Nice video, thank you! One thing: passing from inductor to transformer I would say the coupling should be good in the sense that it should be low enough to show the same stray inductance.
@texasinstruments can I configure to SEPIC provided turn ration is 5:1 the reason here is that the ringing noise is very hard to eliminate. Also is single buck inductor is less noisy than flyback, and if so can I use it to convert 270DC to 12VDC 1 Amp
i have already designed my own linear regulators with mathematical analysis . My next step is buck converters and im so excited of its mathematical analysis and waveforms because i will apply calculus .
Why do you need "Calculus" ?. The current in the inductor is simply. V/L x t. Volts, Henry, second, amps, while the switch is ON, but when it turns off the current cannot stop instantly, and the resulting voltage will depend upon what path is available for the current to decay in. With nothing connected, this will be the tiny stray capacitance, so a damagingly high sinusoidal voltage spike will result. But if the diode is round the right way, it will provide a path, and the current will decay approx. linearly.
Turns ratio 5:1 doesn’t work for SEPIC because voltages at drain/anode have to be balanced to cover leakage energy, BUT if you connect the SEPIC capacitor from first winding at primary (counted from drain) to anode, this will work. Another possibility to get rid of ringing from a poor transformer is an active clamp flyback topology. Easiest way is to build a well-coupled transformer with leakage inductance 0.1%-0.5% max, resulting in less leakage energy & less ringing without additional costs.
Does the turns ratio depend upon the input given? If we don't use different no.of turns for secondary and primary winding then how does the voltage gets boosted in Modified SEPIC with magnetic coupling.
At switch-off the current in the coil cannot stop instantly. Same as a mechanical mass, so the force, voltage, depends upon the impedance it finds to flow through. It can cause a very high voltage sinusoidal pulse if the impedance is a small capacitance, stray C being Minimum possible. If the diode is round the right way, the peak will depend upon what load is connected. The guy explained non of this, yet people are rating this as helpful !.
a bit too quick on the sepic configuration. As it is the most complex schematic, an explanation about what's going on over an on/off cycle would have been nice.
He gives no description of what actually happens during an on-off cycle at all ! He doesn't point out that the half of the cycle that energy is transferred on, depends upon which way round the diode goes. He points out no reasons for anything, just idiotic statements. And he sounds like his pants are two tight. But apart from that, "Very Naice".
