Buck converter controlled by using variable switching frequency technique

In this paper, a linearly tunable voltage controlled oscillator with negatively proportional characteristic, termed VCOTheta, is described. Using the VCOTheta and analog PI controller in feedback path of a buck converter operating in continuous condition mode, a control technique with variable switching frequency is presented. No filtering capacitor is required in the proposed technique that provides the advantage of a simple and compact structure. Experimental results show that the output voltage ripple can be reduced. The output voltage regulation can be also kept in constant without stability problems.