Steady-state modeling of a phase-shift PWM parallel resonant converter

Purpose – To derive an analytical model for a dc-ac-dc parallel resonant converter operating in lagging power factor mode based on the steady-state operation conditions and considering the effects of a high-frequency transformer. Design/methodology/approach – A range of published works relevant to dc-ac-dc converters and their control methods based on pulse-width-modulation technique are evaluated and their limitations in output measurement of higher output voltage converters are indicated. The circuit diagram of the converter is described and the general mathematical model of the system is obtained by deriving and combining the mathematical models of the different converter blocks existing in the system. The derived mathematical model is used to study the steady-state and transient performance of the converter. The deriving procedure of the analytical model for a parallel resonant converter is extensively given and the analytical model obtained is verified by simulation results achieved using MATLAB/SIMULINK and the program written by the authors. Findings – The paper suggests an analytical model for dc-ac-dc parallel resonant converters. The model can be used in the output voltage estimation of a converter in terms of its phase-shift angle and the dc-link voltage. Research limitations/implications – The resources in the library of the authors’ university and also the English resources relative to dc-ac-dc converters reachable through the internet were researched. Practical implications – The analytical model suggested can be used in estimating the output voltage of the converters used in high-voltage applications or where there are difficulties in employing sensors in measurement of the output voltage due to high price or implementation problems. Originality/value – The originality of the paper is to present an analytical model for dc-ac-dc parallel resonant converters. Using this model makes it possible to estimate the output voltage of the converter using the dc-link voltage and the phase-shift angle. The proposed model provides researchers to regulate the output voltage of the converters using feed-forward control technique.