@Kabiru:
thanks a lot for ur reply, is there any relation u can provide me, whether duty cycle is inversely/directly proportional to the speed of the motor?
since duty cycle change the speed of the motor when the on time is reduce, therefore duty cycle= on/on+off, then the speed is directly proportional to duty cycle.note that this is only applicable on dc motors,but in AC motor only the phase is control. what type of motor do you use is it AC or DC ?