Recent Developments of Electrical Drives - Part 34. The book stating the recent developments of electrical drives, can be useful for engineers and researchers investigating and designing electrical and electronic devices as well as for students and young researchers dealing with electrical and electronic engineering, computer sciences (advanced computer modelling, sophisticated control systems with artificial intelligence tools applied, optimal design bye use of classical and genetic algorithms employed), applied mathematics and all the topics where electromagnetic, thermal, mechanical phenomena occur | 328 Tapia et al. Figure 6. Airgap flux components under stator d-axis current variation. Iron-PM ratio . Figure 7. Total airgap flux as a function of the stator d-axis current for different iron magnet ratio. . Axial Flux Surface Mounted PM Machine 329 diminishes in the same proportion. Proper selection of this ratio must be selected in order to accomplish field weakening capability and power delivered for the machine. Reactance parameters Neglecting saturation synchronous machine parameters can be estimated from the fundamental flux density distribution which is by the MMF of the armature reaction. Based on the two-reaction theory this armature reaction is solved for each of the characteristic axis. In this manner it is possible to express reactance parameters in term of the form factors 8 . Form factor The dq-axis mutual reactances can be calculated in terms of the form factor of the stator field armature reaction factors kfd and kfq as Xd kfdXa 1 Xq kfqXa 2 This approach considers the amplitude reduction of the d-axis and q-axis fundamental harmonic of the armature reaction field due to airgap non-uniformity. This is caused by the presence of the PM pole and the air space between the poles. They make it possible to express each component of the armature reaction scaled respect to the magnetic field created in a cylindrical rotor synchronous machine. The armature reaction peak values of the fundamental harmonics are calculated using Fourier series coefficients expressions for the fundamental. d-Axis form factor Where Xa is the mutual reactance for the cylindrical rotor synchronous machines. These form factors are calculated based on harmonic distribution of the flux density over the airgap as kfd B1 and kfq B 3 Bad Bdq The rotor of the AFPM machine combines the structure of a surface mounted PM machine with the structure of the reluctance machine for the reactance calculation purposes. The d-axis flux s path is composed by the salient PM pole and the .
