Low-Speed Performance Enhancement of Induction Motor Drives Using Mamdani Fuzzy Logic–Based V/f Control

Conventional scalar voltage–frequency (V/f) control is widely adopted in industrial drives due to its simplicity and low cost; however, at very low operating frequencies, it often suffers from poor transients, speed oscillations, and excessive start-up currents when a proportional–integral controller (PIC) is used in the speed loop. These limitations hinder stable operation and reliable start-up under load, motivating the need for a more robust low-speed control scheme. This paper presents the design and experimental validation of an improved V/f scalar control based on a Mamdani fuzzy logic controller tuned by particle swarm optimization (PSO). A physical prototype was implemented using speed and current sensing and LN CO3636-3B that enables the control strategies, updates K_p and K_i through Mamdani inference in a discrete PI law, and drives a self-commutated inverter via PWM. Experiments were performed under variable conditions, demonstrating that the proposed controller at 6.06% of rated speed achieves stable regulation with M_p = 10% and t_s = 0.445 s, whereas the PIC exhibits instability with steady oscillations and M_p up to 44%. The proposed controller keeps the inrush current within the design limit below 1.615 A. Overall, the PSO-tuned Mamdani fuzzy controller improves low-speed robustness while respecting transient design constraints.