1. - 1 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service NEW HYBRID MODEL FOR EFFICIENCY OPTIMIZATION OF INDUCTION MOTOR DRIVES Presented by: Branko Blanuša University of Banja Luka, Faculty of Electrical Engineering E-mail: bbranko@etfbl.net Branko D. Blanuša, Petar R. Matić, Branko L.Dokić

2. - 2 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Main goal: Define optimal control strategy for a given operating conditions so the drive operates with minimal energy consumption.

3. - 3 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Content 1.Introduction 2.Power loss modelling 3.Hybrid model for efficiency optimization 4.Simulation results 5.Conclusion

4. - 4 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Results of applied algorithms for efficiency optimization highly depends from the size of drive (Fig.1) and operating conditions, especially load torque and speed (Fig. 2) Fig. 1 Rated motor efficiences for ABB motors (catalog data) and typical converter efficiency.

5. - 5 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig 2. Measured standard motor efficiences with both rated flux and efficiency optimized control at rated mechanical speed (2.2 kW rated power).

6. - 6 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Important conclusions 1. It is possible to minimize power losses by variation of magnetizing flux in the machine, so the balance between cooper and iron losses are obtained. 2. Best results in efficiency optimization of induction motor drives can be achieved for a light loads.

7. - 7 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service According to the literture, there are three strategies dealing with the problem of efficiency optimization of the induction motor drive 1.Simple State Control - SSC, 2.Loss Model Control - LMC and 3.Search Control- SC.

8. - 8 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service The first strategy (SSC) is based on the control of one of the variables in the drive. This strategy is simple, but gives good results only for a narrow set of operation conditions. Also, it is sensitive to parameter changes in the drive due to temperature changes and magnetic circuit saturation. Fig. 3. Control diagram for the simple state efficiency optimization strategy.

9. - 9 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service For LMC methods, a power loss model is used for optimal drive control. These algorithms are fast because the optimal control is calculated directly from the loss model. But, power loss modeling and calculation of the optimal operating conditions can be very complex. This strategy is also sensitive to parameter variations in the drive. Fig. 4. Block diagram for the model based control strategy.

10. - 10 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service In the search strategy, the on-line procedure for efficiency optimization is carried out. The optimization variable, stator or rotor flux, increases or decreases step by step until the measured input power is at a minimum. This strategy has an important advantage over others: it is insensitive to parameter changes. Fig. 5. Block diagram of search control strategy.

11. - 11 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Hybrid methods

12. - 12 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Power loss modelling The overall power loss in electrical drive consists of converter loss and motor losses, while motor power loss can be divided in copper and iron loss: Overall flux-dependent losses are usually given by:

13. - 13 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Loss model of drive is developed in d-q rotational system in such way that that rotor side variables do not depend on leakage inductances while the effect of leakage inductances is incorporated into other variables. Fig.6. Space vector model of induction motor drive.

14. - 14 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig. 7. Steady state model of IM in a rotor flux oriented reference frame, d-axis equivalent circuit, q- axis equivalent circuit.

15. - 15 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Total power losses

16. - 16 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Search controller Fig.8. SC efficiency optimization controller

17. - 17 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig. 10. Overall proposed block diagram of efficiency optimization controller in IMD.

18. - 18 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Simulation results Fig. 11. Load torque and speed reference.

19. - 19 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig.12. Magnetization current, mechanical speed and electromagnetic torque.

20. - 20 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig.13. Magnetization current, mechanical speed and electromagnetic torque.

21. - 21 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig.14. Graph of power loss for nominal flux and applied hybrid method.

22. - 22 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig.15. Graph of power loss for LMC method and hybrid method.

23. - 23 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Fig.16. Graph of power loss for LMC method and hybrid method.

24. - 24 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Conclusion If load torque has a value close to nominal or higher, magnetizing flux is also nominal regardless of whether an algorithm for efficiency optimization is applied or not. For a light load hybrid method for efficiency optimization gives significiant power loss reduction (figs. 14,15 and 16). Also, it shows good dynamic performances (figs. 12 and 13) and negligible sensitivity to parameter changes.

25. - 25 -Niš, Serbia, November 11 th - 14 th, 2010 Projekt ISSNBS DAAD Deutscher Akademischer Austausch Dienst German Academic Exchange Service Thank you