SCR phase angle firing

[Nick]

Hi all,

I am starting on a project where i need to control the output voltage
using SCR. I need to know how the phase angle firing works and how can
i implement it in my project. Please help..

Regards,

Nick.

 

[ehsjr]

Hi all,

I am starting on a project where i need to control the output voltage
using SCR. I need to know how the phase angle firing works and how can
i implement it in my project. Please help..

Regards,

Nick.

http://www.tempco.com/controls/scr_main.htm

 

[Glenn Gundlach]

http://www.tempco.com/controls/scr_main.htm

I've done the phase control with analog and microcontroller. On the
analog side I copied a concept from Ampex to use a cosine ramp rather
than linear to get a linear power change. It compensates for the
sinewave.

In the microcontroller you use a zero cross of the AC line into an
interrupt to synchronize an internal counter. Count off the
'subdivisions' of the AC line to get your firing angle. This works very
well and is not difficult, not to mention an excellent programming
exercise. It also has the virtues of very low parts count and
flexibility. I used the Motorola (now Freescale) 68HC05 and '08
families. I'm sure you could use 8051 family and PICs.

GG