Abstract
Single-phase full-bridge transformerless topologies, such as the H5, H6, or the highly efficient and reliable inverter concept (HERIC) topologies, are commonly used for leakage current suppression for photovoltaic (PV) applications. The main derivation methodology of full-bridge topologies has been used based on both a DC-based decoupling model and an AC-based decoupling model. However, this methodology is not suited to the search for all possible topologies, and cannot verify whether they are inclusive. Part I of this paper will propose a new topology derivation methodology based on unipolar sinusoidal pulse width modulation (USPWM) to search all possible full-bridge topologies for leakage current suppression. First of all, a unified circuit model is proposed, instead of the DC- and AC-based models. Secondly, a mathematic method called the MN principle is then proposed to search for all possible topologies, and a derivation procedure is provided. It was verified that all existing topologies could be found using the proposed method; furthermore, seven new topologies were derived. The proposed topology derivation methodology is extended to search topologies under Double-Frequency USPWM (DFUSPWM). Twenty topologies under USPWM and four topologies under DFUSPWM have been derived.
Highlights
Photovoltaic (PV) sources are among the most promising renewable energy sources, providing clean and emission free energy [1,2]
The Common Mode (CM) current path for grid-tied, transformerless, PV inverter systems is illustrated in Figure 2 [9]
Part of this paper focus on the synthetization topology derivation methodology to achieve could answer the question of how many topologies could be derived, as there is no unified model
Summary
The single-phase inverter has popularly half-bridge inverter[1,2]. 1. be Topologies (a) and (b) full-bridge (named H4). (1) can simplified as half-bridge follows: the leakage current is a key issue [3,4,5]. 1. Topologies of (a) half-bridge inverter; and The (b) full-bridge inverter generated (named H4).by PV parasitic. In single-phase, grid-tied inverter systems, half-bridge full-bridge inverters areis. Current path for grid-tied, transformerless, in [10,11]. The leakage1.current path is equivalent to an LC resonant circuit, as shown. TP1 defined as: N, respectively, and L1 and L2 are the output filter inductors.
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