Abstract: The improved SWISS rectifier has the advantage of eliminating the commutation dead time without introducing active devices. However, the introduction of LCL filter has the problems of difficult parameter selection and current distortion caused by resonance. In this paper, for improving the SWISS rectifier, the relationship between the network-side current distortion and oscillation problems and the damping coefficient of LCL filter is analyzed, the LCL filter transfer function is constructed, the Bode diagram with different damping is compared, and a genetic algorithm passive damping parameter optimization method with minimized inductance ratio, maximized harmonic attenuation and minimized power loss of the objective function is proposed. The simulation results show that the improved SWISS rectifier front-stage LCL filter network side current harmonic content is significantly lower than the traditional trial-and-error method, the overall dynamic performance of the system is better, moreover, the parameters obtained from the global optimization of genetic algorithm have good convergence,and to some extent, the problem of choosing LCL filter parameters is solved because of the tedious steps.

Key words: improved SWISS rectifier, passive damping parameter optimization, genetic algorithm