DESIGN OF PULSE-WIDTH MODULATION CONTROLLERS FOR STABILIZATION AND TRACKING IN DERIVED DC-TO-DC POWER CONVERTERS

Feedback controllers, based on pulse-width-modulation (PWM), are deriv ed for the average input current stabilization and tracking problems i n derived DC-to-DC power supplies of the buck and boost types. The sta bilization problems are solved on the basis of steady-state considerat ions about the current 'ripple' and exactly discretized nonlinear mode ls describing the sampled PWM regulated input current trajectories. In the boost-derived converter, the stabilization problem leads to an im plicit static nonlinear feedback controller, or duty ratio synthesizer , which requires online solutions of a transcendental equation at each sampling instant. The signal tracking problems are solved on the basi s of discrete-time, non-kalmanian state representation models describi ng the average PWM regulated input current. These generalized state mo dels naturally allow for explicit dynamical, rather than static, feedb ack regulators. Computer simulations, including unmodelled load variat ions and external stochastic perturbation inputs, are presented which test the robustness of the proposed PWM controller performances.