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University of East London 1999. FORCED DYNAMICS CONTROL OF INDUCTION MOTOR WITH SELECTABLE DYNAMICS. Prof. Ján VITTEK & Dr. Juraj ALTUS University of Žilina, SK Department of Electric Traction and Energetics Prof. Stephen J. DODDS & Dr. Roy Perryman University of East London, UK
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University of East London 1999 FORCED DYNAMICS CONTROL OF INDUCTION MOTOR WITH SELECTABLE DYNAMICS Prof. Ján VITTEK & Dr. Juraj ALTUS University of Žilina, SK Department of Electric Traction and Energetics Prof. Stephen J. DODDS & Dr. Roy Perryman University of East London, UK School of Electrical and Manufacturing Engineering
FORCED DYNAMICS SPEED CONTROL of EL. DRIVES with Induction Motors Research CO-ORDINATION Prof. Stephen J. DODDS University of East London School of Electrical and Manufacturing Engineering Department of Electrical & Electronic Engineering Longbridge Road DAGENHAM, RM8 2AS United Kingdom • Application of: • block control principle • linearising function • pseudo-sliding mode observers for angular speed estimation • filtering observer including load torque estimation • Achievements: • speed control without shaft sensor • closed-loop dynamics for speed control chosen to suit particular drive application • enhanced reliability of whole electric drive
BASIC PRINCIPLE y nonlinear plant LINEARISING FUNCTION u specified u y nonlinear control law nonlinear plant closed-loop system y i.e., linear and de-coupled closed-loop system with prescribed dynamics MOTION SEPARATION
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 outer-loop sub-plant w d I master control law d slave control law Y d U outer loop inner-loop sub-plant inner loop w Y r I observers CONTROL LAW DESIGN SIMPLIFICATION OF CONTROL PROBLEM BY INNER/OUTER CONTROL LOOP STRUCTURE r Y Rotor speed and rotor magnetic flux norm are demanded values
motor equation desired closed-loop equation motor equation desired closed-loop equation MASTER CONTROL LAWindependently controls rotor speed and magnetic flux norm with first order dynamics and time constants, T1 and T2 linearising functions master control law
1. Constant Acceleration 2. First Order Dynamic 3. Second Order Dynamic Acceleration Demands for Three Various Dynamics
eliminate is based on motor equations Drift Corrections algorithm is used for final magnetic flux filtering SET OF OBSRVERS FOR STATE ESTIMATION AND FILTERING 1.Rotor Flux Estimator
motor equation U I -v For classical sliding -mode observer:- , I* (not used directly) slopeKI For pseudo sliding -mode observer:- , angular velocity extractor Pseudo-Sliding Mode Observer andAngular Velocity Extractor
Rotor angular velocity and load torque observer 3. Filtering Observer
external load demanded a-b demanded three- torque G stator currents demanded L phase voltages rotor speed Slave control law I U d a 1 Master Power Induction hysteresis T U 2 - 3 w 2 / signum d control electronic motor trans U slave CL 3 law drive -form I circuit d b rotor w r T speed 3 - 2 U a transform I U a b I measured a b trans 1 stator $ -formation w $ G I -I I r currents 2 3 b l v a q Rotor flux Sliding-mode Filtering v Angular b eq estimator observer observers * * * Y Y Y velocity * * Y Y * w b extractor a r * w r Overall Control Systems Structure
U U d dem d w w Induction dem r Control Power U U Motor and q dem q Laws Electronics Load I , I d q U , U d q Ideal closed-loop system behaviour 1 1 + s × T w 1 theor Comparison of Control System Response and Demanded Response The actual system response is compared with the simulated output of the ideal speed response of prescribed dynamics .
Voltages Ualpha v. Ubeta Currents Ialpha v. Ibeta 40 1 [A] [V] 20 0.5 0 0 -20 -0.5 [A] [V] -40 -1 -50 0 50 -1 -0.5 0 0.5 1 Flux Links PSIalpha v. PSIbeta Ang. Velocities & Torque v. time 0.1 200 [Vs] [rad/s], [Nm] 0.05 100 0 0 -0.05 -100 [Vs] time [s] -0.1 -200 -0.1 -0.05 0 0.05 0.1 0 0.5 1 1.5 2 Experimental Results for Induction Motor DriveDriven by First Order Dynamics Experimental Bench of East London University, Results: Daniel Vysoudil, AD Developments, Milton Keynes, UK
Second Order Dynamics and Various Damping Factor c) b) a) critically dumped system x=1 underdumped system x=0.5 overdumped system x=1.5
Various Prescribed Dynamicsincluding MRAC a) constant torque b) first order dyn. c) second ord. dyn.
Conclusions and Recommendations • A new approach to the control of electric drives with induction motors, based on feedback linearisation has been developed and experimentally proven. • Three various prescribed dynamics to speed demands were achieved. • Further research will focus on the application of the new approach to: • a) high power electric drives, including magnetic saturation and high speed applications, and • b) enhancement of control system for outer loop based on MRAC or SMC to improve precision of control.