Audio smps 700w (IR2153)

Silvio

Member
Audio smps 550 watts 700watts peak

Here is an audio half bridge smps that can be altered in quite a lot of ways. This smps was designed in such a way that different drivers can be adopted, also that different protection circuits can be adopted. The one presented here is with a current limiter which works very well.

The driver choice at the moment is with the IR2153 which is rather cheap. However other options can be made to be driven with an SG3525 and can be regulated. Options for feed back can be included on a small pcb having an opto coupler and Zener to stabilize the output voltage. Provisions have been made for output inductors. However these are made very small (5uH) at the moment as this smps is intended for audio purposes and not stabilized, the IR2153 works at full duty cycle and not much noise is generated.

The transformer construction is very important and tight coupling was kept in mind during winding. However the input and output snubbers where not needed as the wave forms came out very clean and free of distortion and spikes. A video is available on youtube regarding the construction of the transformer which can be found on this link. https://www.youtube.com/watch?v=_K3ixhcTYFg Here the whole construction of the trafo is seen with some very good tips for good transformer construction for this smps.

Circuit description

As the smps is switched on the rectified DC voltage starts charging the main bulk capacitor limiting the current through the 15 ohm NTC thermistor. As the voltage at the bulk cap reaches around 170 vdc TR1 and 2 are coupled in a constant current source which the voltage at TR1 is clamped at 160v via ZD1. TR 2 is clamped at 10 volts via ZD2. together they start charging C8 when the threshold voltage of around 9.2 volts. The chip starts oscillation The auxiliary supply takes over and stabilize the voltage at the pin 1 of the IR2153 at 13 volts via ZD3 hence the constant current source is switched off. At the same time it starts charging the main secondary caps the current however is limited by the current limiter to around 6 amp on the input of the drain of TR4 and TR5. A 2 turn loop at the transformer supplies the gate of the triac at the input shorting out the NTC thermistor and full power is now available. All this happens in the blink of an eye.

Short circuit and current limiting.
The choice of current limiter was chosen however I admit its not my design and after a few trimmings in the coupling capacitor and also in the some resistor values from the original circuit works very nicely. It limits the output power to 700 watts of which this can also be adjusted for higher and lower power. This will protect both amplifier and the smps itself during over load by reducing the output voltage and the output current drops to around 2.5 amps until the overload is removed.
The current sensing can be done either with a current transformer or with a more simple method which I chose. In my case the current sense is done by sensing the ripple voltage at the center point of the fets. When the threshold is reached TR3 pulls down the supply at pin 1 via Led 1 of the IR2153 and thus switching it off. A point is reached where the load reduces and also the ripple hence and oscillation starts again. This action is repeated until reasonable load is reached and normal operation starts again. If a dead short is present the output current is limited to 2.5 amps. >>>>> Continues in pdf
 

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Silvio

Member
Choice of oscillators and protection

The PCB can be adopted to work with a different oscillator as mentioned before due to the oscillator board and protection circuit is mounted on a separate pin header. This is plugged in the socket provided on the pcb. I also made plans to use different protection circuitry using either a Schmitt trigger or driving an SCR gate with both options pulling down pin 3 of the IR2153 to ground. However these type of protection brings out the need to reset by switching off the supply and waiting for the bulk cap to discharge until it can be switched on again. I prepared the prototype pcbs for these but have not been tried yet

Heat sink and cooling

A good heat sink is needed for the fets and output diodes as these are driven quite hard during the peak output. With the heat sink used the smps can handle the power easily if a small fan is included. I made a fan socket available for this reason. In my setup peak power could be held for quite a long time without things getting hot with the fan on. This was placed at the side to cool also the transformer

Auxiliary output.

An auxiliary output of 12v-0-12v is provided capable of around 800mA. This is intended to drive a preamp stage or some protection circuit on an amplifier. I often see the need of a separate output for this reason.

The design voltage of the smps is 46-0-46 peak at 230 volts input. During my tests the output voltage went down to 78volts at 9.4 amps. The input voltage was 227vac with a power output of 730watts. The efficiency of the smps reached 90%.

IF ANYONE IS INTERESTED IN BUILDING THIS SMPS I WILL SEND THE PDF FILE PRIVATELY


SMPS 700W SCHEMATIC .JPG
 
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steven

New member
This is my first message here.

Hi Silvio,

Very interesting project. I do not really understand how the current limiter works...

According to your experience, is it possible to extend the output voltage around 450V (or more) for tubes power amps supply ?

Steven.
 

Silvio

Member
This is my first message here.

Hi Silvio,

Very interesting project. I do not really understand how the current limiter works...

According to your experience, is it possible to extend the output voltage around 450V (or more) for tubes power amps supply ?

Steven.

Hello Steven. yes it is possible to extend the output to 450 volts but you need to have diodes with around 3 times the voltage rating, The current limiter works by sensing the ripple voltage at the middle of the fets. The ripple increases in amplitude with load. When enough voltage is developed it biases the transistor and this will pull the supply to the IC and switches it off. again the smps starts again when the ripple goes down. if the over load is still present it cycles back until a point is reach where the output power is limited to around 200 watts and stays there until the overload is removed.

hope that helps

Silvio
 

Silvio

Member
This is my first message here.

Hi Silvio,

Very interesting project. I do not really understand how the current limiter works...

According to your experience, is it possible to extend the output voltage around 450V (or more) for tubes power amps supply ?

Steven.

Hello Steven. yes it is possible to extend the output to 450 volts but you need to have diodes with around 3 times the voltage rating, The current limiter works by sensing the ripple voltage at the middle of the fets. The ripple increases in amplitude with load. When enough voltage is developed it biases the transistor and this will pull the supply to the IC and switches it off. again the smps starts again when the ripple goes down. if the over load is still present it cycles back until a point is reach where the output power is limited to around 200 watts and stays there until the overload is removed.

hope that helps

Silvio
 

steven

New member
Hello Silvio ,

Thanks for your message.

Regarding Triac delay: any idea of triac Pd at full load ? Are you using BTA 12/600 or similar ?


For 450VDC@0.4A output (X2), i am planning to use UF5408 bridge. I hope to have enough room for the two secondary winding on ETD39 bobbin (450+450). I am also thinking to use a simple regulation circuit to avoid the output voltage to go too high without load at the ouput (tubes amp warm-up).

Last summer I did one basic prototype using SG3524+IRFP450+ETD39 to supply QUAD2 tubes amp. Results was good, reliable and stable with few components only. I am thinking to use SMPS in the near future instead to expensive and heavy 50hz iron transformers and chokes...
 
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Silvio

Member
Hello Steve,

Regarding the triac yes I am using BTA12/600 I think it is a bit overrated but that I had in my junk box and used it. As you can see from the schematic MT1 and Mt2 are tied across the NTC thermister which this has a value of 15 ohms. Initially the load is carried by the thermister and practically the initial surge is eliminated from the triac.

I made some calculations for you yesterday and found you will be needing around 100 turns or so for a single output of around 420 volts. This voltage is the loaded voltage at 1.2 amp. which gives a power of 540 watts. The peak voltage however will be around 500 volts.

If you are using my smps however it is not regulated and altering the pin header in a different configuration with a different chip.
I did not make a prototype yet.

The output capacitors have to suit the output voltage with some headroom. The current limiter adopted will cater for the initial charge up of the secondary caps and not blowing the secondary rectifier. I recommend you to use the output inductors as if not the transformer sees a dead short in the initial charge up. You can lower the inductance stated in Excellent IT software which I sent you a picture of my results. However the winding fill is above the normal 3.5 for large transformers being around 0.45 now. I don't know if you really need a double winding or a single one. In that case for a single winding you only have to opt for a full wave bridge. The winding fill however will be reduced as you will use a single wire instead of two for the secondary.

I don't know what type of amplifier you are using if its a class A, AB,C or D. The current as you know will vary between the types. usually for class AB the power absorbed will be from around 30 to 60% depending on the volume level and type of music.
Keep in mind that the power supply has to fill the output caps for the next demand with every beat of the music. This now having 60,000 pulses instead of 50 pulses compared to an iron core transformer. For this reason the output caps do need not be large in capacitance value. However a compromise will be set according to the ripple voltage in the final choice.

I will post the PDF file to your mail address. I did this as some people will use the hard work of others for their benefit and earn money from it. I do this purely for the hobby and nothing more.

One last comment The IR2153 can only deliver up to around 200mA of driving power however this is suited for medium power fets such as IRF740 or similar. However if other transistors are used with higher power and larger input capacitance then alterations have to be made such as current amplifier added to the drive chip.

I hope this will guide you for a successful smps.

Regards, Silvio

View attachment HV etd 39 steve.pdfETD 39 HV steve.jpg
 
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kanon

Member
Thanks for the schematic.
I've created a layout in the next week I'll try it maybe explode maybe it works.
ATTACH=CONFIG]6155[/ATTACH
 

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Silvio

Member
Thanks for the schematic.
I've created a layout in the next week I'll try it maybe explode maybe it works.
ATTACH=CONFIG]6155[/ATTACH

I hope you included the bridge rectifier in the input as I forgot to illustrate it

Scematic smps 700 revised.JPG
 

kanon

Member
Yes look.
Steven & Silvio.
If you like to check the layout for errors.

If everything is ok to upload it

Used IR2153D

Check pdf.
 

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kanon

Member
This is the final layout.

T0-220 & T0-247 Mosfet that can be used.

It is based on your schematic, only add silent controller fan, gate zener protection and nothing special.

Final
 

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Silvio

Member
Hi Kanon

I think your layout is ok and good job with the silent fan. I prefer larger capacitor and smaller output inductor to minimize voltage drop. If you want to use a larger mosfet then you have to add current amplifier for output drive on chip IR2153. it cannot drive the hi gate capacitance such as irfp460 etc. IR2153 can sink and source around 200mA and only suitable for medium power fets. Why not etch your prototype and try the smps. There is a video on youtube you can watch me wind transformer etd39 for it.

As you used the IR2153D you can omit the bootstrap diode Uf4007 as the chip has it internally

Do not forget to show us some pictures of your work


regards Silvio
 
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kanon

Member
Tanks.
I already work on it and of course it will upload photographs.
 

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Silvio

Member
@ Kanon

I can see that you adopted for the shmitt trigger for the protection. I did not try it on the smps. Perhaps with capacitive coupling it may not work as it may need more voltage. however it works with current transformer as I only bread board the prototype and it may need around 3 to 5 volts to trigger. You can also play with different series resistor with capacitive coupling to add or reduce current and voltage. The current limiter however need only 0.7 volts to operate.

I can also see that you added another film capacitor on the common line between the switching fets. You don't really need it as the other caps who are dividing the voltage are also film capacitors. The value of these capacitors are 1Uf each and are dynamically seen as 2Uf which are just right for the current handling in the smps. You can make a link instead or you can place a current trafo instead of it.

The Aux supply need only 1 diode and not 2 The voltage with my trafo for 4 turns will be around 20 volts and with only one diode it goes down to 16volts That is why I use only one diode, 200 ohms series resistor is just right for the zener 13volts to supply the chip. It will also help with current limit on the Led when it operates
I made a place for 2 diodes with aux supply because if I need more power with another different chip I can add it.

Silvio
 
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