An FET Full Bridge Switcher for Inductorless Capacitor Charging for Nova
Abstract
Switching power supplies were designed for the Nova 10 mm rod amplifiers. A simmer supply keeps the lamp turned on continuously by providing 70 - 110 milliamperes of de current while a flashlamp supply repeatedly charges and regulates a capacitor before its energy is dumped into the lamp. The chief difference in these two supplies is their output transformer. A full bridge configuration using power MOSFET' s is simple to drive. The transformer is designed to provide adequate inductance to limit rate of rise of charging current to an acceptable level. Fast recovery diodes in the bridge provide excellent FET turn off characteristics, eliminate ringing through the transistors, and provide a path for transformer energy to be transferred to the load at the end of each cycle. The output of the simmer power supply is a 35 microfarad capacitor in parallel with the lamp, so initially it must also charge a capacitor. The peak output voltage is 3.6 kv, but it is normally operated at 2.0 kv. The flashlamp power supply load is 120 microfarads. Its maximum voltage output is 5.0 kv and is typically run at 3.0 kv. It can charge its output to one kilojoule in much less than the maximum ten seconds allowed, but cannot do this indefinitely without overheating the transformer. However, the amplifier glass rod will fail before the transformer will. Both power supplies produce an average power of 300 watts and a peak power of 1 ,650 watts. However, the transistors are medium power and are conservatively run at 6 amperes peak, so they are capable of producing a much higher average power when combined with a higher power transformer. Very high power is realizeable by paralleling high power transistors. Both supplies regulate to + -2 volts at maximum output.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1983
- Accession Number
- ADA637627
Entities
People
- A. M. Mihalka
- B. T. Merritt
- R. E. Burch
Organizations
- Lawrence Livermore National Laboratory