design & performance of six pulse voltage multipliers 2

International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN

0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME

33

DESIGN & PERFORMANCE OF SIX PULSE VOLTAGE

MULTIPLIERS

ShaziaFathima1

Associate Professor, Head of the EEE Department,

Green Fort Engineering College,Bandlaguda, Hyderabad

Dr. Sardar Ali 2

Professor & Head - EEE Department,

Royal Institute of Technology & Science, Chevella, R.R. Dist., Hyderabad, A.P., India

ABSTRACT

Electronic systems quite often require that higher DC voltages be generated internally from

the supply voltage. Voltage multipliers can be used to generate bias voltages of a few volts or tens of

volts or millions of volts for purposes such as high-energy physics experiments and lightning safety

testing.

The most common application of the high voltage outputs of voltage multipliers is the anode

of cathode-ray tubes (CRT), which are used for radar scope presentations, oscilloscope presentations,

or TV picture tubes. The dc output of the voltage multiplier ranges from 1000 volts to 30,000 volts.

The actual voltage depends upon the size of the CRT and its equipment application.

In this paper an attempt has been made to design a 3-phase or 6-pulse voltage multiplier

circuit to produce an output voltage of about 4000v at different load currents from a 440v 3-ph

supply. The performance of 6-pulse has been compared with that of single-pulse multiplier by

simulation and found to be far better. The prototype model requires a step-up transformer of

rating100VA, 440V/1150V. The 3-ph voltage is applied to the step-up transformer which is given as

input the voltage multiplier circuit. The multiplier circuit used here is a 4-stage which multiplies the

output of step-up transformer four times. Simulation has been done using SIMPLORER software. The

results of simulation have been compared with the hardware and found to be in coincidence.

1 INTRODUCTION

A voltage multiplier is an electrical circuit that converts AC electrical power from a lower

voltage to a higher DC voltage by means of capacitors and diodes combined into a network.

One of the cheapest and popular ways of generating high voltages at relatively low currents is

the classic multistage diode/capacitor voltage multiplier, known as Cockcroft Walton multiplier,

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ISSN 0976 - 6480 (Print) ISSN 0976 - 6499 (Online) Volume 4, Issue 3, April 2013, pp. 33-40 © IAEME: www.iaeme.com/ijaret.asp Journal Impact Factor (2013): 5.8376 (Calculated by GISI) www.jifactor.com

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named after the two men who used this circuit design to be the first to succeed in performing the first

nuclear disintegration in 1932-James Douglas Cockcroft and Ernest Thomas Sinton Walton.

Unlike transformers this method eliminates the requirement for the heavy core and the bulk of

insulation/potting required. By using only capacitors and diodes, these voltage multipliers can step up

relatively low voltages to extremely high values, while at the same time being far lighter and cheaper

than transformers. The biggest advantage of such circuit is that the voltage across each stage of this

cascade, is only equal to twice the peak input voltage, so it has the advantage of requiring relatively

low cost components and being easy to insulate.

They have various practical applications and find their way in laser systems, CRT tubes, hv

power supplies, LCD backlighting, power supplies, x-ray systems, travelling wave tubes, ion pumps,

electrostatic systems, air ionisers, particle accelerators, copy machines, scientific instrumentation,

oscilloscopes, and many other applications that utilize high voltage DC.

2 TYPES OF VOLTAGE MULTIPLIERS

Voltage multipliers are alternating current (AC) to direct current (DC) converters that produce

high-potential DC voltage from a lower voltage, AC source. They are used with constant, high-

impedance loads and in applications where input voltage stability is not critical. Voltage multipliers

can receive an input voltage directly from a power source, but often use a transformer to minimize

potential hazards.

There are several types of multiplier circuits:

1. Half Wave voltage doubler

2. Full Wave voltage doubler

3. Voltage tripler circuit

3 SINGLE-PULSE VS SIX-PULSE MULTIPLIERS

3.1 Single Pulse Voltage Multiplier

3.2 Working

The Cockcroft Walton or Greinacher design is based on the Half-Wave Series Multiplier, or

voltage doubler. In fact, all multiplier circuits can be derived from its operating principles. It mainly

consists of a high voltage transformer Ts, a column of smoothing capacitors (C2,C4), a column of

coupling capacitors (C1,C3), and a series connection of rectifiers(D1,D2,D3,D4). The following

description for the 2 stage CW multiplier, assumes no losses and represents sequential reversals of

polarity of the source transformer Ts in the figure shown below. The number of stages is equal to the



35

number of smoothing capacitors between ground and OUT, which in this case capacitors C2 are and

C4.

Let Vmax be the peak value of the secondary voltage of the high voltage transformer. To

analyze the behaviour, let us consider that charging of capacitors actually takes place stage by stage

rather than somewhat simultaneously. This assumption will not invalidate the result but will make

analysis easier to follow. Consider the first part of the circuit containing the diode D1, the capacitor

C1, and the secondary winding. During the first negative half cycle of the applied voltage, the

capacitor C1 charges up to voltage Vmax. Since during the positive half cycle which follows, the

diode D1 is reverse biassed, the capacitor C1 will not discharge (or will not charge up in the other

direction) and the peak of this half cycle, the point a will be at 2Vmax. During the following cycles,

the potential at a will vary between 0 and 2Vmax, depending on whether the secondary voltage and

the capacitor voltage are opposing or assisting.

5 SIMULATION

The simulations of 1-pulse and 6-pulse voltage multipliers have been carried out using Simplorer

software. The results of simulation of both multipliers have been presented to assess the performance

and for comparative study of these multipliers:

5.1 Single-Pulse Multiplier

Fig 5.1.1: Simulation Of 1-Pulse Multiplier

Fig 5.1.2: Single-Pulse multiplier at No-load under transient state



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Fig 5.1.3: Single-Pulse multiplier at No-load under steady state (VNL = 3.65KV)

Fig 5.1.4: Single-Pulse multiplier under full load- steady state

Fig 5.1.5: Single-Pulse multiplier at full-load

The ripple & Regulation of 1-pulse multiplier can be calculated from its simulation graph of full

load(fig--)

Ripple = (3.09 - 2.83)/3.09*100 = 8.4%

Regulation = (3.65K – 2.96K)/3.65K*100 = 19.8%



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5.2 Six-Pulse Multiplier

Fig 5.2.1: Simulation circuit of 6-pulse multiplier

Fig 5.2.2: Six-pulse multiplier at no-load Fig 5.2.3: Six-pulse multiplier

under steady state(VNL=3.7KV) under transient state

Fig 5.2.4: Six-pulse multiplier Fig 5.2.5: Six-pulse multiplier

at full-load at full load(zoomed for clarity)

Ripple = (3.25K – 3.07K) /3.7K*100 = 4.86%

Regulation= (3.7K – 3.15K)/3.7K*100 = 14.4%



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5.3 Comparison of Results

The ripple and regulation of 1-pulse and 6-pulse multipliers have been calculated from the simulation

results. It has been observed that the performance of 6-pulse multiplier is much better than 1-pulse

multipliers. Hence a six-pulse multiplier can be used to generate high DC voltages with comparatively

less ripple & regulation.

6 DESIGN OF 6-PULSE MULTIPLIER

6.1 Ripple and Regulation

Ripple and Regulation of a 6-pulse multiplier circuit are calculated as follows::

Ripple Voltage = δV = nI/6fC= 133.33V

% Ripple = δV/ Vmax*100= 3.33%

Regulation = ∆V = nI/3fC[n2/6-n/4+1/3] = 533.33V

% Regulation = ∆V/Vmax*100= 13.33%

6.1 Components Required

1. Step up transformer- 440V/1150V,100VA.

2. Capacitors of 0.5µF, 2KV - 8Nos

3. Diodes of PIV rating 2KV - 12 nos

4. Load resistors:

1mA load: 500KΩ, 1W- 8Nos

2mA load: 270KΩ, 1.5W – 7 Nos

3.2mA load: 125KΩ, 1.5W - 10 Nos

4mA load: 100KΩ, 1.5W – 10Nos

5mA load: 100KΩ, 2.5W – 8 Nos

6mA load: 100KΩ, 4W – 6Nos

5. Measuring resistor of 10MΩ,1W

6. Micro Ammeter(0-50µA)

7. Milli ammeter(0-10mA)

6.2 Practical Implementation of 6-pulse Multiplier

Maximum voltage the 3-ph multiplier can develop is calculated as follows:

Transformer rating = 415V/1150V, 100VA, 3-Ф

Primary Side: VL-L= 415V

Vph = 230V

Secondary Side: VL-L=1150V

Vph= 660V

Vph= Vrms=660V

Vmax = Vrms*√2*n

Where n – number of stages of multiplier circuit = 4

Vmax = 660*√2*4 = 3.8 kV =~ 4KV

Maximum permissible load current = IL

√3VLIL = 100VA

IL = 100/ (√3*1150) = 50 mA



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Fig 6.2.1: Main circuit & Load circuit of 6-Pulse multiplier

Fig 6.2.2: Complete practical kit of a 6-pulse multiplier (Input supply from a step-up transformer of

440/1150V behind the vertical kit)

6.3 Testing Of 6-Pulse Voltage Multiplier

Fig 6.3.1: Testing of 6-pulse multiplier using a potential divider arrangement



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Fig 6.3.2: Ripple obtained at full load for input voltage of 230V

The ripple and regulations at different loads is measured and tabulated. The results obtained from

theoretical calculation, experimental tests and simulation of a 6-pulse multiplier are compared with each

other and found to be almost equal.

7 CONCLUSION

In this paper, a 6-pulse voltage multiplier circuit has been successfully designed, implemented and

simulated using the SIMPLORER software. Its performance has been tested at different loads. The results

obtained from theoretical calculations, practical observations and simulated graphs have been compared

and found to be in great coincidence.

Simultaneously, the performance of 6-pulse multiplier has been compared with that of 1-pulse

multiplier. It is found that 6-pulse voltage multiplier gives a much better performance in terms of ripple

and regulation. The theoretical, practical and simulated results of the 1-pulse multiplier shows a large

amount of ripple and high regulation, whereas in a 6-pulse multiplier the DC output obtained is much

better comparatively.

Practically, it has been observed that the number of capacitors is reduced and thus the size of the

circuit and cost gets drastically reduced. The 6-pulse multipliers would prove more economical where 3-ph

transformer and 3-ph variac are already present.

Hence it can be concluded that the requirements of high quality DC can be better accomplished by

means of 6-pulse voltage multipliers as compared to any of the multiplier circuits.

8 REFERENCES

1. High Voltage Engineering. Fundamentals. Second edition. ... E. Kuffel, W.S. Zaengl and

J. Kuffel 2000

2. MS Naidu and V. Kamaraju, High Voltage Engineering, Tata mcgraw Hill, 2001

3. CL Wadhwa, High Voltage Engineering, Wiley Eastern Ltd., 1994 .

4. www.blazelabs.com/e-exp15

5. http://en.wikipedia.org/wiki/Voltage_multiplier

6. www.icestuff.com/~energy21/cw1

7. home.earthlink.net/~jimlux/hv/cw1

8. Sanjay M Trivedi, B. S. Raman and Dr. Mihir Shah, “Design of a Unified Timing Signal Generator

(UTSG) for Pulsed Radar”, International journal of Electronics and Communication Engineering

&Technology (IJECET), Volume 3, Issue 1, 2012, pp. 252 - 261, ISSN Print: 0976- 6464,

ISSN Online: 0976 –6472

9. Vishnu Goyal and Dr. Sulochana Wadhwani, “Simulation of Six Pulse Cycloconverter Excited

Induction Machine” International Journal of Electrical Engineering & Technology (IJEET),

Volume 3, Issue 2, 2012, pp. 76 - 83, ISSN Print : 0976-6545, ISSN Online: 0976-6553.

design & performance of six pulse voltage multipliers 2

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