SLIDING MODE BASED OUTER CONTROL LOOP FOR INDUCTION MOTOR DRIVES WITH FORCED DYNAMICS

MODEL OF MOTOR AND LOAD rotor magnetic flux linkage stator currents stator voltages motor torque rotor speed stator, rotor and mutual inductances stator and rotor resistances expressed in stator-fixed frame

CONTROL LAW DESIGN r master control law slave control law observers I inner loop outer loop U d  d  d  inner-loop sub-plant    r I Rotor speed and rotor magnetic flux norm are demanded values

MASTER CONTROL LAW motor equation desired closed-loop equation motor equation desired closed-loop equation linearising functions master control law

SET OF THREE OSERVERS FOR STATE ESTIMATION AND FILTERING FOR IM

is based on motor equations eliminate Drift Corrections algorithm is used for final magnetic flux filtering 1.Rotor Flux Estimator

2. Pseudo-Sliding Mode Observer motor equation U I For classical sliding -mode observer:- For pseudo sliding -mode observer:-,, -v I * ( not used directly ) slope K I angular velocity extractor

Filtered values of and are produced by the observer based on Kalman filter 3. Filtering Observer Electrical torque of SM is treated as an external input to the model where design of: needs adjustment of the one parameter only or as two different poles: Load torque is modeled as a state variable

Original Control Systems Structure  r  U  U  T 32  transform I 2 -I 3 I  measured stator currents I        rotor speed  r I d  demanded  stator currents demanded three- phase voltages   r   l v  eq v  q   I d  U 1 U 2 U 3 I 1 Induction motor Master control law Angular velocity extractor Filtering observers external load torque  L Power electronic drive circuit  trans -formation T 23  trans -form Rotor flux estimator  d rotor speed Sliding-mode observer / signum slave CL Slave control law      r  demande d

Overall Control System Structure Induction motor Power Electronics Inner Loop Controller Power Supply Middle Loop Controller Outer Loop Controller SMC outer loop Middle loop Inner loop

Original Control System Completed with SMC Based Outer Control Loop -u’ m + m K SM S u’ Real System K sT d 1   ' 1 s T  s  d  ’ d u’    r   r - S

Original Control System Completed with SMC Based Outer Control Loop (Continued) Derivation of is eliminated.

S Inner & middle loop Slope, K S s Switching boundary equation: SMC based outer loop

Experimental Verification Parameters of the IM: P n =1100 W;  n =297,9 rad/s; T n =3,7 Nm Equivalent Circuit Parameters: R S =7,15  ; R R =7,15  ; L M =0,474 H; L R =0,482 H; L S =0,482 H Parameters of IGBT Semikron 6MBI-060 are as follows: nominal voltage: 1000 [V], nominal current: 6x10 [A]. Current sensors are as follows: LEM LTA 50P/SPI.

Experimental results for Inner and Middle Loops Alone,  d =200 rad/s, T 1 =0.5 s a) stator currents b) estim. speeds c) rotor speed

a) stator currents b) estim.speeds c) rotor speed Experimental results with SM based Outer Loop,  d =200 rad/s, T 1 =0.5 s

a) stator currents b) estim.speeds c) rotor speed Experimental results with SM based Outer Loop,  d =100 rad/s, T 1 =0.5 s

Experimental results for  d =15 rad/s, T 1 =0.5 s a) stator currents in steady state b) rotor speed 1. Inner and Middle Loop Alone 2. Together with Outer Loop

Conclusions and Recommendations n A new approach to the control of el. drives with induction motors, when original forced dynamic system was completed for outer control loop based on SMC has been developed and experimentally proven. n Further improvement can continue via application of the vector control and space vector modulation. n Precise comparison of the effects of MRAC and SMC based outer control loop is also desirable.