Hi,
I have to control the speed of two AC motors working in a line. I have to synchronize the speed of both. I have used a formal Diac, Triac type controller (modified version of a fan dimmer with a powerfull triac). It works; but not so good. At low speed motor looses the torque and speed is not constant as the load varies. Can you please give some idea about what kind of circuit should I use? Should I change the frequency, voltage or both? Is PWM would be good idea? Please give a block concept of a good and reliable circuit that work smoothly and fine. It would be batter if some one guide me all this in some sequential steps. What to do first then next and next etc. I‘ll try to rebuild the circuit.
Some info is: AC 220V, single phase, 4 pole, Aprox 500 watts power, shaft feed back facility is available.

 

I would simply use a couple of VFD's. It works for us.

 

I would simply use a couple of VFD's. It works for us.

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Yes I can use it but difficult to get/purchase for me. Next I want to build my own.

 

This circuit is a variable speed control with load compensation.
http://www.electronica.mk/all_articles/Miscellaneous/2012/Variable_Speed_AC_Motor_U2008B/U2008B.html

 

This circuit is a variable speed control with load compensation.
http://www.electronica.mk/all_articles/Miscellaneous/2012/Variable_Speed_AC_Motor_U2008B/U2008B.html

Thanks a lot cork_ie, After visitiing the link I think it is what I was looking for. It is a complete project even with PCB design. I'll try it if I found the chip. Thanks again for your great help.