HIGH VOLTAGE DC FROM SINGLE PHASE AC USING CAPACITORS AND DIODES B.Tech Mini/Main Project Report Submitted by Name of Students Roll No ATHIRA DAS JYANEEE012 MILNER PAUL JYANEEE035 SMRUTHI KRISHNA K. JYANEEE048 STEPHY AKKARA JYANEEE050 TONY J. VADAKKAN JYANEEE052 in partial fulfillment of the requirement for the award of Bachelor of Technology Degree in Electrical and Electronics Engineering under the University of Calicut. Department of Electrical and Electronics Engineering J YOTHI E NGINEERING C OLLEGE ,C HERUTHURUTHY Vettikattiri P. O., Thrissur - 679531 (Approved by AICTE, Affiliated to the University of Calicut, An ISO 9001:2008 Certified Institution) March 2016
Transcript
HIGH VOLTAGE DC FROM SINGLE PHASE AC
USING CAPACITORS AND DIODES
B.Tech Mini/Main Project Report
Submitted by
Name of Students Roll No
ATHIRA DAS JYANEEE012MILNER PAUL JYANEEE035SMRUTHI KRISHNA K. JYANEEE048STEPHY AKKARA JYANEEE050TONY J. VADAKKAN JYANEEE052
in partial fulfillment of the requirement for the award ofBachelor of Technology Degree in Electrical and Electronics Engineering
under the University of Calicut.
Department of Electrical and Electronics EngineeringJYOTHI ENGINEERING COLLEGE, CHERUTHURUTHY
Vettikattiri P. O., Thrissur - 679531(Approved by AICTE, Affiliated to the University of Calicut,
An ISO 9001:2008 Certified Institution)
March 2016
JYOTHI ENGINEERING COLLEGE,CHERUTHURUTHY
Department of Electrical & Electronics Engineering
CertificateThis is to certify that the Project Work entitled
“HIGH VOLTAGE DC FROM SINGLE PHASE ACUSING CAPACITORS AND DIODES”
of Sixth/Eighth Semester B-Tech Electrical and Electronics Engineering in partial
fulfillment of the requirement for the award of Degree of Bachelor of Technology in
Electrical an Electronics Engineering under the University of Calicut.
Project Coordinator Project Guide Head of the Department
Saritha P Akhil A. Balakrishnan Ratnan PAsst. Professor Asst. Professor Professor
High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
ACKNOWLEDGEMENT
We take this opportunity to thank everyone who helped us profusely, for the successfulcompletion of our project work. With prayers, we thank God Almighty for His grace andblessings, for without his unseen guidance, this project would have remained only in ourdreams.
We thank our principal Dr. K. K. Babu and our head of the department Mr. Ratnan Pfor their valuable advice and encouragement to carry out this project.
We would like to sincerely thank our guide Saritha P for his guidance and invaluablehelp during the entire project and also correcting our mistakes during our work.
We thank our mini project co-ordinator Ms. Saritha P for her constant encouragementduring the project. We also give our sincere gratitude to all our lab assistants for their extremehelp.
Finally, we take this opportunity to thank all our teachers, friends and all who helped usdirectly or indirectly in successfully completing this project work.
ATHIRA DAS (JYANEEE012)
MILNER PAUL (JYANEEE035)
SMRUTHI KRISHNA K. (JYANEEE048)
STEPHY AKKARA (JYANEEE050)
TONY J. VADAKKAN (JYANEEE052)
Jyothi Engineering College, Cheruthuruthy i Dept . of EEE
High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
CHAPTER 1
INTRODUCTION
1.1 OverviewThe project is to designed and to develop a high voltage DC from a supply source of
230volt AC by using capacitors and diodes. The capacitors and diodes are connected asa ladder network based on the voltage multiplier circuit. Voltage multipliers are primarilyused to develop high voltages where low current. This project describes the concept todevelop high voltage DC from a single phase AC. For safety reasons our project restrictsthe multiplication factor to 8 stages such that the output would be within 1000volt.Voltagemultipliers are AC-to-DC power conversion devices, comprised of diodes and capacitors thatproduce a high potential DC voltage from a lower voltage AC source.
Multipliers are made up of multiple stages. Each stage is comprised of one diode andone capacitor. The most commonly used multiplier circuit is the half-wave series multiplier.All multiplier circuits can be derived from its basic operating principles. Thus, the half-wave series multiplier circuit is exemplify in general multiplier operation. There were nolosses and represents sequential reversals of transformer (TS) polarity. Originally used fortelevision CRT’s, voltage multipliers are now used for lasers, x-ray systems, traveling wavetubes (TWT’s), photomultiplier tubes, ion pumps, electrostatic systems, copy machines, andmany other applications that utilize high voltage DC.
This project describes the design and implementations from a single phase ac to highvoltage DC power supply till 10kV output. The implementation of the hardware work tobuild a high voltage DC power supply is meant for use in the laboratory. The designed DCpower supply can be used in industrial applications also. The design of the circuit involvesvoltage doubler, whose principle is to double the output voltage. The output from the voltagedoubler is given to a series of cascaded circuit that generates up to 10KV but for the studentproject it is advisable to go up to 1KV for safety reasons.
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
1.2 Objective of the projectTo design and set up a high voltage DC from single phase AC using diodes and capacitors.
1.3 Organization of the reportThis report has been broadly divided into 5 chapters. The first one being the introduction,
chapter 2 is on literature survey. Chapter 3 deals with the system description and working.Hardware implementations are listed in chapter 4.Chapter 5 deals with the result, conclusionand future scope.
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CHAPTER 2
LITERATURE SURVEY
2.1 Study of existing systemFirstly, search a literature review to collect more information about this project. The
literature review will take journal, report, internet and books as it reference. To design ahigh voltage DC from a single phase AC using Voltage Multiplier circuit, the theory and allapplication about CW Voltage Multiplier circuit has been studies and understanding. Makea research about circuit theory and the characteristic of each component to redesign theCW circuit. Later, some literature review will used to compare this project with previousexperiment and related project for this title.
The buck–boost converter is a type of DC to DC converter that has an output voltagemagnitude that is either greater than or less than the input voltage magnitude. It is equivalentto a fly-back using a single inductor instead of a transformer.
Two different topologies are called buck–boost converter. Both of them can produce arange of output voltages, from an output voltage much larger (in absolute magnitude) than theinput voltage, down to almost zero. Like the buck and boost converters, the operation of thebuck-boost is best understood in terms of the inductor’s ”reluctance” to allow rapid change incurrent. From the initial state in which nothing is charged and the switch is open, the currentthrough the inductor is zero. When the switch is first closed, the blocking diode preventscurrent from flowing into the right hand side of the circuit, so it must all flow through theinductor. However, since the inductor doesn’t like rapid current change, it will initially keepthe current low by dropping most of the voltage provided by the source.
Over time, the inductor will allow the current to slowly increase by decreasing its voltagedrop. The output voltage is of the opposite polarity than the input. This is a switch with asimilar circuit topology to the boost converter and the buck converter .The output voltage isadjustable based on the duty cycle of the switching transistor. One possible drawback of thisconverter is that the switch does not have a terminal at ground; this complicates the drivingcircuitry. Neither drawback is of any consequence if the power supply is isolated from theload circuit (if, for example, the supply is a battery) because the supply and diode polaritycan simply be reversed. The switch can be on either the ground side or the supply side.
A buck (step-down) converter combined with a buck (step-down) converter.The output voltage is typically of the same polarity of the input, and can be lower or
higher than the input. Also during this time, the inductor will store energy in the form of amagnetic field.
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2.2 Review of research work doneConventional cell equalizers derived from dc-dc converters consist of numerous switches,
sensors, or transformers; thus, their cost and circuit complexity are high. In this paper,Cockcroft-Walton charge equalizers consisting only of capacitors, diodes, and an ac powersource are presented. In addition, a novel charge equalizer that outperforms the Cockcroft-Walton charge equalizers is proposed. The operating principle and derivation of an equiv-alent circuit are explained. Experimental charge tests were performed on series-connectedsuper capacitors to demonstrate its charge performance.
Here we propose a high step-up dc-dc converter based on voltage multiplier withoutstep-up transformer. Providing high step-up rate, the proposed converter is quite suitablefor applying to low-input level dc generation systems. The proposed converter improves theimpractical operation of the conventional boost dc-dc converter at high duty ratio due to non-ideal characteristics of the circuit components, such as the equivalent series resistance of theinductor. For easy design, a commercial average-current-control continuous conduction. Amodified switching function, which is built in CPLD, controls the switches to generate analternating source to the CW voltage multiplier. Under CCM operation, the output voltageripple of the proposed converter can be limited by the flexibly adjustable frequency. A 200Wlaboratory prototype is built for test and the experimental results demonstrate the validityof the proposed converter. Cascade rectifiers for static and dynamic conditions, based ondigital simulations, are presented. Steady-state and transient currents and voltages on anycomponent can be calculated through simulation.
The influence of the voltage source impedance (generally inductive), in the overall per-formance, is shown to be very important. Description of the small-signal dynamics of thevoltage multiplier is obtained through state-space modelling in discrete time. Its small-signalequivalent circuit is a two-port linear network whose four transfer functions are expressed inthe z-transform domain. General formulae for the multiplier with an arbitrary number of cellsare derived; expressions for prime parameters such as the cut-off frequency, gain, and outputresistance are given, and frequency dependences of module and phases. A transformer-lesshigh-performance step-up DC-DC converter based on the voltage multiplier is presented.The proposed converter is suitable for low-input DC generation systems application.
A low input DC voltage is boosted up in the DC-DC converter and then inverted throughthe proposed circuit. An n-stage CW voltage multiplier then converts the obtained AC volt-age to a high DC output voltage. In some of the multiplier circuits discussed are commonlyused in power ICs to allow the switching-on of an MOS device. The models take parasiticcapacitance and current leakage into account. Power supply designed and built at LBL hasbeen tested to 900 kV at the Super HILAC.
Operating at 80 kHz, the power supply features low ripple, moderate stored energy, 10 ma
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
average current, and no bouncer requirement for pulsed loads. Other system features include:inexpensive generating voltmeters and a capacitive pick off for monitoring and regulation inlieu of costly resistance dividers, ”home-made” semiconductor rectifier modules, excellentcomponent protection against sparking, and easy maintenance. This report describes design,construction, and testing of the high voltage system.
2.3 Motivation behind the workRequirement of high voltage is increased day by day as the demand of power is increases.
As more need of high voltages in various applications, because the demand of power forincreasing consumers is increased day by day. As in modern times high voltages are used forwide variety of application covering the power systems, industry and research laboratories.Such applications have becomes essential to sustain modern civilization. High voltages arenecessary for power systems, industries, research laboratories and power transmissions .Thismethod eliminates the requirement for the heavy core and bulk of insulation.
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CHAPTER 3
SYSTEM DESCRIPTION AND WORKING
3.1 Block diagramThe operation of this project for generation f high voltage .We can generate the high
voltage DC up to 1kv by using single phase AC supply. The functional block diagram ofthis project is shown below. It consists of rectifier circuit which converts ac supply into dc,amplifier circuit these amplifies the converted dc power. The voltage multiplier circuit madeof ladder network of diode and capacitors circuit that converts AC electrical power from alow voltage level to a higher DC voltage level and potential divider with 10:1.when 230voltac is supplied to rectifier.
Figure 3.1: Block diagram
Rectifier is converting ac to dc. This amplified voltage is given to the voltage multipliercircuit, these voltage multipliers steps up relatively low voltage into extremely high voltagevalues. Because of such circuit is that the voltage across each stages of cascade is equal totwice the peak input v.(i.e. V max=2*v max).
The high voltage is generates at output of multiplier circuit is very high. So it doesnot measure by simple voltmeter .Thus, by using 10:1 potential divider output voltage ismeasure.
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
3.2 PrototypeThis is the operational block diagram .Here in this project we are designed to develop
the prototype of the same. In the prototype model consists of a transformer 230/12vollt,diode (IN4007) and capacitor (1000uF/63volt). For safety reasons our project restricts themultiplication factor to 8 stages such that the output would be within 1000 volt.
Figure 3.2: Prototype diagram
3.3 Circuit diagramThis voltage multiplier that converts AC or pulsating DC electrical power from a low
voltage level to a higher DC voltage level. It is made up of a voltage multiplier laddernetwork of capacitors and diodes to generate high voltages. Unlike transformers, this methodeliminates the requirement of the heavy core and the bulk of insulation required. Using onlycapacitors and diodes in cascading network these voltage multipliers can step up relativelylow voltages to extremely higher values, while at the same time being far lighter and cheaperthan transformers.
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
And ID1, ID2, ID3......Idn=diode Current.The advantage of the circuit are low in cost, small in size, and be easy to insulate the
circuit. Another advantage of voltage multiplier circuit is its peak to peak voltage at eachstage will be double.
3.4 Working
1.Ts=Negative Peak: C1 charges through D1 to Epk
2.Ts=Positive Peak: Epk of Ts adds arithmetically to existing potentialC1, thus C2 charges to 2Epk through D2
3.Ts=Negative Peak: C3 is charged to 2Epk through D3
4.Ts=Positive Peak: C4 is charged to 2Epk through D4 then Epk(N)where N = number of stages.
This project uses voltage multiplier circuit in multistage using a no of silicon diodes
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
(D1-D8) and a set of electrolytic capacitors of 1000uF/63V connected. Thus 8 capacitorof 1000uF/63V are used for 8 stage voltage multiplication. Thus if the input is 12v rms theoutput will be approximately = [ (sqrt (2)) x input voltage x number of stages output voltage].
Capacitors discharge the voltage exponentially after use. Practically we are giving an in-put of 13.75V.It is because the input voltage vary from the exact input voltage of transformer(12volt) is due to the changes in the Primary and secondary winding in coil turns.
ThusInput voltage to the multiplier circuit or output voltage of the transformer=13.75voltsNo: of stages =8stages
The output obtained: V out= (sqrt (2)) x 13.75 x 8 = 155.8Volts.
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
CHAPTER 4
COMPONENTS
4.1 Transformer
Figure 4.1: Transformer
The transformer that used in the project is centrifugal transformer. It has the input voltagecapability of 230volt.The maximum current that draws by the transformer is 500mA.Thisis a step down transformer. The three terminals of the transformer are (6-0-6).The outputvoltage of the transformer is 12volts. There are many sizes, shapes and configurations oftransformers from tiny to gigantic like those used in power transmission. Some come withstubbed out wires, others with screw or spade terminals, some made for mounting in PCboards, others for being screwed or bolted down.
Transformers are composed of a laminated iron core with one or more windings of wire.They are called transformers because they transform voltage and current from one level toanother. An alternating current flowing through one coil of wire, the primary, induces avoltage in one or more other coils of wire, the secondary coils. It is the changing voltage ofAC current that induces voltage in the other coils through the changing magnetic field. DCvoltage such as from a battery or DC power supply will not work in a transformer. Only ACmakes a transformer work. The magnetic field flows through the iron core. The faster thevoltage changes, the higher the frequency.
The lower the frequency, the more iron is required in the core for the efficient transfer ofpower. In the USA, the line frequency is 60 Hertz with a nominal voltage of 110 volts. Other
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
countries use 50 Hertz, 220 volts. Transformers made for 50 Hertz must be a little heavierthan ones made for 60 Hertz because they must have more iron in the core. Line voltage canvary a little and usually runs between 110 volts and 120 volts or between 220 and 240 voltsdepending on country or power connections. A house in the USA has 220 volts coming inbut is split to two legs of 110V by grounding the center tap (see configuration section below).
The ratio of input voltage to output voltage is equal to the ratio of turns of wire aroundthe core on the input side to the output side. A coil of wire on the input side is called theprimary and on the output side is called the secondary. There can be multiple primary andsecondary coils. The current ratio is opposite the voltage ratio. When the output voltage islower than the input voltage, the output current will be higher than the input current. If thereare 10 times the numbers of turns of wire on the primary than the secondary and you put 120volts on the primary, you will get 12 volts out on the secondary. If you pull 2 amps out fromthe secondary, you will only be using 0.2 amps or 200 milliamps going into the primary.
Transformers can be built so they have the same number of windings on primary andsecondary or different numbers of windings on each. If they are the same, the input andoutput voltage are the same and the transformer is just used for isolation so there is no directelectrical connection (they are only linked through the common magnetic field). If there aremore windings on the primary side than the secondary side, then it is a step down transformer.If there are more windings on the secondary side, then it is a step up transformer.
A transformer can actually be used in reverse and will work fine. For example, if youhave a step up transformer built for transforming 120 volts to 240 volts, you can also use itfor a step down transformer by putting 240 volts into the secondary side and you will get 120volts on the primary side. Effectively, the secondary becomes the primary and vice versa.
4.2 CapacitorsA basic capacitor has two parallel plates separated by an insulating material. A capacitor
stores an electrical charge between the two plates. The unit of capacitance is Farads (F).Ithas 1000uF/63volt.Withstand temperature up to 105 degree C
Figure 4.2: Capacitors
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4.2.1 Working principle of capacitor“A capacitor works by storing energy electro statically in an electric field”. A capacitor
works like a tiny rechargeable battery with extremely very low capacity. The time it takesto discharge a capacitor is usually only a split second. And so is the time to recharge it. Acapacitor is made up of two metallic plates. With a dielectric material in between the plates.When you apply a voltage over the two plates, an electric field is created. Positive chargewill collect on one plate and negative charge on the other. And this is what the physicistsmean when they say that “a capacitor works by storing energy electro statically in an electricfield”. And this is what the physicists mean when they say that “a capacitor works by storingenergy electro statically in an electric field”.
Figure 4.3: Working scheme of capacitor
Electrons on the left plate are attracted toward the positive terminal of the voltage source.This leaves an excess of positively charged holes. The electrons are pushed toward the rightplate. Excess electrons leave a negative charge.
4.2.2 Selection of capacitorsThe size of capacitors used in multiplier circuit is directly proportional to the frequency
of input signal. Capacitors used in off line, 50Hz applications; say 10 kHz are typicallythe range of 0.02 to 0.06 microfarad. The voltage rating of capacitor must be capable ofnumbers of staged used. A good thumb rule is to select capacitor whose voltage rating isapproximately twice that of actual peak applied voltage. For example a capacitor which willsee a peak voltage of 2E should have a voltage rating of approximately 4E.
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4.3 DiodesThe diode used in the project is IN4007.It is used in order to withstand the reverse volt-
age.High surge current capability. Low for voltage forward drop .It is the simplest semiconductor device. It is a Non linear one. Mostly used in power supplies. It is also work asvvoltage limiting circuits. A rectifier diode is used as a one-way check valve. Since thesediodes only allow electrical current to flow in one direction, they are used to convert ACpower into DC power. When constructing a rectifier, it is important to choose the correctdiode for the job; otherwise the circuit may become damaged. Luckily, a 1N4007 diode iselectrically compatible with other rectifier diodes, and can be used as a replacement for anydiode in the 1N4007 family.
Figure 4.4: Diode
4.3.1 Diode selection
4.3.1.1 Reverse breakdown voltage
A diode allows electrical current to flow in one direction from the anode to the cathode.Therefore, the voltage at the anode must be higher than at the cathode for a diode to conductelectrical current. In theory, when the voltage at the cathode is greater than the anode voltage,the diode will not conduct electrical current. In practice, however the diode conducts a smallcurrent under these circumstances. If the voltage differential becomes great enough, thecurrent across the diode will increase and the diode will break down. Some diodes such asthe 1N4007 will break down at 50 volts or less. The 1N4007, however, can sustain a peakrepetitive reverse voltage of 1000 volts.
4.3.1.2 Foward current
When the voltage at the anode is higher than the cathode voltage, the diode is said to be”forward-biased,” since the electrical current is ”moving forward.” The maximum amount ofcurrent that the diode can consistently conduct in a forward-biased state is 1 ampere. Themaximum that the diode can conduct at once is 30 amperes. However; if the diode is required
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to conduct that much current at once, the diode will fail in approximately 8.3 milliseconds.
4.3.1.3 Forward voltage and power dissipation
When the maximum allowable consistent current amount is flowing through the diode,the voltage differential between the anode and the cathode is 1.1 volts. Under these condi-tions, a 1N4007 diode will dissipate 3 watts of power (about half of which is waste heat).
4.4 Components required
Table 4.1: Components
Sl. No. Components Specifications Quantity1 Transformer 230/12 volt 12 Capacitors 1000uF/63 volt 83 Diodes IN4007 84 Common PCB - -5 Connecting wires - As required
4.5 Design
4.5.1 General designLet Output voltage V = (sqrt (2)) x input voltage x no. Of stages(n)
So Vin=13.75V(ac)n=8 stages
Vout= (sqrt (2)) x 13.75 x 8 = 155.8volts (dc)
4.5.2 Series vs. parallel design considerationsIn the process of deciding which type of multiplier assembly best suits the end appli-
cation, it is necessary to address the series and parallel multiplier formats. The theory ofoperation is the same in both the series and the parallel multiplier assembly types. They aresimilar also in package volume, but are slightly different in package shape capability. Paral-lel multipliers require less capacitance per stage than do their series counterparts. However,parallel multipliers also require higher voltage ratings on each successive stage. The limit onoutput voltage in parallel multipliers is determined by the voltage capability of the capacitors(common single-layer ceramic capacitors do not exceed 20kV).
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
4.5.2.1 Voltage regulation
DC output voltage drops as DC output current is increased. Regulation is the drop, fromthe ideal, in DC output voltage at a specified DC output current (assuming AC input voltageand AC input frequency are constant).A close approximation for series half-wave multiplierscan be expressed as:
Where:N = no. of stages, (1 capacitor and 1 diode = 1 stage)f = AC input frequency (Hz)C = capacitance per stage (F)I = DC output current (A)
Example:Calculate the regulation voltage of a 6 stage multiplier with 1000pF capacitors, 50 kHz
Input frequency (sine wave), 1mA DC output current, and 20kV DC output voltage:
This would require increasing the input voltage 167Vp-p (Vregulation / 3 DC capacitors)to maintain 20kV DC output voltage at 1mA.
An equivalent parallel multiplier would require each capacitor stage to equal the totalseries capacitance of the AC capacitor bank. In the above example, the 3 capacitors inthe AC bank would equal 1000pF/3 or 333pF. The parallel equivalent would require 333pFcapacitors in each stage.
4.5.3 Ripple voltageRipple voltage is the magnitude of fluctuation in DC output volt-age at a specific output
current (assuming AC input voltage and AC input frequency are constant). A close approxi-mation for series half-wave multipliers can be expressed as:
Example:Calculate the ripple voltage of a 6 stage multiplier with 1000pF capacitors, 50 kHz input
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
frequency (sine wave), 1mA DC output current, 20kV DC output voltage:
4.5.4 Other design concernsStray Capacitance:
Stray capacitance becomes an important consideration as input frequency increases. As thefollowing expression indicates, an increase in frequency decreases the capacitive reactance,resulting in increased current flow through the insulating materials.
Power losses through insulation, which are negligible at 60Hz, become significant athigh frequency.
Corona:Corona is the result of gas ionization (air, oxygen, etc.), due to a high voltage field.
This extremely destructive phenomenon usually results in slow degradation of the insulatingmaterials, causing latent failures.
Careful design, consistent manufacturing processes, eliminating air entrapment inencapsulation, and a thorough understanding of what causes corona minimize this problems.
Leakage Currents:Losses due to leakage in diodes, capacitors and insulation are significant considerations
in applications using very low capacitor values (i.e. night vision power supplies) and inapplications, which operate at high temperatures (¿125 degree C). Figure 7 (on the followingpage) represents some of the factors affecting multiplier efficiency.
4.5.5 Electrical operating conditionsReasonable ranges practical limits do exist, which determine multiplier design and
application. Here are some typical rules of thumb for the most commonly used VMImultipliers:
1) AC Input Voltage: 0 to 15kV p-p2) AC Input Frequency: 5 kHz to 100 kHz
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
3) DC Output Voltage: 1kV to 150kV4) DC Output Power: 0 to 50W
4.5.6 Input and output voltageThe input voltage is usually specified as peak or peak-to-peak voltage. The theoretical
no-load output voltage is equal to the number of stages times the peak input voltage. Inmost cases, the output voltage will be reduced from the theoretical value due to the effects ofregulation and stray capacitance. In most applications, the output voltage from the multiplieris a primary requirement. The input voltage may need to be increased to provide the requiredoutput voltage. Care must be taken to insure that the voltage stresses on the components donot exceed ratings during multiplier operation at maximum output voltage and current.
4.5.7 Output currentFor typical multipliers, output current can range from 1uA to 5mA. Due to the effects
of regulation, output current can affect the voltage stresses on a multiplier’s diodes and ca-pacitors. Since regulation is directly proportional to output current, and as input voltage isusually increased to compensate for regulation, the diodes and capacitors near the input sideof the multiplier will be subjected to higher voltage stress at higher output currents.
For higher current ratings, it is important to insure that the diodes’ junction temperaturedoes not exceed 125 degree C. A thermal analysis may be necessary to evaluate junctiontemperature. Typically, for output currents less than 1.0mA, the power dissipated in thediodes is low enough to prevent overheating.
4.5.8 Operating frequencyThe lower the operating frequency for a multiplier, the larger its capacitors will need to
be to maintain electrical performance. For low frequency multipliers, the operational charac-teristics must be calculated to determine feasibility. The upper limit to operating frequencywill be affected by diode recovery time, stray capacitance, and inductance effects. Dioderecovery time can be a factor at frequencies above 100 kHz. The effects of capacitanceand inductance will depend on component layout, potting material used, and the choice ofcomponents.
4.5.9 Physical characteristics
4.5.9.1 Size
Custom multiplier assemblies can usually be constructed in a wide variety of shapes andsizes to meet customer needs. The customer may also specify special physical characteris-tics, provided such specifications do not compromise design constraints. Actual design ofthe package size/shape must account for internal mechanical stresses and voltage isolation
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issues.Clearly defining the dimensions and necessary tolerances is very helpful. When the spe-
cific shape and/or size is not defined, as much information as possible should be providedregarding the enclosure where the part will be installed and/or the customer’s preferred phys-ical characteristics. Typically, packaging that is ”as small as possible”, is desired. However,an indication of preferences and expectations, with respect to package size, will aid in thedevelopment of a suitable package design.
4.5.9.2 Mounting
The preferred end application mounting or installation provisions need to be specified.Through holes, integral threads, encapsulated inserts, PCB mount and suspension are someexamples of mounting technique.
4.5.10 Environmental conditions
4.5.10.1 Extreme temperature
Assembly exposure to high or low temperature extremes requires special consideration.This is due to the electrical and mechanical effects of the materials used in the assemblyconstruction. For example, very high temperature extremes, such as in excess of 150 degreeC, can significantly reduce the voltage isolation capabilities of some encapsulants. Addi-tionally, high temperatures can induce significant mechanical stresses, due to mismatches inmaterial thermal expansion coefficients.
Similarly, very low temperature extremes can induce mechanical stresses due to materialthermal expansion mismatches. Low temperatures can also cause radical changes in thephysical characteristics of the encapsulant, making it brittle, or causing the encapsulant toexhibit non linear shrinkage effects.
4.5.10.2 Practical limits
Practical limits do exist, which determine multiplier design and application. Here aresome environmental rules of thumb for the most commonly used VMI multipliers:
1) Operating Temp Range: -55 degree C to +125 degree C2) Relative Humidity: 0 to 100 percent3) Altitude: 0 to space
Note: Altitude and humidity affect materials, terminations, plating, etc. Pleasespecify.
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
4.6 SimulationAs we are doing the prototype model of high voltage DC from a single phase AC using
capacitors and diodes, we done simulation in MATlab. Initially we search the elements fromthe library. After getting all the components such as input ac voltage, source block, outputvoltage block, diodes, capacitors (from the RLC circuit), scope and continuous powergui. Byusing these elements we placed them and connected each other by selecting the componentand drag it.
Figure 4.5: MATLAB simulation circuit diagram
The input AC of 12 volt was set as the value in the parameter table. Also the frequencyof 50 Hz. From the RLC circuit the value of capacitance was given 1000uF with 63 volts.The other circuit parameters were taken as zero. The diode with load was used for thesimulation. As per the theory we used the diodes of family IN400x, i.e IN4007.so here wetook the parametric value as.25uF.
Here we were simulating a voltage multiplier circuit. So a cascade /ladder network isneeded to produce the desired output. Thus by designing the circuit we need 8 stage ofcapacitor and diode connection. The connections were done as circuit diagram. To obtainthe output voltage, the terminals of output voltage block were taken one from the inputvoltage side and other from the last connection of capacitor and diode region. Then theseterminals were fixed to the voltage output block. To run the circuit and to done compilationboth the input voltage block and output voltage block combined, given to the scope. Herewe used the continuous mode of operation. So a powergui of continuous mode was placedin between the input and output region.
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The compilation was done to rectify the errors. If there was error in the circuit diagram orin the parametric block the error position would be showed. Thus it is easy to clear it. Whenall the errors are cleared and compilation was done successfully the time should be givento run the program with less nano-second. After the process was done the input and outputwaveform in the same graph. Here we obtained output voltage of 151.5volt. The designedoutput voltage of the circuit diagram was same. Thus the simulation was done using softwareMATlab successfully.
Figure 4.6: Output waveform
4.7 Hardware implementation
4.7.1 PCB implementationPrinted circuit boards are electronic circuits created by mounting electronics components
on a non-conductive board and creating conductive connection between them. The creationof circuit patterns is accomplished using both additive and subtractive methods. The con-ductive circuit is generally copper: also aluminum, nickel, chrome and other metals aresometimes used. There are three basic varieties of printed circuit boards: single-sided andmulti layered. The special and density requirement and the circuitry complexity determinethe type of board produced. Printed circuit boards are employed in the manufacturing ofbusiness machines and computers, as well as communication, control and home entertain-ment equipment.
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Production of printed circuit boards involves the plating and selective etching of flatcircuits copper supported on a non-conductive sheet of plastic. Production begins with asheet of plastic laminated with a thin layer of copper foil. Holes are drilled through the boardusing an automated drilling machine. The holes are used to mount electronic componentson the board and to provide a conductive circuit from one layer of the board to another.Following drilling, the board is scrubbed to remove fine copper particles left by drill. Therise water from scrubber unit can be a significant source of copper waste. In the scrubber, theCopper is in a particulate form and can be removed by filtration or centrifuge. Equipmentis available to remove this copper particulate, allowing recycle of the rinse water to thescrubber.
However, once mixed with other waste streams, the copper can dissolve and contribute tothe dissolved copper load on the treatment plant. After being scrubbed, the board is cleanedand etched to promote good adhesion and then is plated with an additional layer of copper.Since the holes are not conductive, electroless copper plating is employed to provide a thincontinuous conductive layer over the surface of the board and through the holes.
Electroless copper plating involves using chelating agents to keep the copper in solutionat an available pH. Plating depletes the metal and alkalinity of the electroless bath. Coppersulphate and caustic are added (usually automatically) as solutions, resulting in a growth involume of the plating solution. This growth is a significant source of copper bearing wastewater in the circuit board industry.
Treatment of this stream (and this rinse water from electroless plating) is complicatedby the presence of chelating, making simple hydroxide precipitation ineffective. Iron saltscan be added to break the chelate, but only at the cost of producing a significant volume orsludge
Ion exchange is used to strip the copper from the chelating agent; typically by using achelating ion exchange resin with sulphuric acid produces a concentrated copper sulphate so-lution without the chelate. This regenerative can be either treated by hydroxide precipitation,producing hazardous waste sludge, or else concentrated to produce a useful product.
Growth from electroless copper plate is typically too concentrated in copper to treat di-rectly by ion exchange. Different methods have been employed to reduce the concentrationof copper sufficiently either to discharge the effluent directly to the sewer or to treat it withion exchange. One method, reported by Hewlett-Packard, replenishes growth formaldehydeand caustic soda to enhance its autocatalytic plating tendency and then mixes it with carbongranules on which the copper plates out in a form suitable reclaiming.
Following electrolysis plating, a plating resist is applied to the panel and photo-imagedto create the circuit design. Copper is then electroplated on the board to its final thickness. Athin layer of tin lead solder or pure tin is plated over the copper as an etch resist. The platingresist is then removed to expose the copper not part of the final pattern. The exposed copper
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is then removed by etching to reveal the circuit pattern.
Figure 4.7: PCB layout
Ammonia-based etching solutions are most widely used. Use of ammoniac complicateswaste treatment and makes recovery of copper difficult. An alternative to ammonia etchingis sulphuric acid /hydrogen peroxide etching solutions. This later etchant is continuously re-plenished by adding concentrated peroxide and acid as the copper concentration increases toabout 80g/L. At this concentration, the solution is cooled to precipitate out copper sulphate.
After replenishing with peroxide and acid, the etchant is reused. Disadvantages of thesulphuric acid-peroxide etching solution are that it is relatively slow when compared withammonia and controlling temperature can be difficult.
The circuits were drawn using Proteus and. The drawn circuit diagram was printed onto a photographic paper using printer. Then the circuit diagram was ironed on to a coppercladded board with great care. Using ferric chloride solution, the PCB was completely andwas perfectly etched.
Figure 4.8: PCB layout etched on copper-clad
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High voltage dc dc from single phase ac using capacitors and diodes Mini Project − 2016
Figure 4.9: Implemented hardware
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CHAPTER 5
RESULT, CONCLUSION AND FUTURE SCOPE
5.1 ResultIn this work, a detailed design and implementations of a single phase ac to high voltage
DC power supply is investsigated. This implemented hardware able work to build a highvoltage DC power supply is meant for use in the laboratory. The designed DC power supplycan be used in industrial applications also. The output from the voltage doubler is given to aseries of cascaded circuit that generates up to155.75volts for an input of 13.75 volts.
5.2 ConclusionThis voltage multiplier surface design and implemented in which high voltage generate
by use transformer .There for size of the complete high voltage circuit gives is small andcost is also less. This small size circuit gives high voltage at the end of the multiplier circuit.Because of the light weighted circuit it is portable it gives high reliability. Construction ofwhole circuit is simple and robust in nature/This multiplier circuit is useful for a scientificinstrument, TV sets and CRTs, oscilloscope, x-ray and photomultiplier tubes and field testingof HV cables. Now it is widely used in air ionizer, stun gun, high voltage dc transmission,electron microscope.
(a) Internal part of stun gun
(b) Stun gun
Figure 5.1: Stun gun application
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5.3 Future workIt is mostly wanted need to the future. This can be used where high voltage and low
current needed.Air Ionizer: this circuit is design to solve the problem related to the low quality air in asmall room.
Figure 5.2: Air ionizer
Stun gun- For safety and only used by trained police officers. In high voltage dc trans-mission compared with AC transmission and distribution system, DC system offers signifi-cant advantages, such as low power losses, low harmonics, and negligible reactive power.
Due to this DC systems have been used for point-to –point transmission over long dis-tances or via sea cables. Besides, more and more attention has been captured on these appli-cations including the multi-terminal DC grid, DC distribution system and DC micro grids.With the rapid development the offshore wind farm, new innovative solutions are neededfor the large the integration of large scale wind power. And it seems that the DC distributionsystem is a promising solution for this integration. The advancement of the voltage convertermakes it possible to build a DC grid with many terminals.
The power density of high voltage DC power supplies can be optimized when diode-capacitor voltage multipliers are applied. A further improvement can be achieved by feedingthe multipliers by high frequency series resonant converters, Ideally, the series resonance isformed by the leakage inductance of the transformer and the capacitors of the multiplier. Inthis case the multiplier is practically supplied by an AC current. The performance of a currentfed voltage multiplier bridge topology with an arbitrary number of stages and capacitors hasbeen analyzed for steady state conditions. This concerns the voltage and current stress of thevoltage multiplier. Moreover, an equivalent circuit of the current fed VM has been found. It
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Figure 5.3: Oscilloscope
turns out that a current fed VM can be described by a standard full bridge rectifier, a resistorand a series capacitance. The properties of the equivalent circuit as well as the maximumstress values can be calculated by straight forward formulas.
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