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 derived for the average input current stabilization and tracking problems in derived DC-to-DC power supplies of the buck and boost types. The stabilization problems are solved on the basis of steady-state considerations about the current 'ripple' and exactly discretized nonlinear models describing the sampled PWM regulated input current trajectories. In the boost-derived converter, the stabilization problem leads to an implicit 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 basis of discrete-time, non-kalmanian state representation models describing the average PWM regulated input current. These generalized state models naturally allow for explicit dynamical, rather than static, feedback regulators. Computer simulations, including unmodelled load variations and external stochastic perturbation inputs, are presented which test the robustness of the proposed PWM controller performances.