presentation_vector_control_of_induction_machines_1462466673_205888.ppt
- 1. Vector Control of Induction Machines dq 3 2 IM 3 2 dq s u s i q q ab ab
- 2. Introduction • The traditional way to control the speed of induction motors is the V/Hz-control • Low dynamic performance • In applications like servo drives and rolling mills quick torque response is required. • Desire to replace dc drives led to vector control
- 3. What is vector control? • Vector control implies that an ac motor is forced to behave dynamically as a dc motor by the use of feedback control. • Always consider the stator frequency to be a variable quantity. • Think in synchronous coordinates.
- 4. Basic blocks of a vector controlled drive dq 3 2 IM 3 2 dq s u s i q q ab ab
- 5. Addition of a block for calculation of the transformation angle dq 3 2 IM 3 2 dq s u s i q q ab ab Transformation angle calculation r q
- 6. The current is controlled in the d- and q-directions j ref ref ref s sd sq i i i magnetization torque production
- 7. Vector controller dq 3 2 IM 3 2 dq s u s i q q ab ab Transformation angle calculation r q Current controller ref s i + -
- 8. Rotor flux orientation • Difficult to find the transformation angle since the direction of the flux must be known • Flux measurement is required • Flux sensors (and fitting) are expensive and unreliable • Rotor position measurement does not tell the flux position • The solution is flux estimation
- 9. Rotor flux orientation using measured flux Original method suggested by Blaschke •Requires flux sensors •Flux coordinates: aligned with the rotor flux linkage arctan r r b a
- 10. Rotor flux orientation using estimated flux • The rotor flux vector cannot be measured, only the airgap flux. • Flux sensors reduce the reliability • Flux sensors increase the cost • Therefore, it is better to estimate the rotor flux.
- 11. The current model Current control Current model IM drive f f s s ref rd ref T f s i s s i s s u f s u r w ̂ ̂
- 12. Speed control • Applications: pumps and fans in the process industry, paper and steel mills, robotics and packaging, electric vehicles • Very different dynamic requirements • Most drives have low to medium high requirements on dynamics. These drives are considered here. • Cascade control is sufficient
- 13. Block diagram of a speed-controlled drive system Current controller ref u I i ref i Speed controller Inverter w ref m w m w Electric motor
- 14. Complete system
- 19. CURRENT AND SPEED WAVEFORM
- 21. References • Zambada, Jorge (Nov 8, 2007). "Field-oriented control for motors". MachineDesign.com. • Jump up^ Lewin, Chuck (April 10, 2006). "New Developments in Commutation and Motor Control Techniques". DesignNews.com. • DSP Manual (2007). "3-Phase AC Induction Vector Control Drive with Single Shunt Current Sensing" (PDF). Freescale. p. 25, incl. esp. eq. 2–37. Retrieved May 16, 2012. • Jump up Godbole, Kedar (Sep 23, 2006). "Field oriented control reduces motor size, cost and power consumption in industrial applications". Texas Instruments. • Jump up^ Bose, Bimal K. (June 2009). "The Past, Present, and Future of Power Electronics". Industrial Electronics Magazine, IEEE 3 (2): 11.doi:10.1109/MIE.2009.932709. • Murray, Aengus (Sep 27, 2007). "Transforming motion: Field-oriented control of ac motors". EDN. Retrieved 11 May 2012.