A programmable local controller for AC adjustable frequency drive controllers

It is noted that responsive closed-loop drive operation using the PLC (programmable logic controller) as the controller is usually not practical without extensive additions to the PLC system. It is shown that such operation can be implemented by embedding a local controller within the adjustable speed drive. The control system can be based around existing PLC hardware. The authors describe such a system implementation incorporated into an AC adjustable-frequency-drive controller. Some basic characteristics and attributes of such a system are described