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Aiming at the leakage current problem of single-phase transformerless photovoltaic(PV) grid-connected inverters, the recent proposed topologies are classified and reviewed. These topologies are divided into half-bridge type and full-bridge type. The topology characteristics of transformerless PV inverter are analyzed. This paper presents some of transformerless PV inverter topologies and discusses the evolution laws among various topologies to clarify the interrelationship between them. Furthermore, according to the evolution laws, a new topology is proposed. Finally, Simulations and experiments compare leakage current suppression capability of the proposed topology, H5 topology and HERIC topology.

Notice of Violation of IEEE Publication Principles “Single-Phase Common-Ground-Type Transformerless PV Grid-Connected Inverters” By Zhiling Liao, Chenchen Cao , Diancheng Qiu, and Changbo Xu In IEEE Access, Vol 7, 2019 After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. The content of this paper contains significant similarities with the paper cited below that were presented with insufficient attribution. “Common-Ground-Type Transformerless Inverters for Single-Phase Solar Photovoltaic Systems” by Yam P. Siwakoti and Frede Blaabjerg in IEEE Transactions on Industrial Electronics, Vol. 65, No. 3, March 2018 This paper presents a family of novel common-ground-type transformerless photovoltaic (PV) grid-connected inverters, which requires only five power switches, one capacitor, and one filter. A simple dual-closed led-loop control is used to improve control stabilization and accuracy. The main advantages of proposed inverters are: 1) the leakage current is completely eliminated (unlike traditional topologies, which can only suppress leakage current); 2) the devices used are a few and the cost is low; 3) low loss and high efficiency; 4) the ability of realizing reactive power; and 5) there is no need for high DC input voltage compared with half-bridge-type topologies. The operating principle, modulation mode, and control strategy are introduced in detail. The performance of the proposed topology is compared with that of several traditional topologies. The leakage current suppression ability and efficiency of the proposed topology are superior to those of the traditional topologies. The model predictive control (MPC) is applied in the proposed topology, which is easy to realize and can accelerate the dynamic response. Finally, the simulation and experimental results of a 1-kVA prototype are given, which proves the validity of the proposed topology in PV grid-connected system.

A new nonlinear compact LED model is presented in this paper. The model is useful in the design stage of LED driver system. The parameter extraction procedure is presented step by step. Since the power of a single LED unit is very low, manufacturers often arrange LED units in the form of an array named LED module. On the basis of theoretical I-V characteristic curve of the LED module, the electrical performance of LED module can be tested according to the rated parameters provided by its manufacturers. Five fitting methods are used to obtain the fitting curves. The sum of squares due to error (SSE) and the coefficient of determination (R-square) are compared to choose a better fitting curve. Six terms gaussian fitting method, which has optimal fitting performance among the five methods, is chosen to construct the nonlinear mathematical model of the LED module, and then the simulation model is built with MATLAB/Simulink. A Boost converter simulation circuit adapts this model, and a 25 W dimming prototype is designed to verify the validity of the model. The simulation and test results show that the error of the model is small, and it meets the requirements of practical application.

The lifetime of traditional light-emitting diode (LED) drivers is mainly affected by electrolytic capacitor. Therefore, a single-stage isolated electrolytic capacitor-less LED driver is proposed, with which the electrolytic capacitor is eliminated and the output current ripple is reduced. Firstly, the operation principle and switching mode of the topology are analyzed. Then, the feasibility of the topology is analyzed by using the state space average method. Finally, an experimental prototype of 60 W output power is built to verify the correctness of the scheme.