Usman Nasir | University of Nottingham (original) (raw)

Papers by Usman Nasir

Demand of power is increasing worldwide and this increased demand has motivated the engineers to ... more Demand of power is increasing worldwide and this
increased demand has motivated the engineers to look for
alternative or renewable energy systems. Meanwhile, the data
centers are also employing the solar energy systems to avoid the
AC/DC power conversion losses due to the fact that an efficient
solar system with DC/DC converter will help them to save up to
15% of the power in comparison to the conventional power
supply system using non-renewable energy sources.
The efficiency of the solar energy systems is greatly
dependent on the DC/DC converters and hence, there is a need to
study the comparison of efficiency of such converters which can
be used in Switch Model Power Supplies (SMPS). This paper
provides a comparative analysis between some of the DC/DC
converters i.e. synchronous buck converter, isolated buck
converter and non-isolated buck converter. Moreover, the
important factors such as input voltage variation and the effects
of open and closed loop systems of mentioned DC/DC converters
are also explained.

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This paper presents a design and implementation details of a Quad copter (BalckFalcon) for the in... more This paper presents a design and implementation
details of a Quad copter (BalckFalcon) for the inspection of
power transmission line and other similar civil applications.
Initially PID controller is developed in simulation and hardware
for the robust control .UAV is controlled through remote as well
as autonomous flight schedule. Gyroscope sensors give signal to
the main controller board where the PID controller is embedded.
Further pre planned flight monitoring application is also
developed to watch far off places. A series of experiments are
performed for transmission line fault detection that the proposed
UAV can lift 2.5kg load during its hovering condition and
maintain a stable and smooth landing.

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The aim of project is to design an automated speed detection system which can detect the speed of... more The aim of project is to design an automated speed
detection system which can detect the speed of vehicles and if
over-speeding occurs, extract the license number of vehicle and
send it via email to Toll Plaza to charge fine. The system is
designed for Punjab license plates which are currently
implemented in Pakistan. Doppler effect phenomenon is used for
the speed measurement. If over-speeding is detected, a camera
automatically captures the picture of the vehicle and Digital
Image Processing (DIP) techniques are applied to extract the
license number. MATLAB is used for image processing.
Afterwards, the extracted license plate number is sent via email
to Toll Plaza. The results show that the proposed system
successfully detects over speeding, extracts the license plate, has
high performance and can be deployed on roads to check for
over speeding.

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Three Phase Inverters being used today are based on Field Orientation Control (FOC) and Sine Wave... more Three Phase Inverters being used today are based on Field Orientation Control (FOC) and
Sine Wave PWM (SPWM) techniques because 120 degree or 180 degree conduction methods
produce high value of THD (Total Harmonic Distortion) in the power system. The Indirect Field
Orientation Control (IFOC) method is difficult to implement in real systems due to speed sensor
accuracy issue. This paper discusses the problem with IFOC and a PWM based 180 degree
conduction mode for the three phase inverter. The modified control method improves THD and this
paper also compares the results obtained using modified control method with the conventional 180
degree conduction mode.

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This Paper discusses the Simulink Models of open and closed loop systems of a three phase control... more This Paper discusses the Simulink Models of open and closed loop systems of a three phase controlled rectifier and its study in terms of variation of load. The relationship between the source inductance, firing angle and commutation angle is important as these entities directly affect the Total Harmonic Distortion (THD) of the power system and this paper uses a graphical method to develop a relationship between source inductance, firing angle and commutation angle. This paper also discusses some trade-offs of using a Proportional - Integral (PI) controller in the design of closed loop system of the rectifier circuit and the effects of using active filters to reduce the Harmonic Components of the source current that may lead to commutation failure in the three phase controlled rectifier circuit.

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today, variable speed pumped storage (VSPS) system is an emerging technique, being used in hydro ... more today, variable speed pumped storage (VSPS)
system is an emerging technique, being used in hydro powered
plants to increase the efficiency, quality and control of the power
of the grid. The doubly fed induction machine (DFIM) based
VSPS systems are gaining more importance because of the cheap
price of the converter i.e. back to back power electronics
converter. This paper discuses an efficient method for the rotor
side converter (RSC) to control the active and reactive power
flowing through the stator of DFIM while the grid side converter
(GSC) has been used to maintain the DC voltage level. This paper
also discusses the VSPS systems Worldwide and its comparison
with hydro powered projects which are recently developed in
Pakistan. This paper suggests the use of VSPS systems in
Pakistan to increase the efficiency of the conventional hydro
power projects.

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Power electronic converters play a vital role in a power system and the most commonly used type o... more Power electronic converters play a vital role in a
power system and the most commonly used type of DC/DC
converters is buck converter. This is due to the fact that buck
converters are widely used to step down the voltage as well as
they provide good voltage regulation in critical applications
including power supplies for data centers. Therefore, designing a
buck converter that gives a regulated output, acceptable for
switch mode power supplies is still challenging task. A closed loop
buck converter mitigates the problems such as input voltage unstability
or variation.

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