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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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High-frequency dc-dc converter for ion thrustors using modular design and inductive energy pumping technique for conversion, regulation, and protection
Design of high frequency dc-dc converter modules for power conditioning subsystems, and control system for operating ion engines in space environment
Static dc to dc regulated converter using two-core output transformer
HF design of DC-DC converters with low weight and high performance for spacecraft power systems
Design, modifications, and testing of dc-dc converter
Design and performance of dc-dc converter compatible with pulse width modulation inverter
An alpha particle densitometer was developed for possible application to measurement of the atmospheric density-altitude profile on Martian entry. The device uses an Am-241 radioactive-foil source, which emits a distributed energy spectrum, located about 25 to 75 cm from a semiconductor detector. System response - defined as the number of alphas per second reaching the detector with energy above a fixed threshold - is given for Ar and CO2. The altitude profile of density measurement accuracy is given for a pure CO2 atmosphere with 5 mb surface pressure. The entire unit, including dc-dc converters, requires less than 350 milliwatts of power from +28 volts, weighs about 0.85 lb and occupies less than 15 cubic inches volume.
The voltage multipliers using capacitors and diodes first developed by Cockcroft and Walton in 1932 were reexamined in terms of state of the art fast switching transistors and diodes, and high energy density capacitors. Because of component improvements, the voltage multiplier, used without a transformer, now appears superior in weight to systems now in use for dc-dc conversion. An experimental 100-watt 1000-volt dc-dc converter operating at 100 kHz was built, with a component weight of about 1 kg/kW. Calculated and measured values of output voltage and efficiency agreed within experimental error.
An analytical and experimental study was made of a capacitor-diode voltage multiplier without a transformer which offers the possibility of high efficiency with light weight. The dc-dc conversion efficiencies of about 94 percent were achieved at output powers of 150 watts at 1000 volts using 8x multiplication. A detailed identification of losses was made, including forward drop losses in component, switching losses, reverse junction capacitance charging losses, and charging losses in the main ladder capacitors.
An experimental 100W 1000V dc-dc converter using a capacitor diode voltage multipler (CDVM) with a nominal frequency of 100 kHz is studied. A component weight of about 1 kg/kW was obtained. Design equations for current, output -ripple and -power, efficiency and output voltage are derived. Agreement between experimental results and calculations is fairly good except for ripple.
This paper presents an analytical and experimental study of a capacitor-diode voltage multiplier without a transformer which offers the possibility of high efficiency with light weight. Dc-dc conversion efficiencies of about 94% were achieved at output powers of 150 watts at 1000 volts using 8x multiplication. A detailed identification of losses was made, including forward drop losses in component, switching losses, reverse junction capacitance charging losses, and charging losses in the main ladder capacitors.
A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.
Method of regulating voltage-multiplier dc-dc converter utilizes regulating circuit that directly controls only fraction of input voltage, resulting in lightweight, efficient regulator.
A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.
A power conditioner was developed which used a capacitor diode voltage multiplier to provide a high voltage without the use of a step-up transformer. The power conditioner delivered 1200 Vdc at 100 watts and was operated from a 120 Vdc line. The efficiency was in excess of 90 percent. The component weight was 197 grams. A modified boost-add circuit was used for the regulation. A short circuit protection circuit was used which turns off the drive circuit upon a fault condition, and recovers within 5 ms after removal of the short. High energy density polysulfone capacitors and high speed diodes were used in the multiplier circuit.
A method and apparatus are described for reconditioning batteries utilizing a dc-dc converter. During a discharge of the batteries, each cell is monitored by the converter. When the voltage of a cell decreases to a predetermined level, a converter will assume the load of this cell and inhibit the voltage from reaching zero, thereby preventing voltage reversal of that cell.
Voltage multiplier techniques are extended at medium power levels to larger multiplication ratios. A series of dc-dc converters were built, with from 20 to 45 stages and with power levels up to 100 watts. Maximum output voltages were about 10,000 volts.
The overall objective of the program is to provide the engineering tools to reduce the analysis, design, and development effort, and thus the cost, in achieving the required performances for switching regulators and dc-dc converter systems. The program was both tutorial and application oriented. Various analytical methods were described in detail and supplemented with examples, and those with standardization appeals were reduced into computer-based subprograms. Major program efforts included those concerning small and large signal control-dependent performance analysis and simulation, control circuit design, power circuit design and optimization, system configuration study, and system performance simulation. Techniques including discrete time domain, conventional frequency domain, Lagrange multiplier, nonlinear programming, and control design synthesis were employed in these efforts. To enhance interactive conversation between the modeling and analysis subprograms and the user, a working prototype of the Data Management Program was also developed to facilitate expansion as future subprogram capabilities increase.