Engineering Projects: CONTROL UNIT DESIGNED FOR A DC MOTOR

Model no.2: The aim of this project is control the speed of DC motor. The speed of DC motor is directly proportional to the DC voltage applied across its terminals. Hence, if we control the voltage applied across its terminal, we actually can control its speed. Here we use microcontroller from 8051 family. Two buttons are used as inputs to control the speed of motor. PWM is generated at the output by using program burned into the microcontroller. The program can be written in Assembly language or in Embedded C. PWM (Pulse Width Modulation) wave can be used to control the speed of the motor. Here the average voltage given or the average current flowing through the motor will change depending on the ON and OFF time of the pulses controlling the speed of the motor i.e. The duty cycle of the wave controls its speed. On changing the duty cycle (ON time), we can change the speed. The motor is interfaced to the microcontroller by an IC called motor driver IC i.e., L293D. By interchanging output ports, it will effectively change direction of the motor. The power supply consists of a step down transformer 230/12V, which steps down the voltage to 12V AC. This is converted to DC using a Bridge rectifier. The ripples are removed using a capacitive filter and it is then regulated to +5V using a voltage regulator 7805 which is required for the operation of the microcontroller and other components.

For more details about this project, please visit http://www.efxkits.com/project-kit/microcontroller/1001.html