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SLIDING MODE BASED OUTER CONTROL LOOP FOR INDUCTION MOTOR DRIVES WITH FORCED DYNAMICS. MODEL OF MOTOR AND LOAD. expressed in stator-fixed frame. motor torque. rotor magnetic flux linkage. rotor speed. stator currents. stator voltages. stator and rotor resistances.
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SLIDING MODE BASED OUTER CONTROL LOOP FOR INDUCTION MOTOR DRIVES WITH FORCED DYNAMICS
MODEL OF MOTOR AND LOAD expressed in stator-fixed frame motor torque rotor magnetic flux linkage rotor speed stator currents stator voltages stator and rotor resistances stator, rotor and mutual inductances
w Y inner-loop sub-plant CONTROL LAW DESIGN r w d I master control law d slave control law Y d U outer loop inner loop w Y r I observers Rotor speed and rotor magnetic flux norm are demanded values
MASTER CONTROL LAW motor equation linearising functions desired closed-loop equation motor equation master control law desired closed-loop equation
eliminate 1.Rotor Flux Estimator is based on motor equations Drift Corrections algorithm is used for final magnetic flux filtering
angular velocity extractor 2. Pseudo-Sliding Mode Observer I motor equation U -v For classical sliding -mode observer:- I* (not used directly) , slopeKI For pseudo sliding -mode observer:- ,
3. Filtering Observer Filtered values of and are produced by the observerbased on Kalman filter Load torque is modeled as a state variable where design of: needs adjustment of the one parameter only or as two different poles: Electrical torque of SM is treated as an external input to the model
T 2 - 3 T 3 - 2 $ w $ G r l * * * Y Y Y * * Y Y * w b a r * w r Original Control Systems Structure external load demanded a-b demanded three- demanded torque G stator currents L phase voltages rotor speed Slave control law I U d a 1 Master Power Induction U signum w 2 / d control electronic motor trans U slave CL 3 law drive -form I circuit d b rotor w r speed U a transform I U a b I measured a b trans 1 stator -formation I -I I currents 2 3 b v a q Rotor flux Sliding-mode Filtering v Angular b eq estimator observer observers velocity extractor
Induction motor Overall Control System Structure Power Supply Outer LoopController Middle LoopController Inner LoopController Power Electronics Inner loop Middle loop SMC outer loop
1 $ w K r d ' s 1 + sT w & $ w r T w Original Control System Completed with SMC Based Outer Control Loop Real System + u’ S u’ w m u’ ’ w d d KSM - S - u’ m s
Original Control System Completedwith SMC Based Outer Control Loop(Continued) Derivation ofis eliminated.
Switching boundary equation: SMC based outer loop Inner & middle loop S S s Slope, K
Experimental Verification Parameters of the IM: Pn=1100 W; wn=297,9 rad/s; Tn=3,7 Nm Equivalent Circuit Parameters: RS=7,15 W; RR=7,15 W; LM=0,474 H; LR=0,482 H; LS=0,482 H Parameters of IGBT Semikron6MBI-060 are as follows: nominal voltage: 1000 [V] , nominal current: 6x10 [A]. Current sensors are as follows: LEM LTA 50P/SPI.
b) estim. speeds a) stator currents c) rotor speed Experimental results for Inner and Middle Loops Alone, wd=200 rad/s, T1=0.5 s
b) estim.speeds a) stator currents c) rotor speed Experimental results with SM basedOuter Loop, wd=200 rad/s, T1=0.5 s
b) estim.speeds a) stator currents c) rotor speed Experimental results with SM basedOuter Loop, wd=100 rad/s, T1=0.5 s
Experimental results forwd=15 rad/s, T1=0.5 s a) stator currents in steady state b) rotor speed 2. Together with Outer Loop 1. Inner and Middle Loop Alone
Conclusions and Recommendations • 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. • Further improvement can continue via application of the vector control and space vector modulation. • Precise comparison of the effects of MRAC and SMC based outer control loop is also desirable.