Spectral modeling of switched-mode power converters

A new modeling approach for the spectral analysis of pulsewidth modulated (PWM) converters with independent inputs is developed. The key of this approach is to extend the Volterra functional series to nonlinear systems with multiple independent inputs. After formulating the state-space equations describing the dynamical behavior of PWM converters, the Volterra transfer function characterizing the output frequency response can be obtained, which is then symmetrized to form the spectral model. Since the model is developed in a closed form, it is suitable for computer analysis. The modeling approach has been applied to various PWM converters, and the results are verified. The spectral models of different power converters can readily be obtained by using this general approach.published_or_final_versio

A fast and exact time-domain simulation of switched-mode power regulators

A new approach for the time-domain simulation of switched-mode power regulators is developed. The concept of this approach is to model each switch element by a linear time-varying nodal equation, thus formulating a modified nodal equation system that describes the global dynamic behavior of the power regulator. By using the symbolic Laplace transform inversion, the time-domain expressions can be obtained in a closed and continuous form, which allows a fast and exact simulation of the system. The time efficiency of the proposed approach is shown by comparing it with a standard numerical integration method. Various transient responses of a practical switched-mode power regulator due to the start-up, the step change in input voltage, and the step change in reference voltage have been simulated. The simulations include the overcurrent protection limitation, the duty-cycle limitation control, the discontinuous conduction mode, and the continuous conduction mode of operation.link_to_subscribed_fulltex

Computer-aided modeling of quasi-resonant converters in the presence of parasitic losses by using the MISSCO concept

The DC and small-signal models of quasi-resonant converters, operating in both half-wave and full-wave modes, are developed in a suitable form for computer simulation. The starting step is the extraction of a minimum separable switching configuration (MISSCO) containing all power switches but a minimum number of other components (resonant ones). By using the step-response analysis and average technique, and by perturbing and separating the DC and AC components in the resulting equations, the equivalent models of MISSCO are derived. They are introduced in the converter structure to replace the circuit initially extracted. Models of different quasi-resonant converters can be obtained by this general approach. The analysis takes into account the conduction losses of the switching devices and reactive elements, which improves considerably the model accuracy. Model-based computer simulation agrees with the experimental results.link_to_subscribed_fulltex