Study On The Reduce Harmonic Method Of Mid-frequency Power Transformer Based On Eliminating Dead Zone Current Principle

Intermediate frequency power inductive heating, heating speed, emission small, no pollution, in the foundry industry has basic instead of traditional cupola equipment. At present, the domestic factory mainly produces the most electric furnace parallel resonant intermediate frequency electric stove is given priority to, in recent years series resonant intermediate frequency electric stove is rapidly developing, and with the low voltage into line small six pulse rectifier electric furnace is in the majority, its advantage is rectifier transformer of three-phase380V output voltage can be Shared with other equipment, the manufacturing cost is low; Its defect for energy consumption is higher, transformer into line current5,7times more than the harmonic content, power factor is low. For low voltage into line intermediate frequency electric stove faults, this article through the study of traditional three-phase into line of intermediate frequency electric stove, rectifier circuit analysis and harmonic characteristic, was put forward based on the dead zone of the harmonic current eliminate use principle, and the intermediate frequency electric stove three-phase bridge type all control the main circuit of the rectifier circuit the harmonic use improvement of control circuit design, and simulation validation eliminate harmonic and harmonic use the effect. The following are the major work:(1) The three-phase into line parallel resonant electric furnace system, the main analysis and moderate frequency power main circuit principle and the reasons of the harmonic.(2) Research and analysis of the current passive filter and active filter device, especially introduced the single tuned some characteristics of the passive filter, analyzes their advantages and disadvantages.(3) Analyze each phase current dead zone causes and to the entire circuit power factor and the influence of the harmonic.(4) Research is put forward by using variable current technology means three-phase eliminating every dead area principle, the equivalent load is linear, can achieve lower harmonic and increase the energy utilization rate role.(5) Rectifier circuit and its auxiliary circuit to control circuit design, so as to realize the eliminate dead zone current lower intermediate frequency power to achieve energy new use of harmonic goal.(6) With auxiliary circuit of the6veins rectifier circuit simulation modeling, and the traditional6veins rectifier circuit for comparative analysis, come to the correct conclusion.