Abstract:
This paper presents a general method for designing the
transformer of flyback switching AC-DC converters based on
nonlinear finite element analysis (FEA) of electromagnetic field
coupled with external circuit. For that, the variation patterns of
the PWM duty ratio and the current flowing through the windings
of transformer versus the input voltage are introduced first, and
then several important principles for the design of the transformer
are given by using analytical method. As the magnetic saturation
and control delay possess heavy influence on the safety of the
operation, a MATLAB/Simulink based simulation model, in which
both the nonlinear differential inductance and the control delay
are included, is built to predict the converter transient
performance. The nonlinear differential inductance is calculated
by a general program of nonlinear 2-D FEA in Matlab/Simulink
surrounding. By running the model, the performances of the
converter with different loads and input voltages are obtained.
Simulation results are in good agreement with theoretical analysis.
