I am looking at a multiple boost converter active power factor correction circuit like below:
vin = 160*|sin(2pi*60*t)| input filter is a LC lowpass, with cutoff somewhere between 60Hz and F_PWM
|-------------[input filter]-|---[inductor1]--|-[diode]-|---|----| | | | | | | | | [PWM1]--[fet1]-[gnd] | | [load] [vin] | | | | | |---[inductor2]--|-[diode]-| [cap] | | | | | | | | | [PWM2]--[fet2]-[gnd] | | | | | | | | | |---[inductor3]--|-[diode]-| | | | | | | | | | | [PWM3]--[fet3] | | | | | | | | | |----------------------------|----------------|---------|---|----| | [gnd]
My question is about the PWM controllers. My sampling rate is 100kHz so I make my adjustments to the duty cycle at 100kHz.
should I run the PWMs separately and possibly have overlap so in the 10us period: PWM1 can be on from 0 to 5us PWM2 can be on from 2.5us to 7.5us PWM3 can be on from 5us to 10us (each PWM has the same duty %)
or
A single multiplexed 300kHz PWM so that with no overlap in the 10us period: PWM1 can be on from 0 to 3.333us PWM2 can be on from 3.333us to 6.666us PWM3 can be on from 6.666us to 10us (each PWM has the same duty%)
Scott