PLC-based fuzzy logic controller for induction-motor drive with constant V/Hz ratio

This paper presents the design and implementation of a PLC-based fuzzy logic controller for an induction motor speed control at constant V/Hz ratio. The PLC has arithmetic and logic operations instructions set that was utilized in the implementation of the fuzzy control of induction motor speed control. Fuzzy logic algorithm applies rules obtained from human expert of a system. The input signals to fuzzy controller are the linguistic variable of speed error and change of speed error, while the output signal is frequency of PWM inverter. The supply voltage to the induction motor is ascertained from frequency output requirement using constant V/Hz ratio. The objective of the controller is to provide stability in responds to disturbance and sudden changes in reference speed. Results of the proposed system show satisfactory performance.