Recent Developments of Electrical Drives - Part 8. 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 | 56 Kolehmainen Table 2. Comparison of nominal load results Measured V-shape Calculated V-shape Calculated U-shapeA Calculated U-shapeB Tn Nm 875 875 875 875 In A Cos w n Angle Tk Nm 1 688 1 557 1 418 Ik A Cos w Angle Magnets thickness Magnets width 52 52 Magnets area current. Only copper losses in stator winding are taken account in efficiency n calculations. Other losses are relatively small. In the table first calculated U-shapeA results are calculated with the design with same total magnet length and thickness per pole than with V-shape design. The second calculated results U-shapeB are calculated with design with longer and thinner magnets per pole. Magnets thickness width and area are also shown in the table with unit of mm. Dimensions of V-shape design are real dimensions of one magnet and for U-shape designs dimension are values which corresponds values of V-shape design. The maximum output torque with the first U-shapeA design is smaller than with the V-shape design and it has also smaller load angle difference. This is due to smaller reluctance torque and effect of iron bridges between the magnets. Torque and reluctance torque curves are shown in Fig. 10. Figure 10. Torque and reluctance torque of motors with V- and U-shape designs as a function of load angle. 57 I-5. Finite Element Analysis ofPMSM with Buried Magnets Reluctance torque is larger with V-shape than with U-shapeA design because the magnetic structure of rotor. By comparing torques of U-shapeA and U-shapeB designs can also see the effect of decreasing of magnet thickness. Reluctance and maximum torque is smaller with thicker magnets. Power factors of V-shape and U-shape designs are shown as a function of torque in Fig. 11. Power factor of the motor with the U-shapeA design is larger up to the nominal point and with the .
