Maintain v/f ratio in pic microcontroller output

Thread Starter

innovetion

Joined Oct 16, 2015
4
Hello,

I am using PIC18f4550. My aim is to control AC induction motor. For that I have generated required PWM pulses for required frequencies. But I need to maintain V/F ratio at the output. Which I am unable to do.

Please suggest me.
 

crutschow

Joined Mar 14, 2008
24,122
The PMW modulation frequency determines the AC frequency applied to the motor, and the PWM duty-cycle along with the PWM carrier voltage determines the AC voltage applied to the motor.
So from the modulation frequency you calculate the needed duty-cycle to get the desired motor voltage for the PWM carrier voltage you are using.
 

dannyf

Joined Sep 13, 2015
2,197
Change the period register and maintain 50 percent duty cycle.

Better use a v/f converter or a pic with NCO.

If the frequency isn't too fast, consider dds in software.
 
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