Abstract
At present, the research on five-level inverters mainly involves the modulation algorithm and topology, and few articles study the five-level inverter from the control strategy. In this paper, the nonlinear passivity-based control (PBC) method is proposed for single-phase uninterruptible power supply inverters. The proposed PBC method is based on an energy shaping and damping injection idea, which is performed to regulate the energy flow of an inverter to a desired level and to assure global asymptotic stability, respectively. Furthermore, this paper presents a control algorithm based on the theory of passivity that gives an inverter in a photovoltaic system additional functions: power factor correction, harmonic currents compensation, and the ability to stabilize the system under varying injection damping. Finally, the effectiveness of the PBC method in terms of both stability and harmonic distortion is verified by the simulation and experiments under resistive and inductive loads.
Highlights
An effort to extend the scope of the applications of multilevel inverters to clean energy harnessing from photovoltaic arrays and fuel cells has been pursued, wherein their superior harmonic performance and ability to support independent maximum power point tracking are advantages noted for these lower voltage implementations [1,2,3,4]
Sinusoidal pulse width modulation (SPWM) strategies have been used widely for the switching of multilevel inverters due to their simplicity, flexibility, and reduced computational requirements compared to space vector modulation (SVM)
The results show that the typical harmonic in the grid current by the passivity-based control (PBC) method is smaller than that by the traditional Proportional Intergral (PI) control method due to the superior stability performance
Summary
An effort to extend the scope of the applications of multilevel inverters to clean energy harnessing from photovoltaic arrays and fuel cells has been pursued, wherein their superior harmonic performance and ability to support independent maximum power point tracking are advantages noted for these lower voltage implementations [1,2,3,4]. The aforementioned control methods offer various advantages and disadvantages related to dynamic response, robustness aginst parameter variations, steady-state error, and stability. In the literature [28], it is noted that PBC strategy can improve the dynamic and static characteristics of the system, which has strong robustness to parameter changes. In the literature [30], PBC strategy has a fast dynamic response compared with the droop control, which can improve the stability of the system. The literature [31] proposes that passivity-based control (PBC) can simplify the control algorithm, which has a high anti-perturbation reaction to the parameter change in contrast with the traditional vector control. The research on the five-level inverter mainly involves the modulation algorithm and topology, and few articles study it with the control strategy. The validity of the control strategy based on passive Euler (E-L) model is verified by the prototype experiment
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