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The inherent double line ripple power in single-phase systems is adverse to the performance of power electronics converters, e.g., limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active converter topology based on a symmetrical half-bridge circuit is(More)
Nine-switch converter is a reduced-switch equivalence of the widely used 12-switch back-to-back converter. Like other reduced-switch topologies, the nine-switch converter experiences operating constraints, which may limit its efficiency. This is, however, not universal, meaning losses of the nine-switch converter can at times be lower than the 12-switch(More)
The second-order generalized integrator based quadrature signal generator (SOGI-QSG) is able to produce in-quadrature signals for many applications, such as frequency estimation, grid synchronization, and harmonic extraction. However, the SOGI-QSG is sensitive to input dc and harmonic components with unknown frequencies (e.g., interharmonics). To overcome(More)
This paper presents the benchmark study of ac and dc active power decoupling (APD) circuits for the second-order harmonic mitigation in kilowatt-scale single-phase inverters. First, a brief comparison of recently reported APD circuits is given, the best solution that can achieve high efficiency and high-power density is identified and comprehensively(More)
Wind speed variations make the power of wind turbine system to fluctuate, which could increase the thermal stress of the power converter and reduce its lifetime. In order to relieve this problem, short-term energy storage technologies are applied to improve the thermal performance of a 3 MW grid side wind power converter. The cost, weight and cycle life of(More)
Power fluctuation caused by wind speed variations may be harmful for the stability of the power system as well as the reliability of the wind power converter, since it may induce thermal excursions in the solder joints of the power modules. Using the wind turbine rotor inertia energy for power leveling has been studied before, but no quantified analysis or(More)
This paper presents the benchmark study of ac and dc active power decoupling circuits for second-order harmonic mitigation in kW-scale single-phase inverters. First of all, the best solutions of active power decoupling to achieve high efficiency and power density are identified and comprehensively studied, where the commercially available film capacitors,(More)
Power decoupling circuits can compensate the inherent double line frequency ripple power in single-phase systems and greatly facilitate their dc-link capacitor design. Example applications of power decoupling circuit include photovoltaic, light-emitting diode, fuel cell, and motor drive systems. This paper presents the dq synchronous reference frame(More)
Due to a series of unique merits, modular multilevel converters (MMCs) have been developing dramatically in the last decade. However, in some applications, such as offshore power transmission, the MMC modules are subjected to a variety of tough temperature profiles with adverse working conditions, and all of these could lead to thermomechanical fatigues in(More)
Converters with reduced switch counts usually face some performance tradeoffs, which make them suitable for some applications but not others. The same applies to the nine-switch converter, which is a reduced-switch version of the back-to-back twelve-switch converter. The nine-switch converter has since been shown to experience a higher voltage stress, which(More)