#### yubaraj

Joined Oct 22, 2011
6
Hey I am doing my minor project in DC adaptor having following input
110-240v Ac , 50 Hz

Output- 19.5V Dc.

Can anyone help me how to simulate the adaptor circuit in matlab simulink which can give the constant dc output voltage of 19.5v DC from the variable ac voltage source from 110v to 240v Ac at 50HZ frequency?

#### ogbuehi

Joined Jan 13, 2011
2
Sounds like you'd need a simple rectification circuit.

#### BillB3857

Joined Feb 28, 2009
2,546
With the input range specified, it will be a little more complex than a simple rectifier circuit. Think SMPS (Switch Mode Power Supply)

#### chrisw1990

Joined Oct 22, 2011
551

#### chrisw1990

Joined Oct 22, 2011
551
just make sure you match the current for the laptop (assuming you are going to use on a laptop)

#### BillB3857

Joined Feb 28, 2009
2,546
This sounds more like a school lab project than a need for a laptop PS. Am I correct?

#### chrisw1990

Joined Oct 22, 2011
551
could be right hence the simulation..

#### yubaraj

Joined Oct 22, 2011
6
Yes i know that i need the simple rectification circuit but the ac voltage may not be constant and how can i get the constant dc voltage from variable ac source i.e Ac can vary from 110 to 240 volts.

#### chrisw1990

Joined Oct 22, 2011
551
what is the purpose of this adapter?

#### BillB3857

Joined Feb 28, 2009
2,546
I must repeat post #3. Very common approach to solving your problem.

#### yubaraj

Joined Oct 22, 2011
6
what is the purpose of this adapter?
My purpose is just to design the adaptor in the matlab simulink. I got the result at the constant ac source(220V AC) but i don't know how can i get the constant Dc voltage in the variable ac source from 110v to 240v

#### yubaraj

Joined Oct 22, 2011
6
This sounds more like a school lab project than a need for a laptop PS. Am I correct?
Actually this is not the school lab project. If you know please help me to design the circuit using matlab simulink. I have no idea to get constant dc voltage for a variable ac input source.

#### chrisw1990

Joined Oct 22, 2011
551
look into switched mode power supplies (as someone mentioned earlier post #3)
thats your best bet. then all you need is a little transformer and rectifying circuit, switched mode power supplies are very good, i have just designed one for a 3.3V 4A supply, but its input current at 24VDC is only 400mA (Thereabouts)therefore it would be a cheap and easy matter to create the rectifying circuit for it as low current is a lot easier!

#### BillB3857

Joined Feb 28, 2009
2,546

#### chrisw1990

Joined Oct 22, 2011
551
BillB3857, not sure here, if he just wants to simulate it?

#### BillB3857

Joined Feb 28, 2009
2,546
Plug this into Google (without the quotes) and look at the first hit.. "matlab simulinik smps simulation" It takes you to a pdf document with a lot of simulation information, graphs, etc.

#### yubaraj

Joined Oct 22, 2011
6
Thank you for all the friends who support me. Finally i did the project.

#### yubaraj

Joined Oct 22, 2011
6
Please check My project regarding the AC adaptor. If any problem please inform me. How to design the circuit in the PCB?

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#### mixed_signal

Joined Dec 5, 2009
22
Please check My project regarding the AC adaptor. If any problem please inform me. How to design the circuit in the PCB?
Looks about right to me on quick inspection... You should check the waveforms at the AC input, output of the diode bridge, the gate of the switching FET the output. Could you post some of those?

In general, if it works over a range of input AC voltages and load currents then it's regulating, at least.

By way of free advice... It's always important to "back up" your simulation results with hand calculations. If the two are inconsistent then either your understanding or the circuit are incorrect in some way. Don't rely on only simulation since you may easily miss some conditions that cause trouble, e.g. instability. SMPS have a number of potential problem areas. Also, your Simulink models may be quite ideal (not sure?), so frequency response or voltage drops may be unrealistic. You might want to consider using a SPICE simulator (e.g. PSpice, LTSpice, ngspice, etc.).

Cheers.