Abstract: According to the analytic results of the paper, the operating characters of the forward converter based on LC series resonance magnetic recycle (without magnetic recycle winding) are totally and perfectly showed with both of family of the equivalent curves of the parameters (Vm/E and Toff/LC) in the plane of taking T/LC as horizontal axis and D as vertical axis. The figure has importantly theoretic significance and practical value, because it can make the designer estimate intuitively the operating characters according to the values of the parameters T, L, C and D, and can be used to determine the values of the parameters T, L, C and D based on the operating characters requested beforehand.

Key words: forward converter, phase plane analysis