Novel interspersed windings to reduce space flux harmonics caused by fractional-slot of synchronous machine
Fractional-slot windings is widely used in synchronous machine due to give us more flexibility on selection of the number of slot at design stage. It is also known that fractional-slot windings produces additional harmonics compare to integral-slot windings. These harmonics may cause increasing of stray losses and stator core vibration This paper describes the result of space flux harmonics caused by fractional-slot windings and propose novel interspersed windings that reduces the even order and/or fractional number space flux harmonic components. The advantage of proposed winding was confirmed by using numerical analysis and experiment using model winding machine.
Design and Analysis of Synchronous Alternator for Reduction in Harmonics and Temperature by Short Pitch Winding
In industry, for manufacturing of Synchronous alternator full pitch stator winding is used and the stamping design always remains constant. Stamping cannot be changed frequently because it needs tool development for making the new type of stamping and cost increases enormously which is not acceptable to the industries. To reduce the cost of design and for more profit all the research and development is being done on the existing stamping only. Therefore we concentrated our investigation work on the distribution type of winding only and we got the benefit in terms of reduction in harmonics, temperature rise and resistive drop. Considering the harmonic present in the machine, our concentration was on pitch factor. Design and analysis of synchronous alternator for different chording factor and find the pitch factors for optimum efficiency and got the expected results which is excepted by industry.
Ionization by drift and ambipolar electric fields in electronegative capacitive radio frequency plasmas.
Unlike α- and γ-mode operation, electrons accelerated by strong drift and ambipolar electric fields in the plasma bulk and at the sheath edges are found to dominate the ionization in strongly electronegative discharges. These fields are caused by a low bulk conductivity and local maxima of the electron density at the sheath edges, respectively. This drift-ambipolar mode is investigated by kinetic particle simulations, experimental phase-resolved optical emission spectroscopy, and an analytical model in CF(4). Mode transitions induced by voltage and pressure variations are studied.