doubt in a project named ac motordrive

[thomas33]

hai all,is there any variation in the voltage when supply frequency changed.It is must in ac drive that the frequency and voltage should be constant according to the v/f method.Then only the torque must be constant.For that we are doubted and guys please help me.

 

[BradtheRad]

For your particular motor, there will be a speed where it delivers its greatest torque. (Generally speaking.)

The speed of your AC motor is determined primarily by the frequency of the AC supply.

It doesn't work well to reduce voltage and/or current into the motor to reduce its speed to where you want it. If you try to do that it will greatly reduce the power and you won't get much torque from the motor.

Or you can use a triac (as in a lamp dimmer type circuit) to reduce motor speed. However that also greatly reduces torque.

If you want maximum output from the motor, you will have to change your AC supply until it is at the proper frequency to drive the motor at its best speed.