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As one of the basic insulating materials, polyimide films have been widely used in the insulation system in wind turbine generators. However, the pulse voltage from the converter often causes overvoltage and localized high electrical field in the insulation system. Surface charge could affect the dielectric property and cause the breakdown of insulation. Direct fluorination is a method to modify the...
Graphene has already been verified to have potential applications in sensor development due to its unique properties, such as large specific surface area, high carrier mobility, conductivity and optical transparency. Here, we discuss our development of a micro bubble generator that could be used to generate and actuate micron-scale bubbles based on monolayer graphene made from chemical vapor deposition...
This paper investigates the fault detection problem of quantized feedback systems with actuator faults, and system outputs are respectively quantized by a uniform quantizer and a non-uniform quantizer. A new method is proposed to deal with quantization errors, that is, the quantization errors are considered as the unknown inputs of the residual generator. In order to detect the faults, an optimal...
Currently, there is significant attention being paid to the development of high-speed machines including motors and generators. In particular, permanent magnet machines are gaining more traction due to their outstanding efficiency, high power density, small size, low weight, simple mechanical construction, easy maintenance and good reliability. The higher the motor speed, the smaller the electric...
Direct-drive permanent magnet (DDPM) generators have been widely adopted in the wind power applications due to the higher reliability, and lower maintenance cost, compared to that of the doubly fed induction generators (DFIG) with the gearbox [1]. However, the magnets are vulnerable to be demagnetized under the short circuit condition. Due to the reliability concerns, the demagnetization performance...
Large-scale superconducting direct-drive (SCDD) generators have received lots of attention in recent years, featuring high torque density, efficiency and reliability [1]. Due to the application of SC field windings, airgap flux density is large and often more than 2 Tesla (no more than 1 T in traditional machines), which could result in huge electromagnetic radial forces and vibrations in SCDD generators...
For the complex structure of the large capacity turbo-generator in end region, the accurate calculation of the leakage magnetic field became key factor in large generator design. Affected by the leakage magnetic field, there is a problem that the end stator ladder packets, copper screen, press plate has a local high temperature. The three-dimensional electromagnetic field of a 330 MW water-hydrogen-hydrogen...
With advantages of low emissions, fuel flexibility, high efficiency and energy saving, micro turbines (MTs) are one of the most important technologies for distributed generated systems (DGSs) [1,2]. With many advantages such as high power density, simple structure, and higher efficiency, high speed permanent magnetic generator systems (HSPGSs) attract more attentions from the world wide researchers...
Compared with the slotted tubular generators, air-cored tubular generator has no attraction force, smaller thrust ripple and lower moving mass. The advantages of high respond speed and high output stability make the air-cored tubular generators to be research focus in recent years. It is used in energy conversion systems of ambient vibrations, free-piston engine, ocean wave energy and so on. And in...
As one of the most important kinds of distributed generation systems, the micro turbine generation system can be flexibly installed near the end user, and becomes an important trend of development in DGS gradually. The high speed permanent magnetic generator (HSPMG) can be properly applied in a micro turbine generation system and benefits the system from high efficiency, high power density, simple...
As wind turbines increase their power rating, the size and mass grows as well. The higher reliability is demanded in order to minimize the maintenance. Permanent magnet direct drive (PMDD) synchronous generators are a good solution since they omit the gearbox. While the large generator mass has been also a key difficult problem limiting the practical use of PMDD generator, which makes them difficult...
The steady flow and electromagnetic fields of a demonstration helical-channel seawater MHD (Magnetohydrodynamic) generator were investigated by 3D numerical simulations and then the performance characteristics were studied. The results show that the flow and electrical fields in end regions of the helical wall are very complex. There appear small vortexes, flow irregularity, dead zones, eddy current,...
Researchers at the National Institute for Occupational Safety and Health (NIOSH) are advancing the emerging technology of electromagnetic proximity detection, which provides a promising means of protecting workers around any machinery that presents striking, pinning or entanglement hazards. This technology is particularly applicable to mobile underground mining equipment such as remote-control continuous...
This paper presents a summary of the most important characteristics of wind turbine generators applied in modern wind power plants. Various wind turbine generator designs, based on classification by machine type and speed control capabilities, are discussed along with their operational characteristics, voltage, reactive power, or power factor control capabilities, voltage ride-through characteristics,...
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