Design of Multiple Feedback Control Loops for a Single-phase Full-bridge Inverter Based on Stability Considerations

Abstract

Single-phase inverters employ LC filters for the purpose of reducing pulse-width modulation harmonics. The drawback of LC filter is its stability problem at resonance frequency. Passive damping offers simple and reliable solution, but it decreases the overall system efficiency. Active damping is lossless and provides flexibility of controlling the damping performance; however, it is sensitive to parameters variation. This article presents stability analysis of a single-phase full-bridge inverter to improve dynamic performance and stability. Design of LC filter is carried out considering both undamped and damped structures. The effect of filter parameters on pole-zero locations of the inverter is presented, and variation of the phase margin over a wide range of parameters variation is examined. Active damping using closed-loop current control of the full-bridge inverter to mitigate the resonance oscillation is designed and compared with passive damping. The disturbance rejection via dynamic stiffness with and without active damping is examined to justify the proposed current controller. Simulation and experimental results are presented to validate the effectiveness of the proposed design. It is found that the proposed control of the inverter provides excellent voltage regulation with low total harmonic distortion and ensures good performance and robust stability under parameters variation.

Keywords:

• full-bridge inverter
• current control
• active damping
• dynamic stiffness
• LC filter
• stability analysis

Additional information

Notes on contributors

Mohamed S. Zaky

Mohamed S. Zaky was awarded his B.Sc., M.Sc., and Ph.D. in electrical engineering from Minoufiya University, Shebin El-Kom, Egypt, in 2001, 2005, and 2008, respectively. In 2002, he became an instructor with Minoufiya University and then an assistant lecturer in 2006. From 2008–2013, he was a lecturer in the Department of Electrical Engineering, Faculty of Engineering, Minoufiya University, where in 2013 he became and is presently an assistant professor. His research interests include control of electrical machines, applications of power electronics, DSP-based real-time control, and renewable energy applications.