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Status of Booster Bending Magnets Power Supply refurbishment

POCPA3 – DESY, May 21-23, 2012. Status of Booster Bending Magnets Power Supply refurbishment. Marco Cautero. 2010 Status: Kempower PS Specs. 2010 Status: Operation at 2.5GeV. Output modules IGBTs explode randomly without triggering any hardware protection . 2010 Status: Kempower actions.

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Status of Booster Bending Magnets Power Supply refurbishment

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  1. POCPA3 – DESY, May 21-23, 2012 Status of Booster Bending Magnets Power Supply refurbishment Marco Cautero

  2. 2010 Status: Kempower PS Specs POCPA3 – DESY, 21-23/05/2012

  3. 2010 Status: Operation at 2.5GeV • Output modules IGBTs explode randomly without triggering any hardware protection POCPA3 – DESY, 21-23/05/2012

  4. 2010 Status: Kempower actions • The modules are undergoing continuous modifications, upgrades and substitution of faulty IGBTs and triggering cards after failures, without finding the real cause of malfunctioning. Kempower team spends lots of time in Italy. • Usually when you buy a car, you expect everything is working at the right place, you don’t go opening the central control board and have a reverse enginnering...Elettrateam decided to study the complete converter schematic, finding dramatic design flaws POCPA3 – DESY, 21-23/05/2012

  5. Early 2011: PS-Group actions • What was wrong with Kempower power supplies? • The power supply output stages have been found lacking important features like Over Current alarms, Vcesaturation alarms, NTC temperature alarms and anti-cross conduction circuitry. Anything left??? POCPA3 – DESY, 21-23/05/2012

  6. Mid 2011: PS-Group actions • Current transducer was inversely mounted • As two boards are wire-ORed, output pins are connected together, if one has no error, ties pin low and no further errors are detected • Output fuses switches not cabled correctly and when tripped, no indication fed to control POCPA3 – DESY, 21-23/05/2012

  7. Mid 2011: PS-Group actions • Only one card had NTCs connected (3 IGBTs), so the other card inputs were left open, thus output is wire-ORed and was always tying pin low (no error) • Most of these errors were caused when a new trigger card has been added to remove the distortion caused by driving only the slash IGBTs POCPA3 – DESY, 21-23/05/2012

  8. Mid 2011: PS-Group actions 3 • No cross-conduction circuitry between channels 1 and 3 nor 2 and 4. Each board separately drives slash and back-slash IGBTs 4 2 3 2 IGBT layout 1 1 4 POCPA3 – DESY, 21-23/05/2012

  9. Mid 2011: PS-Group actions • Kempower disabled VCEsat circuitry because it was triggering too many false alarms. Two DC/DC converters are shorted together to get doubled output current (not a good habit) This schematic is still tripping us... POCPA3 – DESY, 21-23/05/2012

  10. Mid 2011: PS-Group actions • Original output filtering circuit has been designed with wrong capacitor types (DC-link MKP caps). Electrical contact is made only through the two feedthrough visible on the photo. POCPA3 – DESY, 21-23/05/2012

  11. Late 2011: PS-Group actions • Original output module had three complete H-bridge IGBTs in parallel connection. • We decided to put two rugged half bridge IGBTs per module. We used a known commercial driver custom built over the IGBT (450 Adc) which has almost the same chars as the original. POCPA3 – DESY, 21-23/05/2012

  12. Late 2011: PS-Group actions • This driver board has been developed by Elettra and embeds all features that allow a proper and safe operation. • Some insulated signals like input signals, NTC temp and input current are made available for troubleshooting • Furthermore it is compatible with all the Kempower circuitry behind POCPA3 – DESY, 21-23/05/2012

  13. Early 2012: constraints • Any intervention must be completed during shutdown periods. • All systems must be working at least one day before restart. • Booster Service Area cannot be accessed during uptime. Shutdown periods: light green POCPA3 – DESY, 21-23/05/2012

  14. Mid 2012: New Output Module • Using the same case and heat sink, we have rearranged all new componentsand fulfilled all electrical constraints • the new output stage passive filter with high current snubber capacitors is displayed in the central part POCPA3 – DESY, 21-23/05/2012

  15. Perspectives • Situation now: The original modules had some of the flaws fixed. The output filters are still using the wrong capacitor types and will need replacing soon. Two prototypes of the new kind are up and running since January on the quadrupoles power supply • By 2013 our goal is to substitute all original output modules with Elettra ones. • In the next years we intend to modify the AC/DC modules and work at full power@3.125 Hz POCPA3 – DESY, 21-23/05/2012

  16. Acknowledgements • Works are on the good way, thanks to the following people: • Denis Molaro • PiergiorgioTosolini • Walter Cortivo • Alessandro Gubertini • Alessandro Carniel • Christian Amasoli And last but not least: Roberto Visintini Thanks for Your attention POCPA3 – DESY, 21-23/05/2012

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