buck converter design

[sanmoy]

I have a constant 110v dc source. Is it possible to design a buck converter to regulate the voltage from 0-110v? Load will draw 1A max. load is a relay(electromagnetic switch). Please post the circuit diagram with components.

Thanks in advance

 

[Diver300]

If the load is a relay, you can just use a PWM system where an transistor turns the power on and off very quickly. The average voltage on the coil is the supply voltage multiplied by the fraction of the time that the power is turned on.

You need a freewheel diode across the coil, and the switching has to be fast enough that the current in the coil doesn't vary very much. However, with a relay coil that has a lot of inductance, you probably only need to be above 50 Hz or so.

 

[sanmoy]

The key point is whether we can regulate it from 0v - 110v. I need a linear regulation preferably. Also, the load may not be a relay always.

 

[crutschow]

A linear regulator would dissipate up to 110W @ 1A which would require a large fan-cooled heatsink.

To avoid that you would need a switching regulator.

What type of regulation accuracy do you need?

 

[sanmoy]

Sorry, my mistake. I need a buck converter only, which would regulate the voltage 0 - 110v, but in a linear scale. 0,1,2,3...110v. Not in logarithmic scale or so.

 

[MrAl]

Hello,

ybreethi:
You should start your own thread for that.

sanmoy:
Yes you can use a buck regulator circuit. You may not be able to use PWM directly though because a coil will not turn off suddenly like a resistive load will, so a full buck converter may be necessary. We can look into this more.

 

[MrAl]

Hi,


Unfortunately you're not describing your circuit operation that well. You should post a schematic too probably.
But this would be better in a new thread.