I hate to be asking this, but I just don't understand the operation. I've been reading various resources, mostly this: http://services.eng.uts.edu.au/~venkat/pe_html/ch07s1/ch07s1p1.htm though. From what I understand, when the voltage source is connected to the circuit, current flows through the circuit like so:
When this is happening, presumably the capacitor is being charged as well. But even at this point I seem to be misunderstanding: surely the load receives the input voltage as well? So even if you wanted the load to receive say 20V stepped down from 120V, when the source was connected at least, there would be 120V across it. Surely this could damage components rated for 20V? I suppose with PWM you could minimise the time that the load was exposed directly to the input voltage to negligible times, but I'm not sure. I'd just really appreciate it if someone could clear up my confusion about this.
In terms of general operation: one way I can think of the buck converter working is if the capacitor is charged to the 'Output' voltage and then the inductor is used to keep the capacitor near this voltage during the presumably much longer off cycles?