Critical wavelength of eddy currents and its influence on harmonic losses in solid poles

Critical wavelength concept is proposed in the paper in order to describe the different behaviors of eddy currents and different harmonic losses in solid poles or non-insulated laminated poles of electrical machines. The concept is developed from an eddy current model which is commonly used for the calculation of slotting effects in solid rotors. Two synchronous machines are used for illustrating the critical wavelength for space harmonics and time harmonics. Further discussions are made on the influences of pole material properties and air gap length.