بهینه سازی هندسه ترمز جریان چرخش روتور جامد با استفاده از تجزیه و تحلیل حساسیت و عناصر محدود 3D

The paper presents an optimization procedure for eddy current brakes, considering both copper and solid iron rotors. The rotor geometry optimization has been performed based on analytical solutions and 3D finite elements combined to sensitivity analysis technique. Optimum dimensions of copper parts and solid iron slots have been investigated.

Eddy current brakes can be attractive rivals of mechanic brakes used for over-speed protection of wind turbines in cases of disturbances. They provide important advantages such as good reliability, low cost and involve no maintenance requirements. Especially for wind turbines equipped with permanent magnet generators, they can provide reliable braking operation in cases of loss of the grid connection due to faults. In such situations the decelerating torque provided by the generator connected to dump loads, can be substantially increased by the parallel connection of an eddy current braking machine connected on the same shaft. The configuration of a wind turbine system operating under such disturbance conditions is shown in Fig. 1. Full-size image (5 K) Fig. 1. Configuration of the wind turbine electric part in case of grid connection loss due to fault (PM generator supplying the eddy current brake and the resistive dump load). Figure options This work is related to a project concerning the design and construction of a 25 kW grid connected, stall regulated, variable speed wind turbine, equipped with a permanent magnet (PM) generator. The PM generator has already been optimized and tested through a prototype [1]. In order to enable braking operation the number of poles of the induction machine brake must be greater than the one of the PM generator. Moreover, in order to obtain a simple structure only solid rotor machine configurations have been considered. The design of the brake as well as the evaluation of the equivalent circuit parameters can be obtained by using finite element techniques [2] and [3]. However, the optimization of the rotor geometry may require laborious and expensive numerical schemes especially when 3D configuration should be considered [4] and [5]. Although both stochastic [6] and deterministic optimization algorithms can be implemented [7], [8] and [9], the sensitivity analysis technique combined with finite element methods enables robust and fast convergence [1].

A geometry optimization methodology based on analytical solutions and 3D finite elements combined to sensitivity analysis technique has been presented. This method has been applied to optimize the rotor geometry of a solid rotor eddy current brake used as over-speed protection in a permanent magnet generator wind turbine. The method involves a reduced number of design variables and constraints and requires a very limited number of iterations.