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Ripple Free Torque Operation in Switched Reluctance Motors

Thesis Info

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External Link

Author

Saleem, Yasir

Program

PhD

Institute

University of Engineering and Technology

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2008

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2864/1/1275S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727105823

Similar


This thesis investigates the control of current and torque at different speed of the switched reluctance motor observing the motor constructional properties, mathematical model equations, operating principle and power converter topologies. The switched reluctance motor has gained popularity in industry with the fact that it is simple to construct and suitable for harsh environment. The electromechanical energy conversion is produced from rather simple machine design than as it is done in conventional motors. The other advantages are its rugged construction, low maintenance cost, and ability to operate over a wide speed range at constant power. The merits of switched reluctance motors are marred by the requirement of expensive control and its innate torque ripple issue, which is also a cause of vibration and acoustic noise. Torque ripple is produced from successive excitation of phase currents. The current through phase windings produces magnetic force with tangential and radial components where former component contributes to the average torque production and the latter is the major cause of vibration and acoustic noise in switched reluctance motors. Torque ripple reduction leads to smooth operation, thus it also improves the vibration and acoustic noise. This reduction can be achieved either through better machine design or with superior control techniques. Better machine design involves basic design parameters like number of stator poles, rotor poles and also their shape which is generally determined using detailed magnetic analysis. In this piece of work literature review of both approaches is included but the latter current control approach is adopted for detailed research. This thesis also discusses the split stator winding technique to improve reduction in torque ripple. This is unique strategy to introduce a compensation torque and remarkable reduction in torque ripple. This technique requires the slight change in shape of stator. This technique has ability to eliminate the negative torque generation and also the starting problem in switched reluctance motors. The control techniques deal with the electronic part of complete drive systems. The torque and current are directly related to each other, so the torque control can be implied by current control methods. This dissertation discusses the new current control technique with efficient bipolar power converter for torque ripple mitigation control. This piece of work also elaborates the new unique strategy of split stator winding for torque ripple reduction. In this thesis motor mathematical model is simulated using new control strategy along with two power converter topologies, conventional asymmetric half bridge converter and proposed symmetric full bridge converter. In addition split stator winding technique is simulated with suggested bipolar drive to show the improvement in ripple reduction. The experimental setup is also included in this thesis, where specific motor is operated using complete drive system. The design and implementation of this drive system is discussed in detail. This drive system is capable to perform both conventional and bipolar operations. At the end, practical results and simulated results are acquired and compared. The effect of excitation and de-excitation angles on torque production is observed and simulated. Torque and current relationship is observed to conclude which drive is suitable for smooth torque operation and have better current control at different speeds. The apparent cost difference is also analyzed and it is found that full bridge drive is more suitable for general purpose solution in industry with bearable increase in cost.
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5۔ تحفظ مال

5۔ تحفظ مال
مقاصد شریعت میں ایک اہم مقصد ما ل کی حفا ظت ہے۔ بنیادی ضرریات کی تکمیل کے لیے روپے پیسے اور مال کا ہونا ضروری ہے اس کے بغیر زندگی گزارنا محال ہے اور اس کا حصول بعض اوقات انسان کو موت اور کفر تک پہنچا دیتا ہے اور باعث فتنہ ہے۔ اسلام انسان کے مال کے تحفظ کے لئے اقدامات کرتا ہے اور ناجائز ذرائع سے مال کا حاصل کرنا حرام قرار دیتا ہے، جیسا کہ ارشاد باری تعالیٰ ہے:
﴿وَلَا تَأْكُلُوا أَمْوَالَكُمْ بَيْنَكُمْ بِالْبَاطِلِ ۔ ﴾253
"اور تم ایک دوسرے کا مال ناحق طریقے سے نہ کھاؤ۔ "
اس آیت کی رو سے اللہ تعالیٰ نے ہر اس طریقے سے مال کمانا حرام قرار دیا ہے جو غیر قانونی ہو اور جس کے ذریعے سے دوسرے کے مال کو ناجائز طریقے سے لینے کی کوشش کی جاتی ہو یہی وجہ ہے کہ اسلام نے مال کے مالک کو یہ ہدایت کی ہے کہ وہ حلال ذریعہ سے کمائے گئے اپنے مال کی حفا ظت کرے ۔
انسان کو دین ، اولاد ، جان اور مال بہت پیارا ہوتا ہے ان کے لیے وہ سر دھڑ کی بازی تک لگا دیتا ہے۔ اسلام نے اپنے مال کی حفاظت کرتے ہوئے مرنے والے فرد کو شہید کہا ہے ۔ عبداللہ بن عمر سے مروی ہے کہ رسول اللہ ﷺ نے ارشاد فرمایا
"مَن قُتِلَ دونَ مالِهِ؛ فهو شَهيدٌ "254
"جو اپنے مال کی حفاظت کرتے ہوئے قتل ہو جائے ، پس وہ شہید ہے۔ "
مالک کو ہدایت کی جا رہی ہے کہ مال کی حفاظت کے سلسلے میں ظاہری اسباب کو اختیار کرے، پھر اللہ تعالیٰ پر توکل کرے اور مال کو دوسروں کے رحم وکرم پر نہ چھوڑے ، جیسا کہ رسول اللہ ﷺ نے ارشاد فرمایا
"اعْقِلْهَا وَتَوَكَلْ ۔"255

آداب الحوار في القرآن الكريم والسنة النبوية صلى الله عليه وسلم

Human beings are innately filled with prejudices and biases. Interaction of these biases and building alternative views involve dexterous efforts. The dialogue approach could be thought of as positive disposition to others which encourages the virtues of neighborliness, friendship and mutual trust and caring. The current paper discusses the importance of dialogue in every field of life, if there is any misunderstanding or controversies among individuals, communities, societies, and religions. Islam has emphasized on the dialogue for resolving the misconceptions. The present study defines dialogue literally and technically by denoting its legitimacy from primary sources of the Islamic Law. The present study mani-fests the differences of several terms relevant to dialogue such as Jidal and Munazarah. It also denotes some illustrations of dialogue from the Holy Qur’an and Ahadith of the Holy Prophet (PBUH).  The main focus of the article is on the ethics of dialogue in the light of Qur’an and Sunnah including the conditions and qualifications of a person, who is capable for dialogue in accordance attributes prescribes by Shari‘ah. The conversation must be in a good environment and usage of the words, phrases, and statements have much more importance in the success of a perfect dialogue. The research concludes that an expert and competent person should be selected for such dialogues and recommends that such scholars should be trained in developing strong communication and debating skills in every situation.

Role of Heads of Teaching Departments in the Promotion of Communication at Postgraduate Level

Communication plays a very important role in the management of an educational institution. It is the soul of an organization. An institution cannot be run without proper communication. The purpose of the study was to investigate the role of heads of teaching departments in the promotion of communication at postgraduate level. The population of the study consisted of all heads and teachers in universities and postgraduate colleges in Khyber Pakhtunkhwa, Pakistan. For this purpose, eight universities and eight postgraduate colleges were randomly selected by the researcher as a sample. The sample consisted of 441 (148 heads and 293 teachers) respondents. A questionnaire consisted of 27 items was utilized for data collection. Mean, t-test, and One-Way ANOVA were used for data analysis. The role of heads of teaching departments was positive in all aspects of communication. Type of institute of the heads did not differentiate the two groups of heads in their opinions about their role in the promotion of communication. Insignificant difference was found between the views of heads of natural and social sciences departments about their role in the promotion of communication. A significant difference was found between heads and teachers’ views regarding the role of heads in the promotion of communication. Insignificant difference was observed between the views of universities and postgraduate colleges’ teachers, teachers from natural and social sciences departments, and between male and female teachers about the role of heads in the promotion of communication. Insignificant difference was found among the views of heads by age, qualification, experience as a chairperson, and total length of service in the present department regarding their role in the promotion of communication. Teachers were not differentiated by qualification, designation, age and experience in their views. It viis concluded that heads of teaching departments play positive role in the promotion of communication at postgraduate level. Demographic characteristics of the heads, i-e, age, qualification, total length of service in the present department, experience as a chairperson, type of institute and nature of department do not affect their role in the promotion of communication. This is also evident from the views of teachers that heads promote communication in their respective institutions. To make heads more effective in the process of communication, a course of communication skills may be arranged for newly inducted as well as for those heads who are already working as heads of teaching departments. For this purpose communication training institute may be established in every university. For the development of language proficiency of the heads and teachers, a language laboratory may be established in every institution of higher education.