An externally hosted image should be here but it was not working when we last tested it.
The fisrst circuit shown is an unregulated full-bridge transformer-coupled converter. The switches are operated at a fixed duty cycle approaching 100% by means of a simple control IC (like TL494 or even a CD4013 flip-flop), thus there is no way to control output voltage nor to limit output current.
The second circuit shows a full-bridge transformer-coupled buck converter with regulated outputs. The switches are operated at a variable duty cycle by means of complex control circuit that senses output voltage and current and contains one or more feedback loops and error amplifiers. This converter is somewhat harder to get working properly (particularly when smooth and precise current limiting is desired under overload conditions) since you have to face not only magnetic design and switching behaviour optimization but also output filter design and control loop stabilisation and dynamics. In return for such a huge effort you get a converter whose output is 'rock solid' regulated and may be overloaded and even shorted without damage.
Currently I'm working on one converter of that kind that produces an adjustable 0-15V output with an adjustable 3-120A current limit and features true active current-sharing so that multiple units could be connected in paralell without current hogging. It has took me about 4 years to learn by myself how to make such a thing work, but finally I have a working prototype
Concerning safety, I have posted some tips several times but I don't remember where, I think the last ones were in a thread called 'Beginning SMPS'. Use the search feature of the forum.
and up to 9kw smps
Hi there,
Pls. check this site up: www.audiopowerelectronics.com about smps for audio.
Thanks
Hi there,
Pls. check this site up: www.audiopowerelectronics.com about smps for audio.
Thanks
Re: Re: and up to 9kw smps
Pls. check this site up: www.alab-pro.com about smps for audio
gearheadgene said:
Pls. check this site up: www.alab-pro.com about smps for audio
Some thoughts about these power supplies:
- Output inductors are of very small value, they are actually rod inductors of those ones used for pi-filters, so current ripple is going to be huge (maybe 50%). There is no additional pi filter at the output so hundreds of milivolts of voltage ripple are guaranteed.
- The number of power devices, heatsink size and transformer size suggest that these power supplies are rated for audio. This means that the advertised power rating is actually the maximum output peak power of the PSU, and that the continuous rating is going to be something like 5 times smaller.
Switching at high freuencies above 150Khz reduces transformer size but increases switching losses so huge heatsinks are required, and vice versa, so there is no magic solution in order to use both small transformers and heatsinks.
Note that these power supplies usually show efficiencies between 90% and 95% and this means that a 4200W unit is going to dissipate between 200W and 400W at full load. Now take a look at the heatsinks...
- There is not enough clearance (5mm) between primary side and secondary side PCB tracks
- It looks like the designer is having trouble with his tiny hard-switched PFC stage, and this is no surprise to me because a true 6.5KW PFC (without using the nasty bypass-diode trick) requires three or four inductors of the size of a fist and two or three capacitors of the size of a beer can. Not to talk about those 300W of losses at full load.
çéHI EVEva said:
-Output inductors = 6uH*3 and switching I test from Power amp Output power =64.8V AT 2OHM/CH AND TEST 33msON AND 66ms off full load
- The number of power devices =HGHT30N60C3D IGBT 63A600V FOR 4200W AND transformer size FOR 2400W=E55/28/21 OR ETD49
FOR 3600W=E55/28/25 OR ETD54
FOR 4200W =ETD54 AND UP 6500W=ETD59
-heatsink size yes very small but I use pan for cooling
and pls. check http://www.camcoaudio.com/pdf/tecton_p-partnertest.pdf he can made
-and PFC I use EE55 For PFC and ETD59 For swittching
Re: Re: Re: Re: and up to 9kw smps
Hi MZZ
thank for commen pdf file and I trying convert to EN
Yes. I happen in thailand but hot if you move in thailand I can
take care you but you and i thoung speaking by hand
mzzj said:
Hey, your pdf's are in thai, damn slow to read
Do you happen to have free engineer positions in samut sakhon, Finland is way too cold in winter, I would like to move to there
Hi MZZ
thank for commen pdf file and I trying convert to EN
Yes. I happen in thailand but hot if you move in thailand I can
take care you but you and i thoung speaking by hand
Hi alabpro
I like the idea of an SMPS for Audio amps, and although I was going to build my own, I'm willing to entertain the idea of picking up one of yours and saving me some time.
However the size of your 4200W SMPS power transformer worries me. I'm estimating its size based on nearby components such as DIP IC's, and it definitely does not appear to me that this transformer has the cross sectional core area of a 4200W.
I have been looking for ferrite cores for a while for my own application, and I've seen a lot of cores lately in every power range, and this looks more like a 1000W core.
So my question:
If I take your 80-0-80 Volt / 26 Amp SMPS, and put a resistive dummy load of 3.1 Ohms accross EACH of the outputs, (so I'm pulling 160V at 26A), mow much will the output voltage sag?, and how long can I draw this current for?
SMPS are specified by how much power they can supply continuously, I hope we understand each other here.
Cheers
Adrian
I like the idea of an SMPS for Audio amps, and although I was going to build my own, I'm willing to entertain the idea of picking up one of yours and saving me some time.
However the size of your 4200W SMPS power transformer worries me. I'm estimating its size based on nearby components such as DIP IC's, and it definitely does not appear to me that this transformer has the cross sectional core area of a 4200W.
I have been looking for ferrite cores for a while for my own application, and I've seen a lot of cores lately in every power range, and this looks more like a 1000W core.
So my question:
If I take your 80-0-80 Volt / 26 Amp SMPS, and put a resistive dummy load of 3.1 Ohms accross EACH of the outputs, (so I'm pulling 160V at 26A), mow much will the output voltage sag?, and how long can I draw this current for?
SMPS are specified by how much power they can supply continuously, I hope we understand each other here.
Cheers
Adrian
alabpro said:
Huh thanks! Then, I think I can use N67 material for this frequency...
Another question: How much power can be acheved with an ETD34 core made from N67 material? And how much, if the material is N87? (becouse of N87, higher frequency can be used with lower core losses)
And how much witch ETC39?
These power supplies are definitely not going to continuously sustain the claimed output (peak) power, altough no audio amplifier fed with audio signals will demand it either (IGBTs are well suited to high peak to average ratio current requirements since they feature I*K loses instead of I^2*K MOSFET loses).
Hi dankoDanko said:
Huh thanks! Then, I think I can use N67 material for this frequency...
Another question: How much power can be acheved with an ETD34 core made from N67 material? And how much, if the material is N87? (becouse of N87, higher frequency can be used with lower core losses)
And how much witch ETC39?
N67 material not work this 96kHz-up it hot andpower for ETD34-N67at100kHz=494W and N87=680W
What is ETC39?
hi alabpro --
I'm not quite clear on how to read the specs on your power supplies. the project I have is a 6 channel amp, 4 300W channels and 2 60W channels all into 8 ohm speakers. If I just add up the watts it looks like the 2400 model is the right one, but is this correct?
The 300W channels run at 60V but the 60W channels run at about half that.
I'm not quite clear on how to read the specs on your power supplies. the project I have is a 6 channel amp, 4 300W channels and 2 60W channels all into 8 ohm speakers. If I just add up the watts it looks like the 2400 model is the right one, but is this correct?
The 300W channels run at 60V but the 60W channels run at about half that.
Hi Eva
The question is not whether audio program content requires this SMPS to deliver rated power continuously.
It is that if it does not deliver rated power contiuously, it cannot cost the price of one that does.
(what if I don't want to use it for audio; then what?)
This is not a direct comparison, but I can find new 400W switchers these days for $11. (ATX supplies which *are* continuously rated). Just as a theoretical exercise, scale up the complexity and parts count of that by a factor of 5, and you get an idea of what you should get, at what price.
All other SMPS specs indicate continuous power capacity. That's how I can compare prices. If we invent a new way of quoting power ("Audio RMS power") for an SMPS, it's either because we are trying to inflate our price, or deceive the gullible, or both.
It's sad that in the audio field there are two kinds of information disseminated: science and pseudo-sceince.
I like your scrutinizing and often incisive attacks on bullsh*t, even if they often elicit backlashes. Somebody's gotta do it.
(wanna have some fun? --ask about creepage)
Adrian
The question is not whether audio program content requires this SMPS to deliver rated power continuously.
It is that if it does not deliver rated power contiuously, it cannot cost the price of one that does.
(what if I don't want to use it for audio; then what?)
This is not a direct comparison, but I can find new 400W switchers these days for $11. (ATX supplies which *are* continuously rated). Just as a theoretical exercise, scale up the complexity and parts count of that by a factor of 5, and you get an idea of what you should get, at what price.
All other SMPS specs indicate continuous power capacity. That's how I can compare prices. If we invent a new way of quoting power ("Audio RMS power") for an SMPS, it's either because we are trying to inflate our price, or deceive the gullible, or both.
It's sad that in the audio field there are two kinds of information disseminated: science and pseudo-sceince.
I like your scrutinizing and often incisive attacks on bullsh*t, even if they often elicit backlashes. Somebody's gotta do it.
(wanna have some fun? --ask about creepage)
Adrian
alabpro said:
Hi danko
N67 material not work this 96kHz-up it hot andpower for ETD34-N67at100kHz=494W and N87=680W
What is ETC39?
ETC39 means ETD39, sorry .... I'm a typo-kign!
I'm designing an SMPS, which operates about 100khz (or 160khz?), the transformer is ETD49, with N67 material, but it is not hot. It's warm, but i can easily touch it.
How can I achieve about 0.5kW from an ETD34?
I think the key is the good magnetic coupling, isn't it?
without block capacitor, risk of transformer satuation
well I am glad to see that the subject matter has gotten back on course! I think some of the discussions got a little off.
I need some help on the feedback network. Using LT Switchercad for simulation, I am trying to build a full bridge switcher using their LTC3721. In place of mosfet, I am using voltage controlled switches (I'll move onto mosfets and their parasitics later, once I get a good understanding of the basic 'ideal' operation).
This part has a feedback arrangement with a direct relationship between the voltage and the duty cycle of the pwm. This I have verified using a ramping voltage on the feedback pin. OK, simple enough. But, I don't understand how the feedback network from the isolated secondary is supposed to work. The sample circuits (from data sheet) use opto-isolator in feedback loop. Doesn't the opto work in saturation mode, that is it switches on/off and never goes linear? If so, the feedback voltage winds up as either 0, or VCC. So how does the pwm get duty cycles other than 0% or 50%?
I need some help on the feedback network. Using LT Switchercad for simulation, I am trying to build a full bridge switcher using their LTC3721. In place of mosfet, I am using voltage controlled switches (I'll move onto mosfets and their parasitics later, once I get a good understanding of the basic 'ideal' operation).
This part has a feedback arrangement with a direct relationship between the voltage and the duty cycle of the pwm. This I have verified using a ramping voltage on the feedback pin. OK, simple enough. But, I don't understand how the feedback network from the isolated secondary is supposed to work. The sample circuits (from data sheet) use opto-isolator in feedback loop. Doesn't the opto work in saturation mode, that is it switches on/off and never goes linear? If so, the feedback voltage winds up as either 0, or VCC. So how does the pwm get duty cycles other than 0% or 50%?
The opto-coupler must be operated in its linear region. Furthermore, it must be biased in such a way that the full duty cycle range is obtained without saturation or cutoff. Otherwise the PSU will oscillate or the control circuit won't be able to limit output voltage.
The purpose of the optocoupler is to feed the control IC with a sample of the error signal electrically isolated from the output. To do so, you will have to compare a fraction of the output voltage against a fixed reference and feed the photodiode with a current proportional to that difference. The phototransistor will act as a controlled current source whose current would be roughly proportional to photodiode current. Note that this arrangemebt will act as a new error amplifier and frequency compensation should be pladed in the photodiode side, while the error amplifier of the control IC should be operated as a buffer for phototransistor output.
The purpose of the optocoupler is to feed the control IC with a sample of the error signal electrically isolated from the output. To do so, you will have to compare a fraction of the output voltage against a fixed reference and feed the photodiode with a current proportional to that difference. The phototransistor will act as a controlled current source whose current would be roughly proportional to photodiode current. Note that this arrangemebt will act as a new error amplifier and frequency compensation should be pladed in the photodiode side, while the error amplifier of the control IC should be operated as a buffer for phototransistor output.
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