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4773375.ppt

  1. 1. Field-Oriented Control of Induction Machine Dr. Nik Rumzi Nik Idris Department of Energy Conversion, Faculty of Electrical Engineering, Universiti Teknologi Malaysia
  2. 2. • IM is superior to DC machine with respect to size, weight, inertia, cost, speed Why FOC ? • DC motor is superior to IM with respect to ease of control – High performance with simple control due de-coupling component of torque and flux • FOC transforms the dynamics of IM to become similar to the DC motor’s – decoupling the torque and flux components
  3. 3. Basic Principles DC machine Current in Current out a f By keeping flux constant, torque can be controlled by controlling armature current Te = k If Ia
  4. 4. Basic Principles of IM a b b’ c’ c Stator current produce stator flux s r Interaction between stator and rotor fluxes produces torque Space angle between stator and rotor fluxes varies with load, and speed Stator flux induces rotor current  produces rotor flux
  5. 5. FOC of IM drive Torque equation : s s e i 2 p 2 3 T    s r r m e i L L 2 p 2 3 T    In d-q axis : ) i i ( L L 2 p 2 3 T sd rq sq rd r m e    
  6. 6. FOC of IM drive In d-q axis : ) i i ( L L 2 p 2 3 T sd rq sq rd r m e     Choose a frame such that: r rd r    0 r rq  
  7. 7. FOC of IM drive Choose a frame such that: r rd r    0 r rq  
  8. 8. FOC of IM drive ) i i ( L L 2 p 2 3 T sd rq sq rd r m e     Choose a frame such that: r rd r    0 r rq   qs ds s i r  sq i rq  sd i rd  As seen by stator reference frame:
  9. 9. FOC of IM drive r sq r r m e i L L 2 p 2 3 T    s i Choose a frame such that: r rd r    0 r rq   qs ds r  dr qr r sd i r sq i ) i i ( L L 2 p 2 3 T sd rq sq rd r m e     Rotating reference frame:
  10. 10. FOC of IM drive To implement rotor flux FOC need to know rotor flux position: (i) Indirect FOC g r r g g r g s r r m g r r r ) ( j dt d i L R L L R 0             r slip r r sq r sd r r m r r r ) ( j dt d ji i L R L L R 0            Synchronous speed obtain by adding slip speed and rotor speed Rotor voltage equation: g r r g g r g r r ) ( j dt d i R 0         g s m g r r g r i L i L    Rotor flux equation:
  11. 11. FOC of IM drive - indirect dt d i L R L L R 0 r r sd r r m r r r       d component r slip r sq r r m ) ( i L R L 0       q component   r slip r r sq r sd r r m r r r ) ( j dt d ji i L R L L R 0           
  12. 12. FOC of IM drive - indirect dt d i L R L L R 0 r r sd r r m r r r       d component r slip r sq r r m ) ( i L R L 0       q component   r slip r r sq r sd r r m r r r ) ( j dt d ji i L R L L R 0            m * r sd L * i r    r sq r * r r m slip i L R L ) (     m r r * e sq L L p 3 T 4 * i r   
  13. 13. FOC of IM drive - indirect T* * 2/3 1/s ir sq* ir sd* isq* isd* ia* ib* ic* CC VSI slip r + + Rotating frame Stationary frame m * r sd L * i r    m r r * e sq L L p 3 T 4 * i r    r sq r * r r m slip i L R L ) (     ej
  14. 14. FOC of IM drive g r r r s r r m r r r j dt d i L R L L R 0         (ii) Direct FOC Rotor flux can be estimated by: Rotor flux estimated from motor’s terminal variables s r r m e i L L 2 p 2 3 T    Express in stationary frame
  15. 15. FOC of IM drive g r r r s r r m r r r j dt d i L R L L R 0         (ii) Direct FOC ) j ( j dt ) j ( d i ) ji i ( L R L ) j ( L R 0 rq rd r rq rd sq sd r r m rq rd r r                                dt i L R L L R rq r sd r r m rd r r rd                 dt i L R L L R rd r sq r r m rq r r rq d q rd rq       2 rq 2 rd r      
  16. 16. FOC of IM drive - direct T* r* 2/3 isq* isd* ia* ib* ic* CC VSI TC FC ir sq* ir sd* ej  Te r s r r m e i L L 2 p 2 3 T    g r r r s r r m r r r j dt d i L R L L R 0         Rotating frame Stationary frame

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