Which 3 method will be easy?
1.Stator voltage control
2.Frequency control
3.Rotor voltage control
4.current control
5.Voltage frequency control
6.vectrol control

 

I'm not sure that the six options you list are necessarily different. AC induction machine control could be broadly split into two categories, Scalar Control and Vector Control.

Scalar control is more straight forward and can be implemented using a simple "v over f control scheme". Vector control is somewhat more complicated. Both will require manipulation of the input voltages so you could argue they were both voltage/frequency control.

 

What is the nature of the motor? Shaded pole? PSC? Start & run cap?
1ph induction motors are notorious for very poor for variable speed control .
How do you intend using rotor voltage control if it is an induction motor?
Max.

 

I just write a post on my blog. Maybe it works for you. If you want to know about Controller related information, this controller technical data is useful,

 

I just write a post on my blog. Maybe it works for you. ,

How is that relevant to the OP?
Max.

 

The easiest way to control an AC motor........is reactance control.