Multi-level bang-bang control of DC motors using a PLC

Programmable logic controllers (PLC) have been widely used in industrial process control, due to their low cost, high reliability and integrated logic functions. This paper reports the development of the multi-level bang-bang control (MLBB) scheme, a simple and robust non-linear control algorithm for PLC implemented closed-loop control system. The developed MLBB algorithms have been tested and verified using a DC motor variable speed drive controlled by a PLC. Test results have shown that under MLBB regulation, the DC motor drive is capable of maintaining the desired speed under both speed demand changes and load variations.<>