Повышение энергетических показателей трехфазного тиристорного преобразователя для устройств электронагрева

Abstract

В работе проанализированы схемы трехфазных тиристорных преобразователей переменного напряжения для регулирования мощности в устройствах электронагрева. Произведено сравнение их энергетических показателей. Для трехфазного преобразователя предложен новый способ оптимального управления. Суть предложенного способа состоит в том, что для обеспечения заданной мощности в нагрузке, формируется такая комбинация углов управления силовыми ключами, при которой обеспечиваться наилучшее из возможных значений того или иного энергетического показателя.Various schemes of three-phase thyristor AC voltage converters for power control in electric heating devices are analyzed in paper. The peculiarity of the considered converters is that the phase and line voltages of the three-phase mains supply are used together to control the power in the load (phase-by-stage regulation). Comparison of their energy parameters, which assess the electromagnetic compatibility of the converter with the power supply system, has been made. It is shown that such converters havea higher power factor, the value of which also significantly depends on the method of controlling the power switches. For a three-phase converter, in which each phase voltage was simultaneously combined with twolinear - leading and lagging, a new optimal method control was proposed. The essence of theproposed method is that in order to ensure a given power value in the load, such a combination of the control angles of the power switches is formed, at which the best possible value of one or another energy parameter is ensured. The results of studies of changes in energy parameters as a function of active power in the load while optimizing the power factor, shear factor and distortion factor are presented. Researches have shown that the method of optimal control of a three-phase AC voltage converter is especially useful at high load powers with a large thermal time constant.