Operational results of the spallation neutron source (SNS) polyphase converter-modulator for the 140 KV klystron RF system
This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltageswitching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three 'H-Bridge' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.
- Publication Date:
- OSTI Identifier:
- Report Number(s):
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- Resource Relation:
- Conference: Submitted to: PAC 2001 Particle Accelerator Conference, Chicago, IL, June 18-22, 2001
- Research Org:
- Los Alamos National Laboratory
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- Country of Publication:
- United States
- 43 PARTICLE ACCELERATORS; ACCELERATORS; BYPASSES; CAPACITANCE; CAPACITORS; DESIGN; ENERGY STORAGE; FEEDBACK; INDUCTANCE; KLYSTRONS; MODULATION; NEUTRON SOURCES; POLYPROPYLENE; RF SYSTEMS; SPALLATION; TRANSFORMERS; TRANSISTORS; WAVE FORMS
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