LCI DRIVE FOR SYNCHRONOUS MOTORS ONLY

[duki]

Can someone explain why an LCI drive topology can be used with synchronous motors only. I understand a VSI type drive can be used with both induction and synchronous.

 

[ozmosis]

A synchronous motor provides the capacitive reactive power that allows for the commutation of the inverter, hence the name Load Commutated Inverter. This is not possible with an asynchronous motor.

 

[CJCPE]

As sed2developer says, only a synchronous motor provides the ability to adjust the exitation to provide a leading power factor. That makes it possible for the load to commutate the inverter.

 

[motorspert]

I have seen LCI used with induction motors, but needs a large capacitor across the motor terminals to allow commutation. They have a very poor speed range though I think PWM drives are much cheaper these days for induction machines.