Abstract

This project investigates the application of model reference adaptive system (MRAS) for the speed sensorless control of an induction motor. The rotor speed can be accurately estimated by employing the closed-loop observer named reactive MRAS. Therefore, this observer eliminates the need of a speed sensor for the control of the motor speed. The method is robust to stator and rotor resistance variations due to change of temperature. The dynamic system equations of the induction machines are formulated, and the motor control system performance is studied. Both scalar voltage-to-frequency (V/f) control and vector field oriented control (FOC) schemes, implemented using digital signal processor (DSP), are investigated. The design of the speed sensorless DSP-based controller is completed. Software packages have been developed to implement the design. An experimental system using the proposed controller has been built. Various tests have been conducted to verify the technical feasibility of the control technique. The experimental results confirm the feasibility of the proposed speed sensorless V/f control scheme using MRAS speed estimator. The designed V/f profile has been tested. Even with step change of the load or that of the command speed, the system can achieve the correct steady state after a short transient operation. The experimental results also confirm the feasibility of the proposed speed sensorless FOC control scheme using MRAS speed estimator. The current regulators meet the design requirements. Both the flux-producing current component and the torque-producing current component can be controlled separately. In the implementation, digital signal processor (DSP) TMS320 FL2407 and voltage source inverter (VSI) Skiip 342GD120-316CTV are employed. The modular strategy is adopted to develop the software package.

Highlights

  • I Induction motors are relatively economical and reliable machines because they are built without slip rings and commutators compared to dc machines

  • In the VIf control, the speed of induction motor is controlled by adjusting both the magnitude V and the frequency f of the stator voltages in such a way that the air gap flux is always maintained at the desired steady-state level [11]

  • The three phase voltages are reconstructed from the DC-bus voltage and three switching functions of the upper switching devices of the inverter. This module includes the Clarke's transformation that converts three-phase voltages into two-phase stationary (a,B) voltage. 4- model reference adaptive systems (MRAS)----This module is a speed estimator module for the 3-phase induction motor, based on the reactive power model reference adaptive system. 5- PID----Digital PID controller regulates the slip speed. 6- RAMP_CNTL----This module implements a ramp up and ramp down function to make the output equal to the input in designed ramp time. 7- V/f----This module generates an output command voltage for a specific input command frequency according to the specific VIf profile. 8- SVGEN---- This module calculates the appropriate duty ratios needed to generate a given stator reference voltage using space vector pulse width modulation (PWM) technique

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Summary

, Acknowledgments

I would like to express my sincere gratitude and appreciation to Professor Richard. I Cheung, my supervisor, for his guidance throughout the entire period of this degree program. I sincerely thank Professor Bin Wu, Dr S. Xu and my classmates for their valuable suggestions and help. I thank Ryerson University for the Scholarship. My special appreciation is extended to Ms Shuping Yang, my wife, for her support.

Introduction
Conventional Speed Control Schemes for Induction Motors
Improved Speed Sensorless Control Schemes for Induction Motors
Project Objectives
Project outlines
Chapter 2 MRAS-Model Reference Adaptive System
Park Transformation of (a,J}) to (d,q)
Dynamic Model of Induction Machine
MRAS Speed Estimator
Reference Model
Adaptive Model
Per Unit, Discrete Time Representation
Implementation of MRAS
Background for Vlf Control of Induction Machine
The Hardware Organization
The Software Organization
Debugging ofthe Software
Numerical Considerations
The VIf Profile Design
Slip Speed PID Controller Design
Load Design
Chapter 4 Field Oriented Control Using MRAS
Space Vector Pulse Width Modulation
Figure 4-2
Background of FOC Control of Induction Motor
The Basic Scheme for the FOe
Proposed Speed Sensorless FOC Control Scheme Usil1g MRAS
Software Implementation of the Proposed FOe Scheme
Chapter 5 Experimental Results
1: No load test
2: Load test
Open Loop Speed VIf Control
Closed-loop Speed V/f Control
1: Step Change in Load
2: Step Change in Speed
Open Loop Speed FOC Control
Summary
Conclusions
Main Work in This Project
Suggestion for the Future Work
Module Name: S Y SIN I T
Full Text
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