|
Ignoring the ugly drive to the MOSFETs, this circuit demonstrates the working of a 2-Switch Forward power supply. This topology is used when the power demand is between 100W-200W. This particular circuit is delivering almost 150W of power to the 1ohm-equivalent resistive load.
This type of circuit is more efficient and powerful that a flyback converter. Flybacks are good only upto around 100W, and are not as efficient as a Forward Converter. In flybacks, a bit of energy is lost in the core of the transformer and in the snubber network. Moreover, if not designed properly, the switching transistor of a flyback can see huge spikes of almost a kilovolt at its drain. Forwards do not see such huge spikes. The input DC voltage is about all it's going to see. Flybacks return some residual power that doesn't make it to the secondary back to the input capacitor, through diodes, decreasing losses and improving efficiency.
If you look at the scope, the frequency of the voltage and current keep jumping up and down. That's the ripple frequency. The switching frequency is a constant 10kHz PWM.
|
