300W SMPS for audio amplifiers +-50V out

[Mnt]

Hi there I made this power supply but I haven't tested with load. I've ordered class d audio module but its not shipped yet. I need to wait 2 more weeks.

I measured +-50V without load at all. Please tell me, I need to know what will be the voltage with 150W load since there are no regulation. Im wondering. :bsdetector:

The sch consists of 5A fuse->bridge->150uF 400V->IR2153+IRF840+rewinded PC ATX trafo by me. Bootstrapping by BA159 diode + 1uF electrolytic. Timing by 15k + 1n (50khz)

There is no protection but I will use another 3A fuse after the big electrolytic.
I think this will be enough.

 

[schmitt trigger]

If you would post a complete, well drawn schematic schematic, perhaps we could be able to provide an answer.

For instance: how are you driving the Mosfets? What is the duty cycle? What frequency?

 

[Mnt]

If you read carefully the frequency is there. I said its 50khz.

Also I explained the circuit because its simple. Mosfets are well driven. IR2153 is oscilator+high side driver+deadtime generator. The duty cycle is 50%

IR2153 is having internal zener diode and its supplied from 320Vdc via 33k resistor and additional 47u electrolytic.
Its not working without this 47u !

I wrote its timed via RC network 15k+1n. Its interfaced to the mosfets via 22 ohms gate stoppers.

Im not using half-bridge because Im using a principe used in class D amplifiers (explained in the 2nd attach of my initial post)(its same as half-bridge).

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Output caps are 1000u 50V, im uploading the original camerashot again edited with added component values.

 

[schmitt trigger]

Ok, I missed the 50Khz. But you will still have to agree that your initial information is incomplete.
A circuit may be simple to the person who has worked on it, but not to other individuals.

I don't see an output inductor. it is required on a SMPS. Otherwise the output capacitors and/or rectifier diodes will see enormous ripple current and will fail prematurely.

Edit: you have three MUR1640 rectifiers. How are they connected?

 

[Mnt]

Im not having a schematic, I will draw tommorow.

you have three MUR1640 rectifiers. How are they connected?

These are connected this way


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I don't see an output inductor. it is required on a SMPS. Otherwise the output capacitors and/or rectifier diodes will see enormous ripple current and will fail prematurely.

Is this very required ? Im not aiming this to be a top quality smps.

 

[Warpspeed]

Is this very required ? Im not aiming this to be a top quality smps.

No reliability and freedom from blowing up is not always required.
The choice is entirely up to you.
You can make it as rough and risky as you wish, its YOUR supply.

 

[Mnt]

How to attach the inductors, look at the attachment:
1st or 2nd way ? I think it must be the first way but ive never seen it in schematics. I've seen only the second way which doesnt make sense to me.


Edit: I forgot to draw a schematic.

 

[schmitt trigger]

These are connected this way
View attachment 130963

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That is not a schematic.

I never cease to be amazed people who attempt to build circuits, any type of circuits, without a proper schematic....how can you follow your wiring? How can you check for connection errors? How do you document component values? How do you assign signal names?

I would advise you to start by downloading a free schematic capture program. There are many on the web.

 

[Mnt]

schematic

 

[Audioguru]

I made the awful scribbled schematic black and white and increased its contrast a few thousand times. It looks OK except for the inductor location.

 

[c_mitra]

I do not understand your circuit; do you have a high /low side for the fet drivers? Do you not need any regulation og the output voltage? Some degree of output regulation is not only desirable but essential.

 

[Audioguru]

Most audio amps do not have a regulated power supply voltage. They simply use a large enough mains transformer, rectifiers and a large filter capacitor. The DC voltage normally rises a little when the amplifier plays quietly or idles then drops a little at full output power. The little voltage fluctuations are ignored by the circuit.

 

[Mnt]

I made the awful scribbled schematic black and white and increased its contrast a few thousand times. It looks OK except for the inductor location.

Audioguru thanks but why the inductor should be there ?


What would be the output voltage with 150W load when its 50V without load ??

Edit: I think i undestanded for the inductor but im not sure :grin: