Microcontroller Based Adjustable Speed Closed-Loop DC Motor Drive
The speed control of DC motors is very crucial especially in applications where precision and protection are of importance. This work investigates and implements a microcontroller-based adjustable speed drive system for a DC shunt motor. The theory of the armature voltage control algorithm in a c...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/243/1/549523_FK_2004_3.pdf |
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| Summary: | The speed control of DC motors is very crucial especially in applications where precision
and protection are of importance. This work investigates and implements a
microcontroller-based adjustable speed drive system for a DC shunt motor. The theory of
the armature voltage control algorithm in a closed loop system has been successfully
implemented.
An IGBT switch is used in buck configuration to control the armature voltage of the
motor. The PWM signal that controls the IGBT is generated from a Motorola 68HC11
microcontroller. The speed of the motor is measured by a shaft encoder and directly fed
to the microcontroller along with a speed reference signal.A data acquisition routine reads the measured speed and the reference speed in digital
format and generates the error value signal. The error value signal is directly fed into the
proportional controller routine to commute the controller output.
Finally, the controller output is used to generate a PWM, which completes the loop by
controlling the switch. To protect the motor from high current, a current monitoring
routine is implemented to read the motor current through a Hall effect sensor. If the
motor current is higher than its rated current halting the PWM generation routine will
stop it.
Experimental results obtained have supported the idea of the design. The speed of the
motor could be controlled over a wide range using the dc chopper and the PWM.
Employment of a microcontroller has shown a great improvement in the acceleration,
speed reduction, and deceleration and over current protection of a dc motor. |
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