At the present there lacks proper optimization method for internal dielectric properties of dielectric functionally-graded-material(d-FGM). An optimization algorithm of internal permittivity distribution for multi-layer permittivity FGM(ε-FGM)insulator under AC voltage is proposed
which aims at weakening the maximum electric field(e-field)strength along the insulator surface. According to design parameters
such as current e-field strength
objective e-field value and permittivity range
the permittivity value of each layer is self-adaptively updated with iterations to obtain the optimized permittivity distribution. The iterative coefficient and shrinking coefficient are adjusted to control the convergence process and shorten calculation period. Compared with uniform insulator
e-field distribution inside and along the surface of ε-FGM insulator is more uniform and the maximum e-field strength along surface is weakened more than 60%
and the layer thickness of the multi-layer ε-FGM insulator ought to be set as small as possible under the allowed fabrication conditions. The maximum surface e-field strength decreases nonlinearly with the increasing permittivity upper limit and saturates as the upper limit reaches certain threshold value
which has positive correlation with the maximum e-field strength before optimization.
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