phase shifted full bridge controller for qcw
Gregory, Mon Mar 04 2013, 04:16AMRe: phase shifted full bridge controller for qcw
ScotchTapeLord, Mon Mar 04 2013, 11:54AM
Looks like regular ol' PWM to me. Should work though.
Be careful not to make the same mistakes I made. Be sure to do the math with switching losses, or just use switches similar to FGH60N60SMD because I was planning on doing something similar with slower switches but the math didn't work out (way too much power dissipation).
ScotchTapeLord, Mon Mar 04 2013, 11:54AM
Looks like regular ol' PWM to me. Should work though.
Be careful not to make the same mistakes I made. Be sure to do the math with switching losses, or just use switches similar to FGH60N60SMD because I was planning on doing something similar with slower switches but the math didn't work out (way too much power dissipation).
Re: phase shifted full bridge controller for qcw
Gregory, Mon Mar 04 2013, 06:44PM
I will use fgh60n60smd they are chip and the best for this type of aplication. its the old regular pwm but the ramp generator is synced with feedback
Gregory, Mon Mar 04 2013, 06:44PM
I will use fgh60n60smd they are chip and the best for this type of aplication. its the old regular pwm but the ramp generator is synced with feedback
Re: phase shifted full bridge controller for qcw
Steve Ward, Thu Apr 25 2013, 05:59PM
Looks good Gregory! Looks like you did it all with basic logic ICs? Theres no reason that cant work just fine, but i do find CPLDs to be much nicer than a pile of chips
.
I notice some small distortions in the pulse-width length, are you using some clocking for the PWM logic that is asynchronous with the feedback signal?
Good luck with the rest of the project. These QCW coils are a lot of fun for indoor coiling... so quiet and so little ozone, yet so powerful.
Steve Ward, Thu Apr 25 2013, 05:59PM
Looks good Gregory! Looks like you did it all with basic logic ICs? Theres no reason that cant work just fine, but i do find CPLDs to be much nicer than a pile of chips
. I notice some small distortions in the pulse-width length, are you using some clocking for the PWM logic that is asynchronous with the feedback signal?
Good luck with the rest of the project. These QCW coils are a lot of fun for indoor coiling... so quiet and so little ozone, yet so powerful
.Re: phase shifted full bridge controller for qcw
Gregory, Mon Apr 29 2013, 02:39AM
Thanks Steve! The distortion is because in this video I was using the signal generator to generate the ramp and it wasn't in perfect sync with the system. I will be using a atmega to generate the ramp signal clocked with the start pulse. I'm wainting for the pcb return from OSH park to start the real tests!
I'm using only basic logic ICs as a simple puzzle, it appears to works great and for me was very fun create the circuit.
I will come back with more results. Thanks!
Gregory, Mon Apr 29 2013, 02:39AM
Thanks Steve! The distortion is because in this video I was using the signal generator to generate the ramp and it wasn't in perfect sync with the system. I will be using a atmega to generate the ramp signal clocked with the start pulse. I'm wainting for the pcb return from OSH park to start the real tests!
I'm using only basic logic ICs as a simple puzzle, it appears to works great and for me was very fun create the circuit.
I will come back with more results. Thanks!
Re: phase shifted full bridge controller for qcw
Linas, Mon Apr 29 2013, 03:48AM
Try to use UCC3895 pwm from TI. Fore some reason i couldn't make it work for my X-ray supply.
SG3525 works with no problem .
DataSheet
Linas, Mon Apr 29 2013, 03:48AM
Try to use UCC3895 pwm from TI. Fore some reason i couldn't make it work for my X-ray supply.
SG3525 works with no problem .
DataSheet
Re: phase shifted full bridge controller for qcw
Gregory, Mon Apr 29 2013, 04:01AM
UCC3895 is real great PWM controller. but the shift concept of a qcw is a bit diferent. I will only tur off one of the half bridge first, and the diodes will sustaing the voltage to create the shifting. I choosed turn off because the turn off of IGBTs appear to be a lot lower than turn on. A bit of capacitance que be use to help the transition state. A kind of class DE switching.
Gregory, Mon Apr 29 2013, 04:01AM
UCC3895 is real great PWM controller. but the shift concept of a qcw is a bit diferent. I will only tur off one of the half bridge first, and the diodes will sustaing the voltage to create the shifting. I choosed turn off because the turn off of IGBTs appear to be a lot lower than turn on. A bit of capacitance que be use to help the transition state. A kind of class DE switching.
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