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TitleTesla Transformer for Experimentation and Research
LanguageEnglish
File Size2.1 MB
Total Pages96
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Page 48

High-frequency converter POWER SUPPLY DESIGN

34 Marco Denicolai

The theoretical power achieved with these components is:

( )
W2083

10600

5000101.05.05.0
6

262
1 =


⋅⋅⋅

=


∆⋅⋅
=





t

VC
P (5-12)

The calculated power capacity is more than sufficient to ensure an actual value surely
greater than the targeted 1.25 kW.

5.2.2. Bridge switch design

The bridge switch module includes four IGBT solid-state switches, their drive circuitry plus
additional components generating 560 V, 15 V and 5 V DC.

The IGBT is a relatively new power semiconductor device, which provides the best
features of both the MOSFET and the BJT [Tak95]. Among its advantages:

• Low-power, voltage-driven gate turn-on and turn-off. Gate impedance as high as a
MOSFET.

• Low conduction losses.
• Positive temperature coefficient. The device will not experience thermal run-away

typical of BJTs.

• Possibility to use either integrated or external anti-parallel diode.
The traditional disadvantage of the IGBT is its slow turn-off speed that results in the well-

known current tail. For this application, as the SLR converter commutations take place
always when the load current is zero, the slow turn-off doesn’t represent a problem. The
IGBT used is the IRG4PH40UD type, which features an integrated anti-parallel diode with a
relatively fast and soft reverse recovery characteristic The manufacturer recommends it for
hard-switching operation up to 40 kHz, but for resonant-mode operation guarantees 200 kHz
functionality.

Table 1: Absolute maximum ratings for the IRG4PH40UD device

Parameter Value

Collector-to-Emitter breakdown voltage 1200 V

Continuous collector current 30 A

Pulsed collector current 120 A

Diode continuous forward current 8 A

Diode maximum forward current 130 A

Even if the commutations take place at zero current, unwanted spikes and noise in general
are present in many nodes of the schematics, due to:

• Parasitic capacities Cce, Cgc and Cge internal to the IGBTs.
• PCB traces impedance.
• Reverse recovery time of the anti-parallel diodes.
• Electromagnetic radiation and coupling within the converter PCB.
The most significant source of unwanted noise is, anyway, the Tesla transformer itself.

When the spark gap conducts and the charged capacitor is quickly discharged on the primary

Page 96

REFERENCES

82 Marco Denicolai

[Phu91] Phung, B.T.,Blackburn, T.R. & al.: Tesla Transformer Design and Application in
Insulator Testing. Seventh International Symposium on High Voltage Engineering,
p. 133 – 36, vol. 5, 1991.

[Pod91] Podlesak, T. F., Carter, J. L. & al.: Demonstration of Compact Solid-State Opening
and Closing Switch Utilizing GTO’s in Series. IEEE Transactions on Electron
Devices, p. 706 – 11, vol. 38, no. 4, 1991.

[Ree88] Reed, J. L.: Greater voltage gain for Tesla-transformer accelerators. . Review of
Scientific Instruments, pp. 2300 – 2301, vol. 59, no. 10, October 1988.

[Ric??] Rickley, M., Belling, M., Hitchcock, R. N., et. al.: A large, 500 kV double resonant
transformer for testing HV probes and HV resistor materials ???

[Roc77] Rockwell International Electronics Operations: An electrical surge arrestor (ESA)
model for electro-magnetic pulse analysis. IEEE Transactions on Nuclear Science,
vol. NS-24, December 1977.

[Smy50] Smythe, W. R.: Static and dynamic electricity. McGraw-Hill, 1950.

[Sne88] Snelling, E. C.: Soft Ferrites Properties and Applications. Butterworths, second
edition, London, 1988.

[Str90] Strickland, B. E., Garbi, M. & al.: 2 kJ/s, 25 kV high-frequency capacitor charging
power supply using MOSFET switches. Proc. 1990 19th Power Modulator Symp.,
pp. 531-534, June 1990.

[Tak95] Takesuye, J., Deuty, S.: Introduction to Insulated Gate Bipolar Transistors.
Motorola Semiconductor Application Note AN1541, 1995.

[Ter43] Terman, F. E.: Radio Engineers’ Handbook. McGraw-Hill, 1943.

[Tes14] Tesla, N., Apparatus for transmitting eletrical energy. Patent n. 1119732, 1
December 1914.

[Tes78] Tesla, N., manuscript edited by Marincic, A.: Colorado Springs Notes 1899-1900.
Nolit, 1978.

[Tes91] Tesla, N., System of electric lighting. Patent n. 454622, 23 June 1891.

[Tes94] Tesla, N., Means for generating electric currents. Patent n. 514168, 6 February
1894.

[Uma87] Uman, M. A.: The lightning discharge. Academic Press, 1987.

[Uni93] Power Transformer design for Switching Power Supplies. Unitrode Seminar
Manual SEM900, Topic M5, rev. 7/86, 1993 (originally published in SEM100,
1986).

[Wat96] Waters, R.T.: The long spark and lightning simulation. IEE Colloquium on
Advances in HV Technology, pp. 4/1 - 4/3, no. 173, 1996.

[Whe28] Wheeler, H. A.: Simple Inductance Formulas for Radio Coils, Proceedings of the
I.R.E., Vol. 16, pp. 1398-1400, October 1928.

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