Modelling and measurement of high‐frequency conducted electromagnetic interference in DC–DC converters

Abstract

Abstract-Conducted EMC noise qualification tests are normally carried out after a prototype has been designed, built and tested and the process is repeated in the event of non-compliance. The ability to determine compliance with EMI standards at the design stage is therefore desirable. This paper will present conducted EMC noise modelling and measurement techniques, yielding simulated and measurement noise results accurate enough to serve as a prequalification test at the design and prototyping stages respectively.Accurate models of the power feed-line connecting the LISN to the DUT (converter), including the load are developed. Predictive conducted EMC modelling is accomplished using detailed active level 3 SPICE-based models, creating a real-time circuit model consisting of a complete converter in its operational state, without the need to separate into equivalent models. Effects of the power feed-line length on EMI noise measurements are investigated as currently available literature has not dealt adequately with this issue. To detect possible radiating frequencies that might emerge with the conducted noise and are detectable in the conducted emission test, results have to be accurate not just in the prescribed frequency band, but all the way up to 100 MHz. The modelling and measurements are performed using software and instruments available in a development laboratory.

Switching converter EMI conduction modelling and verification

“…Equations (2) and (5) are used to separate the noise voltage of the LISN port, which are given in [2][3][4]. However, in some literature, the expression of U DM is…”

“…The authors of [2] propose the circuit analysis method but ignore the device's influence on ground distribution parameters and power feeders. In [3], the conducted emission test can be extended to the very high‐frequency band based on the High‐Frequency Linear Impedance Stabilisation Network, which helps to investigate the radiation effects of the switching power sources, but it does not propose the modelling method. Rondon Pinilla et al [4] used a high‐precision full‐link model to test EMI in the 30 MHz range but does not consider the effects of power feeders and loads.…”

“…This impedance measurement method provides a complex high‐order model and analysis process but has no actual test verification. With the development of computer technology, the accuracy of conducting EMI based on impedance model [3, 4] and SPICE simulation [4] is gradually recognised. Consider the drawbacks of the different approaches, hence comes the need for advanced EMI analysis and inhibitory techniques for correctly calculating and modelling, which is the main motivation for initiating this Letter.…”

Study on Emi Analysis and Inhibitory Techniques for Switching Converter Devices

“…The input signal of the noise separator circuit is the noise voltage from the live line and the neutral line in the LISN, and the output signal of the circuit is the common mode (CM) or differential mode (DM) noise component [9,10]. The differential mode output is connected to the spectrum analyzer, and the common mode output terminal is connected with 50 Ω matching impedance [11]. Conversely, if common mode noise is measured, the common mode output terminal is connected to the spectrum analyzer, and the differential mode output terminal is connected with 50 Ω matching impedance [12].…”

Automatic EMI Filter Design for Power Electronic Converters Oriented to High Power Density

“…Therefore, EMI attenuation solutions are necessary to ensure both the reliability and the electromagnetic compatibility of the system of which the power electronic converter is a part. In particular, EMI filtering is required to ensure the compliance with the emission limits imposed by the stringent technical standards [3][4][5][6][7][8][9][10][11][12], and behavioral models of electric motors can also be used to predict conducted interferences [13]. It is worth noting that electromagnetic compatibility and power density in power electronic converters are closely related issues.…”