In this article, feasible minimum limits for IE4 class are analyzed, taking into account the estimated efficiency limits and rated efficiency for emergent or commercially best available line-start PMSM technologies. The presented results can be useful to set up future international standard super-premium or IE4-class levels/limits. The practicability and technical limits associated with the IE4-class efficiency levels are addressed, taking into account technical and economical limitations. It is expected that advanced technologies will enable manufacturers to design motors for the IE4-class efficiency levels, with mechanical dimensions compatible with the existing IMs of lower efficiency classes (e.g., flanges, shaft heights, or frame sizes as defined in standards EN 50347 and NEMA MG1). NEMA frames sizes are larger than the IEC frame sizes, allowing the use of more active materials. In addition, 60-Hz operation enables higher power density and higher efficiency levels with the same frame sizes.

Standards for Efficiency of Electric Motors

Line start permanent magnet synchronous motors: Challenges and opportunities

Small industrial three-phase induction motors (IMs) normally suffer from poor operational efficiency and power factor. This paper presents a high-performance line-start permanent magnet synchronous motor (LSPMSM) which is developed by simple modifications of an off-the-shelf small industrial three-phase IM with minimized additional costs. Two-dimensional (2-D) dynamic finite element analysis (FEA) models are employed to assess the machine performances, which are validated by comprehensive experimental results. The experimental comparisons between the amended LSPMSM and the original IM have indicated that significant improvements in efficiency and power factor can be achieved by the proposed LSPMSM.

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A High-Performance Line-Start Permanent Magnet Synchronous Motor Amended From a Small Industrial Three-Phase Induction Motor

Magnetic gears are a new and rapidly emerging technology. Compared to mechanical gears, they enjoy the advantage of having inherent overload capability. However, their torsional stiffness is much lower than mechanical gears, resulting in oscillations during transient changes in speed and load. Damper windings have been used in synchronous generators to suppress oscillations due to transients, and they are applied to the magnetic gear for the same purpose. It is believed that this is the first attempt to add a passive means of oscillation damping to the magnetic gear, whereas all other previous means have been active.

Passive Suppression of Transient Oscillations in the Concentric Planetary Magnetic Gear

Three-phase line-start permanent magnet motors (LSPMs) are a recent entrance in the marketplace. In general, such motors are designed to meet IE4/Super-Premium Class requirements. As with squirrel-cage induction motors, LSPMs can benefit in terms of efficiency and power factor from a proper magnetizing flux adjustment as a function of their load. This is important to improve the motor performance when it is oversized and/or driving variable-load fixed-speed applications. In this paper, an experimental study on the improvement potential of steady-state partial-load efficiency and power factor in special multiconnection LSPMs with up to six different flux levels is presented. Some novel conclusions are offered regarding the efficiency and power factor gains and connection-mode management as a function of motor actual load, including the delta-star change in conventional six-terminal LSPMs. With the proposed solution, efficiency gains of 6-8% points and power factor gains of 0.4-0.5 points can be obtained in LSPMs at light partial loads, representing a very significant performance improvement. Moreover, it is demonstrated that reactive power injection into the mains grid is possible with LSPMs.

Stator Winding Connection-Mode Management in Line-Start Permanent Magnet Motors to Improve Their Efficiency and Power Factor

This paper aims at optimal analysis and design of a three-phase line-start PMSM with simple structure, low cost and good performance. A prototype with 4 magnet poles is designed and manufactured. Simulation and experimental results are approximately the same and the prototype essentially satisfies the design request. Moreover, measures are taken to further optimize the design.

Optimal design and experimental verification of a line-start permanent magnet synchronous motor

Metabolomics and transcriptomics analysis of vitro growth in pitaya plantlets with different LED Light spectra treatment

Alternaria alternata is among the most common fungi in our environments, such as indoor facilities, the soil, and outdoor air. It can cause diseases in >100 crop and ornamental plants. ABSTRACT Alternaria alternata is an opportunistic human fungal pathogen and a ubiquitous phytopathogen capable of causing diseases to >100 agricultural crops and ornamental plants. To control plant diseases caused by A. alternata, triazole fungicides have been widely used both in open crop and vegetable fields and in indoor growth facilities such as greenhouses. At present, the effect of fungicide use on triazole resistance development in A. alternata populations is not known. Here, we isolated 237 A. alternata strains from nine greenhouses around metropolitan Kunming in Yunnan, southwest China, determined their genotypes using 10 short tandem repeat markers, and quantified their susceptibility to four triazoles (difenoconazole, tebuconazole, itraconazole, and voriconazole). Abundant allelic and genotypic diversities were detected among these A. alternata strains. Significantly, over 17% of the strains were resistant to difenoconazole, and both known and new drug-resistance mutations were found in the triazole target gene cyp51. Our findings of high-level genetic variation of A. alternata in greenhouses coupled with high-frequency fungicide resistance call for greater attention to continued monitoring and to developing alternative plant fungal disease management strategies in greenhouses. IMPORTANCE Alternaria alternata is among the most common fungi in our environments, such as indoor facilities, the soil, and outdoor air. It can cause diseases in >100 crop and ornamental plants. Furthermore, it can cause human infections. However, our understanding of its genetic diversity and antifungal susceptibility is very limited. Indeed, the critical threshold values for resistance have not been defined for most antifungal drugs in this species. Greenhouses are known to have heavy applications of agricultural fungicides. In this study, we analyzed strains of A. alternata from nine greenhouses near metropolitan Kunming in southwestern China. Our study revealed very high genetic diversity and identified strains with high MIC values against two agricultural and two medical triazole antifungals within each of the nine greenhouses. Our study calls for greater attention to this emerging threat to food security and human health.

Guang Yang

Papers

Optimal design and experimental verification of a line-start permanent magnet synchronous motor

Metabolomics and transcriptomics analysis of vitro growth in pitaya plantlets with different LED Light spectra treatment

Genetic Structure and Triazole Antifungal Susceptibilities of Alternaria alternata from Greenhouses in Kunming, China