Modulated-Ramp PWM Generator for Linear Control of the Boost Converter's Power Stage

In this paper, the concept of a modulated-ramp pulse-width modulation (PWM) generator is presented. The specific nonlinear behavior of this generator enables an exact linear control-to-output static conversion characteristic of DC-DC switching converters, such as the boost (step-up), buck/boost, Ćuk, or SEPIC, operating in continuous conduction mode. The resulting linearization leads to a significant improvement of the control accuracy and simplification of the converters, operating mainly in the open-loop architecture. In this paper, the concept of the modulated-ramp PWM generator is described, followed by a detailed steady-state and small-signal AC analysis. The key aspects for practical implementation are also highlighted. All results and benefits of the modulated-ramp PWM generator are demonstrated here on the boost converter power stage.