29 research outputs found
Sensorless Adaptive Fuzzy Logic Control Of Permanent Magnet Synchronous Motor
Full text linkPermanent Magnet Synchronous Motors (PMSM) require an electromechanical rotor
position sensor to operate. The rotor position sensor has disadvantages, such as
reliability, size, higher cost, and increased electrical connections. PMSM is used in
many speed and position control industrial applications. Proportional integral (PI)
and proportional integral derivative (PID) controllers have been widely utilised as
speed controllers in PMSM drives. However, these controllers are very sensitive to
step change of command speed, parameter variations and load disturbance.
In this work, an adaptive fuzzy logic speed controller is proposed. The main features
of the proposed controller are; quick recovery of motor’s speed from load
disturbances and insensitivity to parameter variation over a wide speed range.
The proposed controller is a hybrid model reference adaptive speed controller
(HMRASC) which mainly consists of two functional blocks. The first block is a
direct FLC that has the error and the change of error as inputs. The error signal is
measured between the actual motor speed and the desired speed and the output is the change in the torque command. The second block implements a model reference
adaptive controller. In the proposed system, the output speed of the reference model
is compared with the actual speed of the motor and the resulted speed error is applied
to a PI controller. The output signal of the PI controller is added to the direct FLC
output to compensate any deviations in the motor speed from the reference speed due
to parameters variation and disturbances in the load.
The design and optimisation of the FLC are carried out using an adaptive fuzzy
inference system network that uses the backpropagation, least square and gradient
algorithms. The fuzzy inference system is trained and designed using an adaptive
network. The rules and the implication method used are also optimised and
minimised in order to shorten the computation time. In addition, the effect of
different types and distributions of the membership functions were investigated and
presented.
This work also presents the estimation of the rotor position, which works effectively
with nearly zero estimation error over wide speed range, to replace the
electrometrical rotor position sensor. An estimation method based on the back EMF
and flux estimation is presented to calculate the rotor position for medium to high
speed. At low speed, the rotor position is calculated using signal injection where a
high frequency low voltage signal is injected on the stator winding. In the proposed
method, the measured motor’s current and the estimated motor’s voltage are
processed through a signal processing block and a PI regulator to calculate the angle
of the rotor position.Finally the performance of the HMRASC and the rotor position angle estimation
algorithms are evaluated by simulation and verified experimentally for two motors
using MCK2407 kit and IMDM15 board which are based on the TMS320LF2407
fixed point Digital Signal Processor (DSP) for different operating conditions. The
first motor is rated at 50W and the second is rated at 380W. Both experimental and
simulation results obtained from the HMRASC and the position angle estimation
algorithms showed superior results compared to other methods presented in the
literature
Development of Smart Lead-Acid Battery Charger for Electric Vehicle Application
Full text linkThe battery charger is a critical part in an electric vehicle (EV) because it
charges the battery, which is the weakest part of it. An unduly long charging time
limits the use of the EV. Currently, it takes a long time to charge a battery of
limited capacity, making EVs rather impractical to use.
The objective of this thesis is to design, simulate, construct and test a smart
charger for fast charging a battery. The charger consists of two units - the power
processing unit and the battery management unit. The power processor is based on
a step-down DC-to-DC converter topology. The battery management unit uses
first a current control (constant current mode) and then voltage control (constant
voltage mode) to charge the battery. The smart control mechanism is based on current and voltage sensing
combined with sequenced average current and voltage control to charge the battery
as fast as possible and to maximise its charge.
The charger was tested successfully on single-phase and three-phase
voltage supplies at different output voltages and currents. The charger developed
was able to charge a 30 Ah lead-acid battery in two hours as opposed to six hours
using a conventional charger.
The research showed that it was possible to develop a battery charger
which can charge a battery to its limits quickly without gassing and overheating. It
is likely that the battery life will be extended without the detrimental effects
experienced
Techno-Economic Analysis of a Residential PV-Storage Model in a Distribution Network
Full text linkThe high penetration level of photovoltaic (PV) generation in distribution networks not only brings benefits like carbon savings, but also induces undesirable outcomes, like more harmonic components and voltage fluctuations. Driven by decreasing costs of energy storage, the focus of this paper is to investigate the feasibility of applying energy storage in the grid-connected PV system to mitigate its intermittency. Firstly, to appreciate the functionality of storage, a generic PV-battery-supercapacitor model was simulated in MATLAB/Simulink, and a flat load profile was obtained to enhance predictability from the network management point of view. However, the usage of supercapacitors at the residential level is limited, due to its high startup costs. Secondly, a detailed residential PV-battery model was implemented in the System Advisor Model (SAM) based on local data in Dubai. The optimal sizing of a battery system was determined by assessing two criteria: The number of excursions, and average target power, which are contradictory in optimization process. Statistical indicators show that a properly sized battery system can alleviate network fluctuations. The proposed sizing method can be also applied to other PV-storage systems. Finally, economic studies of PV-battery system demonstrated its competitiveness against standalone PV systems under appropriate tariff incentives
Investigation of Voltage and Frequency Variation on Induction Motor Core and Copper Losses
No full textThis paper presents a dynamic induction motor(IM) model which incorporates all the power losses. Thepresented module is entirely built in Simulink to investigate theeffect of varying the applied voltage and frequency on IMefficiency for different load applications. The model includes thepower losses such as copper losses, core losses, stray load andmechanical. The accurate determination of induction motorefficiency depends on the estimation of all above mentionedpower losses which are modeled and presented in this paper. Theeffect of variation in applied voltage and frequency on inductionmotor efficiency is investigated at various load conditions and theresults are tabulated and evaluated accordingly. The obtainedresults show that the efficiency of the IM is significantly affectedby the voltage and frequency levels especially at low load.Therefore matching the right applied voltage and frequency tothe motor terminal based on the load condition will reduce themotor losses and hence increase its efficiency
Robust sliding mode controller for buck DC converter in off-grid applications
Full text linkThis paper presents a robust sliding mode controller of DC-DC buck converter for renewable energy applications, such as photovoltaic systems in off-grid configurations. Photovoltaic systems in off-grid configuration are exposed to significant variations in input voltage and power loads. The proposed sliding mode controller presents a simple and efficient method of continuously updating the duty cycle of a pulse width modulation unit (PWM) of a buck converter. The PWM unit is operated at constant switching frequency of 10 kHz carrier signal and varying duty cycle. The differences in input voltage and power load are treated as two bounded uncertainties, thus eliminating the need for input voltage sensor and output current sensors leaving the system with a single sensor required to measure the converter output voltage. That is, measured output voltage is compared with the reference voltage to continuously update the average duty cycle value of PWM unit. Adjustment of PWM duty cycle is performed while maintaining the sliding condition always fulfilled. The simulation results of the proposed controller showed robustness and accuracy against power load fluctuation, changes in desired output voltage, and variations in the input supply voltage that may result from the varying level of irradiance and temperature.</p
Impact of PV and Wind Penetration into a Distribution Network Using Etap
No full textAccording to IRENA the number of countries adopted a target to ratify the renewable energy on their electricity grid went from 43 countries to 164 over a course of 10 years only. These targets which will increase renewable energy share on the electricity grid, implies the use of Distributed Generation (DG) like roof-top PV panels or the construction of small scale dispersed renewable-based power plant like wind or PV farms. The aim of this paper is to study the impacts of high PV and wind penetration into the grid. To address these impacts,a comprehensive study performed on a test system provided by IEEE to model the integration of DG plants into a 33kV distribution network using Etap software. Three levels of integration were modeled to reflect the impact of DG plants penetration on gradual basis, 6 scenarios have been assumed and two types of tests have been carried out to investigate their impact on the grid; fault level and frequency transient stability were performed individually at each level of penetration.Additionally, in order to examine the grid performance during extreme weather conditions, several events have been assumed to model the intermittent properties of renewable energy generation. The obtained results showed very good performance of the grid for penetration less than 30% while higher level of PV and wind penetration requires further attention and modification on the grid side
Techno-economical analysis of stand-alone hybrid renewable power system for Ras Musherib in United Arab Emirates
No full textThe aim of this study is to model and design a hybrid renewable energy system for the remote area in Ras Musherib located in the western region of Abu Dhabi. The hybrid system, which consists of photovoltaic (PV) array, wind turbines, batteries and diesel generators, is designed to meet three known electric loads, 500 kW, 1 MW, and 5 MW to be able to fulfill the primary load for 250, 500 and 2500 households. Different combination of wind turbines, PV, batteries and generators were evaluated in order to determine the optimal combination of the hybrid system based on the lower Net Present Cost method. The proposed hybrid system is modeled, optimized and simulated using Hybrid Optimization Model for Electric Renewable (HOMER). The obtained results show that the hybrid system with 15% of photovoltaic and 30% of wind turbine penetration found to be the optimal system for 500 kW average load with initial cost of 14,504,952 over 25 years. The reduction in CO2 emission achieved in this study for the 500 kW optimal hybrid system is 37% compared to the conventional diesel generator only power system. (C) 2013 Elsevier Ltd. All rights reserved.</p
Investigation of Voltage and Frequency Variation on Induction Motor Core and Copper Losses
No full textThis paper presents a dynamic induction motor(IM) model which incorporates all the power losses. Thepresented module is entirely built in Simulink to investigate theeffect of varying the applied voltage and frequency on IMefficiency for different load applications. The model includes thepower losses such as copper losses, core losses, stray load andmechanical. The accurate determination of induction motorefficiency depends on the estimation of all above mentionedpower losses which are modeled and presented in this paper. Theeffect of variation in applied voltage and frequency on inductionmotor efficiency is investigated at various load conditions and theresults are tabulated and evaluated accordingly. The obtainedresults show that the efficiency of the IM is significantly affectedby the voltage and frequency levels especially at low load.Therefore matching the right applied voltage and frequency tothe motor terminal based on the load condition will reduce themotor losses and hence increase its efficiency
Potential of energy and water efficiency improvement in Abu Dhabi's building sector – Analysis of Estidama pearl rating system
No full textEnergy and water infrastructure in Abu Dhabi provides a strong example of the interconnection between energy and water, where the majority of its electricity and water demand is jointly produced from cogeneration plants. The total cost of fuel used for cogeneration plants are heavily depending on the efficiency level of end-use energy and water consumption. Buildings are the major electricity and water consumers with 84.6% and 92.2% respectively from the entire demand. The aim of this study is to analyze the energy and water consumption reduction by implementing Estidama pearl regulations and compare it with Business as Usual -the normal execution of things as they always do-for three sample buildings (villa, multistory residential and office building). For energy assessment, eQUEST software was used to examine the energy performance of the chosen buildings and to evaluate the energy saving potential after applying Estidama requirements. While for water assessment; Estidama and LEED calculation tools were used to do the same. The results of energy simulation and water analysis of the chosen buildings showed a potential of electricity reduction between 31% and 38% and a potential of water reduction between 22% and 36% depending on building type and other parameters. Also, a total monetary savings of 19 Billion AED can be achieved cumulatively over ten years period (2011–2020) after Estidama regulations have been applied. In addition, a reduction of 31.4 Million ton of CO2eq cumulatively can be achieved
