A Flexible Supraharmonic Group Method Based on Switching Frequency Identification

Abstract

The extensive use of power electronic devices has led to supraharmonic issues.The concept of harmonic groups has been widely used to minimize energy leakage. Moreover, the distribution of supraharmonics is related to the switching frequency of harmonic sources. Given the diversity of switching frequencies and emissions distribution, harmonic groups need to be flexibly adjusted. A switching frequency identification method based on correlation analysis is proposed in this work. In addition, the switching frequencies of supraharmonic sources are identified through a correlation analysis of the supraharmonic emissions of a measurement point. Furthermore, a flexible supraharmonic group method in which bandwidth can be adjusted according to switching frequency is proposed. This method can avoid inconsistency between the emissions and group centers and minimizes energy leakage successfully. Finally, the method is validated via simulation and test data.

A Quantification Method for Supraharmonic Emissions Based on Outlier Detection Algorithms

“…Furthermore, the frequency error corresponding to the maximum amplitude should also be considered. The formula for calculating the relative error of the maximum amplitude (δ m ) and frequency error (∆ f ) is shown in Equations ( 9) and (10).…”

“…To improve the accuracy of the frequency and amplitude of the measurement results, some scholars have investigated this issue from the perspective of the frequency domain. In [10], a variable bandwidth grouping method was introduced based on the switching frequency. Compared with the fixed 200 Hz bandwidth, this method could reflect the amplitude and frequency of supraharmonics more accurately.…”

Harmonic and Supraharmonic Emissions of Plug-In Electric Vehicle Chargers

“…As most supraharmonic emission sources are switching power converters with emissions mostly of the pulse-width-modulated (PWM) type, attention must be paid to the width of each PWM carrier (or switching frequency multiple k f s ) and the side bands, spaced by even multiples of the modulation frequency m f m . Each switching+modulation PWM group of components is characterized by some amount of power that spectral grouping should try to capture and preserve in the resulting representation [62]. From this, the exigency to set B to a value bracketing most of such side-band components belonging to the same PWM group.…”

“…From this, the exigency to set B to a value bracketing most of such side-band components belonging to the same PWM group. However, such justification should be accompanied by the determination of the switching carriers and their harmonics, so as to align the grouping bandwidth B [62], which complicates spectrum evaluation; • In a scenario of several EV chargers of the same type, whose emissions overlap with plausible shifts of the switching frequency due to normal tolerance of components and settings and related drift over time, a sufficient bandwidth value should be set to correctly compose alike spectral components and observe the expected compensation, if phase displacement occurs. This is demonstrated in [63], where a 1 kHz bandwidth puts together slightly different peaks around the nominal 10 kHz switching frequency, resulting in mutual compensation, although beating phenomena also take place.…”