DocumentCode :
1079397
Title :
Development of a Comprehensive Model and a Multiloop Controller for Z-Source Inverter DG Systems
Author :
Gajanayake, Chandana Jayampathi ; Vilathgamuwa, D. Mahinda ; Loh, Poh Chiang
Volume :
54
Issue :
4
fYear :
2007
Firstpage :
2352
Lastpage :
2359
Abstract :
This paper presents the modeling and design of a closed-loop controller for a Z-source inverter. The Z-source inverter is a recently proposed single-stage power converter, and it is capable of operating in both buck and boost modes. Hence, this inverter gives an economical solution for power conversion in distributed generation (DG) applications, particularly by eliminating the need for a two-stage conversion. Moreover, applications such as DG demand quality output waveforms, and additionally, when the system is subjected to input- and load-side disturbances, their effects need to be minimized. This can be achieved with closed-loop controlling. Toward this end, the system is modeled first with large- and small-signal modeling techniques, and relevant transfer functions are derived. The dc-side of the Z-source inverter shows a non-minimum-phase characteristic, and the output voltage of a Z-source impedance network shows a significant overshoot and undershoot, following a step change in the input due to energy resettling. These effects could be transferred to the ac-side, giving rise to the undershoot and overshoot in the ac output as well. Hence, the proposed controllers should be able to minimize such effects. The ac- and dc-sides are considered separately when designing the controllers. An indirect controller is employed in the dc-side, whereas the ac-side controller is designed in the synchronous reference frame. The modulation index, shoot-through time, and saturation levels are appropriately selected so that the dc-side effects are prevented from propagating into the ac-side. The simulation results are obtained using a state-space-averaged inverter model, and an experimental prototype is built in a laboratory to prove the efficacy of the proposed algorithm. Simulation and experimental results show good reference-tracking and disturbance-rejection properties, validating the desired functionality of the proposed controller.
Keywords :
closed loop systems; control system synthesis; distributed power generation; invertors; power distribution control; power generation control; transfer functions; Z-source impedance network; Z-source inverter DG Systems; closed-loop controller design; closed-loop controller modeling; distributed generation applications; large-small-signal modeling techniques; load-side disturbances; modulation index; multiloop controller; power conversion; saturation levels; shoot-through time; single-stage power converter; small-signal modeling techniques; synchronous reference frame; transfer functions; Distributed control; Impedance; Inverters; Modulation; Power conversion; Power generation economics; Power system economics; Power system modeling; Transfer functions; Voltage; $Z$ -source inverters; Buck–boost; distributed generation (DG); inverters; small-signal analysis;
fLanguage :
English
Journal_Title :
Industrial Electronics, IEEE Transactions on
Publisher :
ieee
ISSN :
0278-0046
Type :
jour
DOI :
10.1109/TIE.2007.894772
Filename :
4280921
Link To Document :
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