Use ESD5500E with flywheel generator
Can I use the AC signal of the flywheel generator instead the speed control sensor?


It is very unlikely that this will work. The generator will give one or two AC cycles per revolution depending on the number of poles on the alternator. The controller is designed to monitor the speed using a magnetic pickup reading a gear ring so it may have in the order of 100 teeth. Having  more teeth means shorter time between pulses. The higher the feedback frequency the better the resolution and response time for speed control.