Variable Speed Control For A Dc Motor
Posted 13 February 2007 - 04:37 AM
I would appreciate ideas on how i can change motor speed depending on the weight of snow in the snow blower. Help will be greatly appreciated.
Posted 17 February 2007 - 07:42 PM
You can vary the speed using a DC controller, and you could use a nmber of options for detemining the weight of the snow.
One possible option, wold be to determine the load on the motor and compare this with a known look up table.
A DC motor is not a very good speed regulator unless there is a closed loop, so it will slow down with increasing load. To get the motor to operate at a fixed speed, you will need to adjust the excitation to compensate for the shaft torque required. This is normally done automatically using some form of feedback which can be a shaft encoder, tachogenerator, or a voltage feedback from the motor windings.
If you compare the level of excitation against the speed reference at any given speed in a closed loop system, you will get a measure of the load on the motor.
Create a look up table of running speed against load and adjust your reference accordingly.
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