An Incrementally Variable Phase-Locked Control for a Polyphase Inverter

In practice there is often a requirement for two separate polyphase supplies, the relative phase of which can be controlled precisely and varied at will. A relatively simple circuit, incorporating a phase-locked loop and coincidence detector, is presented which enables any conventional polyphase inverter to be triggered from any other polyphase source, to produce a second polyphase supply having any desired phase relationship with the first. A pulse input causes a step change in phase, of any size determined by initial design. Variations may be positive or negative, random or continuous; so providing the possibility of precise open-loop position and speed control of doubly fed devices.