A Theoretical Analysis of Sideband Harmonics on the Inverter DC-link Current for an Electric Railcar

Abstract

The harmonics of the return current may interfere with the signaling current along with the rails. In this paper, we present the theoretical studies of the return current harmonics in the inverter-controlled DC electric railcar, aiming at contributing future work to improve the compatibility with the signaling current.We theoretically derive sideband harmonics of the DC-link current. Then, in order to verify the theoretical study, we experimentally measure the harmonics and numerically simulate the harmonics. As a result, we concluded the theoretical DC-link current is enough accurate to be utilized for the future improvement of the inverter harmonics current.

A Study of the Commercial Frequency Component and Doubled Component on the dc Side of Three‐Phase Rectifiers and Their Influence on Electric Railways

“…Track circuit malfunctions of this sort are caused by current components of the same frequency flowing in the return rails when they exceed the permissible limit. Such frequency components can also be produced by inverter‐controlled railcars, but this case has already been studied theoretically . Commercial‐frequency or doubled‐frequency components induced from power converters located within a dc‐fed section are also of interest, and since these issues have not yet been addressed, and thus we focused on investigating them.…”

<b>Development of Estimating Method of Low-frequency Return-current of DC Electric Railcar</b>

“…However, no theoretical analysis methods exist for low-frequency currents, while several theoretical analysis methods exist for estimating harmonics using switching function [1,2]. This paper describes a method for estimating the array (frequency and amplitude) of low-frequency return currents on DC electric railcars.…”