Phase control using SCR?

[angeloduca22]

Can anyone help me, how to design PIC16f84 for phase control application and SCR as triggering for DC load.....

I would like to make AVR (DC) for genset that will monitor the output voltage of genset at thae same time it controls the triggering or firing of SCR...


Please help me on this....


Angelo

[BobEdge]

Hi

Is it three phase or single phase you want to control?

[angeloduca22]

Hi Bob,

It's single phase... but if you can add extra for 3 phase it will be great...my sole purpose for this is to control brush and brushless generator that will be feed DC voltage to it's exciter coil....


please help,

thank you...


Angelo

[btaylor]

I'm not sure of your real application but you will have big trouble trying to pulse width modulate a DC exciter current with an SCR. An SCR will initially be off but once turned on needs to see the current fall to zero before it will turn off again. this is fine on AC where the SCR will turn off at the next zero crossing but bad news for DC.

You might look at some high current FETs instead.

HTH
Brian

[angeloduca22]

Hi Btaylor,

It is not actually a pure DC rather it is halfwave or fullwave rectification and no large caps to mentain it ripples or wave on its output so falling of waveform with the 60Hz freq will be available at the output...

[BobEdge]

Hi,

What voltage is the rectified wave form? If it is highish voltage it is easy to connect this straight into a pic, through large value resistors. This is how you detect the zero point of the waveform.

It is NOT a good idea to rectify mains, some sort of transformer must really be used, for safety.

Regards Bob...