1. RESONANT BASED SOLID STATE MARX GENERATOR1
RESONANT BASED SOLID STATE MARX GENERATOR 1

2. OVERVIEW OBJECTIVES INTRODUCTION CONVENTIONAL MARX GENERATOR
RESONANT BASED MARX GENRATOR
CIRCUIT ANALYSIS
CONCLUSION 2

3. OBJECTIVES To give a small introduction about PULSED POWER TECHNOLOGY
To study about the MARX GENERATOR
To introduce the concept of RESONANCE in MARX GENERATOR 3

4. 4
INTRODUCTION
Accumulates energy over a long period and releases it quickly
Increases instantaneous power
Pulsed Power Technology evolved during WWII
Developed mainly for radars
Further developments in Sandia National Laboratories
Sandia National Laboratories house the largest X-ray machine – Z machine
Basic Power supply of Z machine: Marx Generator 4

5. The Z machine at Sandia Laboratories5
Cylindrical in layout
Houses huge capacitors discharging in Marx Generator
Uses the principle of Z pinch
Fast discharge of capacitors in a tube causes it to collapse towards the centerline under the influence of Lorentz Force
Due to the production high voltages the power feeding equipment submerged in transformer oil and deionized water which acts as insulators.
The Z machine at Sandia Laboratories 5

6. Conventional Marx Generator6

7. First described by Ervin Otto in 1942
A number of capacitors are charged in parallel
And then discharged in series via spark gap switches
Ideally produces a voltage of n x V, n being the number of stages
Performance of the Marx generator depends upon selection of capacitor and the discharge timing
Doping of electrodes in spark gap with radioactive isotopes improves switching performance 7

8. Resonant Switch Converters
Basically divided into two:
Zero Current Switching
Topology in which the switch turns on and off at zero current
Zero Voltage Switching
Topology in which the switch turns on and off at zero voltage
Resonance phenomenon in power electronics reduces the switching losses
The switches are turned on or off at zero current or voltage 8

9. Resonant based Marx Generator9

10. Marx Topology With Reduced Components10

11. General configuration
Consists of an ac-dc converter, voltage regulator, dc-ac converter and the Marx Topology
The large capacitor provides the rest of the topology with a smooth and continuous voltage level
Single leg inverter is used so as to utilize fewer active power switches
Three levels of voltage applied to the inductor
Each two stage of the topology consists of two capacitors, two diodes and two power switches
Has three switching states
Positive charging mode
Negative charging mode
Load supplying mode 11

12. (a) positive charging mode
Switches S1 andS3 are turned on
As S1 is on positive voltage appears at the output of inverter
Diodes D1, D3 and DS3 are forward biases and C1 and C3 are being charged
Reverse energy transmission prevented by the diodes
Therefore the capacitors keep the charge till the load supplying mode
(a) positive charging mode 12

13. S2 and S3 are turned ON
As S2 is ON negative voltage appears at the output of inverter
Diodes D2 and D4 are forward biased
Hence capacitors C2 and C4 are charged with reverse polarity
The capacitors keep the charge till the load supplying mode
(b)Negative charging mode 13

14. All the switches except S4 are turned OFF
S4 connects the capacitors in series
All the diodes are bypassed
The output high voltage pulse will be eight times the input voltage
Breakdown phenomenon at he load side due to high voltage
(c) Load Supplying Mode 14

15. Current and Voltage Waveforms Accompanied By Relevant Switching signal patterns
Gate switching signals and voltage current waveforms 15

16. Circuit Analysis Analysis of the circuit done in two modes
Single shunt operation
Done initially
To test the capability of the Generator in producing the pulses
Repetitive mode operation
The single shut operation is extended to get this mode
The component behavior during resonance is expressed as follows during
the positive charging mode 16

17. Simulation Results For (A)Single Shunt Mode (b) Repetitive Mode17

18. Switching frequency cannot be more than the resonant frequency unless inverter switches have antiparallel diodes 18

19. 19 Capacitor charge and inductor charge different in two half cycles
Generated voltage levels are impossible to control
Causes malfunction to the normal operation of the converter
Bidirectional switching state installed to give feasibility 19

20. Triggered just for voltage adjustability
Bidirectional solid state switching path provides a reserve path for current when the inverter switches are off during resonant cycle
Stored current in the inductor has sufficient time to be delivered to the capacitors
Triggered just for voltage adjustability
Bidirectional Solid State Switching Path 20

21. Conclusions Generated voltage is twice the supply voltage
The number of diodes and switches are reduced
Power loss reduction in capacitors charging process
Pulse generation frequency restricted by resonant frequency
Smaller values of inductor and equivalent capacitor higher repetition rate achieved
Single leg inverter used inorder to reduce the switching and conduction losses 21

22. THANK YOU.. 22