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论述在直流供电的地铁系统中,逆变器的回流电流与信号电流都在回流轨中传输,回流电流中的谐波含量势必会对信号电流的传输造成影响。介绍以往在现场测试中对这种影响所进行的评估分析,认为相对于干扰因素较多的现场实测来说,对回流电流谐波的含量进行理论推导更具有普遍意义及可信性。为给谐波对信号的干扰研究提供理论帮助,采用开关函数原理,推导逆变器回流电流的数学表达,并通过仿真验证了数学推导的正确性。
Discussion DC power supply in the subway system, the inverter back current and signal current are transmitted in the return rail, the harmonic content of the return current will inevitably affect the signal current transmission. This paper introduces the assessment and analysis of this kind of influence in on - the - spot test in the past, and thinks that it is more universal and credible to carry on the theoretical deduction to the current harmonic content of the return current relative to the field measurement with more interference factors. In order to provide theoretical help for the research on the interference of signals by the harmonic wave, the mathematical expression of the inverter’s return current is derived by using the principle of the switch function. The correctness of the mathematical derivation is verified through the simulation.