Sensorless Speed Control of Induction Motor Report

This document is a detailed report on the development of a sensorless speed control system for an induction motor, focusing on the implementation of the Model Reference Adaptive System (MRAS). The report outlines the project's background, objectives, and the author's specific contributions as a team member. It delves into the theoretical aspects of MRAS, the engineering skills applied, and the challenges encountered during the project. The report also includes the use of MATLAB/Simulink for simulation and analysis, and the collaborative efforts involved in the project. The author successfully estimated the speed of the induction motor without mechanical sensors, demonstrating a comprehensive understanding of motor control and simulation techniques.

COMPETENCY
DEMONSTRATION REPORT
Career Episode 3
AKSHAY KIRAN MURALIDHARAN

CE 3.1 Project Information
Name of the project: Sensorless Speed Control Of Induction Motor
Location of the project: [Please Fill]
Project Duration: [Please Fill]
Organization: [Please Fill]
Role and Designation during the time: Team Member
CE 3.2 Project Background
CE 3.2.1 Characteristics of the project
Since the day of its invention, the induction motor has lead to the significant increase in
the application of house appliances, robotics, and several industrial process. I have observed
thaw the increased application of the induction motor in the industrial sector was due to its cost
effectiveness, reliability and simplicity in the design of implementation. In various industrial as
well as home appliances, the control of speed has become a significant constraints for the motor.
There exists various speed control mechanism that has been imposed on the induction motor for
managing and controlling their proper speed. I have learned that the application of vector control
theory has obtained significant attention for controlling the speed of the induction motor. I have
observed with the vector control theory, various sensors are used for detecting the current speed
of the induction motor. This results in increasing the size and cost of the speed control system.
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Therefore, I have undertook this project for the design and implementation of the low cost,
simple yet effective speed control system for the induction motor.
CE 3.2.2 Objectives developed for the project
I took this project with the significant aim of proposing a speed control system for the
inductive motor. I have worked for the reducing the complexity, cost and size of the speed
control system for the induction motor. For the efficient completion of the system development
and proper implementation, I have prepared the following objectives:
 To identify and evaluate the appropriate theory and concept of dynamics of induction
motor;
 To develop the prototype model of the induction model and speed monitoring system;
 To identify the appropriate design and operations for the speed control system of the
induction motor;
 To estimate the exact speed of the induction motor without the application of the
mechanical sensors mounted on the motor shaft;
 To employ the theory of Model Reference Adaptive System to control the speed of
the inductive motor;
 To analyze the developed prototype model using MATLAB simulation software;
CE 3.2.3 My area of work
In spite of being associated in this project as a team member, I have followed multi
dimensional work module for the development of the sensorless speed control of the induction
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motor. During the initial phase of the project, I have determined the working principle and
dynamics of the induction motor for controlling the speed of the motor. In addition to that, I have
evaluated the operation while constructed the induction model for this project.
CE 3.2.4 Project Group
Figure 3.1: Team Members Associated with the development of the
project
CE 3.2.5 My responsibilities throughout the project
I have developed the appropriate model of the induction model with the application of the
appropriate techniques and process for implementation. Apart from that, I had the responsibility
of elation various process and concept that can be used for the sensor less speed control while
selecting the appropriate model for this project.
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CE 3.3 Distinctive Activity
CE 3.3.1 Comprehending the theory of the project
Before initiating the practical development of the speed control system, I have evaluated
and studied various process used for the sensors less monitoring and control of induction motor
speed. After detailed analysis and review, I have selected the application of the MRAS (Model
Reference Adaptive System) techniques used in the adaptive control of the wireless motor. In the
MRAS system, I have used adaptive mechanism and adjustable model for estimating the speed
of the motor. For implementing the MRAS speed estimation structure, I have developed the
reference model for calculating the rotor speed. I have achieved this with the calculation of the
current, terminal voltage, and state variable of the induction motor. I have further calculated the
error of the rotor speed value of estimated and calculated variable that I have used in the adaptive
mechanism for generating the speed of the motor.
Figure 3: Block Diagram for the Model Reference Adaptive System
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CE 3.3.2 Engineering knowledge and skills applied in the project
Figure: MRAS model applied in the induction model
While designing the reference model for the motor, I have used stator current and stator
voltage as the required input to the motor. For this purpose, I have used the following equation:
dλ d
dt =
L2
M Vd-R1 id + σ L1
di d
dt
dλ q
dt =
L2
M Vq- R1 iq + σ L1
di q
dt
In the above equation, I have used L1 and L2 as the static inductance and rotor self-
inductance. On the other hand, I have used T2 as the rotor time constant, R1
as the stator resistance, M as the mutual inductance of the motor.
Furthermore, I have used v, i and Λ as the stator voltage, stator current and
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rotor flux. Similarly, I have developed the appropriate formula for
determining the adaptive model and appropriate mechanism. Apart from
that, I have used Dspace for testing and developing the appropriate
mechanical functionalities of the implemented induction motor. Through the
application of DSpace I was successfully able to calibrate the system and
determine the appropriate connectivity between them. I have further utilized
the RTI (eal time interface) for reading the values obtained from the control
desk of the Dspace.
CE 3.3.3 Accomplishment and task performed
I have used two observers independent in nature for estimating the rotor flux vector of the
induction motor. I have used one individual observer for observing the quantity and utilised it as
reference model. On the other hand, I have used another observer for detecting the rotor speed
and utilised it as the adaptive model. Furthermore, I have used utilised the error for driving the
adaptive mechanism of the motor.
CE 3.3.4 Identified issues and their solutions
Issue: While developing the speed control system for the inductive motor, I have found
that determination of the error between the adaptive model state and the reference model state
was essential for providing the appropriate control mechanism of the motor speed. I have
utilised the PI controller for minimising the error to zero. I have found significant technical issue,
when the calculated value of error did not match the obtained value from the development of the
control system.
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Figure 3: Speed estimator developed for the MRAS
Solution: For the elimination of the technical issue, I have studied and reviewed the
calculation as well as the developed prototype model of the speed control system. I have
observed that the overall stability of the system was not taken into consideration during the
calculation of the error. Therefore, for the mitigation, I have included overall stability and
determined the dynamic characteristic of the desired value. From the modification I was able to
obtain the linear time varying system of both the model.
CE 3.3.5 Plan to produce creative and innovative work
In order to provide innovation and creativeness within the project, I have used
MATLAB/SIMULINK package for simulating the closed and open loop control, and speed
estimator of the speed control system. I have considered the preset model while feeding the stator
current and voltage to the speed estimator of MRAS. Through this, I was able to obtain the
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estimated and actual waveform of the MRAS model. Apart from that, I have utilized the sensor
less field oriented control technique on the closed loop control for controlling the speed of the
inductive motor. Through this, I was able to obtain the independent control of the torque and
rotor flux decupling.
Figure 3: Actual Speed of the Preset Model
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Figure 3: Estimated Speed of the Preset Model
CE 3.3.6 Collaborative work
I have focused and aimed at developing the project with collaboration with the other team
members associated with the project. In addition to that, I have consulted with the assistance
professor for understanding the project plan. Apart from that, I have discussed the theories and
techniques used in the project for proper implementation and completion.
CE 3.4 Project Review
CE 3.4.1 Project Overview
I was successful in estimating the speed of the induction motor using MRAS (Model
Reference Adaptive System). Through the application of the sensor less
control, I was able to control the shaft encoder of the motor. In addition to
that, I have used Matlab Simulink for simulating the performance of the
proposed system. Furthermore, the proposed system of the speed control
was successful and completed within the deadline of the project.
CE 3.4.2 My contribution to work
I have worked as a team members for the development and implementation of the sensor
less speed control system for the induction motor. In this project I have showed my knowledge
and understanding of the various models and theories of induction motor and speed control in
this project. Apart from that, I have showed my efficiency and understanding of the application
of the MATLAB Simulink for simulating the performance of the proposed induction motor.
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