Design and Experimental Validation of a New Outer Rotor Double PM Excited Flux Switching Generator for Direct Drive Wind Turbines

An outer rotor double permanent magnet (PM) excited flux switching generator is designed and optimized in this paper for direct drive wind turbine applications. This generator consists of two sets of PMs: ferrite PMs embedded in the stator yoke and neodymium PMs sandwiched between the rotor segments. In this regard, the main justification for employing ferrite PMs in the stator yoke is that the risk of demagnetization of ferrite PMs at high temperatures is lower than that of neodymium PMs (the temperature of the machine's stationary parts is higher than that of its rotating parts). For the design of the machine, the Taguchi design of experiments is deployed, while a decision-making algorithm based on the technique for order of preference by similarity to the ideal solution is used to solve the contradiction that results from the Taguchi design of experiments in the multi-objective design optimization process. During the multi-objective design optimization steps, simultaneously maximizing the no-load phase voltage and minimizing the cogging torque and total harmonic distortion of the no-load phase voltage are defined as the objective functions. The optimally designed machine is prototyped and subsequently subjected to experimental validation to verify the predictions in satisfying the objective functions.