buck converter with microcontroller

[eng.hasan.power]

microcontroller buck converter

Dear All;

i need to make a power supply out variable 0-18v and 0-3A from 220v AC

what's the way i should walk through??
im little familiar with buck converter, and Motorola controllers and PIC controllers; but i prefer FreeScale-motorola-

i need to do it by microcontroller not a special IC,

the questions are.
1- is there's any other ways to do it; w/o Buck converter?
2- and if the answer NO, how can I make it by Buck, i make Buck converter once but without feedback where i should replace the voltage sensor, and what current sensor i should use -resistor for example-; and where can i place it

any help will be appreciated;

 

[kender]

pic buck converter

1- is there's any other ways to do it; w/o Buck converter?

Yes, of course. You can do it with linear reglulator and a digital pot. The efficiency will be lower, but there will be much less EMI (noise) and the design will be a lot simpler.

 

[kishore2k4]

buck converter pic

If you need it in some other projet then you can get ready-made DC-DC converters available in wide range of voltage,current and power ratings. If you are doing this itself as a project then buck converter is the simplest of all step-down converters. As kender suggested Linear regulators are ok, as long as your power requirements are not that high and proper thermal management is done. The reference to the Linear regulatator can be provided with a DAC, if available or just make using one of the controller ports and a weighted resistor ladder.

You can use a simple resistive divider to measure the output voltage at the load, be careful to choose a ratio so that when the Vo is at 18V your ADC should not see more than 5V or whatever you ADC can withstand.

For current measuring use a 0.1% or better 0.1-0.5 ohms resistor depending on the noise present in your circuit, higher resistance are ok as long as you know the type of load voltages and currents you are going to supply.

For control, just sample and the voltage and adjust the duty cycle accordingly, you can measure caliberation offsets during testing and later program them into the microcontroller.

 

[kesha]

Hello guys!

Does anyone know how to create the block in simulink to convert to binary code from the value i.e. 12v 4-bits, 12v 9-bits.
Thank you
Kyle

Added after 3 minutes:

I have to build the sys model for digital current control with bits and max voltage. for i have to know the output in binary code for my DPWM.