Would a power supply with PFC work properly on a UPS that outputs either a "stepped sinewave" or "modified sinwave"?
I ask because if PFC is supposed to line current look like a sinewave what would it do on the other type of waveforms?
Thanks
Dave.
I ask because if PFC is supposed to line current look like a sinewave what would it do on the other type of waveforms?
Thanks
Dave.
Most PFCs are designed so that the input current 'tracks' the input voltage. If the voltage is not sinusoidal, the current will be distorted. I don't think this will work well.
PFC output
I would like to discuss the output of PFC circuits. Do you know what should be the output ripple voltage frequency? I think it should be 100Hz if we use 50Hz Single Phase 220Vac Source?
I would like to discuss the output of PFC circuits. Do you know what should be the output ripple voltage frequency? I think it should be 100Hz if we use 50Hz Single Phase 220Vac Source?
reply to ifrythings...
if your line voltage is sine wave then your current has to be sine wave to get PF=1 🙂) if your line voltage is not sine wave for example its stepped sinewave or something different; then your current wave should be also same with it. Point is you should analyse inductor wave form and PWM outputs(Duty Cycle) which give you a good starting point... Think that line voltage(PFC input voltage ) is constant at some time interval delta (t) as a result
dV=L*di/dt
di/dt must be constant which means currnet is triangler wave
peak current value is delta(t)*V(constant) / (L)
You should ask your control chip to make input current constant at delta(t) time interval. However you have triangler sample.....
As a result PFC should not work
if your line voltage is sine wave then your current has to be sine wave to get PF=1 🙂) if your line voltage is not sine wave for example its stepped sinewave or something different; then your current wave should be also same with it. Point is you should analyse inductor wave form and PWM outputs(Duty Cycle) which give you a good starting point... Think that line voltage(PFC input voltage ) is constant at some time interval delta (t) as a result
dV=L*di/dt
di/dt must be constant which means currnet is triangler wave
peak current value is delta(t)*V(constant) / (L)
You should ask your control chip to make input current constant at delta(t) time interval. However you have triangler sample.....
As a result PFC should not work
Modified sinewave UPS will have trouble with the high input capacitance of high power PFC converters. Otherwise, it would work fine.
Hi Eva,
I am desiging of a PFC circuit. Before connecting it to universal input i am supplying a DC input 116Vdc to analyse everything is fine or not. Problem is MOSFET is being damaged somehow. I didnt understand why. Could you help me
I am desiging of a PFC circuit. Before connecting it to universal input i am supplying a DC input 116Vdc to analyse everything is fine or not. Problem is MOSFET is being damaged somehow. I didnt understand why. Could you help me
Hi,
The schematic is the same with the page 4 at below link
http://focus.ti.com/lit/an/slua177a/slua177a.pdf
i am using UC3854A
It seems trr of boost diode cause output cap to decharge on mosfet but i am not sure
The schematic is the same with the page 4 at below link
http://focus.ti.com/lit/an/slua177a/slua177a.pdf
i am using UC3854A
It seems trr of boost diode cause output cap to decharge on mosfet but i am not sure
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