SPEED CONTROL OF DC SHUNT MOTOR USING MICRO CONTROL BASE
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INTRODUCTION:-
DC motor speed controllers are very useful for controlling the motion of robotic and industrial automation systems. The controller presented here uses the PWM technique. The PMW wave for speed control is generated using Atmel AT89C51 microcontroller. To control the speed of the DC motor, you need a variable power supply. When the DC motor is switched on, it take the certain time to reach the full speed. As soon as the power supply is switched on, the DC motor starts gaining speed and if you switched off the power supply before it reaches the maximum rated speed, starts to slow down. In case of switching off are done in quick succession, the motor rotates sat allows speed between zero and full speed. This is what a PWM technique based controller does.


APPLICATION:-
230V AC mains are stepped down by transformer to deliver secondary output of 12V, 500mA. The secondary output is regulated by IC 7805. Capacitor C2 bypasses any ripple in the regulated C1 and regulated output.LED L1 acts as power on indicator. Resistor R1 limits the current passing through LED. Diode D5 cause a voltage drop of 0.06V.



WORKING PRINCIPAL:-
Shows the circuit diagram of micro control based dc motor speed control. IC AT89c52 is a low-power, high-performance, 8-bit micro controller with a 8kb of flash programmable and erasable read only memory, 256 bytes of RAM, 32 input/output lines, three 16-bit timers/counters, a six vector two level interrupt architecture, a full duplex serial port, on chip operation down to zero frequency and supports two software-selectable power-saving modes. The idle mode stops the CPU while allowing the RAM, timers/counters, serial port and interrupt system to continue functioning. The power saving modes. The idle mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The power-down mode saves the RAM contents but freezes the oscillator, disabling all chip functions until the next hardware reset is activated.