A novel strategy of the high power PWM inverter with the series active filter

Abstract

It is generally known that the low voltage switching power devices, which have fast and low loss switching characteristics, are difficult to apply to high voltage and high power inverters. Therefore, the problem that large harmonic current contained in the inverter output is pointed out. In this paper, a novel control strategy of a high power PWM inverter combined with a series active filter is presented. In the proposed high power PWM inverter, low speed and high voltage switching devices, such as high voltage IGBT, are applied. An LC filter is installed in order to eliminate the harmonic components of which the frequency is at around the modulation frequency of a high power PWM inverter. In the proposed system, a fundamental component is controlled by a high power PWM inverter by means of feedback control, and the harmonics component is controlled (cancelled) by a series active filter. By installation of the LC filter in the output of a high power PWM inverter, the oscillatory response in the current loop of a high power inverter occurs. In this paper, in order to control this oscillatory response, the new control strategy of a series active filter is presented.