Analysis Of The Harmonics Of High Power Frequency Converters

With the increase demand of electricity continually, it is expected to develop higher distribution voltage grade in our country and developed countries, focusing on reducing the transmission loss. And the main trend in our country is to develop 10KV voltage grade main distribution circuit and corresponding high voltage AC motor. The topology and harmonic suppression technology of high voltage and large capacity converter have been a focus of study and concern since modern times.Scholars home and abroad with the aim of reducing the input and output harmonic, have carried out in depth studies to the high power converter topology and control methods. So far, high power variable-frequency technology has not formed the unified structure and control plan, each kind of plan structure, the principle and input output harmonic frequency spectrum also are different from each other.High power variable frequency converter topologies are summarized in the paper, then the paper has analyzed the structure, working and characteristics of various topologies. Taking the multi-pulse rectifier technology as study object, the harmonic suppression technology of high power converter input, which is also known as the rectifier circuit, are proposed, and have analyzed the net-side current harmonics thoroughly. Several kinds of converter output topologies are also presented, including transformer-coupled output, multi-level and multiple structures, and have some detailed analysis about the inverter output harmonic, and also provided harmonic content of each kind of inverter circuits without other filter.In this paper, the comparison between harmonics of high power variable frequency converters and IEEE-519 standard are made. And the harmonic feature of each converter are showed, it will provide an important reference to choose high power variable-frequency technology plan in the project application.