CN110244148A - A kind of new-energy automobile dynamic operation condition EMI test method based on FFT with point frequency scanning - Google Patents
A kind of new-energy automobile dynamic operation condition EMI test method based on FFT with point frequency scanning Download PDFInfo
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- CN110244148A CN110244148A CN201910583488.8A CN201910583488A CN110244148A CN 110244148 A CN110244148 A CN 110244148A CN 201910583488 A CN201910583488 A CN 201910583488A CN 110244148 A CN110244148 A CN 110244148A
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/001—Measuring interference from external sources to, or emission from, the device under test, e.g. EMC, EMI, EMP or ESD testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/005—Testing of electric installations on transport means
- G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
Abstract
The invention discloses a kind of based on FFT and puts the new-energy automobile dynamic operation condition EMI test method of frequency scanning, including carrying out first time EMI test, acquisition full frequency band EMI is analyzed based on FFT spectrum, EMI measured value and EMI testing standard limit value subtraction calculations EMI characteristic value, calculate characteristic frequency point, car speed is acquired, pickup is calculated；Vehicle behavior is recognized according to speed, acceleration, calculates each operating mode feature frequency point distribution map；According to each operating mode feature frequency point distribution map, each operating condition maximum eigenvalue respective frequencies and characteristic frequency point density maximum region respective frequencies range are calculated；Second of EMI test is carried out, a frequency scanning is carried out to each operating condition maximum eigenvalue respective frequencies, while FFT spectrum analysis is carried out to each operating mode feature frequency point density maximum region.This method need to only acquire full frequency band EMI and car speed, and high-precision new-energy automobile dynamic operation condition EMI test can be realized, ensure that new-energy automobile EMI test validity and accuracy.
Description
Technical field
The present invention relates to EMI test methods, more particularly to the new-energy automobile dynamic operation condition based on FFT with point frequency scanning
EMI test method.
Background technique
Current new-energy automobile is quickly grown, and just gradually becomes the important vehicles.But compared with other types automobile,
New-energy automobile has more, more complicated electronic equipment, under charging, discharge condition, can generate serious electromagnetic interference
(Electro Magnetic Interference, EMI), EMI test are one of necessary test items of new-energy automobile.
The related EMI testing standard of new-energy automobile is (such as: CISPR 12:2009,10.05 ECE, SAE J551- at present
5-2012, GB/T 18387-2017 etc.) only regulation automobile steady state condition (such as SAE J551-5-2012 predetermined brake, idling,
Cruise three operating conditions, car speed, acceleration are constant) test EMI, it not can truly reflect out motor racing under steady state condition
EMI situation in the process.
When carrying out FFT spectrum analysis, frequency point number is more, and a frame frequency spectrum analysis time-consuming is longer, then composes in certain single frames frame frequency
Under analysis is time-consuming, frequency range is larger, then frequency resolution may be lower.
Summary of the invention
In order to solve the above technical problems, the present invention provides a kind of new-energy automobile dynamic work based on FFT with point frequency scanning
Condition EMI test method, the purpose of the present invention are realized by technical solution below:
A kind of new-energy automobile dynamic operation condition EMI test method based on FFT with point frequency scanning, comprising:
A carries out first time EMI test, and based on FFT spectrum analysis acquisition full frequency band EMI, EMI measured value and EMI are tested
Standard limited value subtracts each other to obtain EMI characteristic value, then calculates characteristic frequency point again, acquires car speed, calculates pickup；
B recognizes automobile dynamic operation condition, and calculates each operating mode feature frequency point distribution map according to car speed, acceleration；
C calculates each operating condition maximum eigenvalue respective frequencies and characteristic frequency point density according to each operating mode feature frequency point distribution map
Maximum region respective frequencies range；
D carries out second of EMI test, carries out a frequency scanning to each operating condition maximum eigenvalue respective frequencies, while to each work
Condition characteristic frequency point density maximum region carries out FFT spectrum analysis.
Compared with prior art, one or more embodiments of the invention can have following advantage:
This method establishes industry and mining city mathematical model according to each dynamic operation condition speed, acceleration feature, according to characteristic frequency point
Distribution map characteristic frequency point determines mathematical model, only need to acquire full frequency band EMI and car speed, find frequency range interested, Ji Keshi
Now high-precision new-energy automobile dynamic operation condition EMI is tested, and ensure that new-energy automobile EMI test validity and accuracy.
Other features and advantages of the present invention will be illustrated in the following description, also, partly becomes from specification
It obtains it is clear that understand through the implementation of the invention.The objectives and other advantages of the invention can be by specification, power
Specifically noted structure is achieved and obtained in sharp claim and attached drawing.
Detailed description of the invention
Attached drawing is used to provide further understanding of the present invention, and constitutes part of specification, with reality of the invention
It applies example and is used together to explain the present invention, do not constitute and the present invention is limited.In the accompanying drawings:
Fig. 1 is the new-energy automobile dynamic operation condition EMI test method flow chart based on FFT with point frequency scanning；
Fig. 2 is the new-energy automobile dynamic operation condition EMI test method program frame based on FFT with point frequency scanning.
Specific embodiment
According to the technique and scheme of the present invention, in the case where not changing connotation of the invention, those of ordinary skill in the art
It can propose multiple frame modes and production method of the invention.Therefore following specific embodiments and attached drawing are only this hairs
Bright technical solution illustrates, and is not to be construed as whole of the invention or is considered as the restriction of technical solution of the present invention
Or limitation.
Present invention will now be described in further detail with reference to the embodiments and the accompanying drawings.
Fig. 1 is the test side new-energy automobile dynamic operation condition EMI based on FFT with point frequency scanning of example according to the present invention
Method flow chart, below with reference to Fig. 1, the process for embodiment that the present invention will be described in detail.
As shown in Figure 1, the test side new-energy automobile dynamic operation condition EMI provided by the invention based on FFT with point frequency scanning
Method the following steps are included:
Step 1 carries out first time EMI test, based on FFT spectrum analysis acquisition full frequency band EMI, by EMI measured value and EMI
Testing standard limit value subtracts each other to obtain EMI characteristic value and then calculates characteristic frequency point again, acquires car speed, calculates pickup；
Step 2 recognizes automobile dynamic operation condition, and calculates each operating mode feature frequency point distribution map according to car speed, acceleration；
Step 3 calculates each operating condition maximum eigenvalue respective frequencies and characteristic frequency point according to each operating mode feature frequency point distribution map
Density maximum region respective frequencies range；
Step 4 carries out second of EMI test, carries out a frequency scanning to each operating condition maximum eigenvalue respective frequencies, while right
Each operating mode feature frequency point density maximum region carries out FFT spectrum analysis.
Such as Fig. 2, above-mentioned steps 1 are specifically included: being placed antenna in screened room and received EMI signal, and using FFT to the letter
Number carry out spectrum analysis, obtain EMI measured value, including the multiframe spectrogram in a period of time, a frame frequency spectrogram measured value is denoted as
Pmeasured=[p1(x1, y1), p2(x2, y2), p3(x3, y3) ..., ps(xs, ys) ..., tmark], wherein x is frequency
Rate, y are amplitude, tmarkFor time label, measurement amplitude set is denoted as Y=[y1, y2, y3..., ys], according to correlative measurement test-object
Standard, amplitude limit value function are denoted as flimit(x), then amplitude value set Ylimit=[flimit(x1), flimit(x2), flimit
(x3) ..., flimit(xs)], then characteristic value collection Ychar=Y-Ylimit.Then the frame frequency chromatogram characteristic frequency point is psuspect
(xsuspect, ychar_max, tmark), wherein ychar_max=max { Ychar}。
Speed probe is installed at chassis dynamometer rotary drum and acquires rotary drum angular speed, on wheel and chassis dynamometer
Rotary drum is without under opposite sliding condition, the dry rotary drum linear velocity such as car speed v, acceleration a are as follows:
Wherein Δ v is velocity variable, and Δ t is time variation amount.
Such as Fig. 2, above-mentioned steps 2 are based on speed, acceleration automobile dynamic operation condition discrimination method are as follows:
If new-energy automobile very short time tobserveInside there are n velocity measurement, sets of speeds Vmeasured=[v1,
v2..., vi..., vn], acceleration collection is combined into Acalculated=[a1, a2..., ai...], then there is tobserveInterior minimum speed
vmin=min { Vmeasured, minimum acceleration amin=min { Acalculated, peak acceleration amax=max { Acalculated}。
If detecting amin> aT_acc, to avoid judging by accident, wherein aT_accFor a positive threshold value of very little, then it can determine whether new energy
Source automobile is in accelerating mode；If detecting vi≥vmin> vidling、amax<-aT_slide, wherein vidlingFor idle speed, it is
It avoids judging by accident, aT_accFor a positive threshold value of very little, then it can determine whether that new-energy automobile is in coastdown operating condition；If detecting ai
≤amax< aslide-aT_brake, wherein aslideFor idling acceleration, to avoid judging by accident, aT_brakeFor a positive threshold value of very little, then
It can determine whether that new-energy automobile is in braking deceleration operating condition.
If the accelerating mode period is t1~t2, the coastdown operating condition period is t2~t3, the braking deceleration operating condition time
Section is t3~t4.Work as t1≤tmark< t2, then this feature frequency point is the data in accelerating mode characteristic frequency point distribution map；Work as t2≤
tmark< t3, then this feature frequency point is the data in coastdown operating mode feature frequency point distribution map；Work as t3≤tmark< t4, then should
Characteristic frequency point is the data in braking deceleration operating mode feature frequency point distribution map.
Above-mentioned steps 3 specifically include:
If the characteristic frequency point collection in a dynamic operation condition is combined into
Pchar=[pchar_1(xchar_1, ychar_max_1, tmark_1) ..., pchar_z(xchar_z, ychar_max_z, tmark_z)], then
Characteristic frequency point amplitude collection is combined into Ychar_max=[ychar_max_1..., ychar_max_z], maximum eigenvalue yU_max=max
{Ychar_max, then maximum eigenvalue respective frequencies fU_max。
Taking a frequency left margin is fleft, band width w, amplitude lower boundary be Udown, amplitude length l=Umax-Udown
Rectangular area be used as part observation area Πf, then ΠfCharacteristic frequency point amplitude range is [Udown, Umax], frequency range be
[fleft, fleft+w].Equipped with N number of characteristic frequency point in ΠfIn region, then the ratio for defining N and wl is characterized frequency point density p, i.e. ρ
=N/wl.Mobile rectangle part observation area Πf, obtain characteristic frequency point density maxima ρmax, then ρmaxRegion respective frequencies model
It encloses for [fρ_max, fρ_max+w]。
Although disclosed herein embodiment it is as above, the content only to facilitate understand the present invention and
The embodiment of use, is not intended to limit the invention.Any those skilled in the art to which this invention pertains are not taking off
From disclosed herein spirit and scope under the premise of, can make in the formal and details of implementation any modification with
Variation, but scope of patent protection of the invention, still should be subject to the scope of the claims as defined in the appended claims.
Claims (5)
1. a kind of new-energy automobile dynamic operation condition EMI test method based on FFT with point frequency scanning, which is characterized in that the side
Method determines mathematical model based on full frequency band EMI acquisition, car speed acquisition, industry and mining city mathematical model, characteristic frequency point, comprising:
A carries out first time EMI test, based on FFT spectrum analysis acquisition full frequency band EMI, by EMI measured value and EMI testing standard
Limit value subtracts each other to obtain EMI characteristic value, then calculates characteristic frequency point again, acquires car speed, calculates pickup；
B recognizes automobile dynamic operation condition, and calculates each operating mode feature frequency point distribution map according to car speed, acceleration；
C calculates each operating condition maximum eigenvalue respective frequencies and characteristic frequency point density is maximum according to each operating mode feature frequency point distribution map
Region respective frequencies range；
D carries out second of EMI test, carries out a frequency scanning to each operating condition maximum eigenvalue respective frequencies, while special to each operating condition
It levies frequency point density maximum region and carries out FFT spectrum analysis.
2. the new-energy automobile dynamic operation condition EMI test method according to claim 1 based on FFT with point frequency scanning,
It is characterized in that, the step A is specifically included: placing antenna in screened room and receive EMI signal, and the signal is carried out using FFT
Spectrum analysis obtains EMI measured value, and including the multiframe spectrogram in a period of time, a frame frequency spectrogram measured value is denoted as Pmeasured
=[p1(x1, y1), p2(x2, y2), p3(x3, y3) ..., ps(xs, ys) ..., tmark] wherein x be frequency, y is amplitude, tmarkFor
Time label, measurement amplitude set are denoted as Y=[y1, y2, y3..., ys], according to associated test standards, amplitude limit value function
It is denoted as flimit(x), then amplitude value set Ylimit=[flimit(x1), flimit(x2), flimit(x3) ..., flimit(xs)], then
Characteristic value collection Ychar=Y-Ylimit.Then the frame frequency chromatogram characteristic frequency point is psuspect(xsuspect, ychar_max, tmark), wherein
ychar_max=max { Ychar}；
Speed probe is installed at chassis dynamometer rotary drum and acquires rotary drum angular speed, on wheel and chassis dynamometer rotary drum without
Under opposite sliding condition, car speed v is equal to rotary drum linear velocity, acceleration a are as follows:
Wherein Δ v is velocity variable, and Δ t is time variation amount.
3. the new-energy automobile dynamic operation condition EMI test method according to claim 1 based on FFT with point frequency scanning,
It is characterized in that, in the step B: recognizing automobile dynamic operation condition method according to car speed, acceleration are as follows:
If new-energy automobile very short time tobserveInside there are n velocity measurement, sets of speeds Vmeasured=[v1, v2...,
vi..., vn], acceleration collection is combined into Acalculated=[a1, a2..., ai...], then there is tobserveInterior minimum speed vmin=
min{Vmeasured, minimum acceleration amin=min { Acalculated, peak acceleration amax=max { Acalculated}；
If detecting amin> aT_acc, to avoid judging by accident, wherein aT_accFor a positive threshold value of very little, then it can determine whether new-energy automobile
In accelerating mode；If detecting vi≥vmin> vidling、amax<-aT_slide, wherein vidlingFor idle speed, to avoid missing
Sentence, aT_accFor a positive threshold value of very little, then it can determine whether that new-energy automobile is in coastdown operating condition；If detecting ai≤amax<
aslide-aT_brake, wherein aslideFor idling acceleration, to avoid judging by accident, aT_brakeFor a positive threshold value of very little, then can determine whether new
Energy automobile is in braking deceleration operating condition.
4. the new-energy automobile dynamic operation condition EMI test method according to claim 1 based on FFT with point frequency scanning,
It is characterized in that, the step B calculates each operating mode feature frequency point profiling method are as follows:
If the accelerating mode period is t1~t2, the coastdown operating condition period is t2~t3, the braking deceleration operating condition period is t3
~t4；Work as t1≤tmark< t2, then this feature frequency point is the data in accelerating mode characteristic frequency point distribution map；Work as t2≤tmark<
t3, then this feature frequency point is the data in coastdown operating mode feature frequency point distribution map；Work as t3≤tmark< t4, then this feature frequency
Point is the data in braking deceleration operating mode feature frequency point distribution map.
5. the new-energy automobile dynamic operation condition EMI test method according to claim 1 based on FFT with point frequency scanning,
It is characterized in that, the step C maximum eigenvalue respective frequencies and characteristic frequency point density maximum region calculation method are as follows:
If the characteristic frequency point collection in a dynamic operation condition is combined into
Pchar=[pchar_1(xchar_1, ychar_max_1, tmark_1) ..., pchar_z(xchar_z, ychar_max_z, tmark_z)], then feature
Frequency point amplitude collection is combined into Ychar_max=[ychar_max_1..., ychar_max_z], maximum eigenvalue yU_max=max { Ychar_max, then
Maximum eigenvalue respective frequencies fU_max；
Taking a frequency left margin is fleft, band width w, amplitude lower boundary be Udown, amplitude length l=Umax-UdownSquare
Shape region is used as part observation area Πf, then ΠfCharacteristic frequency point amplitude range is [Udown, Umax], frequency range be [fleft,
fleft+w]；Equipped with N number of characteristic frequency point in ΠfIn region, then the ratio for defining N and wl is characterized frequency point and concentrates bulkfactor ρ, i.e.,
ρ=N/wl；Mobile rectangle locally observes [region Πf, obtain characteristic frequency point and concentrate bulkfactor maximum value ρmax, then ρmaxRegion
Respective frequencies range is [fρ_max, fρ_max+w]。
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