Design of a PWM Speed Controller for DC Motors Used in Industrial Conveyor Systems in Oshodi, Lagos

This project designs and implements a pulse-width modulation based speed controller for direct current motors used in small-scale industrial conveyor systems in Oshodi, Lagos State, South West Nigeria. Oshodi houses a dense concentration of small manufacturing workshops producing furniture, food products, and packaging materials, many of which employ simple DC motor-driven conveyors that lack smooth speed control, resulting in product handling damage and reduced throughput flexibility. The controller uses an IR2110 gate driver and an N-channel MOSFET full H-bridge power stage capable of handling motor currents up to 20A at a supply voltage of 24V DC. A PIC16F877A microcontroller generates the PWM signal at a switching frequency of 20kHz and adjusts duty cycle in response to a potentiometer speed reference input. A closed-loop control structure employs a tachometer-based speed feedback signal to maintain constant motor speed under varying load conditions using a proportional-integral controller implemented in firmware. Torque and speed response were characterised for a 150W DC motor under no-load and full-load conditions. Results show smooth speed control from 5 percent to 100 percent of rated speed, with load-induced speed regulation within 3 percent of the set-point under closed-loop operation. The controller demonstrates fast dynamic response with settling time under 200ms following a step load change. Energy consumption measurements show a 19 percent reduction compared to a resistive voltage divider speed control method previously used in the test workshop. Keywords: PWM speed controller, DC motor, conveyor, industrial automation, Lagos.