Abstract
In recent years, distributed clean energy sources such as fuel cell and solar cell systems are promoted greatly in many countries. These alternative systems are often used in remote areas as stand-alone power supplies. Generally speaking, the output of fuel cells or solar cells is a low-voltage DC source. Thus, in many applications, a step up DC/DC converter is required for boosting the voltage to a higher value, for the following Voltage-Source Inverter. However, the two-stage configuration has some drawbacks such as high cost and complex control. In view of the above drawbacks, a single-stage DC/AC converter integrated based on Generalized Zero Vector (GZV) is adopted in this thesis to operate as a single phase inverter. In fact, the main purpose of this thesis is focused on modeling and design of the novel inverter with step up/down and bidirectional power flow capabilities. Basically, the contributions of this thesis can be summarized as follows. First, both the DC and small-signal models of the proposed inverter are derived for simplifying the design of close-loop control. Second, both state equations and equivalent circuit model for the double line frequency of the voltage and current at DC side are derived. Based on these models, the harmonic magnitude can be calculated accurately. To the author’s best knowledge, these derived models for describing the double line frequency components are proposed for the first time. Third, a passive ripple cancelling cell (RCC) is proposed for reducing the volume and weight of the traditional second-order LC filter significantly to achieve clean output current waveform at the AC side. Fourth, based on the models and analytic forms of the doubly line frequency components, a design guideline of LC parameters is given to achieve faster design for different applications. Finally, a 400W, 48V DC input and 110Vrms AC output prototype is constructed. Both the simulation and experimental results are given to verify the effectiveness of the proposed inverter.