Abstract
In this paper, a sensorless induction motorparameter identification is presented. Sensorless control employsa variety of estimators and observers of motor speed, torque andfluxes, and accurate information about motor parameters iscrucial to obtain a high performance control. The parameters ofthe induction motor equivalent circuit are obtained by means ofDC an AC tests using the voltage-source inverter. When theseparameters are estimated a closed loop flux estimator and an openloop speed estimator are implemented to determine themechanical parameters of the machine. The parameter estimationprocedure has been simulated and tested in a 7.5 kW inductionmotor. With the obtained parameters a sensorless control wasimplemented.
I. INTRODUCTION
The most used control technique with induction machines isthe vector control. This method produces a decoupling betweentorque and flux-producing currents [1]. However, precisedecoupling control of an induction motor requires accuratemotor parameters which must be measured or estimated [2].A mismatch in machine parameters is prone to create controlerrors. In torque control applications, torque is estimated usingmeasurements of currents and estimations of fluxes. Amismatch in parameters will generate erroneous fluxestimation and consequently erroneous torque estimations[3,4,5]. In speed control applications, the system adjustment isdone according to the inertia of the system and frictioncoefficient. A mismatch in these parameters will degrade thedynamic behaviour of the speed loop.The literature contains a rich variety of procedures whichcan be used for induction motor parameter identification[6,7,8,9].Traditionally, the induction machine parameters wereobtained by performing locked-rotor and no load tests. Themain disadvantage of this method is that the motor has to belocked mechanically and usually disconnected from the driver.The commissioning procedures appearing in the technicalliterature are divided in two main categories: statistical anddeterministic. The statistical procedure employs estimationtheory to establish initial parameters that minimize an errorfunction, often in a least squares sense [10]. The deterministictechnique establishes a set of tests to extract the needed controlparameters [11]. The deterministic technique is subdivided intotransient and steady state excitation approaches [12,13,14,15].The proposed method successfully determines all electricalparameters in an induction motor. The stator resistance ismeasured using a DC voltage source. The machine's transientinductance is measured using a short DC pulse. To estimate themagnetizing inductance an AC voltage is used. The rotorresistance is determined measuring the decay voltage in themagnetizing inductance. Finally the mechanical parameters areestimated based on the estimated torque and speed.II. MOTOR MODEL AND EQUATIONSThe mathematical equations for a 3 phase squirrel cageinduction motor in a general rotating reference system

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