I am looking to embark on a project of building a 500W-600W isolated and regulated power supply with PFC. The target specs are:
1.) isolated from line voltage.
2.) 50V, 10A-12A output for use with class D amplifier.
3.) +15, -15V, 500mA outputs for use with analog circuitry
4.) addition of power factor correction.
5.) regulation of the 50V line
6.) linear regulation of +-15V line (lm317,337 or such)
7.) operation from 120V, 60hz lines
I am trying to determine how best to accomplish this goal.
The most elaborate way would use a converter for PFC, a converter for isolation, and a converter for regulation. This seems overly complex.
The next design would be to implement a PFC boost stage, followed by a bridge or double ended stage that has a feedback output on the PT, thus eliminating the need for another regulation stage, but I am worried about load regulation, since the feedback line is not loaded the same as the power output.
the last design would be to use an isolated boost design, with a regulator on the secondary. From what i've found, all choices are not particularly suitable. typically the choices have high ripple current or high voltage stress.
Would it be feasible to use a PFC stage in CCM with a comercially available PFC control IC to boost voltage to 250-400V along with a double-ended forward converter to provide the conversion to 50V, as well as provide isolation and regulation? A half bridge would also seem viable at these levels.
1.) isolated from line voltage.
2.) 50V, 10A-12A output for use with class D amplifier.
3.) +15, -15V, 500mA outputs for use with analog circuitry
4.) addition of power factor correction.
5.) regulation of the 50V line
6.) linear regulation of +-15V line (lm317,337 or such)
7.) operation from 120V, 60hz lines
I am trying to determine how best to accomplish this goal.
The most elaborate way would use a converter for PFC, a converter for isolation, and a converter for regulation. This seems overly complex.
The next design would be to implement a PFC boost stage, followed by a bridge or double ended stage that has a feedback output on the PT, thus eliminating the need for another regulation stage, but I am worried about load regulation, since the feedback line is not loaded the same as the power output.
the last design would be to use an isolated boost design, with a regulator on the secondary. From what i've found, all choices are not particularly suitable. typically the choices have high ripple current or high voltage stress.
Would it be feasible to use a PFC stage in CCM with a comercially available PFC control IC to boost voltage to 250-400V along with a double-ended forward converter to provide the conversion to 50V, as well as provide isolation and regulation? A half bridge would also seem viable at these levels.
Chris,
Please see this thread . Lots of good ideas on control method for the PFC stage, topologies and control method for the PWM DC-DC stage.
At most., you will need 2 converters: the PFC and the PWM. You are best to run CCM -v- CrCM (Continuous -v- Critical conduction mode) at the 500-600W level. Half-bridge topology will make best use of main isolation transformer. Full-bridge will work, too, but is more complex, and is not justified until you hit the 1kW level.
For the PFC, you could also try using a constant-frequency, then synch the PFC and the PWM together to eliminate beat frequencies from forming. Anyway, take a look at the thread.
Cheers,
Steve
Please see this thread . Lots of good ideas on control method for the PFC stage, topologies and control method for the PWM DC-DC stage.
At most., you will need 2 converters: the PFC and the PWM. You are best to run CCM -v- CrCM (Continuous -v- Critical conduction mode) at the 500-600W level. Half-bridge topology will make best use of main isolation transformer. Full-bridge will work, too, but is more complex, and is not justified until you hit the 1kW level.
For the PFC, you could also try using a constant-frequency, then synch the PFC and the PWM together to eliminate beat frequencies from forming. Anyway, take a look at the thread.
Cheers,
Steve
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