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Need Help To Interpret V/h Control In Terms Of S/w


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I am new to this forum....It is a great forum....

I am required to develop s/w for Induction Motor Control......

I am planning to start with V/f control.....

I understand that : 1. To increase speed, I need to increase frequency.

2. To increase torque, I need to increase Voltage(i.e current !).

3. If i need to increase speed and still maintain constant torque, I have to maintain the

ratio of V/f constant.

Is my understanding correct...


My actual question is:

In s/w: 1. what is Voltage...(Duty Cycle ?).

2. what is frequency...(is it the rate at which i throw out the Duty Cycle i.e

sine wave samples ?).


Thanks for any help


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Assuming by

s/w" you mean Soft Ware for generating the PWM output;


"Voltage" would be the combination of duty cycle (number of pulses) and pulse width (length of time each pulse is on) that allows the RMS voltage to rise to the desired level in the induction circuit (the motor).


"Frequency" would be defined as the rate at which you change from Positive DC pulse trains to Negative DC pulse trains.


By the way, Current is NOT the same as Voltage! If you don't already know this, you may be in over your head! Torque is related to the applied voltage at a given frequency, but can be represented by the consumed current.

"He's not dead, he's just pinin' for the fjords!"
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