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A Progress Presentation on The Project “ Design & Simulation of Generation of High Voltage D.C Power Supply, Using Greinarcher Circuit “

submitted in partial fulfillment for the award of the Degree of Bachelor of Technology in Electrical Engineering

Supervisor: Submitted By:

Mr. c.k. dwivedi Kamaldeep singh (Associate Proff.) Vimal Pabri

Pawan Kumar Narendra kumar kumawat

Deepak kumar

Department of Electrical Engineering Sri Balaji Technical Campus, Jaipur Rajasthan Technical University, Kota

Sep-2014

Introduction

The introduction of the project contain the following points have been discussed –

• Firstly we will study about the areas where this project is use

• Study the literature survey of different types of voltage multiplier circuits.

• The analysis of Grienarcher’s voltage Multiplier circuit built in 1926 Voltage triplen, Voltage Quadripler and n-plen circuits at very low Voltage (A.C.single phase, 50 Hz).

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Progress (from 21/07/2014 to25/9/2014)

• Study, design simulation and analysis of n-stages voltage multiplier circuits at low voltage.

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1 Research Background•High voltage testing equipment is generally used in mostly two places, in the research, especially in the field of nuclear physics; and routine testing laboratories in the field of Electrical Engineering to study the behaviour of solid dielectrics. • Besides the above places, it can be used in the industry for proof design of H.T. cables at site & Electrostatic precipitators. It is also used in the field of medical sciences and agricultural application. •The work carried out in research laboratories varies considerably from one establishment to the other and the type of equipment varies accordingly.• A general high voltage laboratory may include equipment for all classes of tests. •The routine testing is concerned with testing equipment such as transformer, switchgear, bushings as well as cables etc. It is sometimes carried out in the factory premises.•The high voltage equipment is required to study the insulation under all conditions, which the apparatus is likely to encounter. Tests are also made with higher voltages than the normal working voltage, to determine the safety factor over the working conditions and to ensure that the working margin is neither too high nor too low.

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The conventional forms of high voltage in use can be divided into the following classes:-•Alternating current voltages•Direct current voltages•Transient voltagesIn the industry, the main application of the DC high voltage is to conduct test on HV & MV cables with a relatively large, which consumes huge quality current if it is tested with AC voltages. The simplest unregulated power supply consists of three parts namely, the transformer unit, the rectifiers unit.

Some portion of greinarcher circuit is very intend. in 1932 CW sugested an improvement over the circuit developed by greinarcher for producing high D.C voltage. soFinally the research work is based on COCKCROFT-WALTON Voltage multiplier circuit.

Voltage Multiplier

• Voltage multipliers are circuits – typically consisting of diodes and capacitors, although there are variations using resistors and spark gaps designed to take in an AC input with a certain amplitude and output a higher voltage at DC.

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Voltage Doublers

• For bridge doublers with an AC input of amplitude A, the top terminal's voltage is equal to the bottom terminal's voltage + 2A.

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Voltage Quadripler

• The Greinacher quadruple works in essentially the same way as the doublers, but in two parts; the bottom right capacitor charges to 2A with respect to ground, as the top right capacitor charges to 2V with respect to the bottom right capacitor, leaving the top terminal at 4A with respect to ground.

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Voltage Quadripler (continued)

For similar reasons, the ability of the circuit to supply current is Disappointingly low; with a 1k resistor load to ground, the output of the circuit drops to just0.7V, meaning it is not capable of delivering so much as 1 mA even to very small loads. For a much larger 100k load the voltage drops to 19.2V – still below half of its unloaded output – and even for a 1M load the voltage drops by 10% to 36.1V. Despite the circuit’s poor behavior, the fact that the Greinacher doublers was easily adapted to become a quadruple indicates the likelihood of expanding on this design to create circuits that could multiply up to much higher voltages. Indeed, by making a small modification to the design and redrawing it in a more suggestive form, one retrieves the design for what is more commonly known as a Cockcroft-Walton generator.

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Cockcroft- Walton Generator

• The Cockcroft-Walton generator design is much simpler, allowing the DC output voltage to increase ideally, in steps, to arbitrary large voltages by twice the amplitude of the AC input signal simply by attaching another • “stage” consisting of two diodes and a capacitor, and works in virtually the same way as the Greinacher circuits (CW generators are sometimes also referred to as Greinacher multipliers). • In our project, we examined in-depth the CW generator’s behavior from just 1 stage all the way up to 10 stages. Our highest measured voltage output from this circuit was 264V at DC, all from a handful of components and an AC input signal with less than 15V amplitude.

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(block diagram of project)

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Power circuit

13Power and Control Circuit

Fig shows the block diagram, and Fig. shows the schematic scheme for fabrication and simulation of the project. From Fig it is clear that total set-up is in two parts i.e. low voltage side and Cockcroft-Walton generator. So, this set is suitable for field work due to its light weight, feasibility of transportation and friendly operation. The circuit of this project is very simple. This set will be used for testing of High Voltage cable at side, and can also be used as prime High Voltage DC source for VLF,OWT and as charging unit for Impulse generators.

Continue…….

• Cock croft-Walton Generator

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Continue..

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Continue…..

• In fact, for higher stages the output voltage is frequently higher than the expected value by as much as 8V. This is not an intrinsic property of the CW generator, but rather an effect due to the high frequency and circuit itself, which act on the AC signal from the function generator with nontrivial distortions visible on the oscilloscope that have the effect of slightly boosting the average amplitude of the AC signal itself for high numbers of stages; these slight distortions are then themselves magnified up to 20 times as they go up the chain

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Improvements

• While high ripple voltage, low current, and even higher unloaded voltage drooping at constant frequency is a chronic problem for Cockcroft-Walton generators, there are a number of established ways to improve a CW generator's performance. The simplest is simply to mirror the design to create a full-wave CW generator. Shown below is a 2-stage full-wave CW generator.

• This “doubles” the input frequency in the sense that there twice as many charging cycles per second, which has the effective of lowering voltage droop as more stages are added, decreasing ripple voltage, and raising the maximum current output, all for the cost of just 50% more components

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Conclusions

The following conclusions could be made from this work:-• CockCroft-Walton Voltage multiplier circuit is used when higher

magnitude of output high voltage DC power supply is required without changing the input transformer voltage level. It is used only in special applications when the load, under test, is highly capacitive or where the input voltage stability is not critical.

• This kind of high voltage DC power supply test set is of simple control, low cost, portable due to its light weight, robust and high reliability. Different magnitude of High voltage DC output can be taken from different stages without changing the input voltage.

• This developed equipment will be very useful for field testing of HV cables of different voltage grade, as a prime DC source for VLF & OW testing set and charging unit of impulse generators.

• As this test set is divided in two parts [i.e. (i) transformer and control unit and (ii) multiplier circuit] ,it is very easy for transportation to test sites and this test set can be assembled in few minutes. 18

References

1, Kuffel, E. and M. Abdullah, 1984. High Voltage Engineering. Pergamon Press, Oxford.

2. Naidu, M.S. and V. Kamaraju, 2004. High Voltage Engineering. Third Edn. McGraw- Hill Company Ltd.

3. Khan, N., 2004. Lectures on Art and Science of High Voltage Engineering. Published in Pakistan.

4. Mazen, A.S. and R. Radwan, 2000. High Voltage Engineering Theory and Practice. Sec. Edn., Revised and Expanded, Marcel Dekker, Inc. Am. J. Applied Sci., 3 (12): 2178-2183, 2006 2183

5. Joseph, M.B. Using rectifiers in voltage multipliers circuits. General Semiconductor.

6. Spencer, D.F., R. Aryaeinejad and E.L. Reber. Using the Cockroft-Walton Voltage Multiplier Design in Handheld Devices. Idaho National Engineering and Environmental Laboratory, P.O.Box 1625, Idaho Falls, ID 83415.

7. Juichi, T. and I. Yuzurihara, 1988. The high frequency drive of a new multi-stage Rectifier Circuit. Kyosan Electric Mfg. Co. Ltd., 2-29, Heian- Cho, Tsurumi-Ku, Yokohama, 230, Japan, IEEE.

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References

8. Aintablian, H.O. and H.W. Hill, 1994. A new single phase AC to DC harmonic reduction converter based on the voltage –doubler circuit. Department of Electrical and Computer Engineering, Ohio University, Athens, IEEE.

9. John, C.S., 1993. Circuit topologies for single phase voltage –doublers Boost rectifiers. IEEE Trans. Power Elect., 8: 4.

10.Yamamoto, I., K. Matsui and F. Ueda, 2000. A power factor correction with voltage doubler rectifier. Chubu University, Dep. Electrical Eng. Japan, IEEE.

11.Zhang, M., N.L. Iaser and F. Devos. An optimized design of an improved voltage tripler. IEF, AXIS, University of Paris, 91405 Orsay, France.

12.Zhang, M., N. Liaser and F. Devos, 2002. Experimental results of an optimized voltage Tripler. IEF, AXIS, University of Paris, 91405 Orsay, France.

13 J.S.Burgler, “Theoretical performance of voltage multiplier circuits” IEEE.Journal of solid state circuits publications, vol.6,issue3, pp132-135, June 1971

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Any Question/Suggestion?

Thank for your kind

attention

Please.

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