well yes, however pulse after pulse you reach saturation under this condition since the primary current is not being allowed to properly discharge since the diode create a path of low resistance for it to keep flowing and so it wont be able to allow the field to collapse...
that can still be the right way, i´m not saying anything... what i see here is that when i add the diode the core saturates and the voltage drops... when gating the voltage rise again untill it saturates again...
to reset the core the dischage path of the diode should have the same impedance of the power supply at least to allow the core to properly reset during off time...
the diode completely kill the flyback voltage multiplication action too... if you add a resistor of proper value you still have a square wave output top but the bottom may be that of negative exponential of a coil discharging into a resistor...
donald L smith tallks about a resistor that must go in parallel with a primary
basically its value would depend on the frequency to be applied but if its usually greater than the impedance of the power supply that charged the coil it will be already enough to reset the core.... since the time it takes to charge the coil depends also on the load side i guess we might think of it as a whole system..
in my case here i have a 250ohm in parallel with the primary in series with the diode... this give me 1000v when i switch off the primary when there is 4 amps into it...
the power supply i use has around 10ohms to 5 ohms depending on the applied voltage on the variac thats because before the full wave bridge rectifier i have a step down isolation transformer with secondary over rated to have low resistance... so when my variac goes from 0 to 250v the step down makes it from 0 to 100 with up to 10 amps ability i also have a 3 10mf capacitors in series connected to the full wave bridge rectifier output... the dc is isolated from mains ground in my case..the step down transformer is a variac that i took out of the case and wound enough 18awg wire to give 100v feeding from the similar variac... i guess were 120t cant remember...
in my case steve i´m using tvs that limit the voltage of the primary to a predetermined level depending on the current level
a 400v tvs that will develop 400v at 1 amps have than 400 ohms aproximately of resistance... but adding this in parallel wont bring the resistance down much but wold increase so as would increase the amps handling... since a lower current is discharged thru each device it will discharge at a higher voltage at each theretoo a higher resistance for each ...
its essencial in this design to not allow the primary to burn the igbt of mosfet in use..
using the diode in parallel with the primary the voltage during the pulse of at the drain of the mosfet should be a little smaller than the dc supply because of the voltage drop of the diode because of the current from the primary...
