Implementation and analysis of PLC SCADA controlled closed loop four quadrant speed control of chopper fed DC motor

In this paper, a scheme for closed loop speed control of DC motor in four quadrants using Programmable Logic Controller (PLC) is discussed. The armature voltage is varied using a Class E chopper circuit. The individual switches in the chopper circuit are switched using Pulse Width Modulation (PWM) control signals generated by PLC. Duty cycle of PWM signals are varied by PID controller of the PLC. Three main modes of operation have been implemented: Speed control mode, sinusoidal input tracking mode and step input tracking mode. The resulting current, voltage and speed waveforms are recorded on Digital Storage Oscilloscope(DSO) and analyzed. Speed, set point and control variables are observed on GUI made using SCADA software.