AN APPROXIMATE MODEL FOR STUDYING HARMONIC CURRENT AMPLIFICATIONS IN CURRENT-SOURCE INVERTER FED INDUCTION-MOTORS

The nature of harmonic current amplification in the current-source inverter fed induction motors is studied through a six-pulse current-source inverter. An approximate model consisting of the induction motor and the parallel and series capacitors is used to simulate the circuit under the multiple commutation mode. The thyristor currents are treated as the source currents. The analytical result shows that the steady phase harmonic current amplification of the six pulse inverter-fed motor goes from the high frequencies down to the fifth order of harmonic when the values of the capacitor reactances of the approximate model are reduced. Experimental study shows that the fifth harmonic current amplification is significant under a multiple commutation mode.