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Why is PWM better than a variable power supply?
Motors as a class require very high currents to operate. Being able to vary their speed with PWM increases the efficiency of the total system by quite a bit. PWM is more effective at controlling motor speeds at low RPM than linear methods.
Is there an advantage of PWM over variable resistance?
3 Answers. Power efficiency The induction of the motor will cause the current to average. At the same time the transistors in PWM mode have very low impedance and therefore a low voltage drop and low power dissipation. In case of a series resistor a lot of power is dissipated in the series resistor.
Why do DC motors use PWM?
Using PWM allows precise current control in the windings. Hence, the output torque, which is linearly proportional to the average winding current, can be correctly controlled in coreless motors.
How does a variable resistance PWM work?
4) If you want a variable resistance, do your PWM like this: As shown, the job of the capacitor is to destroy the MOSFET. ie it is incorrectly shown. When the MOSFET turns on it will dissipate the capacitor energy in the MOSFET.
How is the resistance of a variable resistor controlled?
I found this circuit design for constructing a variable resistor. Its seems that the resistance can be controlled by the duty cycle of PWM on MOSFET. Would you explain what is the purpose of having capacitor connected in parallel with the MOSFET?
Why does my PWM not do what I want?
2) Your PWM won’t work to do what you want, all it’ll do is toggle the value of the resistor pair between 1 and 11 ohms if the MOSFET can go from an open to a short. 3) All of the PWM circuitry is floating.
Which is better 6V on avaerage or constant current?
Having a 0.5 Duty Cycle for a 12V supply, gives a 6V on avaerage, and using the switching we control the speed. Better precision is arguable; the motor acts as a filter and uses the mean value (or something related to it) of the input current to move; so it really doesn’t matter to feed it with a constant current (resistance case) or a PWM.