DC motor speed and direction control
| DC motor control Control of a direct current motor means controlling both the speed and the direction of the rotation of the motor. The control of direction is done by a method called H-bridge: By controlling the switches the direction of the current is set. Path 1: V+ --> B --> motor --> C --> Gnd Path 2: V+ --> A --> motor --> D --> Gnd The H-bridge can be made out of transistors or can be a single IC component such as the L293 with an output current of 1A per channel or the L298 with an output current of 1A per channel. (L298HN includes protective diodes and by so eliminates the need to add additional components) Example of wiring a DC motor with an L298HN controlled by a pic18f452 micro-controller: Speed control The speed control to the motor can be done by one of two ways. When the motor is planned to rotate at a constant speed a potentiometer can be added between the voltage source and the input of the IC L298HN supply voltage - pin 4. The second way is controlling the motor speed by suppling it only measured amounts of energy. This is called PWM - pulse width modulation. And its a mean of controlling the average voltage. This can be achieved by switching on and off at a required rate the enable pin - pin 6 in the L298HN through the micro-controller. back to basic electronic circuits for robotics page |
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