synchronization of two ac motors

[ayyub]

I GOT TWO AC MOTORS.I WANT TO SYNCHRONIZE THEM I.E IF ONE MOTOR ROTATES SAY ABOUT 1450 RPM THE OTHER SHOULD HAVE THE SAME.LETS TALK IN FREQUENCY IF ONE MOTOR'S FREQ IS 25HZ THE OTHER SHOULD ALSO HAVE THE SAME FREQ.
I HAVE CONNECTED DANFOSS VFD TO ONE MOTOR AND SCHNEIDER'S ALTIVAR VFD TO ANOTHER.ACTUALLY IM HAVING A PROJECT OF EXTRUSION LINE.SO I WANT TO RUN THE TWO AC MOTORS WITH SAME PARAMETERS BUT WITH DIFFERENT VFDs.THERE IS NO FEEDBACK FOR FREQ I AM THINKING TO USE THE CURRENT FEEDBACK.THESE TWO DRIVES ARE CONTROLLED BY PLC THROUGH MODBUS COMMUNICATION

 

[FvM]

There's no other synchronisation option than supplying the same setpoint to both VFDs. Even with same VFD and motor type,
the motors possibly won't run at exactly the same speed, e.g. due to different friction moments. True synchronisation can
be only achieved with positional feedback (incremental encoders) and VFDs supporting position control.