Mechatronics Systems Engineering - Theses, Dissertations, and other Required Graduate Degree Essays

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RCPC: A Multi-agent System for Coordinated Control of Power Electronic Converters in Microgrids

Author: 
Date created: 
2016-05-25
Abstract: 

The objective of this thesis is to describe the implementation of an innovative agent-based architecture of controllers for stand-alone DC microgrids. The controllers have to regulate voltage to the required level and manage energy flow in the system. In addition, they should maintain a deterministic time frame on the order of a few tens of milliseconds for a system with tens of power electronic converters with no limitation in the number of events which might happen concurrently. Optimal power sharing ensures minimum transmission and distribution loss while enforcing constraints such as generators’ capacity limits. Multiple agents take part in the process to determine optimum power sharing for the converters. The thesis compares system complexity using numerical analysis of different distributed lookup algorithms based on defined metric values for a standalone DC microgrid including 32 converters. The numerical analysis results aid in choosing a publish-subscribe model as the most efficient and scalable solution for developing agent technology for standalone DC microgrids. Application of publish-subscribe agent-based control is presented for real-time coordination of power converters in a defined microgrid. To test the design, a sample DC shipboard microgrid with eight converters is used as a case study. Results of implementing the agent-based publish-subscribe control system using Java Agent DEvelopment Framework (JADE) are illustrated in the thesis. Simulation results affirm the accuracy of numerical analysis results.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Mehrdad Moallem
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Empirical Membrane Lifetime Model for Heavy Duty Fuel Cell Systems

Author: 
Date created: 
2015-07-17
Abstract: 

Heavy duty fuel cells used in transportation system applications such as transit buses expose the fuel cell membranes to conditions that can lead to lifetime-limiting membrane failure via combined chemical and mechanical degradation. Highly durable membranes and reliable predictive models are therefore needed in order to achieve the heavy duty fuel cell lifetime target of 18,000 h. In the present work, an empirical membrane lifetime model was developed based on laboratory data from a suite of accelerated membrane durability tests. The model considers the effects of cell voltage, temperature, oxygen concentration, humidity cycling, humidity level, and platinum in the membrane using inverse power law and exponential relationships within the framework of a general log-linear Weibull life-stress statistical distribution. The obtained model is capable of extrapolating the membrane lifetime from accelerated test conditions to use level conditions during field operation. Based on typical conditions for the Whistler, British Columbia fuel cell transit bus fleet, the model predicts a stack lifetime of 17,500 h and a membrane leak initiation time of 9,200 h. Validation performed with the aid of a field operated stack confirmed the initial goal of the model to predict membrane lifetime within 20% of the actual operating time.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Erik Kjeang
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.

An Energy-Regenerative Vehicle Suspension System – Development, Optimization, and Improvement

Author: 
Date created: 
2016-08-23
Abstract: 

With the rapid development of hybrid and fully electric vehicles, electromagnetic suspensions have shown great potential for capturing energy while offering high-level ride comfort. The objective of this research was to develop an electromagnetic-based vehicle suspension system that allows for regeneration of road-induced vibration energy and supplies better dynamics control. A small-scale proof-of-concept system consisting of a mass-spring-damper system, ball screw mechanism, and direct current (DC) machine was designed. The vibration energy in the mass-spring-damper system caused vertical motion of sprung mass and the ball screw mechanism to convert the translational motion into rotary motion, which resulted in the generation of back electromotive force of the DC machine. Systematic optimization methodologies were utilized to provide for selective adaption of suspension parameters, such as spring constant (rate) and damping coefficient, according to different road surface conditions, including harmonic and stochastic waveforms. By maximizing the average of power generation or minimizing the root-mean-square of the sprung mass’s absolute acceleration by selecting optimal parameters, the suspension allowed operation in either energy-oriented mode or control-oriented mode. Furthermore, a bandwidth enhancement technique utilizing cubic nonlinearities was demonstrated to improve the energy harvesting capability of the suspension system. A self-powered regenerative Skyhook control strategy was proposed to overcome the trade-off between passive control (insufficient control) and active control (external energy demand) for the suspension system.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Farid Golnaraghi
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) Ph.D.

Noise Measurement in Microsensor Applications

Author: 
Date created: 
2016-08-25
Abstract: 

In this research, spectral coherence noise measurement technique is used to measure noise of capacitive accelerometers, based on measuring the spectral coherence and outputs of two identical sensors exposed to the same input stimulus. This effective technique can be applied to any sensor characterization problem where there is interest in distinguishing instrumental noise from background noise. The simulation study has been done in MATLAB to verify the proposed method reliability to calculate contributions of different noise sources in a system. To verify effectiveness and accuracy of the proposed technique in practical systems, we continue our research in experimental work, using this method on a commercial accelerometer. Then, the technique is applied to measure noise of microsensor systems which consist of MEMS capacitive accelerometer followed by low-noise interface electronics. The proposed technique is also used to measure and quantify the noise contribution of different stages of interface electronics. Experimental results are compared to either reported data on the used devices datasheet, analytical equations, or simulation results. The similarity between experimental results with theoretical values and simulation results verifies the measured noise for microsensor systems. Thanks to spectral coherence noise measurement technique, we will be able to characterize noise behavior of fabricated sensors and reader boards, and determine the lowest noise sensor and interface electronics.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Behraad Bahreyni
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Static and Dynamic Modeling and Simulation of the Umbilical Cable in A Tethered Unmanned Aerial System

Author: 
Date created: 
2016-06-27
Abstract: 

The research at hand has been accomplished in collaboration with our industry partner, Rigid Robotics Inc. and aims to predict and suggest solutions for some of the known and unknown issues that might appear in operation of a tethered Unmanned Aerial System (to be referred to as UAS hereafter). In this work, the static and dynamic behaviour of the power cable connecting a hovering UAS to its base station is studied in different flight scenarios. The mathematical modelling of the cable is carried out using catenary equations for the static case and multi-body dynamics principles are employed for the dynamic condition. In the preliminary stages of the project, for the purpose of the cable and UAS design, a simple technique is used to estimate the maximum tension forces present in the static state of the cable as well as the cable shape function and other related parameters when UAS is in hovering mode. The derivation of the system’s equations of motion is done using Lagrange’s Equations by considering the cable as a discrete multi-body system. The equations of motion are derived for a system of finite segments and are solved numerically using MATLAB™ software package in order to simulate the cable’s motion. The effect of wind on the dynamics of the cable is also implemented using theoretical methods and simulations. The system’s dynamics is modeled in a planar motion as well as a 3D space in separate chapters.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Siamak Arzanpour
Carolyn Sparrey
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Board-Level thermal management systems with application in electronics and power electronics

Date created: 
2016-03-09
Abstract: 

In this study, heat removal and thermal management solutions for electronic devices were investigated at board-level. The generated heat at an electronic chip, installed on a printed circuit board (PCB), can be dissipated either through a heat sink, that is attached directly to the chip, or can be transferred through the PCB to the other side and then be dissipated to the ambient. In any case, thermal interface materials (TIMs) should be used to reduce the thermal contact resistance (TCR) at the solid-solid interface, and also to electrically insulate the live electrical component from the heat sink which is normally exposed to the ambient. Graphite, due to its low cost, lightweight, low thermal expansion coefficient, high temperature tolerance, and high corrosion resistance properties is shown to be a promising candidate to be used as a TIM. In this study, a new analytical model was developed to predict the thermal conductivity of graphite-based TIMs as a function of pressure applied during the production, and flake mechanical properties. The model was verified with the experimental results obtained from testing multiple graphite-based TIM samples. Transferring the heat to the back of the PCB could potentially provide more surface area for the heat transfer, as normally the backside of PCBs is less populated compared to the front side. However, this comes with its own challenges, due to the low thermal conductivity of the FR4, the main material used in the PCB composition. Thermal vias, which are copper-plated through holes, are proposed as a solution, since they can provide a thermal bridge for heat. A new analytical model was developed for predicting the enhanced thermal conductivity of PCBs equipped with thermal vias. The results were validated by the experimental data obtained from testing nine PCB samples. Effects of vias diameter and their arrangement on the thermal performance were investigated. The results indicated that by using staggered arrangement of thermal vias with larger diameters, the effective thermal conductivity of the PCB can be improved.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Flexible Amperometric Biosensor for Sweat Lactate Detection

Author: 
Date created: 
2016-08-16
Abstract: 

A flexible amperometric biosensor using silver nanoparticle-based conductive electrode was fabricated for sweat lactate measurement. The developed sensor was composed of three-electrode configuration for the demonstration of electro-chemical sensing with silver nanoparticles as a single electrode material. Thin-film electrodes with cross-serpentine pattern have been demonstrated to be highly flexible without significant change in their electrical behavior. Fabricated electrodes were annealed for higher conductivity and modified for electrochemical analysis of lactate. The permselective membrane on working electrode was used to enhance selectivity of the sensor against common interfering electroactive anions such as ascorbate. Enzyme was immobilized on the sensor surface for lactate oxidization to produce hydrogen peroxide. The optimum potential (0.65 V) was determined employing cyclic voltammetry and applied for different in-vitro experiments to generate current flow- proportional to lactate concentration. Bleach-assisted-modified in-sensor pseudo reference electrode evinces its long term potential stability against standard commercial reference electrode. The catalytic response of the sensor shows excellent linear behavior between 0~25 mM of lactate. This noninvasive electrochemical lactate sensor also demonstrates excellent behavior to reject anionic interference, resiliency against mechanical deformation and temperature fluctuation which leads to the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Finally, the wireless data transmission using near-field-communication unit is demonstrated for the realization of a practical sensor application to be able to measure sweat lactate portably using human perspiration.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Woo Soo Kim
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Development of Adsorber Beds for Air Conditioning in Vehicle Applications

Date created: 
2016-06-30
Abstract: 

This project set out to design and develop a better adsorber bed for an adsorption cooling system (ACS). The most important characteristic of an ACS is the specific cooling power (SCP), which is defined as the ratio of the cooling power at the evaporator to the product of the cycle time and mass of dry adsorbent. The performance of the ACS is evaluated using an in-situ mass measurement to determine the amount refrigerant that has been adsorbed. A numerical model for the adsorption process within an adsorber bed was developed in ANSYS Fluent with an added user defined function (UDF) module and a comparison was made between the results of the numerical model and the experimental tests. Although the numerical model always over predicts the value for SCP, the results show good agreement. The validated numerical model can be used to predict the performance of the ACS at different working conditions and with different adsorber bed geometries.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Majid Bahrami
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

Design of 3D-Printable Conductive Composites for 3D-Printed Battery

Author: 
Date created: 
2016-08-09
Abstract: 

In this research, a biocompatible nano-composite is designed for the application of 3D printed battery. The nano-composite paste is composed of an electrically conductive silver nanowire (AgNW) filler within a thixotropic carboxymethyl cellulose (CMC) matrix. Experimental demonstration and computational simulations on nano-composites with various filler fractions are performed to find the electrical percolation threshold of the nano-composite. The percolation threshold as 0.7 vol. % of AgNWs is predicted by computer simulations as well as by experiments. Also, maximum electronic conductivity is obtained as 1.19×102 S/cm from a nano-composite with 1.9 vol. % of AgNWs. Also, newly designed paste 3D printing apparatus is built by integrating a commercially available delta 3D printer with a paste extruder.Finally, the 3D printable battery facilitated by the conductive composite is demonstrated. Cathode and anode materials are formulated by addition of cathode and anode active materials to the nano-composite of AgNW and CMC. Rheology study of the cathode and anode paste is carried out and thixotropic (shear-thinning) behavior is observed which is an essential characteristic of the 3D printable paste [1], [2]. Lastly, the performance demonstration on the fabricated 3D printed battery is carried out. The 3D printable conductive paste is expected to contribute in additive manufacturing process for printable electronics.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Woo Soo Kim
Department: 
Applied Sciences: School of Mechatronic Systems Engineering
Thesis type: 
(Thesis) M.A.Sc.

In Situ Modeling of Chemical Membrane Degradation in Polymer Electrolyte Fuel Cells

Author: 
Date created: 
2015-06-23
Abstract: 

Chemical membrane degradation is a major limiting factor for polymer electrolyte fuel cell (PEFC) durability and lifetime. While the effects of chemical membrane degradation are characterized in the literature, the underlying mechanism is not fully understood. This motivates the development of a comprehensive in situ chemical membrane degradation model addressed in this work to determine the linkages between the membrane electrolyte assembly (MEA) macroscopic phenomena, in situ operating conditions, and the temporal membrane degradation process. Chemical membrane degradation through OH radical attack on the membrane, where the radical is produced by decomposition of hydrogen peroxide in the presence of contaminants such as Fe2+, is comprehensively investigated. A redox cycle of iron ions is discovered within the MEA which sustains the Fe2+ concentration in the membrane and results in the most severe chemical degradation at open circuit voltage (OCV). The cycle is suppressed at lower cell voltages leading an exponential decrease in Fe2+ concentration in the membrane and associated membrane degradation rate, which suggests that intermediate cell voltage operation would efficiently mitigate chemical membrane degradation and extend the fuel cell lifetime. Effectiveness of membrane additives (e.g., ceria) in mitigating the membrane degradation is explored. At high cell voltages, abundant Ce3+ ions are available in the membrane to quench hydroxyl radicals which is the primary mitigation mechanism observed at OCV conditions. However, the mitigation is suppressed at low cell voltages, where electromigration drives Ce3+ ions into the cathode catalyst layer (CL). Without an adequate amount of Ce3+ in the membrane, the hydroxyl radical scavenging is significantly reduced. Moreover, the modeling results reveal that proton starvation may occur in the cathode CL due to local Ce3+ accumulation and associated reductions in proton conductivity and oxygen reduction kinetics. Significant performance tradeoffs in the form of combined ohmic and kinetic voltage losses are therefore evident. A lower initial Ce3+ concentration is demonstrated to mitigate voltage losses without compromising membrane durability at high cell voltages. However, the harmful Fe2+ concentration in the membrane increases with the Ce3+ concentration, which suggests that ceria-supported MEAs can experience higher rates of degradation than baseline MEAs at low cell voltages. Strategic MEA design is recommended in order to ensure membrane durability at low cell voltages.

Document type: 
Thesis
File(s): 
Supervisor(s): 
Erik Kjeang
Department: 
Applied Sciences:
Thesis type: 
(Thesis) Ph.D.