01-03-2013, 11:03 AM
Constant boost control of the Z-source inverter to minimize current ripple and voltage stress,
ABSTRACT
This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching frequency. In order to reduce value and cost, it is important always to keep the shoot trough rather constant. At the same time, a greater voltage boost for any given modulation index is desired to reduce the voltage stress across the switch. This method achieves maximum boost while keeping shoot through duty ratio constant all the time, reducing ripple content in inductor current. This method is very suitable for minimizing the Z-source network, especially in low-frequency or variable-speed-drive applications.