Reduction of harmonics in grid-connected inverters using variable switching frequency

• The variable switching frequency is determined by using GA technique.
• Current THD reduces significantly when compared with the constant switching cycle.
• The spectrum of the proposed method is spread in a wide range.
• The simulation and experimental results validated the performance of the technique.

The increasing application of distributed power generation into the power system makes grid interconnection requirements of power quality more and more stringent. The reduction of current total harmonic distortion (THD) of grid-connected inverters to achieve the grid code by increasing of switching frequency in PWM of inverters is one of the popular methods, but this increases the switching loss. The aim of this paper is to propose a PWM technique with the function of variable switching cycle to reduce the current harmonics in grid-connected inverters. The weights of this function are determined by using a genetic algorithm under the constraint of constant switching loss. The simulation and experimental results of the proposed technique as well as the conventional constant technique are given and compared, which validate the performance of the proposed technique.