Synchronous filters

[GOTWW]

Are there some references as to the complex impedence based transfer functions of the inverter driven, shunt connected synchronous unloaded-motor filters used in some UPS systems?

 

[GOTWW]

Case 1: over excited; 1/s; typical power factor correction: shunt cap.
Case 2: excitation twicked to 0 pf; equivelent shunt R
Case 3: underexcited; s; shunt inductance.

But, in all three cases will produce the extra-amps for locked-rotor motor startings.

The basic 1/s, pole at zero, 20dB per decade is not that exciting as a filter, But there must be more to it than that.

We have a case of 400Hz contractor supplied equipment tripping at a turn of the head. As a replacement, maybe the shunt connected motor would stabilize the power, to allow the anal retintive equipment to function.