On the mechanism of noise generation in Cuk converter

In the Cuk DC-DC converter the benefit of zero current-ripple, which can be achieved at either input or output or both ports of the converter by using a coupled-inductor, can be lost when the switching noise is large. The noise is analyzed by partitioning the transistor switching intervals into turn-on and turn-off, and analyzing the transient waveforms in each interval using high-frequency equivalent circuits. The noise generation mechanism and the influences of a number of parastic elements on the output noise are quantitatively clarified. In addition, it is found that a large surge is generated in the loop of the transistor, the energy transferring capacitor, and the diode during each occurrence of noise and transmitted to the output port. The output noise voltage of the turn-on noise is larger than that of the turn-off noise. The validity of this analysis is confirmed by comparison with experimental results.<>