Sensorless Indirect Stator Field Orientation Speed Control for Single-Phase Induction Motor Drive
Abstract
The industrial requirements for the control of an inductionmachine without a mechanical sensor continue to be ofinterest, as evidenced by the most recent publications. The focusis on improvements of control without a mechanical sensor. A newmethod for the implementation of a sensorless indirect stator-fluxorientedcontrol (ISFOC) of a single-phase induction motor (SPIM)drive is proposed in this paper. The proposed method of rotor speedestimation is based only on themeasurement of themain and auxiliarywindings stator currents and that of a reference q-axis currentgenerated by the control algorithm. The error of the measured qaxiscurrent from its reference value feeds the proportional plusintegral controller, the output of which is the estimated slip angularfrequency. Experimental results for sensorless ISFOC speed controlof a SPIM drive are presented and analyzed using a dSPACEsystem with DS1104 controller board based on the digital signalprocessor TMS320F240. Digital simulation and experimental resultsare presented to show the improvement in performance of theproposed sensorless algorithm.Index Terms—Indirect stator-flux-oriented control, sensorlessvector control, single-phase induction motor, speed estimation.
I. INTRODUCTION
SINGLE-PHASE induction motors (SPIM) are traditionallyused in constant speed home appliances, usually in locationswhere only single-phase energy supply is available withoutany type of control strategy. They are found in air conditioners,washers, dryers, industrial machinery, fans, blowers, vacuumcleaners, and many other applications. Variable speed controlsof electrical motors are widely employed in industrial applicationsbecause of the obvious energy-saving benefits. The costreduction and high efficiency of power electronic and microelectronicsdevices are motivating to implement a SPIM drivesin both industrial and domestic applications.During recent years, many research laboratories have focussedon variable-speed drives, especially for the SPIM, andmajor improvements have been achieved. The availability of low-cost static converters makes possible the economic use ofenergy and improvement of the quality of the electromagnetictorque in SPIM [1]–[3]. They are three power electronic convertertopologies of two-phase inverters for SPIM: two-leg,three-leg, and four-leg inverters. In recent years, the topologywith three-leg two-phase with six-transistor bridge voltagesource inverter for SPIM drive systems has been preferred bymany researchers compared to the other topologies [1]–[13].This suitable topology to supply the SPIM with two-orthogonalvoltages system is cheaper than that of the four-leg inverter,and it gives a better performance in terms of harmonic distortionof the output voltage when compared to that of the two-leginverter.Nowadays, field-oriented controlled (FOC) induction motorsarewidely adopted to obtain high-dynamic performance in drivesystems. The FOC represents a better solution to satisfy industrialrequirements. The asymmetry of the SPIM has an importantimpact on the design of the control strategies. However, the statorflux model requires appropriate variable changes [5]. Thedrawback of this method is that the rotor speed of the SPIMmust be measured, which requires a speed sensor. A sensorlesssystem where the speed is estimated instead of measuredwould considerably reduce the cost and complexity of the drivesystem.In the existing literature, many approaches have been suggestedfor sensorless vector speed control of SPIM drivesin [14]–[17]. Some suggested methods for speed estimationusing a machine model fed by stator quantities are parameterdependent; therefore, parameter errors can degrade speedcontrol performance [18]. In paper [14], the authors evaluatea sensorless indirect rotor FOC in which the rotor flux vectorfrequency is estimated directly from measurable stator currentsand voltages but is dependent on SPIM parameters. The sensorlessspeed control strategy using MRAS techniques is basedon the comparison between the outputs of two estimators whenmotor currents and voltages must still be measured [6], [19].The MRAS algorithm sensorless speed vector control of threephaseinduction motor drive is sensitive to resistance variation[20].In this paper, we propose a contribution to the issue ofspeed sensorless indirect stator-flux-oriented control (ISFOC)of SPIM drive based on [18]. The published paper [18] investigatesthe sensorless speed control of three-phase inductionmotor drive. The SPIM model equations are more complex thanthat of the three-phase induction machines, because the mainand auxiliary stator windings have different resistances andinductances.


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