Solid-state Modulator Note - UNT Digital Library

UCRL-ID-136932Solid-State ModulatorTestingEdward G. CookU.S. Department of EnergyLawrenceLivermoreNationalLaboratoryJanuary 10, 2000Approved for public release; further dissemination unlimited

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1/10/00Subject: Solid-State Modulator TestingIn this note is reported the testing of the pre-production version of a solid-state adder typemodulator. In this configuration, the adder consists of transformers that are driven by anarray of MOSFET switches that are connected in parallel but not in series; i.e. the inputvoltage on the transformer is limited to the maximum voltage rating on the MOSFETs.At present, there are only enough printed circuit boards (MOSFET carrier boards) todrive four transformers and two of those are prototypes that are restricted by their gatedrive circuits to a minimum output pulse width of 100ns. We also have two preproduction boards that meet all of our requirements for rise and fall-times and minimumpulse width. The remainder of the production boards are due to be delivered in the firstweek in January and should give us full high voltage capability.The first data represents test results from a single board. Shown below is a simplifiedschematic for the MOSFET circuit that consists of the MOSFET, energy storagecapacitors, and MOSFET control circuit. We are using 1000V MOSFETS that are ratedfor 10 amperes average current. This carrier board has twelve such MOSFETS circuitsthat are electrically connected in parallel at the drain and also share a common ground; allof the capacitors are charged from the same high-voltage source. Each board has a singleinput trigger pulse that is distributed to each of the control circuits. The carrier board isconnected to the single turn transformer in a low inductance manner and the loadresistance is connected to the single-turn transformer secondary. At present the load issimply a parallel array of resistors.CapacitorControlCircuitVchg 0vSwitch-V chgSimplified Schematic of MOSFET CircuitRL

1/10/00The individual MOSFETS and their drive circuits have been tested and havedemonstrated voltage rise and falltimes of less than 10ns (10-90%) at an operatingvoltage of 800V and peak current of 25 amperes/device. A pre-production MOSFETcarrier board with twelve parallel circuits has demonstrated similar performance. Theoscillogr

Subject: Solid-State Modulator Testing In this note is reported the testing of the pre-production version of a solid-state adder type modulator. In this configuration, the adder consists of transformers that are driven by an array of MOSFET switches that are connected in parallel but not in series; i.e. the inputCited by: 1Publish Year: 2000Author: E. G. Cook