multilevel flaying capacitor

[davidnu]

hi all
i am trying to simulate a 5 level flaying capacitor inverter and i have problem with the capacitor balancing
i am using 5 level pd-pwm as a control
can anyone have a sequence recommended
thanks in advance

 

[betwixt]

What on Earth is a 'flaying capacitor' ?

Brian.

 

[BradtheRad]

If you are charging capacitors in series, then one is likely to charge to a higher or lower volt level than the others.

The one that shows more voltage swing is under spec. Try adding a cap in parallel with it.

Or you can balance them by altering time constants. One way is to install a low-ohm resistor inline with a cap. Another is to install a high-ohm resistor across it. Either method wastes power of course.

 

[davidnu]

If you are charging capacitors in series, then one is likely to charge to a higher or lower volt level than the others.

The one that shows more voltage swing is under spec. Try adding a cap in parallel with it.

Or you can balance them by altering time constants. One way is to install a low-ohm resistor inline with a cap. Another is to install a high-ohm resistor across it. Either method wastes power of course.

thanks for the quick replay
i have another qu how do i choose the R-L load parameter

 

[BradtheRad]

If your question is how to avoid creating unwanted RLC resonant action...

then choose component values so it will be much slower than the frequency you are already using in the circuit. One-tenth is probably okay as a guideline.

 

[davidnu]

i am trying to understand the right way for getting a sinus wave with normal amplitude in the out put,if i change the value of the incture or the resistor the all wave is change
i am trying to find a formula for this

 

[BradtheRad]

I cannot be sure but I suppose you want to find values for an LC tank circuit?

Link discussing LC resonance, with formula for frequency:

https://www.allaboutcircuits.com/vol_2/chpt_6/2.html

As for the spread between the Farad value and Henry value, choose values which provide matching impedance to neighboring resistance.

XL = 2 * Pi * f * L

XC = 1 / ( 2 * Pi * f * C )

 

[davidnu]

thanks
but i am looking specific for the flying capacitor designed and in this case the simple formula doesn't work