and I (n) with discrete Fourier transform DFT, obtains fundamental wave
With each harmonic voltage, the frequency domain components U (k) of current signal, I (k) and phase difference θ (k)；
Wherein k (k=1,2,3 ...) is overtone order, then the frequency domain input power of frequency converter are as follows:
Step 7, the frequency domain output power P for similarly obtaining frequency converterout', and the frequency domain according to the formula of step 5 acquisition frequency converter
Efficiency is η ', records time domain efficiency η and frequency domain efficiency η ' value, and take Y=Y+1 period, repeats step 3-7；
Step 8 is then based on corresponding time domain efficiency and frequency domain energy valid value under a certain setting time node, obtains frequency converter to be measured
Efficiency.
2. the method for fast measuring of frequency converter efficiency according to claim 1, which is characterized in that the process of the step 2 has
Body are as follows:
Truncation complete cycle is carried out to the input end signal of frequency converter to be measured, taking periodicity is Y (Y=1,2,3 ...), corresponding time
Window length is t；
Voltage signal U and current signal I are sampled using data collecting card, analog quantity is converted into digital quantity, to input
The every cycle of end signal samples N number of point, and the interception of t time span is also carried out to output end signal, obtains corresponding voltage, electric current letter
Number U (n) and I (n), wherein n (n=1,2,3 ...) is sampled point, takes periodicity Y=1.
3. the method for fast measuring of frequency converter efficiency according to claim 1, which is characterized in that in step 6, obtained
Voltage, the frequency domain components U (k) of current signal, I (k) are indicated are as follows:
4. the method for fast measuring of frequency converter efficiency according to claim 1, which is characterized in that the process of the step 8 has
Body are as follows:
Initially set up error function e (Y)=| η-η ' | and error threshold ε, ε determined according to actual measured results and close to
Zero, Y are input end signal periodicity；
Error function and input end signal periodicity e (Y)-Y relational graph are obtained, the minimum point less than error threshold ε is denoted as Ej
(j=1,2,3L)；
Take E2Corresponding timing node, the average value of corresponding time domain efficiency and frequency domain efficiency is as to be measured under the timing node
The efficiency of frequency converter.
5. the method for fast measuring of frequency converter efficiency according to claim 4, which is characterized in that the method also includes:
If can not find E in e (Y)-Y relational graph2Timing node then extends sampling time window length t, re-starts calculating.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114035099A (en) * | 2021-10-12 | 2022-02-11 | 深圳供电局有限公司 | Method and device for measuring AC/DC conversion efficiency and electronic equipment |
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| CN114035099B (en) * | 2021-10-12 | 2023-12-22 | 深圳供电局有限公司 | Method and device for measuring alternating-current/direct-current conversion efficiency and electronic equipment |
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