Control art of switch-mode converters

This dissertation is on control methods of switch-mode power converters.; This first part (chapter 2) of the thesis presents a general pulse-width modulation (PWM) circuit that is applicable to various constant-frequency control methods available nowadays. A general small-signal model is presented that simplifies the small-signal modeling of switch-mode converters when the general modulator is applied. Unified feedforward, current-mode with linear or non-linear compensation slopes, and some power-factor-correction (PFC) control methods are used as examples of how to apply this general PWM modulator.; The second part (chapter 3) of the thesis is on control methods for rectifiers with PFC. A family of controllers for continuous-conduction-mode (CCM) PFC rectifiers based on the general PWM circuit is presented. These controllers are simple but the performance is equivalent or even better than previously proposed methods. The variety of these controllers provides choices for designers to optimally fit their applications. The performance is analyzed in a boost converter example and verified in four experimental circuits of different control methods and power converter topologies. Another controller is presented to eliminate the current distortion that exists in some DCM PFC rectifiers. This DCM PFC rectifier illustrates how a controller is simplified by adopting the general PWM modulator, compared to methods presented in other papers. This chapter also provides analysis of some common properties of single-stage PFC rectifiers and then presents a topology that achieves PFC rectification, galvanic isolation, and fast output regulation in a single stage.; The third part (chapter 4) of this thesis presents an extension of the one-cycle control for switch-mode audio power amplifiers. This new control method for switch-mode amplifiers has the features of simplicity and robust performance (such as the high power-supply ripple rejection, automatic switch error correction, and fast dynamic response). An instability problem, encountered in the development of the control method, is analyzed and solved. Various implementations of this technique are discussed and experimental results on a half-bridge as well as a full-bridge amplifier are presented to vaildate the concept. This control method is patented.