Power Electronics: Nightmare for Electrical Engineers
After many Electrical Engineers requesting for a post on Power Electronics, finally we are here with a post on How to tackle Power Electronics for GATE in a most efficient way. This subject is a kind of nightmare for most Electrical Engineers including myself and so i was looking to get you guys an expert who handled this subject exceptionally well.
So, this time we have with us Santhosh Kumar Pabbineedi who appeared for GATE-2014 and secured an AIR-141 and has been guiding young GATE Aspirants ever since. So guys, here is what he has convey to you guys regarding Power Electronics:
Now a days I am able to see a few seniors who got good rank in GATE-14 guiding future aspirants. Most of the people attend coaching in various coaching institutes which a act as a bridge between students and textbooks. As they explain not only the concepts but also the exception cases for every concept with which it is easy to answer a question. This method works in almost all cases, for an example in Power Electronics , in case of rectifier with R-load for any firing angle we never get negative average output. You will not find this direct statement in any text book but it is pretty much used while solving problems. 99% of the people never solve unsolved exercises of any text book which are very important. Now I will explain you how to get good grip on Power Electronics.
First of all be clear with the fact that in power electronics we have to deal with a few concepts only. It has pretty less syllabus as compared to other subjects and has got good weightage. In this study plan I strictly suggest you to own the following text books. PS Bimbhra , Rashid and Power Electronics pdf notes which is available in NPTEL website.
Power Electronic Devices:
For Basic operation of various devices follow Bimbhra as their operating characteristics are well explained in it. I still remember the diode problems one must solve before going to thyristor circuits are there in front pages of Bimbhra & they will explain you how a thyristor will work if it gets a continues gate signal or no gate signal. In a page range 30-70 of Bimbhra you will observe that there were some direct gate questions based on diode.
Phase Controlled Converters:
For rectifiers. Bimbhra is more than sufficient and one must be cautious about Fourier analysis of every rectifier. Understand the difference between ripple-free load and normal load. 90% of questions will be based on ripple-free load and in that case if you have all the formulae on finger tips , you can fetch maximum marks. Coming to battery charging problems in rectifiers go through the NPTEL notes & few problems are also there in text book.
For Choppers. Dont Follow Bimbhra . I will explain you why. In case of problems which need attention towards inductor operation. More than the mere formulas we need basic concepts to answer the question. In GATE-14 first session there was a question on ripple current in some chopper , the formula mentioned in Bimbhra is (Vs/(4fL)) , if you apply this you will get an answer but its wrong. In a article I cannot tell you the reason but it must be solved by using basic kirchoff law , which is well explained in Rashid. In Rashid you will find KVL approach to solve almost all equations which I feel very interesting and straight forward but for Fourier analysis follow Bimbhra.
Inverters and Commutation:
For Inverters and Commutation circuits Bimbhra is good. For Inverters also the Fourier analysis is important. Operation is well explained in that and most of the questions are repetitive in nature in gate. Small concepts like PWM methods might be confusing but at maximum you need 5 hours to get a grip on them. There are various methods to solve a single question in inverters which you’ll know by practising .
Cyclo Converters and AC Voltage Regulators:
Cyclo-Converters & AC voltage regulator are a combination of Rectifers and Inverters and very less questions will be asked in that area.
For those who feel Power Electronics as tough. 10-12 Days of first time preparation and two revisions i suggest you before giving gate. Practice as many as problems. Go for discussions. While solving a problem you may see some option as fitting your calculations and you may be tempted to go for it to save time but please do not do that.
So, guys if you found this post helpful for your GATE preparation please share this with your friends and also comment with your queries.
About the Author:
VSK Santhosh Kumar Pabbineedi passed out in 2012 and obtained AIR-141 in GATE-2014 without any coaching. He studied while working parallel till last November . He was selected for PowerGrid, IOCL, HSL, BARC , HPCL ,NHPC but failed in MDL. He is presently working in PGCIL.