An input current ripple-free flyback-type converter with passive pulsating ripple cancelling circuit

In this paper, a passive pulsating ripple cancelling circuit (PPRCC) is proposed for eliminating the pulsating current ripple of power converters. Special features of the proposed PPRCC include simple, modular structure, and high degree of design flexibility. By integrating the proposed PPRCC, an input current ripple-free flyback-type converter is adopted and analyzed as an example because of its comprehensive utilization in small power rating commercial products. The corresponding operating principle, steady- state analysis, and zero ripple design criteria of the proposed PPRCC are provided. Finally, a 100W laboratory prototype is constructed to verify the effectiveness of the proposed principle. Experimental results show that the resulting peak-to-peak input current ripple is reduced by 96% and nearly 2.83% and 10.23% improvement in efficiency can be achieved by the proposed PPRCC, at 70W and 100W load conditions, respectively.