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This paper proposes an input power factor control strategy for a current-source drive with active front-end. The proposed strategy is realized without modification of the drive's pulsewidth modulation and speed control schemes through the collaborative use of two methods: a modulation index regulation method and a flux adjustment method. Specifically, the modulation index regulation method functions to directly control the dc-link current and voltage, and it can effectively correct a leading input power factor as long as the space vector modulation is used for the inverter. On the other hand, the flux adjustment method can improve the power factor when the power factor is lagging or when the selective harmonic elimination modulation is used for the inverter at high motor speeds. When implemented together, the two methods will complement each other's functionalities and improve the overall compensation performance. Experimental results are obtained from a 600-hp and an 1100-hp drive system.
Date of Publication: Feb. 2010