New universal control methods for power factor correction and DC to DC converter applications

Two new methods are described in implementing power factor correction. They are simple, easy to implement, cost effective and provide comparable or better performance over the existing schemes. The first method is a generalization of the nonlinear carrier control method which could be applied to all second order power converters: the buck, boost and flyback power converters with either leading-edge or trailing-edge modulation. Equations are derived for each of these six topologies, and simulation results are presented for the boost power converter with leading-edge modulation. The advantage of using leading-edge modulation is that the RHP zero is eliminated, thus broadening the power converter´s bandwidth. The authors suggest that this generalized technique be called “input current modulation”. The second method is similar to the average current control method employing leading-edge modulation, but sensing of the input voltage information is not required. Slope compensation is achieved by integrating the output of the error amplifier where the slope is controlled by the output level of the error amplifier. This method can be applied to all six topologies mentioned and is called the “input current shaping” technique. The authors implemented a boost power converter with leading-edge modulation on a 2 μm BiCMOS process. Experimental results are provided to demonstrate the robustness of the latter method