A PRESENTATION

ON

A TRIGGER SYSTEM WITH HIGH VOLTAGE ISOLATION FOR MULTIPLE SWITCHING DEVICES

by

S K Rai

Assistant ProfessorElectronics Engineering Department

B K Birla Institute of Engineering & Technology (BKBIET)

Pilani (Raj.)-333 031

Authors: S K Rai, P Tandon, S Jangid & Rahul Varma

Defining Problem:

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The semiconductor switches are the main elements of all kind of power converters or pulse power supply design.

So, the trigger pulses to control these switches play most important role in these designs.

There are a number of research papers related to these designs based on different topologies. But, the trigger pulse generators i.e. trigger systems has not been explained completely.

In this paper, a trigger system with high voltage isolation is described in detail.

Conclusions:

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1. The proposed trigger system is an open loop design.

2. The design of a simple pulse generator has been presented with two different types of pulses:

Pulse-1: 80 s (Fixed)μPulse-2: Variable up to 5 sμDelay between Pulses: 10 s (Fixed)μ

3. Optical isolation has been used.

4. High frequency inverter and induced voltage is used to isolate driver Circuit.

5. The trigger system has been tested successfully with a Marx Generator.

This work has been carried out at IEG, CSIR-CEERI, Pilani.

Frequency: Variable up to 10kHz

Trigger System: Provides trigger pulses to Semiconductor Switches to turn ON or OFF.

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Trigger System

Pulse Generator

(With Controller)

Driver Circuit= +

High

Low

Trigger System & Isolation Issue:

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Reference of Power Circuit

Common

Reference of Trigger System

A Basic Switching Circuit

Trigger Pulse

No issue of Isolation……..

A Basic Switching Circuit

When & Why Isolation Required ???

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Trigger System

Floating or Series Connected Devices

In Power Circuit

Short Circuit

Q1

Q2

Q3

Reference of Trigger SystemShort Circuit

So, Isolation is required among individual trigger pulses

(i.e. Pulses generated by Pulse Generator and driver circuits both should be isolated)

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Proposed Design: Two types of synchronized pulses have been generated with high voltage isolation.

Pulse Generator Specifications:Frequency of the pulses (fs)= up to 10 kHzPulse width of Pulse-1 = 80 µs (Fix)Pulse width of Pulse-2 = up to5 µsDelay = 10 µs (From trailing edge of Pulse-1)

Master Pulse to get Frequency Variation

Max up to 10 kHz

Pulse-1:80 µs

Delay:10 µs

Pulse-2:Variable up to 5 µs

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Pulse Generator Design:

+15VMaster

Frequency Pulse-1 DelayNE555

(Variable Frequency)

+15V

4047BPIn Monostable

Mode+ve Edge Triggered

+15V

4047BPIn Monostable

Mode-ve Edge

Triggered

+15V

4047BPIn Monostable

Mode-ve Edge

Triggered

Pulse-2

PulseGenerator

Variable Resistors to

change Pulse width &

Frequency

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Pulse Generator Testing:

Output PulsesSingle Output Pulses

Pulse-1 (80µ s)

Pulse-2 (up to 5µ s)

Conclusion-1:It is an open loop design.

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Multiple Pulse Generation with Isolation: To get a number of similar pulses, a buffer IC ULN 2003 is used and since, pulses should be isolated to optical transmitters are used to transmit the pulses.

Requirement is multiple isolated pulses.

ULN 2003Optical Transmitter

HFBR1521

Variable Resistors to change Pulse width of Pulse-2 & Frequency of the pulses

Isolated Driver Circuit: Since pulses are transmitted via optical way so driver circuit includes to sub-circuit-(i) Optical Receiver and (ii) Gate Driver Circuit. Again, the driver circuit must be isolated.

Driver Circuit = Optical Receiver + Gate Driver CircuitIt must be isolated i.e.

its DC Supply must be isolated.

DRIVER

Regulator

DRIVER

Regulator

DRIVER

Regulator

Optical Pulse

15

Inverter(Operating Frequency = 20 kHz)

Induced Voltage in the Coil

Regulated DC Power Supply11/1

5

Isolated Gate Driver & Receiver Supply:

DRIVER

Regulator

DRIVER

Regulator

DRIVER

Regulator

Optical Pulse

15

+15 V for the driver from the induced

voltage in the inductor

Conclusion-3: Optical isolation has been used.

Conclusion-4:High frequency inverter and induced voltage is used to isolate

driver Circuit.

Receiver: HFBR2521

Driver: IXDD414CI

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Testing With Marx Generator:

Gate Pulse-2

Gate Pulse-1

Gate Pulse-2

Gate Pulse-1

Gate Pulse-2

Gate Pulse-1

Q1 Q2 Q20

Q21 Q22 Q40

C C1 C2 C20

X

Y

RL

R D1 D2 D3 D4 D39 D40

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Top View of the PCB Prototype Testing Arrangement

Input dc Voltage

Output Pulse

Conclusion-5 The trigger system has been tested successfully with Marx

Generator.

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REFERENCES D. Deb, J. Siambis, R. Symons, and G. Genovese, "Beam Switch Tube Modulator Technology for Plasma Ion Implantation Broad Industrial Application", 9th IEEE International Pulse Power Conf., 1993, pp. 333-336. D. M. Goebel, R. J. Adler, D. F. Beals, and W. A. Reass, “Handbook of Plasma Immersion Ion Implantation and Deposition”, Andre Anders, New York: 2000, pp. 472-477. R. J. Adler, J. Scheuer, and W. Horne, "Thyratron modulators in plasma source ion implantation", 10th IEEE International Pulse Power Conf., 1995, pp. 1243-1248. Rahul Verma and K. S. Sangwan, “Development of a solid state versatile pulsar for high voltage and high power applications”, IEEE Pulsed Power Conference, 2009, pp. 1312 - 1316. H.J Ryoo, J.S Kim, G.H Rim, Danil Sytykh and Guennadi Gussev, “Development of 60kV Pulse Power Generator Based on IGBT Stacks for Wide Application”, 27th IEEE International Power Modulator Symposium, 2006, pp. 511 - 514.