Design and Implement of the Ion Implanter’s Ion Gun Power Supplies by Using the Resonant Converters

Beiranvand, Reza | 2010

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41005 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Rashidian, Bizhan; Zolghadri, Mohammad Reza; Alavi, Mohammad Hossein
  7. Abstract:
  8. In the Ion Implanter system a controled current through a tungesten filament, supplies the heat which causes the thermoionic emmition to ionize the gas molecules. Then the negativly charged electrones that are boiled off the filament, and also the ones that are removed from the outer ring of the gas molecules during the ionization process, are attracted by an adjustable voltage source. In this thesis, two resonant converter topologies are proposed to designe and to implement the adjustable current and voltage sources for ion implantation system. Unlike the PWM converters soft switching techniques, used auxiliary circuits to reduce the switching losses and EMI noises, in the proposed resonant converters not only such circuits are not used, but also all of the parasitic elements are merged in the converters main components. The proposed resonant converters are suitable choices for high switching frequency operation for reducing the converter weight and size, due to the aforesaid features, besides achieving soft switching under all operating conditions. The relationship between the necessary optimum dead-time value and the upper limit of the converters soft switching frequencies under the worst-case conditions has been derived. Also, the converters soft switching frequency variation ranges have been calculated. Then the converters optimum design procedures have been introduced to achieve the given output adjustable ranges, though input voltage and output load vary in wide ranges. It has been tried to reduce the frequency variation range as far as possible in order to use the magnetic components, optimally. A PFC converter has been used to improve the input power factor and to reduce the resonant converters output dependence on the main ac input voltage variations, by regulating the resonant converters dc input voltage. Thus, the resonant controllers’ available frequency variation ranges are assigned to adjust and to regulate the converters outputs. In the PFC stage, the continuous and discontinuous current conduction modes have been combined to achieve their advantages such as: simplicity and high power capability. To overcome the input current zero crossing distortion, an offset voltage has been added to the PFC control circuit. So, it has to transfer more energy at the input current zero crossing. This voltage depends on the ac input voltage peak value. Based on the proposed method, two adjustable voltage and current sources have been designed and implemented. The voltage source is adjustable in the range of 25-165 to supply 0-3 output current. Also, the current source is adjustable in the range of 50-200 . Its maximum output voltage is equal to 2.5 . These power supplies are used in the Ion Implanter system as ARC and filament power supplies.

  9. Keywords:
  10. Ion Gun ; Soft-Switching ; Ionization ; Ion Implantation ; LLC-LC Resonant Converter

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