hello, i am making an IGBT driver for 1200V/50A. i am using LPC 1788 to generate PWM . Generating PWM and AMPLITUDE variation was easy. But my main concern is how to vary frequency keeping V/F ratio of the motor constant of an induction motor. Is it possible with the same processor..How to change frequency of PWM.. MY IGBT DRIVER would be able to make my motor work properly up to 100 hz(of sinewave)..

 

There is probably some register that controls the clock frequency of your PWM (usually referred to as the prescaler). It is the manual. Usually, you give it a value, and it divides the clock by that value. On some uC's, you are limited to values that is a factor of two. Remember the frequency will be calculated by whether or not you use the "Fast PWM" type or the "phase matched PWM" type.