Recent Developments of Electrical Drives - Part 38. 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 | 370 Runcos et al. Figure 11. Dynamic torque vs. speed characteristics Rad 2 x Ra1 . Fig. 10 shows the experimental torque vs. speed curve without external resistances connected to the auxiliary winding terminals. Comparing the experimental torque x speed curves to the analytical simulation we observe that they present a good agreement. Fig. 11 shows the experimental torque vs. speed curve with an external resistance Rext x Ra1 connected to the auxiliary winding terminals in comparison with analytical simulation curves. Vibration analysis For the vibration analysis of the DFTSCIG it is necessary to determine the induction waves generated in the air gap 7 . With these induction waves it is possible to calculate the mechanical forced vibrations due to the electromagnetic excitation of electrical machines regarding to structural vibration. This type of problem can accurately solved using the Modal Superposition Method 7 . The vibration measurements where performed on the four points indicated in Fig. 12. Figure 12. Vibration measurement points. . Performance Analysis ofDFTSCIG 371 Figure 13. Vibration velocities spectrum measured in RMS. Analyzing the measurement results shown in Fig. 13 we see that there are the main vibration frequencies are 120 and Hz with RMS amplitudes of and mm s respectively. The frequency Hz whose vibration mode is r 2 produces the maximum vibration amplitude measured at point 1. The peaks at and Hz are a response to an electromagnetic forced excitation 7 . However the peak at Hz is a response to a mechanical excitation force 70 x Hz and not an electromagnetic force produced by the machine currents. Analyzing the entire measured vibration spectrum the maximum vibration occurs at Hz with excitation mode r 2. This excitation wave force is produced by the fundamental induction harmonic wave pp 6 of 60 Hz frequency generated by the main winding and the .
