Switching regulator configurations and circuit realizations

Methods for obtaining improved performance from switching regulators with respect to their noise generation characteristics and dynamic response are developed through topology selection, refinement and generation, and by application of modern control techniques to both continuous and discrete time converter models. Reduction in switching noise is attained by focusing analysis and design effort on rendering the external converter current waveforms as near to the ideal dc quantities as possible. Three techniques, not relying on conventional low-pass filtering, are promoted and several new or refined converter topologies are generated with these methods. In addition, a power-processing elliptic-function filter specifically designed to meet the requirements of the switching conversion environment and applicable to many common converter types is presented. Performance of the new low-noise converter topologies is substantiated by several circuit realizations and laboratory measurements. Switching regulator dynamic performance is optimized by use of modern control theory in conjunction with the state-space-averaging technique. State-vector feedback coefficients which will minimize transient error excursions are determined through use of generally applicable algorithms for optimal linear regulator design. An alternative approach is developed that relies on a discrete-time formulation of converter and regulator that is the dual to state-space-averaging. Among the important results are a simple expression for duty-ratio-controlled inductive current bandwidth of wide applicability, and a general solution for obtaining the fastest possible transient response from a switching regulator. The results of the control analysis are convincingly supported with laboratory measurements.