Research On The SHEPWM Technique Based On Improved Artificial Fish Swarm Algorithm

With the rapid development of power electronic technology, inverter system is more widely used in the field of high power traction, AC/DC speed control, uninterruptible power supply and solar photovoltaic power generation. Consequently, inverter modulation strategy is becoming a research hotspot. However, the limitations of PWM modulation method make a big harmonic pollution problem. Especially in the field of high demand of switching loss, electromagnetic compatibility and waveform quality, to restrain the harmonics of inverter output has become the main topic of the study. This paper makes research on the SHEPWM, which has better effect to suppress harmonic, on the basis of the study of various modulation strategies.The difficulty of the implementation of SHEPWM lies in the solution of the selective harmonic elimination equations. The main solution methods are the traditional numerical method and intelligent algorithms. Traditional numerical method relies on the appropriate selection of the initial value. Intelligent algorithms such as genetic algorithm and differential evolution algorithm are easy to fall into local extreme, which affect the precision of solution. This paper puts forward artificial fish algorithm for solving the selective harmonic elimination equations, and expounds on the solving process of the artificial fish algorithm. In view of the lacking contact beyond the visible range limitation of artificial fish individuals, this paper introduces the difference mutation operator into improved artificial fish algorithm. Since there are many artificial fish algorithm parameters, this paper makes research and analysis for the influence of mobile step, visible rang, crowding factor and the difference mutation operator. Finally this paper makes simulation analysis and experimental research according to the results of the improved artificial fish algorithm.In this paper, the improved artificial fish algorithm is compared with other intelligent algorithms, proving its superiority in solving the problem of harmonic elimination. Applying improved artificial fish algorithm for different number of switching angles with selective harmonic elimination simulation model, makes it able to control the fundamental wave according to the modulation degree and effectively eliminates the harmonic of the specified frequency, proving the correctness and effectiveness of the improved artificial fish algorithm. According to the analysis of the improved artificial fish algorithm parameters, this paper selects better mobile step length, visible range and finite differential mutation strategy as solving parameter. It verifies the effect of the selective harmonic elimination modulation strategy based on improved artificial fish algorithm under different frequency and different number of switching angles on the two-level inverter power system.