AC motor vf control
AC motor vf control
(OP)
i was planning on implementing an induction motor speed control
i have referred to microchip's application note
but i cannot grasp the concept of generating 3PWM signals which is 120degrees apart
if anyone is willing to help
please have a look at the application note, which is found under the microchip website
http:// ww1.microc hip.com/do wnloads/en /AppNotes/ 00843a.pdf
and also, i have explain the problem in the following link
http://www.edaboard.com/thread203342.html
thanks in advance
your help will be very appreciated
best regards
ryan
i have referred to microchip's application note
but i cannot grasp the concept of generating 3PWM signals which is 120degrees apart
if anyone is willing to help
please have a look at the application note, which is found under the microchip website
http://
and also, i have explain the problem in the following link
http://www.edaboard.com/thread203342.html
thanks in advance
your help will be very appreciated
best regards
ryan





RE: AC motor vf control
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RE: AC motor vf control
i am doing this for a better understanding of how the system works
i am aware that it would cost me much less had i bought the system, i have all the equipments at hand, so cost would not be much of a concern
the application note is very well explained, and i was looking forward to implement the open loop ac drive
but i do not understand how the microcontroller keeps the V/Hz ratio constant
the frequency is varied by carying the timer0 value as i have explained in the post
and the voltage is varied by varying the duty cycle of the PWM
the very thing i cannot understand is how the microcontroller knows for a specific value of frequency input through the analog input, what is its corresponding duty cycle
thank you again for your reply
regards
ryan
RE: AC motor vf control
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: AC motor vf control
i have try searching explanations for these, but i cannot find
what i know is how the frequency of the 3 phase output is changed when i change the analog input, i also know how to compute the PWM duty cycle
what i want to know is how the microcontroller determines the duty cycle depending on the frequency
i would be glad if you could refer me to some of these elementary text, it would be of great help
thank you very much again
b,regards
ryan
RE: AC motor vf control
All you need to know is there.
I read your question about what values to load into different timers. The answer to that question is more about understanding that particular micro and its peripherals than about understanding PWM.
What you probably need to do is to step back a little and first learn about normal three-phase systems and motors. Once you understand that, the rest will come naturally. But we cannot and will not 'high-pressure' anything into your brain. It never works. Take your time.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: AC motor vf control
i know about pwm control and about three phase systems, i wanted to apply this knowledge to microcontrollers
i am going through the datasheet of the microcontroller and i thought a little help might give a push
i will put extra effort in understanding it and get acquainted with the pic microcontroller peripherals
thank you very much for your concern
:)
b,regards
RE: AC motor vf control
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: AC motor vf control
Keith Cress
kcress - http://www.flaminsystems.com
RE: AC motor vf control
If only you knew how many threads i have post on the microchip, which are still unreplied
I am still trying though
Thank you again for your advice
Best regards
Ryan