In order to minimize the effect of the grid harmonic voltages, harmonic compensation is usually adopted for a gridtied inverter. However, a large variation of the grid inductance challenges the system stability in case a high-order passive filter is used to connect an inverter to the grid. Although in theory, an adaptive controller can solve this problem, but in such case the grid inductance may need to be detected on-line, which will complicate the control system. This paper investigates the relationship between the maximum gain of the controller that still keeps the system stable and the Q-factor for a grid-tied inverter with an RL series or an RC parallel damped high-order power filter. Then, a robust passive damping method for LLCL-filter based grid-tied inverters is proposed, which effectively can suppress the possible resonances even if the grid inductance varies in a wide range. Simulation and experimental results are in good agreement with the theoretical analysis.

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C-coated FexCo1−x (x=0.50, 0.45, 0.40, 0.35, 0.30, 0.25) nanoparticles were produced using a rf plasma torch. The only C source was acetylene used as a carrier gas. Structural determination by x-ray diffraction indicated a single disordered bcc α-FeCo phase along with graphitic C for all compositions. A Scherrer analysis of the peak widths revealed particles to have an average diameter of 50 nm. A broad log-normal size distribution was found from transmission electron microscopy observations. Magnetic hysteresis loops have been measured to temperatures exceeding 1050 K and revealed relatively high room temperature coercivities (200–400 Oe), with a strong compositional variation similar to that observed in bulk alloys. Larger coercivities are consistent with particles near the monodomain size for these alloys. The temperature dependence of the magnetization revealed the effects of atomic ordering. The variation of the saturation magnetization as a function of temperature showed a discontinuity near the bulk order–disorder (α→α′) transformation temperature, as well as loss of magnetization at the α→γ structural phase transition temperature. Other features of M(T) near 500–550 °C are consistent with prior observations of a “550 °C structural anomaly” which has been observed in bulk alloys with less than perfect order.

LLCL-filter has been proven to introduce more filtering at the converter switching frequency, while using smaller passive components. However, like other higher order filters, it introduces resonance to the grid when used with a grid converter. Its stability and robustness are also affected by grid impedance variations, making its design more challenging. To address these concerns, a new parameter design method for LLCL-filter has been formulated in the paper, which when enforced, guarantees robust and stable grid current control regardless of how the grid conditions change. It is thus an enhanced method even with no damping added to the grid converter. The method has been applied to the development of an LLCLfilter for testing in the laboratory with a 5-kW, 400-V, and 50-Hz grid converter. The method can also be applied to the lower order LCL-filter with only a slight modification needed.

A flexible and stretchable 3D graphene-coated polyurethane sponge-based conductor was fabricated by electroless plating and vacuum encapsulation. The fabricated flexible conductor exhibited high conductive stability in different deformation states.

The LLCL-filter is emerging into grid-connected converters due to a smaller size compared to the conventional the LCL-filter. Similar to LCL-filter, the high order resonance introduces potential instability to the overall system which should be properly damped either passively or actively. In this paper, different feedback coefficients like the proportional, derivative, integral, high pass and low pass feedback coefficients of the filter capacitor current and the LC-trap circuit voltage are investigated for damping the filter resonance. Active damping methods are analyzed by using the concept of the equivalent impedance with and without the delay effect of an LLCL-filter based gridconnected inverter. Their corresponding equivalent circuits for the purpose of resonance damping are given to identify whether the feedback coefficient should be negative or positive for the different state-feedback methods. Then the stability of the different methods and the design of the feedback coefficient are analyzed and compared using root loci. Finally, experimental results are presented to validate the theoretical analysis.

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Pd-loaded In 2 O 3 nanowire (NW)-like networks were synthesized via electroless plating using carbon nanotubes (CNTs) as templates, followed by oxidation and removal of the CNTs at 550 C. Palladium (Pd) was introduced to activate the surface of the CNTs for subsequent plating. Before calcination, Pd was loaded onto In 2 O 3 . The as-synthesized Pd-loaded In 2 O 3 replicated the structure of the CNTs, forming a porous NW-like network with a very large specific surface area. Furthermore, the NO 2 gas sensing properties of the Pd-loaded In 2 O 3 NW-like network, porous Pd-In 2 O 3 and porous unloaded-In 2 O 3 were investigated. The results demonstrated that the Pd-In 2 O 3 NW-like network exhibits superior sensitivity with short response and recovery times, and demonstrates a significant response when exposed to NO 2 at concentrations as low as 5 ppm at a temperature of 110 C. A synergy of electric and chemical effects has been proposed to explain the gas sensing enhancement.www.rsc.org/advances 30038 | RSC Adv., 2015, 5, 30038-30045This journal is