Rw. Wall et Hl. Hess, DESIGN AND MICROCONTROLLER IMPLEMENTATION OF A 3-PHASE SCR POWER CONVERTER, Journal of circuits, systems, and computers, 6(6), 1996, pp. 619-633
A single processor controls a three phase silicon controlled rectifier
(SCR) power converter. An inexpensive, dual optoisolator interface to
the power line provides noise rejection and an improved measure of th
e zero crossing. A dynamic digital phase-locked loop (PLL) algorithm i
mplemented in an Intel 87C196KD-20 processor achieves frequency tracki
ng, dynamically changing characteristics for improved performance. Dyn
amically modifying the PLL characteristics permits independent capture
and locked dynamics. A feedforward method provides command tracking f
or improved response without loss of performance. This three-component
design (processor, optoisolator, and SCR gate drivers) represents a m
inimal implementation with potential for closed loop voltage and curre
nt control. High speed input and output resources included on the 87C1
96KD processor make an efficient single-device implementation possible
. The processor is less than 1% utilized allowing for additional funct
ions to be added in the future. This system operates on both 50 Hz and
60 Hz power systems without modification or loss of performance.