13PE9

Γ-Z-Source Inverters

Poh Chiang Loh ; Miao Zhu ; Feng Gao ; Blaabjerg, F.

Power Electronics, IEEE Transactions on (Volume:26 ,Issue: 12) DOI:10.1109/TPEL.2011.2122309
Publication Year: 2013, Page(s):3453 - 3463

Project Title : Generalized Multi cell switched-inductor and switched-capacitor Z-

Z-source inverter

Domain :Power Electronics

Reference :IEEE

Publish Year :2013Page(s): 3453 – 3463

D.O.I :10.1109/TPEL.2011.2122309

Software Used:MATLAB

Developed By:Wine Yard Technologies, Hyderabad

Γ-Z-Source Inverters

Voltage-type Γ-Z-source inverters are proposed in this letter. They use a unique Γ-shaped impedance network for boosting their output voltage in addition to their usual voltage buck behavior. Comparing them with other topologies, the proposed inverters use lesser components and a coupled transformer for producing the high-gain and modulation ratio simultaneously. The obtained gain can be tuned by varying the turns ratio γΓZ of the transformer within the narrow range of 1 < γΓZ ≤ 2. This leads to lesser winding turns at high gain, as compared to other related topologies. Experimental testing has already proven the validity of the proposed inverters.

Modern power electronic applications, especially those directly connected to the grid, usually require some voltage boosting. Traditional voltage-source inverters (VSIs) are therefore not satisfactory since they can only step down voltages. To add boost functionality, dc-dc boost converters can be placed before the VSIs. Alternatively, single-stage buck-boost inverters can be used like the Cuk, SEPIC and other similar dc-ac inverters. However, these inverters do not have been intensive follow-up researched. On the contrary, research in another buck-boost inverter, named as Z-source inverter has been proposed.

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Different to the original ZSI, ESL-Γ-ZSI has just one capacitor, and is composed of an extended SL network, a capacitor. The proposed topology provides an extended SL network in front of the inverter bridge, unlike the traditional topology, so there is no inrush current flowing to the main circuit at startup. Like the classical ZSI, ESL-Γ-ZSI has extra shoot-through zero states besides the traditional six active and two zero states. Thus, the operating principles of the proposed inverter are similar to those of the classical ZSI. For the purpose of analysis, the operating states are simplified into shoot-through and no shoot-through states. Fig. 3 shows the equivalent circuits of ESL-Γ-ZSI.

Conclusion:

Operating gain and modulation ratio of the Γ-Z-source inverters have been proven to be the same as the trans-Z-source inverters, and hence higher than those of the traditional Z-source inverter. However, unlike the trans-Z-source inverters, gain increase of the Γ-Z-source inverters is achieved by reducing, and not increasing, their turns ratio in the range of 1 < γΓZ ≤ 2. Transformers needed by the Γ-Z-source inverters might therefore be smaller for high-gain applications. Experimental results have confirmed these performance features of the Γ-Z-source inverters.

Screen shots:

Dc link voltage.

Output current

Unified ac voltage

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