Analyzing of voltage-source selective harmonic elimination inverter

In this paper, the selective harmonic elimination (SHE) technique is investigated to eliminate harmonic brought by PWM inverter. This technique involves the solutions of nonlinear, transcendental equations set representing the relation between the amplitude of fundamental wave and each order harmonic and the switching angles. Newton iteration method is usually applied to solve the equations set, but the convergence depends on the selection of initial value. By using a trial method, the rule is found for many initial values of voltage-source SHE inverter, thus many solutions of switching angles can be obtained. Numerical simulation is conducted to obtain the value of the switching angles in the specified amplitude of fundamental wave and tracks of switching angles changing with the amplitude of fundamental wave. According to the switching angles obtained, the value of each order harmonic and total harmonic distortion for i (THD_i) in the specified amplitude of fundamental wave and their tracks changing with the amplitude of fundamental wave are obtained. The variable voltage variable frequency (VVVF) of a voltage-source SHE inverter is also studied to lay a foundation for the design of the voltage-source SHE inverter. Experiment of the output waveforms of the voltage-source SHE inverter has been conducted to validate the correctness of the theory analysis.