eem2am
Banned
Hi,
I am doing an offline quasi-resonant flyback converter:
I wish to know how to calculate the ripple current in the secondary rail capacitor?
(-or even to know how to calculate the RMS value of the secondary diode current would be fine.)
-the problem is that the load of this flyback is two 5W , hysteretic mode LED drivers (with LM3404 controller)...these switch at about 100KHz.
I am certain that the ripple current seen in the secondary capacitor will vary depending on the relative phasing of the switching of the LED drivers -and also the relative phasing of the switching of the LED drivers with the switching of the flyback.
Do you agree with this?
The reason that i think this, is that i know for a fact that there are such things as IC's which do a boost power factor converter function, aswell as a controller for the downstream flyback, and the switching of these two stages is synchronized to reduce ripple in the capacitor that follows the boost stage.
-so surely the same principle would apply to my flyback and two "downstream" LED drivers?
LM3404 DATASHEET:
**broken link removed**
spec of quasi-resonat flyback:
V(in) = 230VAC
V(out) = 30V
C(in) = 150nF
C(out) = 330uF
Freq switch = ~55KHz, but varies with V(in)
P(out) = 10W
so in summary:
Do you agree that the ripple current in the secondary capacitor will vary depending on the phasing of the LED Drivers' switching?
I am doing an offline quasi-resonant flyback converter:
I wish to know how to calculate the ripple current in the secondary rail capacitor?
(-or even to know how to calculate the RMS value of the secondary diode current would be fine.)
-the problem is that the load of this flyback is two 5W , hysteretic mode LED drivers (with LM3404 controller)...these switch at about 100KHz.
I am certain that the ripple current seen in the secondary capacitor will vary depending on the relative phasing of the switching of the LED drivers -and also the relative phasing of the switching of the LED drivers with the switching of the flyback.
Do you agree with this?
The reason that i think this, is that i know for a fact that there are such things as IC's which do a boost power factor converter function, aswell as a controller for the downstream flyback, and the switching of these two stages is synchronized to reduce ripple in the capacitor that follows the boost stage.
-so surely the same principle would apply to my flyback and two "downstream" LED drivers?
LM3404 DATASHEET:
**broken link removed**
spec of quasi-resonat flyback:
V(in) = 230VAC
V(out) = 30V
C(in) = 150nF
C(out) = 330uF
Freq switch = ~55KHz, but varies with V(in)
P(out) = 10W
so in summary:
Do you agree that the ripple current in the secondary capacitor will vary depending on the phasing of the LED Drivers' switching?