CN110244148B - New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning - Google Patents
New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning Download PDFInfo
- Publication number
- CN110244148B CN110244148B CN201910583488.8A CN201910583488A CN110244148B CN 110244148 B CN110244148 B CN 110244148B CN 201910583488 A CN201910583488 A CN 201910583488A CN 110244148 B CN110244148 B CN 110244148B
- Authority
- CN
- China
- Prior art keywords
- working condition
- max
- emi
- characteristic frequency
- frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Electromagnetism (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
The invention discloses a new energy automobile dynamic working condition EMI test method based on FFT and point frequency scanning, which comprises the steps of carrying out first EMI test, collecting full-band EMI based on FFT spectrum analysis, subtracting an EMI measured value and an EMI test standard limit value to calculate an EMI characteristic value, calculating a characteristic frequency point, collecting automobile speed and calculating automobile acceleration; identifying the working conditions of the automobile according to the speed and the acceleration, and calculating a characteristic frequency point distribution diagram of each working condition; according to the characteristic frequency point distribution diagram of each working condition, calculating the frequency corresponding to the maximum characteristic value of each working condition and the frequency range corresponding to the region with the maximum density of the characteristic frequency points; and performing a second EMI test, performing point frequency scanning on the frequency corresponding to the maximum characteristic value of each working condition, and performing FFT spectrum analysis on the region with the maximum density of the characteristic frequency points of each working condition. According to the method, the high-precision EMI test of the new energy automobile under the dynamic working condition can be realized only by acquiring the full-band EMI and the automobile speed, and the effectiveness and the accuracy of the EMI test of the new energy automobile are guaranteed.
Description
Technical Field
The invention relates to an EMI test method, in particular to a new energy automobile dynamic working condition EMI test method based on FFT and point frequency scanning.
Background
The new energy automobile is rapidly developed and is gradually becoming an important vehicle. However, compared with other types of automobiles, new energy automobiles have more and more complex electronic devices, and generate serious electromagnetic Interference (EMI) in a charging and discharging state, and the EMI test is one of the necessary test items of the new energy automobiles.
At present, relevant EMI test standards (such as CISPR 12: 2009, ECE 10.05, SAE J551-5-2012, GB/T18387-.
When performing FFT spectrum analysis, the more the frequency points are, the longer a frame of spectrum analysis takes, and at a certain time consumption of a single frame of spectrum analysis, the larger the frequency range, the lower the frequency resolution may be.
Disclosure of Invention
In order to solve the technical problems, the invention provides a new energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning, and the purpose of the invention is realized by the following technical scheme:
a new energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning comprises the following steps:
a, performing a first EMI test, acquiring full-band EMI based on FFT spectrum analysis, subtracting an EMI measurement value from an EMI test standard limit value to obtain an EMI characteristic value, then calculating a characteristic frequency point, acquiring the automobile speed, and calculating the automobile acceleration;
b, identifying the dynamic working conditions of the automobile according to the speed and the acceleration of the automobile, and calculating the characteristic frequency point distribution diagram of each working condition;
c, calculating the frequency corresponding to the maximum characteristic value of each working condition and the frequency range corresponding to the region with the maximum density of the characteristic frequency points according to the characteristic frequency point distribution diagram of each working condition;
and D, performing a second EMI test, performing point frequency scanning on the frequency corresponding to the maximum characteristic value of each working condition, and performing FFT spectrum analysis on the region with the maximum density of the characteristic frequency points of each working condition.
One or more embodiments of the present invention may have the following advantages over the prior art:
according to the method, the working condition identification mathematical model is established according to the dynamic working condition speed and acceleration characteristics, the mathematical model is determined according to the characteristic frequency points of the characteristic frequency point distribution diagram, the interesting frequency band is found only by acquiring the full-frequency-band EMI and the automobile speed, the high-precision EMI test of the new energy automobile under the dynamic working condition can be realized, and the effectiveness and the accuracy of the EMI test of the new energy automobile are ensured.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of a new energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning;
FIG. 2 is a new energy automobile dynamic condition EMI test method program framework based on FFT and point-frequency scanning.
Detailed Description
According to the technical scheme of the invention, a plurality of structural modes and manufacturing methods of the invention can be provided by a person with ordinary skill in the art without changing the essential spirit of the invention. Therefore, the following detailed description and the accompanying drawings are merely specific illustrations of the technical solutions of the present invention, and should not be construed as all of the present invention or as limitations or limitations of the technical solutions of the present invention.
The present invention will be described in further detail with reference to the following examples and accompanying drawings.
Fig. 1 is a flowchart of a new energy vehicle dynamic condition EMI testing method based on FFT and point-frequency scanning according to an embodiment of the present invention, and the following describes in detail a flow of an embodiment of the present invention with reference to fig. 1.
As shown in fig. 1, the new energy automobile dynamic condition EMI testing method based on FFT and point-frequency scanning provided by the present invention includes the following steps:
step 1, performing a first EMI test, acquiring full-band EMI based on FFT spectrum analysis, subtracting an EMI measured value from an EMI test standard limit value to obtain an EMI characteristic value, then calculating a characteristic frequency point, acquiring the speed of the automobile, and calculating the acceleration of the automobile;
step 2, identifying the dynamic working conditions of the automobile according to the speed and the acceleration of the automobile, and calculating the characteristic frequency point distribution diagram of each working condition;
step 3, calculating the frequency corresponding to the maximum characteristic value of each working condition and the frequency range corresponding to the region with the maximum density of the characteristic frequency points according to the characteristic frequency point distribution diagram of each working condition;
and 4, performing a second EMI test, performing point frequency scanning on the frequency corresponding to the maximum characteristic value of each working condition, and performing FFT spectrum analysis on the region with the maximum density of the characteristic frequency points of each working condition.
As shown in fig. 2, the step 1 specifically includes: placing an antenna in a shielding room to receive an EMI signal, performing spectrum analysis on the signal by using FFT (fast Fourier transform), and acquiring EMI measurement values, wherein the EMI measurement values comprise multiframe spectrograms in a period of time, and one frame of spectrogram measurement values are recorded as
Pmeasured＝[p1(x1，y1)，p2(x2，y2)，p3(x3，y3)，...，ps(xs，ys)，...，tmark]Where x is frequency, y is amplitude, tmarkFor time stamping, the measured amplitude is set as Y ═ Y1，y2，y3，...，ys]The amplitude limit function is denoted as f according to the relevant test standardlimit(x) Set of amplitude limits Ylimit＝[flimit(x1)，flimit(x2)，flimit(x3)，...，flimit(xs)]Then the set of eigenvalues Ychar＝Y-Ylimit. The characteristic frequency point of the frame spectrogram is psuspect(xsuspect，ychar_max，tmark) Wherein y ischar_max＝max{Ychar}。
A rotating speed sensor is arranged at a rotary drum of the chassis dynamometer to acquire the angular speed of the rotary drum, the vehicle speed v is equal to the linear speed of the rotary drum under the condition that the wheels and the rotary drum on the chassis dynamometer do not slide relatively, and the acceleration a is as follows:
where Δ v is the speed change amount and Δ t is the time change amount.
As shown in fig. 2, the method for identifying the dynamic condition of the vehicle based on the speed and the acceleration in the step 2 comprises the following steps:
setting a short time t of the new energy automobileobserveWith n velocity measurements, the velocity set being Vmeasured＝[v1，v2，...，vi，...，vn]The acceleration is Acalculated＝[a1，a2，...，ai，...]Then there is tobserveInner minimum velocity vmin＝min{Vmeasured}, minimum acceleration amin＝min{AcalculatedThe maximum acceleration amax＝max{Acalculated}。
If a is detectedmin＞aT_accTo avoid erroneous judgment, wherein aT_accIf the threshold value is a very small positive threshold value, the new energy automobile can be judged to be in an acceleration working condition; if v is detectedi≥vmin＞vidling、amax＜-aT_slideWherein v isidlingFor idle speed, to avoid false positives, aT_accIf the value is a very small positive threshold value, the new energy automobile can be judged to be in the sliding deceleration working condition; if a is detectedi≤amax＜aslide-aT_brakeWherein a isslideFor idle acceleration, to avoid false positives, aT_brakeIf the value is a small positive threshold value, the new energy automobile can be judged to be in a braking and decelerating working condition.
Setting the time period of acceleration as t1～t2The time period of the sliding deceleration working condition is t2～t3The braking deceleration working condition time period is t3～t4. When t is1≤tmark＜t2If the characteristic frequency point is the data in the characteristic frequency point distribution diagram under the acceleration working condition; when t is2≤tmark＜t3If the characteristic frequency point is the data in the characteristic frequency point distribution diagram of the sliding deceleration working condition; when t is3≤tmark＜t4If the characteristic frequency point is in the distribution diagram of the characteristic frequency points of the braking deceleration working conditionAnd (4) data.
The step 3 specifically includes:
setting a characteristic frequency point set in a dynamic working condition as
Pchar＝[pchar_1(xchar_1，ychar_max_1，tmark_1)，...，pchar_z(xchar_z，ychar_max_z，tmark_z)]Then the amplitude set of the characteristic frequency points is Ychar_max＝[ychar_max_1，...，ychar_max_z]Maximum eigenvalue yU_max＝max{Ychar_maxF, the frequency f corresponding to the maximum characteristic valueU_max。
Taking a frequency left boundary as fleftFrequency width is w, amplitude lower boundary is UdownThe amplitude length l is equal to Umax-UdownThe rectangular area is used as a local observation area IIfThen, pifThe amplitude range of the characteristic frequency point is [ U ]down，Umax]A frequency range of [ fleft，fleft+w]. Is provided with N characteristic frequency points NfIn the region, the ratio of N to wl is defined as the characteristic frequency point density ρ, i.e., ρ is N/wl. Local observation area pi of movable rectanglefObtaining the maximum value rho of the density of the characteristic frequency pointmaxThen ρmaxThe corresponding frequency range of the region is | fρ_max，fρ_max+w|。
Although the embodiments of the present invention have been described above, the above descriptions are only for the convenience of understanding the present invention, and are not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (4)
1. The new energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning is characterized in that the method is based on full-band EMI collection, automobile speed collection, working condition identification mathematical model and characteristic frequency point determination mathematical model, and comprises the following steps:
step A, performing a first EMI test, acquiring full-band EMI based on FFT spectrum analysis, subtracting an EMI measurement value from an EMI test standard limit value to obtain an EMI characteristic value, then calculating a characteristic frequency point, acquiring the automobile speed, and calculating the automobile acceleration;
b, identifying dynamic working conditions of the automobile according to the speed and the acceleration of the automobile, and calculating a characteristic frequency point distribution diagram of each working condition;
step C, calculating the frequency corresponding to the maximum characteristic value of each working condition and the frequency range corresponding to the region with the maximum density of the characteristic frequency points according to the characteristic frequency point distribution diagram of each working condition;
step D, performing a second EMI test, performing point frequency scanning on the frequency corresponding to the maximum characteristic value of each working condition, and performing FFT spectrum analysis on the region with the maximum density of the characteristic frequency points of each working condition;
and C, the calculation method of the maximum area of the frequency corresponding to the maximum characteristic value and the density of the characteristic frequency points comprises the following steps:
setting a characteristic frequency point set in a dynamic working condition as follows:
Pchar＝[pchar_1(xchar_1,ychar_max_1,tmark_1),...,pchar_z(xchar_z,ychar_max_z,tmark_z)]then the amplitude set of the characteristic frequency points is Ychar_max＝[ychar_max_1,...,ychar_max_z]Maximum eigenvalue yU_max＝max{Ychar_maxF, the frequency f corresponding to the maximum characteristic valueU_max；
Taking a frequency left boundary as fleftFrequency width is w, amplitude lower boundary is UdownThe amplitude length l is equal to Umax-UdownThe rectangular area is used as a local observation area IIfThen, pifThe amplitude range of the characteristic frequency point is [ U ]down,Umax]A frequency range of [ fleft,fleft+w](ii) a Is provided with N characteristic frequency points NfIn the region, defining the ratio of N to wl as the density ρ of the characteristic frequency points, that is, ρ is N/wl; local observation area pi of movable rectanglefObtaining the maximum value rho of the density of the characteristic frequency pointmaxThen ρmaxRegion-corresponding frequency range of [ fρ_max,fρ_max+w]。
2. The new energy automobile dynamic condition EMI testing method based on FFT and point-frequency scanning as claimed in claim 1, wherein the step A specifically includes: placing an antenna in a shielding room to receive an EMI signal, performing spectrum analysis on the signal by using FFT (fast Fourier transform), and acquiring EMI measurement values, wherein the EMI measurement values comprise multiframe spectrograms in a period of time, and one frame of spectrogram measurement value is marked as Pmeasured＝[p1(x1,y1),p2(x2,y2),p3(x3,y3),...,ps(xs,ys),...,tmark]Where x is frequency, y is amplitude, tmarkFor time stamping, the measured amplitude is set as Y ═ Y1,y2,y3,...,ys]The amplitude limit function is denoted as f according to the relevant test standardlimit(x) Set of amplitude limits Ylimit＝[flimit(x1),flimit(x2),flimit(x3),...,flimit(xs)]Then the set of eigenvalues Ychar＝Y-Ylimit(ii) a The characteristic frequency point of the frame spectrogram is psuspect(xsuspect,ychar_max,tmark) Wherein y ischar_max＝max{Ychar}；
A rotating speed sensor is arranged at a rotary drum of the chassis dynamometer to acquire the angular speed of the rotary drum, the vehicle speed v is equal to the linear speed of the rotary drum under the condition that the wheels and the rotary drum on the chassis dynamometer do not slide relatively, and the acceleration a is as follows:
where Δ v is the speed change amount and Δ t is the time change amount.
3. The new energy automobile dynamic working condition EMI testing method based on FFT and point-frequency scanning as claimed in claim 1, wherein in the step B: the method for identifying the dynamic working condition of the automobile according to the speed and the acceleration of the automobile comprises the following steps:
setting a short time t of the new energy automobileobserveWith n velocity measurements, the velocity set being Vmeasured＝[v1,v2,...,vi,...,vn]The acceleration is Acalculated＝[a1,a2,...,ai,...]Then there is tobserveInner minimum velocity vmin＝min{Vmeasured}, minimum acceleration amin＝min{AcalculatedThe maximum acceleration amax＝max{Acalculated}；
If a is detectedmin＞aT_accTo avoid erroneous judgment, wherein aT_accIf the threshold value is a very small positive threshold value, the new energy automobile can be judged to be in an acceleration working condition; if v is detectedi≥vmin＞vidling、amax＜-aT_slideWherein v isidlingFor idle speed, to avoid false positives, aT_accIf the value is a very small positive threshold value, the new energy automobile can be judged to be in the sliding deceleration working condition; if a is detectedi≤amax＜aslide-aT_brakeWherein a isslideFor idle acceleration, to avoid false positives, aT_brakeIf the value is a small positive threshold value, the new energy automobile can be judged to be in a braking and decelerating working condition.
4. The new energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning as claimed in claim 1, wherein the method for calculating characteristic frequency point distribution diagram of each working condition in the step B is:
setting the time period of acceleration as t1～t2The time period of the sliding deceleration working condition is t2～t3The braking deceleration working condition time period is t3～t4(ii) a When t is1≤tmark＜t2If the characteristic frequency point is the data in the characteristic frequency point distribution diagram under the acceleration working condition; when t is2≤tmark＜t3Then the characteristicThe characteristic frequency points are data in a characteristic frequency point distribution diagram of the sliding deceleration working condition; when t is3≤tmark＜t4If the characteristic frequency point is the data in the characteristic frequency point distribution diagram of the braking and decelerating working condition; said t ismarkIs a time stamp.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910583488.8A CN110244148B (en) | 2019-07-01 | 2019-07-01 | New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910583488.8A CN110244148B (en) | 2019-07-01 | 2019-07-01 | New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110244148A CN110244148A (en) | 2019-09-17 |
| CN110244148B true CN110244148B (en) | 2021-04-16 |
Family
ID=67890397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910583488.8A Active CN110244148B (en) | 2019-07-01 | 2019-07-01 | New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110244148B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2627490Y (en) * | 2003-05-20 | 2004-07-21 | 哈尔滨铁路局齐齐哈尔科学技术研究所 | Diesel locomotive equivalent kilometer recorder |
| CN1688874A (en) * | 2002-08-30 | 2005-10-26 | 日本精工株式会社 | Method and device for monitoring status of mechanical equipment and abnormality diagnosing device |
| CN102295002A (en) * | 2011-06-09 | 2011-12-28 | 华南理工大学 | Method for obtaining wheel rotation signal characteristic quantity based on tangential acceleration curve of wheel |
| CN103197183A (en) * | 2013-01-11 | 2013-07-10 | 北京航空航天大学 | Method for correcting uncertainty of independent component analytical method in electromagnetic interference separation |
| WO2014027366A2 (en) * | 2012-08-17 | 2014-02-20 | Airbus Engineering Centre India | System and method for analyzing arrangement of vehicle and building wire harnesses for emi |
| CN104899409A (en) * | 2015-03-05 | 2015-09-09 | 北京理工大学 | Engineering mechanical transmission load signal denoising method based on wavelet analysis |
| CN106092613A (en) * | 2016-08-15 | 2016-11-09 | 华南理工大学 | A kind of brake pressure indirect measurement method based on rotary drum revolution speed sensing |
| CN106485209A (en) * | 2016-09-23 | 2017-03-08 | 北京航空航天大学 | Non-stationary electromagnetic interference signal mode identification method based on EEMD feature extraction and PNN |
| CN107167797A (en) * | 2017-05-04 | 2017-09-15 | 安徽超远信息技术有限公司 | A kind of Digital railway hump measure speed radar and its anti-disturbance method |
| CN207114649U (en) * | 2016-08-31 | 2018-03-16 | 卢俊文 | A kind of magnetic interference measuring system of train to trackside wheel counting apparatus |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8868361B2 (en) * | 2005-05-27 | 2014-10-21 | Exacter, Inc. | Hand-held system and method for detecting impaired electric power equipment |
| CN104572510A (en) * | 2013-10-09 | 2015-04-29 | 杰发科技（合肥）有限公司 | Method and device for judging working state of external equipment |
-
2019
- 2019-07-01 CN CN201910583488.8A patent/CN110244148B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1688874A (en) * | 2002-08-30 | 2005-10-26 | 日本精工株式会社 | Method and device for monitoring status of mechanical equipment and abnormality diagnosing device |
| CN2627490Y (en) * | 2003-05-20 | 2004-07-21 | 哈尔滨铁路局齐齐哈尔科学技术研究所 | Diesel locomotive equivalent kilometer recorder |
| CN102295002A (en) * | 2011-06-09 | 2011-12-28 | 华南理工大学 | Method for obtaining wheel rotation signal characteristic quantity based on tangential acceleration curve of wheel |
| WO2014027366A2 (en) * | 2012-08-17 | 2014-02-20 | Airbus Engineering Centre India | System and method for analyzing arrangement of vehicle and building wire harnesses for emi |
| CN103197183A (en) * | 2013-01-11 | 2013-07-10 | 北京航空航天大学 | Method for correcting uncertainty of independent component analytical method in electromagnetic interference separation |
| CN104899409A (en) * | 2015-03-05 | 2015-09-09 | 北京理工大学 | Engineering mechanical transmission load signal denoising method based on wavelet analysis |
| CN106092613A (en) * | 2016-08-15 | 2016-11-09 | 华南理工大学 | A kind of brake pressure indirect measurement method based on rotary drum revolution speed sensing |
| CN207114649U (en) * | 2016-08-31 | 2018-03-16 | 卢俊文 | A kind of magnetic interference measuring system of train to trackside wheel counting apparatus |
| CN106485209A (en) * | 2016-09-23 | 2017-03-08 | 北京航空航天大学 | Non-stationary electromagnetic interference signal mode identification method based on EEMD feature extraction and PNN |
| CN107167797A (en) * | 2017-05-04 | 2017-09-15 | 安徽超远信息技术有限公司 | A kind of Digital railway hump measure speed radar and its anti-disturbance method |
Non-Patent Citations (4)
| Title |
|---|
| Research on Electromagnetic Interference in the Energy Dynamic Processes of Power Battery in Electric Vehicles;Yanjie Guo et.al;《2013 IEEE Vehicle Power and Propulsion Conference》;20131121;第481-485页 * |
| 新能源汽车EMI测试高速FFT预扫描***研发;李翔;《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》;20180531;C035-66 * |
| 新能源汽车动态工况EMI 测试***构架设计与关键技术分析;钟森鸣 等;《中国测试》;20170831;第43卷(第8期);第76-79页 * |
| 电动汽车动态工况的EMI测试技术需求与方案设计;曾博 等;《中国测试》;20171130;第43卷(第11期);第8-11页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110244148A (en) | 2019-09-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108535012B (en) | A kind of transmission squawk NVH performance off-line test method | |
| CN107238501A (en) | Method and system for testing road sliding resistance of electric automobile | |
| CN107064846A (en) | The sensitivity detection method and device of live testing apparatus for local discharge | |
| CN107655700A (en) | Method and device for determining road sliding resistance | |
| CN105631876A (en) | CT image resolution automatic test method based on global binarization | |
| CN104215454A (en) | Automotive rear bridge main speed reducer noise performance testing method | |
| CN110244148B (en) | New energy automobile dynamic working condition EMI testing method based on FFT and point frequency scanning | |
| CN209400134U (en) | Automobile environment-protection exhaust pollution analyte detection chassis dynamometer integrated correction device | |
| WO2023236672A1 (en) | System and method for determining drift frequency of acoustic vehicle alerting system of electric vehicles running at low speed, and computer device | |
| CN114781466B (en) | Fault diagnosis method and system based on harmonic fundamental frequency of rotary mechanical vibration signal | |
| CN106353616A (en) | System for measuring magnetic field interference from train to trackside axle counter | |
| CN114084764B (en) | Elevator transportation quality detection method and detection system | |
| CN115371801A (en) | Analysis method, test method and device for creep noise of vehicle braking system | |
| CN113607428B (en) | User experience evaluation method for vehicle dynamic acceleration performance | |
| CN115435895A (en) | Background noise measuring method based on probability distribution function | |
| CN103698004A (en) | Near-field tyre/ road surface noise test device | |
| CN203705046U (en) | Near field tyre and road noise tester | |
| CN110569608B (en) | Method and device for determining vibration severity of vehicle-mounted platform | |
| CN111649903A (en) | Method for indirectly measuring aerodynamic drag coefficient by using dynamic model experiment | |
| CN112964480A (en) | Sound leakage testing method for car door sealing strip | |
| CN111308124A (en) | Method for determining time difference of speed measuring sensor of shock tube | |
| CN104807635A (en) | Testing system and method of portable main retarder | |
| Riedelsheimer et al. | Experimental and Numerical Analysis of Sunroof Buffeting of a Simplified Mercedes-Benz S-Class | |
| CN212693061U (en) | Automobile noise source identification device based on acoustic holography method | |
| CN113984392B (en) | Online testing and evaluating method for vibration quality of electric drive assembly system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |