Single-ended forward converter circuit with RC and diode clamp circuit

The single-ended forward converter has a demagnetizing winding and a diode clamp circuit. What we talked about above is the one with a demagnetizing winding. The picture shows a single-ended forward converter circuit with RC and diode clamp circuit. After VTl is cut off, winding N1, VD3, R, and C form a single-ended flyback converter. The excitation current IM is attenuated through VD3, and the reverse polarity voltage of N1 is superimposed on the input voltage U1 and applied between the collector and emitter of VTl. , that is, Uce1=Ui+Uc. When the RC time constant is long enough, the voltage Uc on the capacitor C is the current iD3, that is, the decreasing rule of the excitation current Iu is. Obviously, when Uc is greater than U1, the cut-off time is. toff will be less than the conduction time ton, that is, the maximum conduction pulse width can exceed half of the cycle. Since the turn-on pulse width is allowed to be larger, larger power output can be obtained. The disadvantage is that VTl will withstand a higher voltage and the excitation energy will be consumed on the resistor R.