| Archimedes |
Please help.
Can you use a half bridge or full bridge converter for +12V to +/- 63V PSU?
I have been working on a 1000W PSU for 2 amplifier modules using a Push-Pull converter. I just cannot seem to get pass 750W out of the converter without the output voltage falling to +/- 54V.
:confused: |
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| subwo1 |
| Archimedes, there is no inherent power limitation with either of those two topologies, but practicality may be a factor. Maybe if you open a new thread after you believe the search function cannot lead you to an answer, someone may be able to give a more detailed response. |
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| Archimedes |
Sorry Subwo1 I should have stated the case more clearly.
The topology that is giving me headaches is a CT Push pull converter not a half or full bridge. I have been doing some reading and many people claim that the CT Push Pull is troublesome because of symmetry issues.
I would like to know though if I could use a Full Bridge for a converter that is powered by a car battery. My problem is that I have 2 x 276Wrms amplifier modules that require + and - 63 V at 3.76A per side (1 module) x 2 modules. If I test the converter on 1 module only the output voltages hold up very well. The moment I introduce the second amp the output voltage falls to about + and - 54V and thus I am only able to get out around 200Wrms/ch into a 4R load.
I am using 6 Mosfets per side and full wave rectifier for the output consisting of Fast recovery TO220 diodes.
Any help or directions is most appreciated.:angel: |
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| Eva |
I think this is pretty off-topic here.
Please, could any moderator move Archimedes' posts into a new "12V push pull SMPS" thread?
Thanks. |
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| subwo1 |
Archimedes, here is an idea. On the push-pull circuit, it is possible that your transformer may be starting to saturate. More transformer core volume may help. If you have a scope, look for a sharp rise in MOSFET current at the end of the duty cycle.
It may help to raise the frequency some if you are getting saturation. Then, you will probably have to reduce the number of turns on both the primary and secondary. ? |
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| raidfibre |
Hello Archimedes,
It is very difficult to diagnose a problem without any real data on what is going on.
There have been some good recommendations so far. It is possible that your core is the wrong size for the frequency and power level you want to use.
It is also possible that your windings and source have too high resistance.
What do you have for capacitors on the center tap of the primary side?
What frequency are you running at?
Do you have any pictures or schematics to show us? |
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| Archimedes |
Thanks to the moderator for moving this.
The trafo is a Siemens EPCOS toroid R58,3 × 40,8 × 17,6 (Ae=152.4 sq.mm, Ve=23230 cu.mm) with N87 material. It has Pri:2+2 (8 x 1.61mm wire per primary)
and Sec:14+14 (40 x 0.28 wires twisted per secondary) running at 43kHz. There are 5 (not 6 as previously mentioned) IRFZ44's per switching side. These are driven by a complimentary follower pair made from BD139 and BD140 per side. The chip is an SG3525. I have 4 x 4700uF caps near the centre tap. There is a 22uH choke on the input from the battery + to the caps +.
When I tested the psu I noticed that it had pulled almost 110A at 10.6V battery input measured with a clamp.
The voltages on the secondary of the converter was then + and - 54V at +/- 3A per side. Looking at the waveform on a scope the pk.pk value measured at any drain had fallen to 21V and the waveform was completely square (Full on).
Is the transformer to small ? Just curious Has anyone ever built a Full bridge converter powered by a car battery. Is it really impractical to do so ?
Phew... this looks like a thesis :-) |
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| Perry Babin |
If you post the following information, it may be helpful in troubleshooting the supply.
Core data (link to datasheet showing core material and dimensions would be very helpful).
Number of primary turns (for example, 4+4 or 5+5).
Number of secondary turns.
The amount of copper on the primary and secondary (number of conductors and size of conductors for each turn).
The operating frequency.
The part numbers of the FETs and the rectifier diodes.
A schematic. |
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| subwo1 |
| Your input power being so much greater than output appears to provide assurance that once you locate the bottleneck, whether core saturation or something, the supply should work as you wish. |
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| Archimedes |
4 x BYW29-200 used as full wave rectifier. There are 2 x 470uF/100v 105 deg low esr caps across the outputs of the diodes to the input of the 47uH chokes. This is then smoothed by 1 x 2200uF/100v cap per side at the output of the chokes.
Voltage feedback is provided by ILD55 and BC547. |
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| Pierre |
I think you are driving your transformer with too high flux density:
From your data (2+2 primary, 43KHz, 1.52cm^2 Ac), and 12V input, your peak flux density is about 2300 gauss, perhaps too high. That could lead to transformer saturation.
Try to increase frequency to 75-80KHz or increase primary turns number to something like 3+3 or 4+4 turns.
(If you increase frequency you will have greater mosfet losses than a converter at 43KHz working properly, but in your case, if the transformer is saturating, they must be suffering a lot just now! even at that low freq.)
Your converter should work well with a moderate load before going to high loads. Try with 40-50W first.
Apart from this, I would like to hear why is so uncommon (in fact I have seen none) to find a half-bridge converter in car audio, all of them seem to be push-pull. Is it only a matter of complexity or cost of the gate drive circuit?
Hope this helps. |
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| Eva |
There is nothing inherently wrong with the push-pull topology, and full bridges are exactly as prone to tranformer saturation as push-pulls if things are not done properly. At least 500ns of dead time should be provided, and proper RC snubbers are required in the primary side in order to allow for that small amount of unavoidable gate drive asymmetry, that is always present, to be automatically compensated by faster or slower rise times, depending on the own primary magnetizing current, ie: the longer cycle ends with higher magnetizing current, thus the snubber capacitor is charged faster compensating flux imbalance).
Also, the voltage drop that you describe is absolutely normal for non-regulated converters, it happens because the leakage inductance of the transformer starts to dominate when some current level is reached, and more and more voltage drop is required across that inductance in order to reach the required transformer current level within each cycle. There are several ways to circumvent that: The operating frecuency may be reduced (thus making cycles longer and providing more time for the leakage inductance to be energyzed) if you core allows for that, or more SMPS transformers (or entire cells with switched and diodes) may be paralelled in order to reduce the impact of leakage inductance, or a regulated topology may be considered (altough that would require higher peak currents to be handled, a lot of low ESR filter capacitors and probably a bulky coupled output inductor).
Note that when using multiple transformers, you can connect the secondaries in series, thus reducing the number of turns required in each one and making winding task easier.
Also, are you sure that your turns ratio is 2:14? That should be providing more than +-80V when idle. Is your test battery in good condition? You sould be getting 11,5V or more with 100A load. Finally, don't trust amperimetric clamps at all, they are not likely to cope well with the pulsed current consumption produced by amplifiers and SMPS, they are usually intended for DC measurements only. Use an oscilloscope instead, so that you can see actual waveforms and peak values.
Pierre: A half bridge is almost the same as a push pull, but replacing the coupling capacitor by a dual transformer winding. Then again, where are you going to find capacitors rated at several thousands microfarads and a hundred amperes of ripple current? :) |
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| Perry Babin |
You mentioned voltage feedback so it sounds like a regulated supply. The combination of the input voltage sagging and the regulator hitting the max duty cycle will lead to a significant/sharp drop in output.
As was mentioned, the transformer may be saturating. Many times, you can hear the transformer making noise when it saturates. This is most noticeable when playing music. Also, when it saturates, you may see a flat line at ~1/2 B+ when looking at the waveform at a low sweep rate (where hundreds of cycles are displayed at once).
From my experience, you'll get the best overall performance at ~30kHz and 4+4 on the primary. |
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| N-Channel |
Archimedes,
Voltage-mode controllers like the '3525 cannot adequately deal with the flux imbalance that can occur with C.T. push-pull topology.
Current-mode is needed, ans this can be achieved with such chips like the SG1846/2846/3846, UC3825, or the MC33025. The first one is a standard-speed chip, while the last two are high speed (2MHz oscillator) chips.
I have used the 33025 before with good results. See my other threads where I talk about this chip. It could solve your problems
Steve |
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| Pierre |
Thanks, Eva. Sorry for going a bit off-topic. Although your explanations about why half-bridge is not used seems to go in the right direction, there is still something I don't understand:
-In half bridge, the usual thing is to make a Vcc/2 voltage by means of large capacitors and couple the transformer to that point. But I have also seen single filter capacitors (as in push-pull), the transformer being coupled to GND (or to the mosfets middle) by means of a _small_ capacitor. Is that small-valued capacitor (say, 10uF) with high current rating so difficult to find, or the problem are the big ones? In that case, with push-pull it is the same, isn't it?
Thanks for your help! |
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| Eva |
Keeping frequency constant, the required value for that "small" capacitor is inversely proportional to the input voltage squared, and proportional to the output power.
For a 300V 200W half bridge 1uF is routinely used, so figure out how much capacitance is required for a 12V 1KW half bridge. Also, such a half bridge would put only 6V to the primary winding, so current would get doubled (6250uF with 166A ripple)... |
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| Pierre |
ok, ok... Eva, you have convinced me as usual ;-)
It is only that I was thinking on re-using my current half-bridge PCB for a 12V DC/DC converter ;-)
Have a nice day.
Pierre |
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| Archimedes |
Perry I think you may have a point there. When the output voltage falls off I can hear a slight whine from the transformer. I think I shall try the suggestion with 4+4 on the pri @30kHz. How much of copper do you think is practical ?
Eva I have never seen any car amplifier PSU's incorporating current mode control. How would something like this be done practically anyway. I think the SG3526 does allow current mode control. The turns ratio is 1:7. When I removed the voltage feedback at idle I noticed the voltage shoot up to +/- 92V at 12.6V input. The battery is fully charged. The battery voltage only falls to 10.5 (measured at the CT of trafo) when I think the trafo saturates. Without saturation it stays at 11.2V. (65AH battery).
How would you use a scope to measure current with ordinary probes ?
Eva I was referring to a Full bridge not the half bridge. I know that you will need twice the amount of switches but since IRFZ44's cost here around 70 US cents each it does not seem that unfeasible. Furthermore the way I look at it is that you only need 12 x 1.61mm wires for the Pri and not 24. This should greatly simply the trafo winding process. What do you think?
Can anyone please tell me how much inductance is necessary for the input and output chokes ? I chose values that I saw commonly used. Is there formulae for this purpose so that I don't have to do thumb sucking ?
Can I please ask the gurus out there to take a look at the attached spreadsheet and give me any feedback if possible.
I use it whenever I wind trafo's.
PS. Do you think it will be more feasible to wind a 305.9mm Ac (I have this too) or will the 152.4 Ac give me the required 1000W ?
thanks everyone for your input! |
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| mzzj |
| quote: | [i]
Eva I was referring to a Full bridge not the half bridge. I know that you will need twice the amount of switches but since IRFZ44's cost here around 70 US cents each it does not seem that unfeasible. Furthermore the way I look at it is that you only need 12 x 1.61mm wires for the Pri and not 24. This should greatly simply the trafo winding process. What do you think?
[/B] |
At higher voltages full-bridge is preferred over push-pull, but at 12V push-pull is most cost-efficient solution. To get same rdson-losses you need quadruple amount of similar mosfets for full-bridge compared to push-pull. Actually it would be better to go for 30v mosfets then as they need to withstand only half voltage compared to push-pull. |
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| Perry Babin |
"How much of copper do you think is practical ?"
I'd suggest 5-6 1.6mm conductors per primary turn as a starting point. One conductor per FET would give a nice, simple layout if you were using extended primary leads. This would likely be enough for virtually any audio amplifier. If you want it to be able to run at full power sine wave output continuously at high ambient temperatures, you would need more. |
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| Archimedes |
| quote: | Originally posted by Archimedes
Can anyone please tell me how much inductance is necessary for the input and output chokes ? I chose values that I saw commonly used. Is there formulae for this purpose so that I don't have to do thumb sucking ?
Can I please ask the gurus out there to take a look at the attached spreadsheet and give me any feedback if possible.
I use it whenever I wind trafo's.
PS. Do you think it will be more feasible to wind a 305.9mm Ac (I have this too) or will the 152.4 Ac give me the required 1000W ?
thanks everyone for your input! [/B] |
Are there any formulae that I can use to calculate how much inductance is needed ? Those of you guys that have downloaded the attached spreadsheet what do you think of it ? Is it accurate enough or does it need minor tweaking ? |
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| Archimedes |
| quote: | Originally posted by Archimedes
Are there any formulae that I can use to calculate how much inductance is needed ? Those of you guys that have downloaded the attached spreadsheet what do you think of it ? Is it accurate enough or does it need minor tweaking ? |
Hi All
I have been away for a while. Is there no one on this forum that is able to assist me with my requests ? :)
To those who have downloaded my transformer calculator did it prove helpful or useless ? Any feedback is most welcome.
Just an update on the 12V to +/-63V issue. I have decided to redesign the entire board as I had to redo a transformer and the old board has seen much abuse from soldering and desoldering etc. I have just completed making my own UV light box as well as a glass etching tank complete with pump and heater. Got the Positiv20 and am now ready to do this over the weekend. I got tired of the old Toner ironing method as this proved to be very unsatisfactory.
Can't wait to assemble everything neatly and to test. |
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| sss |
| quote: | Originally posted by Archimedes
Are there any formulae that I can use to calculate how much inductance is needed ? |
it's like asking "how to calculate the filtering cap size" its depends on how clean u want the output voltage to be .... |
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| Eva |
How to calculate filters?
I usually simulate them with some electronics software, and I adjust the values of the components until I get the desired frequency and phase plots. In order to do that, you must consider inductor series resistance, and including capacitor series resistance (ESR) is also desirable.
What you should look for is a reasonable attenuation (let's say 40dB or more) at the switching frequency, and what you should avoid is resonance peaking at the cut-off frequency.
Note that component values are not dependent on output current at all, but the saturation current rating of inductors must be higher than the peak current that they will have to handle. Also note that picking component values randomly usually yields very poor results (particularly when a too big inductor is chosen). |
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| Archimedes |
Thanks Eva... much appreciated. ;)
What simulation software do you use if I may enquire? Lets assume you did not have this software or any other software would you still know how to calculate the filters? :o
I do apologise if I sound ignorant. Its just that my education in Electronics goes as far as Component technician level. I dont wish to stick at that level though. |
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| Eva |
| Electronics Workbench may seem a bit outdated, but it is simple and very useful for that kind of quick bode simulations. I use it also to tune all my audio filters and crossovers. Note that versions older than 5 don't work properly in windows NT, 2000 or XP. |
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| Archimedes |
Eva from your experience buliding high powered PSU's what are typical symptoms to look out for of too much or too little inductance in the output stage?:)
I would very much like to experiment with current mode control but have no idea where to begin. Any advice on where to start please :angel: |
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| Eva |
Too little output inductance yields high inductor ripple currents that reduce efficiency, increase switching and conduction losses, increase output ripple and may cause output capacitor overheating.
Too much output inductance solves all the previously mentioned issues, but it does at the expense of a very slow response to big load changes and a big resonance peak in the open-loop response of the control loop that makes loop stabilisation harder.
I think that the output filter of my 120A PSU has 4dB or so of peaking around 500Hz. Output capacitors make a total of 17.600uF with approx 0.0028 ohms total ESR, and output inductors make a total of approx 4uH (it changes due to progressive saturation) and estimated ESR is approx. 0.007 ohms (including transformer windings and synchronous rectification MOSFETs). Worst case current ripple may be nearly 25% of maximum output current (it changes a lot depending on input and output voltages). |
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| Archimedes |
| quote: | Originally posted by Eva
Too much output inductance solves all the previously mentioned issues, but it does at the expense of a very slow response to big load changes and a big resonance peak in the open-loop response of the control loop that makes loop stabilisation harder.
I think that the output filter of my 120A PSU has 4dB or so of peaking around 500Hz. Output capacitors make a total of 17.600uF with approx 0.0028 ohms total ESR, and output inductors make a total of approx 4uH (it changes due to progressive saturation) and estimated ESR is approx. 0.007 ohms (including transformer windings and synchronous rectification MOSFETs). Worst case current ripple may be nearly 25% of maximum output current (it changes a lot depending on input and output voltages). |
Thanks Eva for the info. I hope you don't mind me asking questions that should seem obvious but please explain in laymans terms what you mean by "big resonance peak in the open-loop response of the control loop that makes loop stabilisation harder."
How do you view current through an inductor with your oscilloscope ? Do you have current probes ?
I noticed on some offline PSU's a small toroid mounted near the main transformer. There is about 2 turns of the main transformer wire that passes through this small toroid. I assume that this is used for the current mode control.
1. If this is so how does one estimate what size toroid to use ?
2. What should the turns ratio be on the secondary of the small transformer ?
3. Is this voltage then rectified and compared to something?
thanks for all your help :cool: |
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| Archimedes |
An update:
I have made a new board and this is what it looks like:
This is the old board compared to the new one:
This what my setup looks like in my miniature lab :)
I have yet to populate the board completely but initial testing of the PWM chip and protection circuits are good.
Will post and update as soon as I have completed successfully. |
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| Archimedes |
| Here are the photos |
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| Archimedes |
| Another one too |
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| Archimedes |
| another one of the old board from the side |
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| Eva |
These prototypes are looking quite good. Do they work? :)
Remember that most of the beauty of a switching circuit is inside it, in its waveforms :D |
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| Archimedes |
Thanks :)
The older prototype is working (was made about 1 year ago) but is the one I described that had the problem maintaining +/-63V at over 660W drawn from it.
In any event this board started out as a 3 x FET per side PSU and eventually after realising that the heat generated was just too much even for such a big heatsink and not to mention blowing up several sets of FETs with spectacular fire and smoke displays I then chopped off the part for the FETs and gate resistors and etched a small board the same size with 5 FETs per side. This worked quite well but the board was rather flimsy (epoxied) and not to mention ugly with all the late additions, soldering and desoldering etc.
I etched the new board last Sunday and I have completed drilling and now am slowly populating the board. I have tested the PWM chip and the protection circuit and everything is looking good. I need to mount the FETs and diodes and then begin testing. I need to juggle a full time job as a DBA and this unfortunately means I can only do a little at a time. |
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| Archimedes |
Help please!
Tests conducted this weekend proved satisfactory yet there are some issues I noticed:
1. The ringing frequency is in the order of 5MHz which required 15R and 680nF cap is series across the primary winding. This seemed to have squared off the waveform but their is still slight ringing noticeable at a 10% duty cycle. Is this normal ?
2. The output voltage regulation does not remain constant at 63V with no load but seems to decrease slowly to about 58V. Something I noticed was that the opto ILD55 seemed to be running a little hot as well as the resistors.When I kept my thumb against the case of the ILD55 the voltage went back up and seemed to stabilise. Any ideas ? Could the series resistors be too low a value ? |
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| Archimedes |
| This is the amplifier modules that are powered from the converter.:) |
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| Archimedes |
Update:
I have tested the converter with both channels connected and measured (33.34V/4R =>276Wrms per channel clipping. The output voltage from the converter held up pretty well considering that the Batt V fell to 10.5V measured at the bus bars in the converter. The total current pulled from the batt was 107A measured with the clamp (yes I know "Its not accurate") but the 2 x 50A fuses are still intact. The transformer though ran hot to a point where you cant keep your fingers on it for longer than 5sec. Heatsink for the converter was cool though. This test was conducted for a full 3mins (amplifier heatsinks was extremely hot).
In real music terms however I doubt any piece of music could place such a tremendous stress on the converter. I also doubt if anyone could sit in a car that has 540+Wrms of sound
A BIG BIG thanks goes out to Perry Babin, Eva, Pierre and others for their valued input. I think my initial problem was transformer saturation due to high flux levels.
There are still a few bugs to iron out.
Like when the power is removed from the remote-on the voltage jumps up for a split of a second to 80V + and then diminishes. |
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| sss |
Archimedes how did u solve the ringing problem?
also , can u show the schematic of your feedback circuit? |
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| Archimedes |
The ringing was sorted out with a snubber.
Visit RidleyEngineering to find out more |
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| Archimedes |
I have conducted some more tests last night and this is what I noted: Ambient temp = 26°C
Eva was right in what she said in a previous post. The battery voltage at 100A is 11.5V. At the input to the CT on the transformer this had fallen to 10.76V. The volt drops were measured and apportioned out to the cabling, connectors and fuses respectively.
I ran the amplifiers at 252 wrms for 6 mins continously and observed that the transformer after this time had reached 82°C and the heatsink 55°C. By this time the battery had almost completely drained as the voltage at the terminals was 11.2V @ 82A of current drain. The input to the CT was then 10.24V and the under voltage protection had then kicked in.
The amplifiers all the while were fan cooled but not the PSU.
Any comments on the data above will be most valued. I need to know if the transformer temperature is too high.
Please see attached snubber design tip from RidleyEngineering. I hope I am not violating any copyright. |
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| Archimedes |
| My resistor load for 250W per channel looks like this submerged in plain water. Using anti - corrosive mixtures seems to change the resistance. |
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| subwo1 |
| I'd say that temperature is getting too high for a transformer. I believe that ferrites do not generally have very high Currie points. I wonder if thermal expansion could crack the core. |
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| Archimedes |
subwo1 I have checked on EPCOS site and noted that the curie temperature for N87 material > 210°C. I think my concern is that the insulation of the wire will create a problem especially the polyurethane ones.
EPCOS quotes that :
Core losses at 25 kHz, 200 mT, 100 °C is 57kW/m3.
Why would they quote at 100 °C if they don't expect the core to get that hot ? |
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| Pierre |
Some cores have less losses at higher temperatures (to a point, of course). For example, my 3C90 core had less losses at 100ºC than at 40ºC.
However, 82ºC at 250W more or less is a bit high, I think. Perhaps excessive flux density?
If you provide the datasheet of your core and the number of primary turns, perhaps I can help.
Best regards,
Pierre |
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| Archimedes |
Pierre where did you get a figure of 250W from
I am using 4 + 4 turns on the primary.
There are 6 x 1.90mm wires per side
R58 core |
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| Perry Babin |
Does the transformer run hot if left on with no load (other than the idle current of the amplifier)?
110C is relatively hot (I think most people try to keep the temperature rise in the core to ~40C above ambient) but if it doesn't go much higher and the wire's insulation can take the heat, the power supply should be reliable. The N87 material has the least loss at ~110C so the temperature of the transformer may level out at approximately that temperature.
I'd suggest running the amp as you would during normal service. There are lots of amplifiers that can't survive full power sine wave output. If this amp is not for commercial production, as long as it performs satisfactorily for listening to music at the levels you desire, the transformer may be OK.
You could always add a small fan to the PS or add a thermistor to the transformer to protect against high temperatures. |
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| Archimedes |
The transformer at idle (both amp modules on) is 3 deg higher than ambient.
I think that I should install a thermistor circuit just in case but am a little unsure at what temp should this kick in at. |
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| Perry Babin |
I would set it to trip at ~120C. If it gets above 110C, the loss will begin to increase and the core will likely increase rapidly in temperature from there.
Have you played it at high volume with music, driving speakers?
If so, how hot did the transformer get? |
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| Archimedes |
Thanks Perry.
No I havent. I have played it with a sine wave at 1kHz into those resistor loads continuosly. At that point after 6mins the water in the container was almost boiling.
I dont have 4Ù speakers that have an rms rating over 250W.
I wonder if there are any car speakers that have such a high rms rating apart from subwoofers.
My intention is to drive an 8Ù 600W subwoofer (that I hope to acquire shortly) in bridge mode |
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| luka |
Archimedes
I was working on my own SMPS, which is not that powerful. Could I see your schematic and/or your PCB?I would build one like yours. |
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| Archimedes |
| Luka unfortunately I cannot give out the schematic as this is still a work in progress. I'd be more than willing to give you any tips though. |
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| luka |
Archimedes
I would like to know next things:
How many turns on PRI and SEC of your transformer,
How many turns on input inductor,
How many turns on output inductor,
Sizes of yours cores,
Operating frequency at which SMPS runs |
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| Archimedes |
Pri 4+4 Sec 24+24
Input choke is 10uH +/-10 turns on T184-26
Output chokes are 100uH +/- 36 turns on T152-26
Freq is 32kHz |
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| luka |
| How many wires in paralel did you use ? |
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| Archimedes |
Get ready for some painful fingers and hands:
Each pri is made up of 6 x 1.9mm
Each sec is made up of 35 x .312mm |
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| luka |
Uff that is a lot.
could I use smaller dia. wire, more in paralel. |
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| Archimedes |
| Look at the 1st or 2nd page of this thread. I have included a transformer calculator. You can play with the figures of the wire for both the pri and sec. |
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| Archimedes |
| Here is the picture of the input side |
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| luka |
Cool pic.
How are input and output connectors called, that you have ? |
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| Archimedes |
| They are called terminal blocks |
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| luka |
| what gate resistors did you use |
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| Eva |
| Your prototypes look even more interesting now. Where did you get those car-audio like heatsinks, terminal blocks and fuse holders? |
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| Tekko |
| Eva, i think the heatinks are regular aluminum U-girders, nothing car audio spesific. Thr fuse holders and terminal blocks i guess is either bought on a car electronics store or salvaged from a broken beyond repair car poweramp. |
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| Archimedes |
The gate resistors are 20R.
Yes the heatsinks are 8mm thick aluminium girders as finding suitable aluminium extrusions are a pain in the butt. These were machined by an engineer to fit the steel plates and PCB. At full power they remain relatively warm after a while +/- 45 deg C.
The connectors are not second hand I assure you. They were obtained from a manufacturer in China that specifically makes terminal blocks. Beats the other forms of connecting power hands down and looks a lot more professional if I may say so myself.
There is nothing in that psu that is not new. |
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| Eva |
Archimedes:
Please, could you tell me how to contact this car-audio terminal block manufacturer or any of its dealers? Please send me a private message in case you feel that posting such information is inappropriate.
Thanks :) |
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| Archimedes |
I dont mind telling you. The only problem is they supply manufacturers of power amplifiers like Alpine, Pioneer etc. so they have a minimum order quantity that would make your eyes pop out. I managed to get a few samples from them and when I requested a pricelist I was astounded as to how cheap they are and let me assure you the quality is excellent.
If you have a few thousand Euros lying around let me know :bigeyes: |
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| luka |
| What is your dead time resistor? |
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| Archimedes |
100R
How is your design coming along ? |
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| luka |
Hi,
PCB is almost complited.
Next year it will be finished.:) |
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| luka |
| this is how it looks pcb now |
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| Archimedes |
:) Not bad at all. Looks very similar to mine.
Have you made and populated the board as yet? |
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| luka |
| no, because i am curently working on other project at a moment. |
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| electronistu20 |
| is there anyone who has a complete pcb and schematics for this SMPS? |
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| luka |
Hi Archimedes
Can you post schematic for your smps or send me email, I would like to see how you made under-voltage shutdown.
Thanks, Luka |
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| Hi Speed |
| quote: | Originally posted by Eva
Archimedes:
Please, could you tell me how to contact this car-audio terminal block manufacturer or any of its dealers? Please send me a private message in case you feel that posting such information is inappropriate.
Thanks :) |
Hi Eva, you are hard to find, no email
if you interest in terminals block for caraudio email me mc_tech@yahoo.com |
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| luka |
Hi
Do you have any data on them? Could you post pic of them. |
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| odnaizutra |
hi Luka,
what are the evidences of a ferrite core when it saturates? |
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| luka |
Hi
If you look at current that goes trough it will get a lot higher than before, also it will start to heat up |
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| djQUAN |
| quote: | Originally posted by luka
Hi Archimedes
Can you post schematic for your smps or send me email, I would like to see how you made under-voltage shutdown.
Thanks, Luka |
ESP has a schem that has under, over voltage and over temp shutdown. :)
http://sound.westhost.com/project108.htm |
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| switchmodepower |
How is your transformer wound? Is it layered or simply Primary/secondary? Winding geometry of the transformer is just as critical as how much you push the core. Also
Can you draw a pic? |
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| eltonseemann |
is possible drive a mosfet gate whith a pull-down low resistance <100R and PNP to 12V which base at open colector at tl494??
is possible make a push-pull converter whitout isolation between pri and sec, earth at center-tap and 12V at primaries extremes. Secondaries = primaries plus more turns in the same wire - self-transformer??. Gate drive via gate trafo in this case??
hihihi |
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| luka |
Hi Archimedes
You didn't use any snubbers on primary side, did you? |
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| Tolik |
| quote: | | What simulation software do you use if I may enquire? Lets assume you did not have this software or any other software would you still know how to calculate the filters? |
Good tutorial about push-pull SMPS by National Semiconductor is here
Wery good FAQ about SMPS
Compleate answer about software simulation of SMPS
I tried hard to find the POWER 4-5-6 program, but all my attempts finished unsucsessful...
For simulation of some stages of SMPS or other analog or digital stuff I`m using Altium Designer 6 for analog, and Proteus 7.2 for sirquits with microcontrollers. |
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| Archimedes |
:D
Hi Luka
I did use a snubber between the primary windings. I followed the procedures outlined by Ray Ridley as to measuring the ringing frequency with a scope and then calculating the components needed.
His suggestions were not to far off albeit I had to play around with component types and values. |
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| luka |
Hi
How did you connect them? Filter over primarys, or from each primary to gnd? |
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| Archimedes |
| RC Snubber between 2 Pri:) |
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| EWorkshop1708 |
What about raising the frequency to 100khz or higher to avoid saturation?
Also, if you get a larger toroid core, would that help?
Also another idea I was thinking about was dual toroids, with each it's own rectifiers, then parallel after the rectifiers.....
BTW GREAT job on your SMPS!!!
Also, check out these MOSFETS from OnSemi.... TO264, over 120A a piece!!! :hot: :eek: :hot:
https://www.onsemi.com/PowerSolutio...do?id=NTY100N10 |
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| Eva |
| Check IRF2907Z and other parts from IR. On-Semi doesn't seem to have real high performance stuff for this application. TO-264 parts are not recommended due to the higher package inductance, a pair of TO-220 works better. |
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| N-Channel |
| quote: | Originally posted by EWorkshop1708
.....Also another idea I was thinking about was dual toroids, with each it's own rectifiers, then parallel after the rectifiers.....
BTW GREAT job on your SMPS!!!
Also, check out these MOSFETS from OnSemi.... TO264, over 120A a piece!!! :hot: :eek: :hot:
https://www.onsemi.com/PowerSolutio...do?id=NTY100N10 |
The NTY100N10s are brutes! 100A drain current and only 9mW Rds(on)! Be careful driving them- they have over 10,000pF gate capacitance! Use a PWM chip with high-current totem-pole outputs, or a separate driver buffer between the PWM chip and the MOSFETs.
Toroids: Each primary should be driven by its own MOSFET pair, while the secondaries can be connected in series (now no longer a center-tap) before the output rectifiers, forcing equal current-sharing. I will try to attach an image of said power stage as soon as the server problem uploading the pic disappears.
Steve |
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| Tolik |
| quote: | | Also, check out these MOSFETS from OnSemi.... TO264, over 120A a piece!!! |
But remember about 75A current limitation for TO220 & TO 247 packages...
Chek also IRFB3077 - these are able to drive a lot of current |
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| Tolik |
http://myworld.ebay.com/forkliffter
My favorite MOSFET`s supplyer. IR & ST are here :hot:, including 110 A
8mR IRF3205 - that was used in 1000W Genesis monoblock`s SMPS... :smash:
I`m very like high speed IXYS`s rectifer bridges :up: |
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| kozetot |
i have a 40mm outer diameter troidal core.
what would be the best swithching fr. and max. power assuming the primary is 5+5 with 5x0.5mm(diameter) wire and secondary 11+11 3x0.8mm wire. the core data is here
troid data
or can you reccomend any of the catalog on this site
cheers |
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| luka |
Hi
Core wouldn't be a problem, your primary wires would be, you wouldn't get much, maybe you would get 40w... |
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| kozetot |
Well,
in the article of ESP project89 it is mentioned that a core with 4cm diameter and cross section of about 1 cm2 is suitable for around 200-250W continuous RMS so mine is with the same diameter, but larger cross section(window area) 1.28 cm2. it should be slightly more powerful i guess???
and what about the primary. are 5x0.5 mm diameter wires not enough for about 30A current (max power)???
Cheers |
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