Modelling and analysis of d.c.-d.c. converter using y-parameters

This paper describes an impulse-response method to find the low-frequency y-parameters of d.c. to d.c. switching converters in both the continuous and discontinuous modes. Using an example of a forward converter, the applications of the y-parameters are illustrated by the determination of: the general equivalent circuit; the d.c. output voltage; the critical condition between continuous and discontinuous modes of operation; the equivalent circuit under steady state condition; the transfer function between small change in d.c. input voltage and the resultant change in d.c.output voltage; the transfer function between small change in duty cycle and the resultant change in d.c. output voltage. The y-parameter approach can easily be applied to other types of converter circuits. Its simplicity makes it particularly suitable for more complex types of converters