Hello all,
I am controlling speed of DC motor with a consant torque using PWM.What I am confused here is : To have a constant torque I need to have constant current becasue current and torque are directly proportional in DC motor. Now to vary the speed I am varying the input voltage of DC motor using PWM. How can the current stay constant when I am varying the speed with input voltage?
Is there anything I am missing in understanding DC motor concept.Please help
As you increase voltage, the motor speeds up. This increases the back emf produced by the motor which, being opposite to the drive voltage, acts against an increase in current. However, as you load the motor the back emf reduces so the current increases.
As you rightly say, current is proportional to torque
Speed (RPM) is proportional to voltage
Power is torque x speed ie current x voltage
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Hi,
You have 3 variables: Speed, Torque and LOAD. At a given speed, the torque is controlled by the load. At a given torque, the speed is controlled by the load.
What kind of load do you have and what are you trying to accomplish??