OK, and Thank You. we have "S1"=900 watts and S6=1200 watts and the voltage listed as 220 to 240 volts 50Hz No mention of DC operation.
If a step-down transformer would be available, getting it up to speed on a lower voltage would be the way to go, if there could then be a way to quickly switch to full voltage.
A common dimmer switch can't work because they are only good for perhaps 250 watts, or possibly 400 watts.

I have ordered a dimmer rated up to 4000W. Should get here soon.

 

Got this "220V 4000W AC dimmer motor controller"
Wouldn't this work?

 

If it is sold as a motor controller then it should work as a motor controller. BUT I am thinking that it could be wise to bypass the dimmer before putting much load on the motor.