1kW PFC-Boost - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th September 2007, 01:58 AM   #61
diyAudio Member
 
Join Date: Jun 2004
Location: California, USA
Indeed, I've worked on projects that had over 100A running through PCB traces without problems. Just make sure you use enough copper and, like mzzj said, layout is critical. TI app notes are generally pretty good - you may want to read this app note on layout http://www-s.ti.com/sc/techlit/slup230.pdf for information on how to determine how much copper to use and some of the app notes on this page http://focus.ti.com/analog/docs/tech...tion=app_notes are also worth checking out. As long as the solder doesn't get so hot it melts it should be OK - and you've probably got a big problem if the solder is melting Good luck.
  Reply With Quote
Old 10th September 2007, 02:00 PM   #62
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Many questions;

A 1.2 kW boostmode what frequency are you going to use if you are to use a IGBT ?

Soft or hard switching ?
What AC line voltage and efficiency are you expecting ?

Thought about CoolMos ? Do the gate impedance homework first and imperative to use twin sided board.

As a golden rule at this power level.. use a driver buffer.,i.e MC34152 etc for driving power semi's. This will avoid nasty spikes causing jitter.
EMI ? the layout for EMI solution sometimes takes up more room that the actual power circuitry.

Any more ? Lots !
richj
  Reply With Quote
Old 10th September 2007, 08:14 PM   #63
diyAudio Member
 
Join Date: Sep 2007
At first I thank you all for your valuable concern,

My plan is firstly design a 1.2kW PFC with IC UC3854 and encounter with difficulties of design , later I'll try to upgrade it with insertation of an active snubber to make comparison (I'm planning to use UC3855 for the purpose) and at last I will try to advance the power level up to 10kw_if I'll have enough time and patience_ because of my aim to reach high power levels I chose IGBT as power switch.

Other specifications of my system are:
input voltage range : 180V-260Vrms
Switching frequency: 40kHz
Output voltage: 400Vdc

As richwalters' suggestion I am planning to use MC33153 for driving the IGBT (APT25GP90BDQ1), I think that IC will serve my purpose. (Unfortunately it is sometimes difficult to acquire electronic cmponents if you purchase small amounts so if I cannot buy that IC I can use BJT for gate capacitor discharging)

All of your ideas and suggestions are wellcome, I will continue sharing my progress with you...
  Reply With Quote
Old 10th September 2007, 09:26 PM   #64
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Quote:
Originally posted by corcbest
My plan is firstly design a 1.2kW PFC with IC UC3854 and encounter with difficulties of design [/B]
Murphies Law will give problems. I suffered too at 750W.

At 180V AC a soft active snubber may not give you the extra efficiency versus cost and space, an odd % may claim. I dropped the idea and opted on a very tight power switch/diode/cap layout using both sides of pcb to reduce parasitics. It worked.
Assume low AC volts line, n=92 to 95% at 1kW thats at least 50W vanished in hot air so forced cooling is a must. It's too much to ask for circuit board to swallow heat so power components must be fitted with ceramic whites to heat sink.
I don't like the UC3854. (omo) It lacks onboard overvoltage protection compared to the ST L4981A, otherwise same brick concept. At a kW at 40Khz operation more copper required and larger transformer. Core size ? I recon you'll will be using E65 gapped.
You will probably use current sensing transformer instead of low value current sense resistor.- again the resistor is a power loss.

The design of the gate switching stage and switching grounding of IGBT/MOS to output cap is paramount to the sucess of the design as well as reducing EMI. If you have a good idea of how to tackle EMI you are close to your goal. Radio knowledge and interference is all the same stuff.
These are only pre build considerations. The ST site has some interesting application notes. Read them!
The old Unitrode application notes have fragmented.....unless one can find them on the web.

richj
  Reply With Quote
Old 12th September 2007, 06:50 AM   #65
diyAudio Member
 
Join Date: Sep 2007
Iím sure you are aware of APTís 3.5kW PFC design notes. I based my design on this document and used the same start up circuit. But I have some doubts about the biasing circuit, since auxiliary power supply is not fully regulated VCC bias voltage is not regulated. In UC3854 datasheet, it is recommended not to exceed 20V bias, but in my opinion keeping the bias voltage constant with the circuit configuration used by both APT and TI is very difficult and sensitive to resistor and transistor parameters very much. So I locate a voltage regulator. LM317, in front of VCC pin (schematic given in attachment) but I donít know how this circuit will behave in start up.

Now I want to mention about my design;

I had some current transducers (LEM) from my preceding project, and since this will be an experimental setup, I will sense inductor current with LEMs.

I wound the inductor around Magneticsí 00K8020E026 Kool Mu E core.

A heatsink will be placed near the PCB and IGBT, diode and input diode rectifier will be propped against that heatsink.

I will use APT25GP90BDQ1 for IGBT and APT30DQ100B but I have some sample Cree SiC diode, I want to use them in order to see their contribution to performance (I donít hope a significant improvement) Do someone have some experience with these diodes?

I want to monitor switch current for experimental manners. Do you have experience about current monitoring? I found a company named Pearson in the web, they manufacture current monitoring devices. I will try to contact them.
Attached Files
File Type: zip start-up&bias.zip (11.3 KB, 177 views)
  Reply With Quote
Old 12th September 2007, 10:26 AM   #66
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
I am a always highlighting the importance of a reliable voltage supply.
But I would not be concerned to much about the 20V limit, when using this circuit.
The start up / supply circuit formed with Q1 and Q2, cannot be so bad. From my understanding the output voltage would be dominated by the treshold voltage + Id vs Ugs characteristic of Q2 and secondly by the zener diode. R18 is chosen in a way that the zener will always operate at some hundrets of uA, which should result in less than 0.5V change of the zener voltage.
All other resistors should have minor influence, because this circuit is closed loop with reasonable loop gain.
From first glance I would expect not more than +/1V change of the output voltage during all normal load and input voltage conditions.

Did you try it or are you just suspecting issues with the stabilization behavior? If you did not try it, then I would definitely recommend to try it on a breadboard before wasting your time on a high end supply, which might not be honored by the UC3854 anyway, but could cause several unexpected headache.
  Reply With Quote
Old 13th September 2007, 05:31 PM   #67
diyAudio Member
 
Join Date: Sep 2007
I did not try the circuit, only simulated it, and, ChocoHolic, u are right, it is hard to talk about the circuit without experiencing. I will set it up but before I would like to clear my mind. As it is seen from schematic vcc voltage is related on auxilary transformer secondary voltage and it is related to mains voltage. A dramatic change in mains voltage (for example from 220V rms to 270V rms) may damage the IC without a regulator like LM317, but this is only a prediction without trying the circuit it is hard to propose.
  Reply With Quote
Old 16th September 2007, 03:49 AM   #68
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
Quote:
Originally posted by corcbest
I did not try the circuit, only simulated it, and, ChocoHolic, u are right, it is hard to talk about the circuit without experiencing. I will set it up but before I would like to clear my mind. As it is seen from schematic vcc voltage is related on auxilary transformer secondary voltage and it is related to mains voltage. A dramatic change in mains voltage (for example from 220V rms to 270V rms) may damage the IC without a regulator like LM317, but this is only a prediction without trying the circuit it is hard to propose.
Hm,... you have simualted it.
I must admit such behaviors usually can be simulated quite good and I would trust your simualtion more than my first glance feeling.
If this circuit is really so soft, then I am wondering why you do not consider the most simple circuit.
Resistor-Zener-BJTemitterfollower ?
I am using this supersimple circuit to supply a IR halfbridge driver for a universal testing halfbridge. The allowed input supply voltage ranges between 100V-450V without issues.
  Reply With Quote
Old 17th June 2009, 09:05 AM   #69
diyAudio Member
 
Join Date: Jun 2004
Location: Slovakia (middle of Europe :-))
Default Maybe this will help somebody ..

Recently I have finished my bachelor's project - 1kW active boost PFC with quasi resonant switching, controlled by UC3855. I have not used the exotic Saturable reactor (core available only from Toshiba - MS or MT type). Instead, I have used the resistive damping (44ohm 10W resistor with MUR1560 in series, from ground to ZVT switch's drain). The efficiency we measured was about 92% at 230V line voltage. Efficiency was constant from about 30% to 100% load, lower at lower voltages and loads. The ZVT diode and ZVT switch were heating the most, main switch was almost totally cool (heatsinks with about 2,3K/W for mosfets, about 6K/W for main and ZVT diode), we think it was caused by the presence of full input voltage at ZVT switch when switching on (would be reduced by saturable reactor) and a too fast -dV/dt at the zvt diode anode (because current to load flowed through it until ZVT switch turned on - this would be also removed by saturable reactor).
When we removed the ZVT circuit, the efficiency IMPROVED by about 2%, everywhere.
From this I have concluded that this circuit needs the Saturable reactor to increase efficiency against non-resonant operation
The power factor was, however, very good - above 0,98 at loads >30% and was not influenced when we removed the quasi-resonant circuit.

So if you folks will ever try to design with UC3855, you will, most likely, not gain efficiency without the utilization of saturable reactor.
  Reply With Quote
Old 17th June 2009, 02:07 PM   #70
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Default Re: Maybe this will help somebody ..

Quote:
Originally posted by Disney_SK
The efficiency we measured was about 92% at 230V line voltage.##
When we removed the ZVT circuit, the efficiency IMPROVED by about 2%, everywhere.
From this I have concluded that this circuit needs the Saturable reactor to increase efficiency against non-resonant operation
The power factor was, however, very good - above 0,98 at loads >30% and was not influenced when we removed the quasi-resonant circuit.


That 92% efficiency figure seems a bit low for 230 AC line. Have you carefully measured every bit of energy ? At high line volts using the SGS L4981A and hard switching, I'm getting repeatedly 95-97% efficency rate using an IGBT at 100KHz. Although my design isn't for 88-120VAC, the low line 88V AC is a sure efficency test for any SMPS boost converter..(The IGBT is lossy at low line)
You may find the ZVT reactor will recover the 2% efficiency at low line volts. Again, have you done precise measurements ?Otherwise at high Vin, it's hardly worth implementing it and it certainly shouldn't be sucking valuable efficency..What operating freq are you using ?


richy
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
11.5-12.8v to 13.8-14.4v boost star882 Power Supplies 16 19th May 2010 03:13 AM
[enquiry] Treble Boost/High frequency Boost circuitry elnino86 Parts 2 18th December 2008 12:33 PM
1kW Boost allanon77 Power Supplies 17 4th February 2008 12:18 PM
1W Boost allanon77 Power Supplies 1 22nd January 2008 09:13 AM
EQ boost and Q......help Javaman Multi-Way 1 20th January 2002 02:15 PM


New To Site? Need Help?

All times are GMT. The time now is 04:32 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2