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Lecture – 2 Power Electronics

Lecture – 2 Power Electronics
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Yeah hey in my last class we discussed the necessity for making use of electric vigour very efficaciously however the want for conserving electrical power and in case of induction desktop which is a workhorse of enterprise we discovered the more than a few approaches of saving electrical vigor in case of induction laptop to avoid wasting vigor there needs to be a separate energy processing unit in between the supply and the weight simply by way of connecting the supply instantly to the machine and just isn’t viable to save clicked ignites or it’s only now not viable to operate the computer the place the effectivity is highest so you must or there has to be a separate energy processing unit which system the power and which gives the desired enter to the computer now let us say in the case of DC laptop C DC laptop has an extraordinarily fine manipulate characteristics it is extremely handy to manipulate the torque armature current and subject present are invariably there at quadrature in 90 measure perspective between ia and that i F is at all times 90 degrees hence torque per ampere is highest but then we all know the hazards it requires typical renovation is just not suitable for top-velocity functions and quite a lot of different problems see all these obstacles are addressed in induction computer so induction laptop is an awfully rugged computing device it’s in a position of jogging at very high pace but then anything the talents that we had in see machine it simply no longer there it’s it is very complex to manage or torque control of induction machine is difficult see on this particular urine circuit the rotor present identical rotor present and the magnetizing present the vector sum of these two is a stator present so anything that happens within the rotor circuit will have an impact on the magnetizing present and accordingly the stator current in DC laptop yes the similar the rotor present and the field current they are continuously at 90 levels so we would manage them independently now the question is am i able to design a some type of a controller in which i can get the characteristics similar to that of a DC desktop from an induction computing device so i’ve practically i’ve it will have to everything induction desktop is very rugged all the dangers are of induction DC desktop they are interested or eradicated so here’s a manage scheme together with the vigour processing unit i will be able to get the traits of individually excited DC computer from an induction laptop is it possible we can see whether it is feasible or not by the way thus far i’ve now not told you the definition of energy electronics and the goal of vigour electronics I simply inform you the various avenues where that you may keep electric vigor could also be toes finish of my lecture let’s assume whether or not you’re utilizing power electronics do we deal with all these problems could also be answer could also be very obvious one so we mentioned induction desktop let’s speak about the synchronous motor by and large excessive power computer ok but then it isn’t a self-starting motor so our computer instructor advised us that probably the most ways to begin a synchronous motor is begin like an induction desktop making use of a cage winding and excite the subject when the speed is roughly equal to this synchronous pace or when it can be attains a rated speed shut the or excite the field winding computer will pull into synchronism what is the drawback right here there’s a balance obstacle indispensable if there’s a transient loading if the machine is all of the sudden loaded it should fall out of step in this machine the rotor pace depends upon the deliver frequency syrota a velocity of the synchronous computing device is is consistently equal to the synchronous pace and synchronous velocity is governed by means of the supply frequency so in other words the provide frequency determines the velocity of rotation that in case of a at conventional synchronous motor related to a 3-phase provide so can i tackle the steadiness concern see instead of making the rotor speed depends upon the stator frequency or stator discipline am i able to generate the stator frequency from rotor velocity sale repeat i’m generating the desired state of frequency from the rotor speed so in case it is a sudden transient loading on the rotor on the computer the rotor will decelerate so routinely there must be a discount in the stator frequency so if that happens there is not any stability obstacle at all synchronism is perpetually guaranteed the is it viable to put into effect this scheme what is it mother Aminu endives you see in case you are speakme about power conservation see I take for illustration i have a high vigor machine strolling a running or going for walks a higher shear load excessive inertia load J is very excessive ok now you need to stop the motor to decelerate it and convey it to sizzling so in the event you put up the provide which is a average factor to do what’s going to happen because J could be very significant laptop will take an extended time to decelerate and come to a halt see the equation this is the equation JD Omega by using DT plus B into Omega is the same as t minus T where T is the electromagnetic torque developed TL is a load torque so if I forget about the friction D Omega by way of DT is given with the aid of t minus TL divided by means of J so if I put up the supply might be electromagnetic torque will come zero ok so laptop will decelerate relying upon mechanical time constant the entire vigor that’s stored in the inertia is dissipated as heat proper computing device takes a long time to return to hot you’re speaking about vigor conservation as an alternative of dissipating the vigour saved within the inertia am i able to get well it and feed it again to the supply simultaneously am i able to expand the fee of deceleration correct like you are now not killing two birds in one stone one is recovered the energy which is stored within the inertia of feeded again to the source and expand the price of deceleration see here say diva mega through DT its highest when after I do like this te plus TL / J i have made a T in bad now T bad so if T is constructive for mode response T terrible implies if the producing motion so by means of making T negative i have increased the expense of deceleration now D Omega via DT is e plus TL / J k T is negative it implies that producing motion power is fed again on this supply so is it viable to do that or put into effect this we are going to see you later now coming to the DC power give that’s used in the laboratory the regulated DC energy deliver you realize digital electronics you require zero to 5 phrases in analog electronics perhaps relying upon the biasing voltages for a BJT or or op amp it could be plus or minus Phi or plus or minus – L see here’s a regulated vigour give regulated vigour provide 30 volts dual regulated energy give 30 volts to factor four amperes equal into 2.5 so wattage is approximately one hundred fifty watts ok twin power supply a hundred and fifty words see it’s heavy really heavy and notice there are some instruments or there’s a heat sink and a few transistors are hooked up outside appears like for warmth dissipation have got to they must be getting hot that is why they are hooked up it outside with a large heatsink and quite heavy this is what we’re utilising or you could have utilized in a laboratory regulated DC energy give why it is so heavy see here an additional vigour provide lab which is used in computer systems 200 watts i will carry it safely in my my pump so right why it’s so light 200 watts and the vigour deliver this I confirmed you is a hundred and fifty words and there may be nothing like heatsink outside and in some transistor about some devices outside there is most effective a input AC deliver and these are the outputs why this is so mild and why that is so heavy my mobile is so excessive it is so heavy since there may be what’s referred to as an extraordinarily susceptible element that is a 50 Hertz step-down transformer so it need to the entire regulated energy give that we’re utilizing within the lab has a 50 Hertz regulating transform step-down transformer so can we eliminate this ransomware thereby lowering the dimensions weight vigour give see after I used to be a scholar probably in 90s please the pace of the pc was once 20 megahertz pc eighty it was once presupposed to be a today’s computing device 20 megahertz laptop eighty now the velocity is of the order of set 2.4 gigahertz or so perhaps higher I do not know the pace of the Pentium computer or velocity of the laptop is an multiplied without doubt there are I sees ok in order the clock velocity increases undoubtedly some of them some of the IC which are there must be running at that pace adequate in order the clock pace raises perhaps one of the ices have to switch or alternate a state at that cost there is anything known as the switching losses take place and these losses they expand with frequency the switching now a method I used to lessen the switching let it slash the clock frequency which isn’t feasible every person desire a very speedy laptop but then I have got to redo this losses how do I scale down the losses an extra way to cut back the pace is to reduce the biasing voltage itself considering when the output is excessive the output of the TTL is also VCC and it’s if the output is low it becomes zero so can i cut back a biasing voltage itself see I used to be told that two years down the road the biasing voltage we will come right down to as little as 0.9 volts zero.9 volts so two years down the road the energy provide requirement is zero.9 volts 100 amperes DC energy supply zero.9 volts hundred amperes DC vigor supply can we design this power supply using a step-down transformer and what now not is it viable or can we need to use alt with one more amount we are going to see now coming to vigor programs see here’s a single line diagram a protracted transmission line i’ve now not shown the parameters good enough transmission line parameters here is a sending end voltage vs is the sending end voltage link the transmission line could be very excessive say i will do not forget as an extended transmission line which you could have studied in a power procedure path and right here is the receiving finish voltage VR is a receiving finish voltage it’s anticipated that what is required that VR stays regular k Mia stays steady approximately one per unit it remains constant it’s desired however then we find that voltage on the receiving end normally Falls with load and this VR magnitude of VR is much much less compared to V s because the lagging watt demand raises in different words if the vigour component turns into very poor lagging vigor aspect okay lagging energy element a big inductive load is being linked here okay you’ll find that the change between V s and V R is excessive in other words if I maintain vias constant we are drops okay so if the lagging warfare demand increases or in other phrases because the vigour element attitude raises that implies lagging energy element angle raises this magnitude of V are false now how do i make stronger the voltage profile at the receiving result in different words how do I maintain we are at one per unit or how am i able to preserve that we are a steady worth I advised that one of the most factors we needed to fall is the reactive vigor demand has elevated the transmission line is feeding a tremendous reactive load so one of the most approaches to support the vigour element which our circus thought we learnt is that to attach a capacitor on the receiving result in different words you connector a capacitor here so this capacitor will provide the desired lagging used to be to the weight so thus the supply will recognize the transmission line or this current is handiest a unity vigour aspect present this is a unity vigor aspect present the complete the reactive demand is being met with the aid of the capacitor now i have connected a capacitor to supply the reactive power demand of the weight voltage at this point is falling okay so as this voltage Falls the was once furnished by means of the capacitor also Falls C in view that it’s given by way of this Q is we r squared divided via XC i have linked C at the receiving finish and Q is we r squared divided through X C so as we’re false Q also Falls what is required for the transmission line as Q are false sorry as we’re false Q must expand say L repeat for the transmission line as we’re false or the voltage at the receiving finish Falls Q will have to increase handiest then it’s tried it will attempt to keep the voltage on the required value however here i’ve linked a capacitor and we determined that as this voltage of the recipient Falls the two furnished through the capacitor also Falls so some sort of unreliable buddy when you wish to have that acquaintances help isn’t there same thing is going down here the capacitor is supposed to deliver higher Q at as we are false but then as we’re first the capacitor conflict additionally Falls a unreliable pal what’s the second thing you need to fear the capacitor capacitance in order to differ Q and a tender variation in C just isn’t viable a smooth variant in C shouldn’t be viable it’s going to be in steps so the question is will we design a circuit which presents each plus or minus Q was once lagging words as good as main Wars and it is impartial of we are voltage at the receiving it i’ll repeat canny or is it viable to design a circuit in which it will have to be possible to supply plus or minus Q very easily smooth variant of Q and it will have to be independent of the voltage of the receiving end voltage apparent is it feasible there may be a question that i am asking we will see some time later the reply to this question the 2nd kiss in pasteurization see take into account again in a transmission line i’m just representing a transmission line via the reactance excess some reactors are referred to as it as exist so voltage at this point i have maintained at v1 and voltage at this factor is v2 i’m taking v1 because the reference and perspective between V 1 and V 2 is Delta so what is the vigor transmitted by way of this transmission line it’s V 1 into V 2 divided by way of extra into sine Delta that is the expression that derive spare v1 and v2 are the voltages correct two ends of the transmission line extra is the interconnecting reactance and Delta is the section attitude difference between v1 and v2 okay now we count on that V 1 and V 2 are 1 per unit now how did I consume you to get v2 is equal to 1 per unit we will be able to see later good enough now expect V 1 and V 2 is the same as 1 per unit so get P is the same as sine Delta divided by way of exes adequate and again so see right here is the profile P versus Delta and we are informed two from this equation we can to find that version is feasible theoretical variant theoretical restrict is Delta is ninety degrees Delta is 90 levels there the theoretical worth may be in precise observe this Delta would be of the order of say 30 to 40 degrees in genuine follow Delta perspective between the 2 ends is of the order of 30 to forty levels ninety levels is simply on the blackboard or on the notebooks let self now the question is is it viable to broaden P vigour transmitter to the line securely securely am i able to broaden the vigor transmission energy that’s transmitted to the line securely take for this example the equal thing equal thing say v1 at one finish of the transmission line v2 at other finish of the transmission line Delta is perspective between V 1 and V 2 and on the midpoint and at the midpoint someway i’m retaining a voltage VM which is one per unit ok see somewhere at this factor via presenting only the reactive vigor i am just connecting a reactive element right here i am just connecting a reactive detail here okay and making the voltage at this factor on the midpoint of the transmission line is one per unit okay so there’s no lively vigor switch to the gadget right here it can be just the reactive vigor switch right here i am just presenting Q at this factor at the middle factor same voltage at this factor is one per unit now i can find that attitude between V 1 and V M is Delta by 2 Delta by using 2 with the aid of symmetry so now what is the power transmitted via this line the equal power will will go by way of to this factor it is V 1 into V M divided by way of the reactance between it is X via 2 into sine Delta with the aid of 2 now so that is the expression now i will plot within the previous case theoretical restrict is 90 degrees theoretical now we just see even Delta is the same as PI it’s on the top theoretical restrict again so it is feasible to transmit better power by way of the existing transmission line with the aid of providing some type of a reactive energy aid on the midpoint of the transmission line okay now what exactly is its unit or what’s to be or what’s the function of vigor electronics to acquire this again we can see later once more a 3rd application once more in power systems so we have now a long transmission line probably vigor that is produced within the rural areas a remote finish and bulk is consumed within the city areas so you require a particularly lengthy transmission line and the second that an extended-time period vision line there are various problems steadiness predicament voltage drop k now can you handle this trouble see alternatively of transferring the power that is some thing that’s generated instantly to the receiving middle or to the city place do we convert the AC power to DC converter AC vigor to DC transmitted transmit this DC vigour and again at the receiving station you invert to AC considering the fact that vigor that is utilized practically all of the masses they require AC k power that’s generated additionally could also be AC but then if I transmit the AC vigour then the concern balance hindrance voltage situation so what i’ll do is this AC power we converted to DC how again i am now not answering that question no no i am telling you ways exactly to do that correct now now there are best two words constructive’ bus DC bus and a negative DC bus in AC we had three transmission three traces now there is simplest the resistance of the conductor a good way to come into image and this DC i will convert it again to AC okay and in this case let me inform you one thing there is not any stability quandary in any respect there aren’t any balance issues so this scheme is often called high voltage DC transmission excessive voltage this iteration so the question is can the bulk power be transmitted through changing it to DC yeah a lipid will we transfer bulk vigor via converting it to DC reply later now that’s about power that is being consumed through motors and we mentioned the various disorders in energy transmission the 1/3 point or the lighting I mentioned bulk is worried by way of motors and 2nd is by lighting fixtures we all know that lumen per watt for an incandescent bulb it’s much cut down in comparison with that of a fluorescent lamp lumen per watt for a bulb may be very less compared to females for what ground fluorescent lamp or for a tube gentle motor so what is the hindrance in the fluorescent lamp Oh bulb we just require a holder and a wire what do you require here we require a ballast somebody’s gonna say choke a starter why do you need a ballast or choke is since that the lamp has a terrible characteristics once the arc has been struck so i’m not going to element of the working of the fluorescent lamp i am simply telling you that the lamp has a terrible characteristics poor impedance traits negative resistance traits as soon as the Arkansas it operates at 50 Hertz it requires a a choke or a ballast consistently a magnetics that’s used at 50 Hertz they create objectionable noise ok it is aggravating on account that it’s within the audio variety they’re lossy and total vigour element is again negative what is an additional outcome there’s anything known as a stroboscopic influence seeing that lamp is being turned off and ignited at each 100 2nd data each zero crossing that’s some thing known as a stroboscopic influence so this would be objectionable or it would be damaging in the save ground due to the fact say assume that there’s a blade which is rotating at the equal pace and if the both the frequencies suit now what is going to happen the rotating blade will show up as if it is stationary so it would be hazardous except it is ready ting but it surely appears to be stationary that’s known as so it might be smooth harmful so what’s observed is the lumen output of the lamp raises if the frequency of operation is increased as the frequency of operation raises or if the lamp is of the lamp is operated at a better frequency lumen output also increases now the frequency of operation is excessive the dimensions of the magnetics or storage elements additionally comes down in order the frequency of operation increases the scale of L and required or maybe C or Tony fedele’s required all come down and everyone knows that if if the frequency is ready 20 kilo Hertz 20 kilo Hertz it’s within the above of the audible variety you cannot hear the noise produced okay so appears like there are benefits via running the lamp at a frequency bigger than say at 20 kilos or so ok so one is it is the audible range above the audible variety you cannot hear that noise lumen output can also be extended dimension of the magnetics has come down also it’s feasible to beef up the source aspect vigour aspect so right here i’ll simply show you the plot of plot of lumen this can be a diamond output versus the frequency this frequency in kilohertz please no longer Hertz we have best 50 Hertz deliver i have plotted for kilo Hertz see might be one hundred at an awfully low frequency of fifty Hertz 50 Hertz it might be round a hundred it attends a peek around said 20 kilo Hertz or so so again now we have a 50 Hertz supply and here I ought to operate at 20 kilo Hertz i want somewhere I need a frequency converter ok that’s about lighting so thus far we mentioned concerning the problems or even yours we’re in to save lots of vigour or to transmit extra power or to enhance the power transmission potential if we must have a separate equipment ok now allow us to see energy from the alternate sources considering with the intention to so as to lengthen the whatever the lifestyles interval that I had told you was the so-referred to as 200 years I need to use a method to use it very effectively in other ways to appear for different alternative sources yes see here’s a overall image okay the vigor from non-conventional sources or the renewables see in the event you return to the ancient power sources our ancestors forefathers they use a quite simple technological know-how there is a very simple science utilising wind power wood k and that i drew a quite simple science they used to supply energy slowly slowly we change into to today’s power sources we used oil coal and nuclear okay just now I instructed you that so this vigor stations are normally located at far off finish in order that has to be transferred to the weight centers in general on the urban locations the long run trend is going to be what’s known as the allotted vigour iteration in the experience if there is a demand you mounted a small vigor plant there itself as an alternative of generating the energy maybe round three to 4 hundred kilometres we are transmitting it so if you wish to have if there’s a small load center you mounted a small plant k utilizing renewables and take a look at to feed the nearby field what is known as the disbursed vigor iteration ok that’s going to be the future ok so once more the longer term is going to be using renewable sources like sun wind energy biomass hydro so it appears like Venus completed it is one fallacious see we are we were here our forefathers did this additionally they used wind vigour hydro the future is also it can be been projected and which is little bit authentic there’s going to be sun wind vigour with the aid of a mass and hydro future and this historical appears like one complete circle or the wheel has completed its circle ok now however then what are the disorders here exceptional within the experience solar and wind they considered to be very easy good enough however we all know that Solon is bit luxurious sunlight is costly however the similar lining is rate is falling it is decreases fee per unit is lowering adequate and another hindrance it solar is output is DC is a DC vigour output and most of the masses except for incandescent bulb might be all require is how about wind supposed to be very the most affordable environmentally smooth see it is projected that see here this what is Oprah put in the literature wind vigour now provides more than 31 thousand megawatt of vigour world wide that is reported within the literature and in India the mounted capability is nineteen hundred megawatts set up capability is nineteen hundred megawatts in India is nothing new toward them and our target is to hu six thousand megawatts by way of 2012 and it’s also estimated that wind might provide twelve percent of the sector’s electricity demand by two zero two zero it could give worse 12 percentage demand by using 2 zero t0 just the projection is any projector nothing what’s the hindrance right here sunlight is DC anything most likely you have got to have an additional power processing gear wind we all know that what one is it is highly unreliable okay see that is the difficulty with the non-conventional sources sun unreliable on the cloudy day there would be no vigor at all wind again it’s seasonal find it even if it’s seasonal what are the problems there as the wind velocity changes okay there’s a turbine the the speed at which the turbine is rotating the rotor of a computer additionally changes k see the block diagram right here so this can be a variable velocity so thus the magnitude of the voltage as good as the frequency is a operate of the wind speed k it can be like you realize conductor is rotating a magnetic field voltage brought about in the conductor is proportional to the pace of rotation or the relative pace and second is the frequency also will depend on so at this point we have now a variable frequency AC supply grid requires a consistent voltage and steady frequency supply ok you are not able to have a grid where the frequency and voltage varies over a vast range however here’s a wind the pace is varying over a huge range so absolutely there needs to be a some sort of a vigor processing unit okay what is that this vigour processing in it we will be able to see some time later see there are there are instantly grid linked grid related induction mills are there but then in this day and age so called the fixed speed the moment I join an induction generator straight to the grid the pace the frequency stator frequency depends upon the grid so rotor pace also is fixed now it will have to be greater than larger than the synchronous speed however then now in this day and age the variable pace wind generators variable velocity wind generators with everlasting magnet machines are gaining status they’re emerge as increasingly fashionable variable velocity wind turbine see right here variable pace wind turbine variable pace wind generators with permanent magnet machines they’re gaining popularity increasingly end up trendy so what’s the obstacle right here again I advised you this now output frequency and the voltage is a perform of pace magnitude is a operate of speed ok this requires steady frequency consistent voltage so that you require a vigour processing event k what is that energy processing unit last one city air pollution ok will also be lowered through the popular use of electric automobiles rather of getting a autos which are operated in gasoline you’ve electrical vehicles or say hybrid electrical autos so if you happen to use electric autos or hybrid electrical vehicles there is going to be a giant reduction in the city air pollution you understand everyone knows that gasoline based autos are effective at a certain pace so what is Reyes operate the IC engine at that precise pace and other speeds water driving the wheels so thereby that you could cut down the pollution as well as store the fuel so that’s about the quite a lot of avenues the place it that you could both keep vigor or try to make a difference in making improvements to the exceptional of lifestyles there are various extra still left now earlier than discussing these problems I provides you with the definition and purpose of energy electronics say right here is that the power electronics is the science related to effective conversion and control of electric vigor via vigor semiconductor instruments see L repeat is the vigour electronics is the technological know-how related to effective conversion and control of electrical energy by way of energy semiconductor instruments and what’s the intention of energy electronics it’s to control the waft of vigor from electrical source to electrical load see here is a block down there’s a source here is the burden interfacing is completed by means of a vigor digital equipment k so relying upon the character of the source and the character of the Lord this apparatus or the configuration additionally alterations why is this vigour electronics so trendy why is being when put next with computer systems I stated two applied sciences will dominate one is desktops an additional one is energy electronics white is being stated that power electronics is an enabling science for disbursed vigor generation I told you it the the longer term goes to be allotted energy iteration and vigour electronics is the enabling technological know-how for dispensed vigour iteration white is being stated that boy electronics presents the lifeblood for communication equipments electronic programs and computers or in different phrases why that is so popular see the success of any technological know-how it is dependent upon the following it must be tremendously effective this 2nd is it should be risk-free 1/3 the dimensions weight and rate should be low see maybe it is amount to booing against the regulation of nature since it might not be viable to hindrance all these motives like high efficiency high reliability k dimension weight and cost low now they’re very tricky to gain all these reasons let’s see which of the explanations that may be issued take for instance what occurs if the efficiency is excessive so if the effectivity is high it implies that there’s low power loss so if there is low vigour loss cooling requirement or the warmth sink requirement comes down now the energy loss is low temperature upward push can also be low so i will be able to package the more than a few elements very densely in other words packaging density will also be expanded if the packaging density increases measurement comes down okay so if i attempt to obtain high efficiency okay i will be able to limitation other parameters additionally appears just like the effectivity of this power give unit have got to be very low that’s the cause it is so heavy and it’s being there may be a big warmness sink and add-ons are being established outside is heavy whereas the efficiency of this have to be excessive that is why it has end up so small compact and so light okay so how this energy electronics achieves this we will see it within the subsequent class thank you