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The news D-Amp DLS3000....

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Here some pick of our news prototype of the D-Amp DLS3000...It's a 1000W RMS per ch/4 ohms and 1500W RMS per ch/s ohms in class B-D, powered by a pair of STW50NB20 at +/- 92V by an IGBT heat sink less switching power supply. Full power measured for 15 min, 8 hours burn-in at 1/3 of maximum power. Sound is very nice. Some cue about the amp...Hight side of the drivers is powered by NE555 charge pump, 0-100% duty cycle, current sens only on the negative side, power limited in 2 ohms by an NSL32 optocoupler in the feedback loop, reduce distortion in 2 ohms and improve stability, first time I try this, and it sound very nice! Clipping limiter by JFET j112 into error amp, work very well and very fast too!

I will talk to you soon about news prototype of combinated amplifier and switching power supply in phase modulation, heat sink less for about 2 Kw per ch...seem to work well now, but some little thing to fix...

Have a nice views!

www.d-amp.com
 

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YOUR AMPLIFIER IS VERY NICE !!!
I'm not open another post again,please help me !
I find this schematic in a Sony project amplifier car class D ( XM-D1000P5 ).
I was trying to simulate this schematic in Orcad soft,but the rezultat is not good.
I don't find in my library KTC,KTA tranzistors ,but I simulate with another pnp and npn tranzistors.I don't find diod ISS226.
The rezultat of my simulate is good but the amplitudine of my output is just 10 mV. I can't up this amplitude indiferent of level of in.
This amplifier are supply power at +/- 90 V but the output power recomended by Sony is :
RMS: 500W/4
900W/2
and maximus output :
1000W/4
1600W/2
The power of 900W/2 at a rail supply +/- 90V IT ISN'T TOO SMALL?
What eficience has this amplifier?

Best regards ,mgm2000ro!

http://img146.imageshack.us/img146/852/sonyy3hn.jpg
 
I think you can maybe simulate with the 2N5401 and 2N5551 for the transistor. This look like a very low frequency PWM amplifier..Try to reduce the output capacitor, 100uF (the two 220uF in serie) will slow down a lot the switching frequency. For your diode, for sure use 1N4150, this is just a clipping diode for the error amp. If it dont work for the transistor, try the D45H and is complementary, this is fast hight voltage transistor. Anyway, I dont suggest you to go on that way, the mosfet drivers seem to work at hight power, so lot of dissipation in them...Try to modify it with a bootstraped version for the hight side, or at least with a IR2110...Have a nice day!

Fredos

www.d-amp.com
 
Hi Fredos,

You primarly design your amp for 4 ohms rating and than derate their power rating for 2 ohms with the current limiter...Your Mosfet is having a low gate charge and its similar to IRFP260 except its gate charge is 234nC...

A very good approach....you have followed...

I have designed amp only for dedicated 2 ohms power level and recently used APT50M65B2LL Power mosfet to get 2KW at 2 ohms with Rails at +-110V Idle...
Also designed with IRFP260N ...1200W @ 2 Ohms .....

Cheers,
K a n w a r
 
Hello Workhorse

It was in B-D? What I mean is that their is no carrier, or just some pulse some time at the input of the output filter? Only positive pulse when positive signal and negative pulse with negative signal? It was full range? Why did you need +/- 110V for 2 Kw 2 ohms? You should get nears 3 Kw of power! Have you try the 300V version of APT? They have lot lower RDSon! I will try as soon as Y received my 300V mosfet to push it a little more, the only power dissipation I have so far is in the bridge rectifier of the power supply...Have you try a ESD1 diode in parralel of power mosfet? This help a lot for the recovery if you are in class B-D!

Have a nice day!

Fredos

www.d-amp.com
 
That will be a nice RF transmitter considering the rated 330ns reverse recovery time and 21A reverse recovery current at 100A/us for those STB50NB20 MOSFETs. Current spikes in excess of 50A rising at 500A/us are guaranteed with such an output stage. These MOSFETs are not suitable at all for classic class D topologies, there are special devices with faster body diodes for these duties but that is achieved at the expense of higher Rds-on.

Also, what do you exactly call class B-D? The pictures show a bare two-switches-and-a-LC-filter output stage, the one that almost everybody uses.

And last but not least, are those common-mode filters of the SMPS really wound on the classic yellow-white coloured iron powder cores??? :whazzat: They are not going to filter anything that way :D
 
Hi Fredos,

Mine design was just a simple half bridge type not a full bridge in BD mode...
The carrier Frequency was 250KHZ...
For 2KW in 2 ohms 110V rails were needed....
Yes I have Tried APT30M85BVR....also Nice results....

I put the Schottky diodes in series with Mosfets and connect an anti parallel diode to that combination to deal with freewheeling current and also it helps alot in case of short circuit also....

Cheers,
K a n w a r
 
The output configuartion is standard, 2 output in half bridge, but the drive circuit is different. No pulse or a very narrow pulse with no input signal, and when input become more positive, positive pulse is feed to the output filter with no negative pulse, except the reverse enegy feeded by the inductor. Same for negative input. The ESD1 in anti parrallel with the STW50Nb20 over come the slow recovery of the body diode. Just remember in my case that output did not work in complementary fashion, so recovery could be very soft. That's what I call B-D, like a class B, nothing happen with no input signal. Less EMI, higher effiency, faster feedback recovery! Yes the common mode is done with yellow-with iron poweder coil, with 2 filter at 22uH, but I also use a IEC power line filter that not show in picture. The 2 common mode is just to lower emission between board and line filter!

And before you ask me, a NE555 in charge pump feed the power for the hight side mosfet when no signal is feeded to power amp!

Fredos

www.d-amp.com
 
except the reverse enegy feeded by the inductor.

Wich means some 10 Amperes, and can easily hold diode opened till the next positive pulse. Forward voltage of an ES1D (I think you meant this) is much more than MOSFET's, so how could it reduce recovery loss?

Eva!

These MOSFETs are not suitable at all for classic class D topologies,

Despite of this Tripath recommends the very similar STW34NB20. I don't really understand!
 
Yes Workhorse, similar, but with some 2N7000 as buffer to provide all current needed, directly referenced to V--.

Pafi. ES1D, sorry for this, yes, but they only work in the first fews nano second of switching, after that, the body diode of mosfet take care of the current. That why I use a higher voltage drop diode, just for the speed of them, after that, the body diode take care of all the rest!

Tekko: sorry, but it was a free running class d amplifier...The first op amp is the error amplifier, and all transistor was configured as a hight voltage comparator...Like the UCD, but at lower frequency.

I wish that this tread give a lot of idea to everyone!

Fredos

www.d-amp.com
 
fredos said:
The output configuartion is standard, 2 output in half bridge, but the drive circuit is different. No pulse or a very narrow pulse with no input signal, and when input become more positive, positive pulse is feed to the output filter with no negative pulse, except the reverse enegy feeded by the inductor. Same for negative input.

There is no diode recovery phenomena at idle and low output levels because inductor current crosses zero during each cycle causing the switches to turn on at zero voltage, so that "B-D" mode of operation does not have any impact over EMI, but does increase cross over and low level distortion due to the inherent discontinuity. It's preferable to turn-on the switches in a straight complementary way with minimum dead time as that shunts the body diodes during most of the cycle, thus almost preventing them from conducting. That in turn improves efficiency (particularly with low Rds-on devices) and reduces diode recovery issues because much less charge is stored in the junctions. Remember that stored charge depends on the amount of time that the diode has been previously conducting, and that reverse recovery times and currents are dependent on the amount of stored charge. In practice, it means that a plain body diode recovers much faster if the MOSFET was shunting it just 50ns before it's required to turn off.


The ESD1 in anti parrallel with the STW50Nb20 over come the slow recovery of the body diode. Just remember in my case that output did not work in complementary fashion, so recovery could be very soft. That's what I call B-D, like a class B, nothing happen with no input signal. Less EMI, higher effiency, faster feedback recovery! Yes the common mode is done with yellow-with iron poweder coil, with 2 filter at 22uH, but I also use a IEC power line filter that not show in picture. The 2 common mode is just to lower emission between board and line filter!

And before you ask me, a NE555 in charge pump feed the power for the hight side mosfet when no signal is feeded to power amp!

Fredos

These cores are not suitable. The resulting filters will show very low inductance and RF impedance. There are special materials intended to show high impedance in the 10Mhz to 100Mhz critical range. Also, the required turn counts are somewhar higher (maybe a dozen on each side).
 
Eva

That's why I use these core, just for radiated emission. Conducted emission are take by the IEC line filter...I think you should revise your last post about recovery phenomena, because inductor create a big reverse voltage swing with verey narrow pulse....So? And sorry, no crossover distortion with this topology. Hysterisis depend of input signal, so lower is it, lower is the hysterisis of the comparator, fews 1/100 mv at input make change at output...A trick here!

Fredos

www.d-amp.com
 
Escuse me fredos for using your topic with my question.

I'm looking a schematic class D amplifier with a high power output up to 1kW for my car amplifier (i intend to built). I'm intrested in schematics already built and works. I'm a student and my knowledge of class D amp. are very poor.

I notice that are a lot of users with very good knowledge of cass D amplifiers, but they don't show their designs/projects, even olders or abandonated.

Please share some of old project (no longer needed) or schematic built by companies, for helping us (unexpirienced users) in imaginate how to build an amplifier D. It's like u teach an child how to play football, but the child never see the ball and any play...only with words. It's only my opinion and i hope u don't feel upset or be angry with me.
 
An amp that large are not a good beginner project.

Im planning a class d amp myself but i sight for just earbud power to begin with.

I suggest you check out these "complete class d amp in a chip" ICs that just needs a few external components, or a kit. if it has to be a class d amp. Tho none of those ar even close to a kilowatt but you will never need more than 100w anyway.
 
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