A new circuit design and control to reduce input harmonic current for a three-phase ac machine drive system having a very small dc-link capacitor

This paper presents a new circuit topology to meet the input harmonic current standard for an ac machine drive system which has a very small dc-link capacitor. The proposed circuit topology is based on a harmonic current injection method, and it keeps up size and cost competitiveness of an ac machine drive system having a very small dc-link capacitor. Also, this paper proposes an appropriate control algorithm and a stability analysis for the proposed circuit topology. Experimental results reveal the validity of the proposed circuit topology and its control method. Also, it is confirmed that the harmonic current standard can be satisfied with the proposed circuit and its control method.