Full time-domain electromagnetic interference measurements and applications
This thesis presents a technology that has been called the Full Time-Domain Electromagnetic Interference measurement systems and its applications. Full TDEMI measurement systems are an implementation of an FFT-based receiver that enables the usage of oscilloscopes for EMI measurements. They follow t...
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| Format: | doctoral thesis |
| Status: | Published version |
| Publication Date: | 2018 |
| Country: | España |
| Institution: | CBUC, CESCA |
| Repository: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/587194 |
| Online Access: | http://hdl.handle.net/10803/587194 https://dx.doi.org/10.5821/dissertation-2117-120990 |
| Access Level: | Open access |
| Keyword: | Àrees temàtiques de la UPC::Enginyeria electrònica 621.3 |
| Summary: | This thesis presents a technology that has been called the Full Time-Domain Electromagnetic Interference measurement systems and its applications. Full TDEMI measurement systems are an implementation of an FFT-based receiver that enables the usage of oscilloscopes for EMI measurements. They follow the virtual instrumentation approach for transforming oscilloscopes into a compliant CISPR 16-1-1 receiver. Full TDEMI measurement systems have been assessed for characterizing their performance using waveform oriented calibration procedures that bridge the gap between direct measurements in the time domain and the processed frequency domain magnitudes. As a result, the conformity of Full TDEMI receivers is attested with respect to the requirements defined in the standards. Full TDEMI systems have advantages over the conventional swept receivers for performing challenging measurements typical of EMI assessments. Time-domain captures enable full spectrum measurements that allow analyzing transient phenomena. The number of channels available in most oscilloscopes enable synchronous measurements that allow recording the EMI using a combination of transducers. Some of the applications of the multichannel EMI measurements are the single stage evaluation of the conducted EMI of all the EUT mains lines, the instantaneous measurement of the common-mode and the differential mode voltage noise, the concurrent conducted and radiated EMI measurements, and the parallelization of multi-antenna radiated emissions testing. Such alternative test methods, have improved the EMC testing process in a variety of industries by reducing the time and the efforts required for performing a complete EMI evaluation due to the following reasons. First, Full TDEMI measurements deliver faster results because the interferences' spectrum is simultaneously estimated for all the weighting detectors. Second, the number of measurement iterations is reduced because of the multichannel possibilities and also because of an agile identification of the worst case emissions. Thirdly, Full TDEMI measurement system are a cost-effective alternative to the real-time spectrum analysers. Full TDEMI measurement systems have extended the state-of-the-art with the expected maximum detector and the empirical interference decomposition. The expected maximum detector is a statistical measure of the most probable level of the peak emissions that is based on a time-frequency modelling of the measured EMI using the extreme value theory. Using the variability information of the EMI level at each frequency bin, the expected maximum detector estimates the equivalent max hold value of a random EMI. The expected maximum detector also provides a model for quantifying the uncertainty of peak detector measurement of stochastic EMI. The Empirical Interference Decomposition is a modified implementation of the Hilbert-Huang transform with time-gating capabilities that allow a heuristic determination of characteristic oscillatory patterns without neither domain transformation nor a predefined set of basis function. The EID has been used successfully for ambient noise cancellation purposes during outdoor EMI measurements, obtaining more than 20 dB of attenuation of the usual broadcasting signals. The fundamentals of the ANC by means of EID is the identification, in the time and in the frequency domain, of intrinsic modes of emissions that area attributable to the EUT while subtracting the residual modes from the measurement results. Applications of the Full TDEMI measurement systems have been published in recognized conferences and journal. From the reasons mentioned before, the Full TDEMI measurement technology has advantages for EMI testing, analyzing and troubleshooting. It provides a complementary approach to the typical measurements entirely focused in the frequency domain and it exhibits a level of maturity that could allow it to be standardized in forthcoming years. |
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