Controlling Motor Speed with PWM: Advantages and Alternatives Explained

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SUMMARY

The discussion focuses on using Pulse Width Modulation (PWM) with the 68hc12 microcontroller to control motor speed. PWM offers significant advantages over alternatives like function generators, including precise control of frequency and duty cycle, which allows for efficient motor operation. The use of the Analog-to-Digital (ATD) module to sample voltage from a potentiometer is crucial for determining the duty cycle. Understanding the relationship between inductance, impedance, and motor speed is also emphasized as a key factor in effective motor control.

PREREQUISITES
  • Understanding of Pulse Width Modulation (PWM)
  • Familiarity with the 68hc12 microcontroller
  • Knowledge of Analog-to-Digital (ATD) conversion
  • Basic concepts of inductance and impedance in electrical circuits
NEXT STEPS
  • Research the implementation of PWM in the 68hc12 microcontroller
  • Explore alternatives to PWM for motor control, such as H-bridge circuits
  • Learn about the effects of duty cycle on motor performance
  • Investigate the relationship between inductance, impedance, and motor speed
USEFUL FOR

Electronics engineers, hobbyists working with microcontrollers, and anyone interested in motor control techniques using PWM.

EvLer
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I need some help on lab questions...

a short description: we are using Pulse Width Modulation (PWM) module of a 68hc12 microcontroller to control speed of a motor hooked up to the microcontroller; the potentiometer connected to ATD channel provides a DC voltage that is sampled using ATD module which determines the duty cycle of the output pulse wave, and based on the settings of the PWM registers, that pulse wave is driving the motor at a set frequency.

So the question is: what are the advantage of using PWM vs other alternatives?

All i can think of is function generator, what could other alternatives can drive motor?
And as far as advantages, well... it allows one to set the frequency and duty cycle, and generate interrupts stuff like that... is there something i am missing?
Thanks in advance...
 
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Here's a recent thread from the EE forum that will help you out:

https://www.physicsforums.com/showthread.php?t=116324

Also, when thinking about this problem, remember what you are driving in the motor. When the rotor is stopped, the value of inductance and impedance is very low, right? What is the drive impedance at full speed? So what is it in between?
 
oh, right... thanks berkeman... :smile:
 

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