Hi all,

We are developing a universal power controller board to control 220/380V~ motors and lamps. We do this with thyristors via phase controlling. We measure the zero-cross point of the sinus and trigger (via an interrupt) on it. For lamps works this method very good. It works less good for inductive loads like motors because the current and the voltage are not in phase. For 3-phase motors is it even worse. We could measure the current for every phase but we have not enough digital or analog inputs. Is there a simple and effective way whith minimal inputs to solve this problem. We have 20 outputs which this has to work for.

Dennis.