A simplified approach to the first order approximations of a closed loop, non isolated dc-dc converter with synchronous rectifier circuit behavior by using the ORCAD PSPICE

摘要

In this paper, we present the significance of computer simulation program, such as ORCAD PSPICE, in analyzing, first order approximations of circuit behavior, a closed loop, non-isolated dc-dc converter with synchronous rectifier circuit. Following techniques have been adopted to simplify the process of simulation. They are: (1) Ideal switches are incorporated in the power stage of the converter to eliminate the gate diver requirement which in turn reduces the simulation run time; (2) Diodes are connected in series with switches, which eliminates dead time control circuit, to prevent cross conduction of switches and (3) TL494 Pspice model, which is readily available in library of most of the versions of the ORCAD PSPICE, is employed for pulse width modulation. As an example, non-inverting synchronous buck boost converter is considered for demonstrating the approach. Simulation was carried out for an input voltage range of 6 to 35V and load resistance was varied from 12 to 48 Ohms. Output voltage was regulated at 12V for both input voltage and load current perturbation. Physical prototype was implemented and simulation result was tested for steady state output.