In the past decade, solar energy, the fastest growing renewable energy, has been a growing interest in integration to the utility grid. Power electronics converters play important role in renewable energy integration, e.g., integrate the distributed photovoltaic (PV) panels to the grid. In many applications, particularly in the residential area, a single-phase rather than three-phase inverter is used to regulate the voltage from one form to the other while tracking the maximum power point of the PV system. The input voltage and current are DC and its maximum power is desired to be a constant value. However, in the single-phase PV inverter, the sinusoidal voltage and current waveform makes the output power pulsated with double frequency, which results in the power mismatch between the input and the output. Therefore, it is necessary to use energy buffer to balance the power, i.e., the power decoupling. In this work, a power decoupling method first is developed in d-q rotation frame and is optimized so that the energy buffer can be minimized. The power decoupling controller designed in the d-q frame has the superiority of simplicity so that the traditional proportional integral (PI) control can be used. Besides, a composite power decoupling method which includes both DC side passive and AC side active power decoupling is developed. Due to the use of two stage power decoupling, the energy buffer, e.g., capacitance at the DC and AC side, is minimized. Meanwhile, the important functions such as the maximum power point tracking (MPPT) and relatively high power quality are achieved.


Qun Zhang

Committee Member

Vincent Winstead

Committee Member

Jianwu Zeng

Date of Degree




Document Type



Master of Science (MS)

Program of Study

Electrical Engineering


Electrical and Computer Engineering and Technology


Science, Engineering and Technology



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