SMALL DC MOTOR PWM SPEED CONTROLLER

摘要

There are numerous applications for motor speed controllers, ranging from train sets and radio-controlled cars, to the area of robotics. About a year ago I needed to control the speed of a small 12 volt DC motor attached to a peristaltic pump used for water sampling. A peristaltic pump is a type of suction pump that squeezes a piece of rubber tubing which, in turn, causes a vacuum. The challenge with these pumps is that they require quite a bit of torque to squeeze the tubing, and in my situation, they had to run from as little as three revolutions per minute to full speed. In thinking about the problem, I knew that simple methods of motor speed control — such as using a potentiometer or a transistor as a variable resistor — were out of the question. Both methods have serious drawbacks. If you use a potentiometer, you quickly discover that it gets very hot, and that the only way to alleviate that is to exchange it for an expensive rheostat.