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Parallel AC Induction motor question

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jrz126

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I have an application with 2 induction motors running on the same 3phase inverter. Say the motors are running at full speed, and that motor A has twice the inertia of motor B.
What will happen when the inverter is switched off? I was told the motors will regen into each other and coast down at the same speed. Wouldn't there need to be a source of some sort to excite the magnetic fields?

The issue i'm having is trying to restart the motors quickly while they are still coasting.
 

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If theres no excitation then there will be no regen, that said smaller motors can have slightly magnetised rotors so there may be a small amount.
Most drives have the facility for a braking transistor, to abosrb the energy produced by regen into a resistor, I'dve thought you'd be able to set up your drive so its on all the time, and gets a speed reference voltage signal from the control, then the drive itself can decide whether to brake or accell.
The smaller motor will probably to some extent be restricted by the larger one, as if you want to accelerate the drive will probably go into current limit caused by the bigger motor, forcing the smaller motor to go a similar (but not exact) speed.
 
if you're driving with an H bridge, turning both sides on high or both sides on low will brake and hold. Any regen will act to drive the rotor in the reverse of the way it is trying to spin.
 
Mike are you thinking of a brush motor, this is an induction.
 
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