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,
INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN
ENGINEERING AND TECHNOLOGY (IJARET)
ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
Volume 4, Issue 3, April 2013, pp. 33-40
© IAEME: www.iaeme.com/ijaret.asp
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© I A E M E

34
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

36
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%

37
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%

38
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: 500K , 1W- 8Nos
2mA load: 270K , 1.5W – 7 Nos
3.2mA load: 125K , 1.5W - 10 Nos
4mA load: 100K , 1.5W – 10Nos
5mA load: 100K , 2.5W – 8 Nos
6mA load: 100K , 4W – 6Nos
5. Measuring resistor of 10M ,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

39
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

40
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.

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