An Improved Modulation of the Selective Harmonic Elimination Controlling

Abstract

In the application of the traditional selective harmonic elimination technique, the lowest un-eliminated harmonic and the total harmonic distortion factor are obviously enlarged usually, which would do great harm to the power system. In order to solve the problem, this paper presented an improved harmonic elimination technique. In this new technique, a new circuit topology is proposed and only a small additional direct current source is added. In the time of eliminating the selected harmonics just like the traditional SHE-PWM technique, the system total harmonic distortion factor will reduce greatly, and the switching frequency in the circuit is only half of the traditional SHE-PWM technique, so the system performs better and the latter filter circuit could be of small size. In the analysis, it is clear that the traditional selective harmonic elimination is only a special example of the improved harmonic elimination technique, so the improved harmonic control technique will be more flexible and have better behavior than the traditional selective harmonic technique. In the end, the Fourier analysis in an example validates the feasibility of the improved harmonic elimination technique.