The 30-cm ion thruster power processor

A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range

Resonant Behaviour of Pulse Generators for the Efficient Drive of Optical Radiation Sources Based on Dielectric Barrier Discharges

Dielectric barrier discharge (DBD) excimer lamps emit vacuum-UV optical radiation. This work presents novel methods for efficiently operating DBDs with short, high-voltage pulses. Transformer-less systems utilising SiC power semiconductor switches are presented. Pulse frequencies of up to 3.1 MHz and peak inverter efficiencies of 92 % were achieved. The work encloses both mathematical backgrounds of pulsed resonant circuits and practical implementation of low-inductive power stages

Electronic operation and control of high-intensity gas-discharge lamps

The ever increasing amount of global energy consumption based on the application of fossil fuels is threatening the earth’s natural resources and environment. Worldwide, grid-based electric lighting consumes 19 % of total global electricity production. For this reason the transition towards energy efficient lighting plays an important environmental role. One of the key technologies in this transition is High-Intensity Discharge (HID) lighting. The technical revolution in gas-discharge lamps has resulted in the highlyefficient lamps that are available nowadays. As with most energy efficient light solutions, all HID lighting systems require a ballast to operate. Traditionally, magnetic ballast designs were the only choice available for HID lighting systems. Today, electronic lampdrivers can offer additional power saving, flicker free operation, and miniaturisation. Electronic lamp operation enables additional degrees of freedom in lamp-current control over the conventional electro-magnetic (EM) ballasts. The lamp-driver system performance depends on both the dynamics of the lamp and the driver. This thesis focuses on the optimisation of electronically operated HID systems, in terms of highly-efficient lamp-driver topologies and, more specifically, lamp-driver interaction control. First, highly-efficient power topologies to operate compact HID lamps on low-frequency-square-wave (LFSW) current are explored. The proposed two-stage electronic lamp-driver consists of a Power Factor Corrector (PFC) stage that meets the power utility standards. This converter is coupled to a stacked buck converter that controls the lamp-current. Both stages are operated in Zero Voltage Switching (ZVS) mode in order to reduce the switching losses. The resulting two-stage lamp-drivers feature flexible controllability, high efficiency, and high power density, and are suitable for power sandwich packaging. Secondly, lamp-driver interaction (LDI) has been studied in the simulation domain and control algorithms have been explored that improve the stability, and enable system optimisation. Two HID lamp models were developed. The first model describes the HID lamp’s small-signal electrical behaviour and its purpose is to aid to study the interaction stability. The second HID lamp model has been developed based on physics equations for the arc column and the electrode behaviour, and is intended for lampdriver simulations and control applications. Verification measurements have shown that the lamp terminal characteristics are present over a wide power and frequency range. Three LDI control algorithms were explored, using the proposed lampmodels. The first control principle optimises the LDI for a broad range of HID lamps operated at normal or reduced power. This approach consists of two control loops integrated into a fuzzy-logic controller that stabilises the lamp-current and optimises the commutation process. The second control problem concerns the application of ultra high performance (UHP) HID lamps in projection applications that typically set stringent requirements on the quality of the light generated by these lamps, and therefore the lampcurrent. These systems are subject to periodic disturbances synchronous with the LFSW commutation period. Iterative learning control (ILC) has been examined. It was experimentally verified that this algorithm compensates for repetitive disturbances. Third, Electronic HID operation also opens the door for continuous HID lamp dimming that can provide additional savings. To enable stable dimming, an observer-based HID lamp controller has been developed. This controller sets a stable minimum dim-level and monitors the gas-discharge throughout lamp life. The HID lamp observer derives physical lamp state signals from the HID arc discharge physics and the related photometric properties. Finally, practical measurements proved the proposed HID lamp observer-based control principle works satisfactorily

Synthesized High-Frequency Thyristor for Dielectric Barrier Discharge Excimer Lamps

Dielectric barrier discharge (DBD) lamps, being capacitive loads, must be associated with bidirectional current sources for an appropriate control of the transferred power. Pulsed current source supplies, which are known to offer very interesting performances, require specific power switches that are able to manage bidirectional voltage and unidirectional current at much higher frequencies (several hundreds of kilohertz) than commercial thyristors. This paper proposes the detailed design of such a high-speed synthesized thyristor, using discrete components: a MOSFET in series with a high-voltage (HV) diode and a logic circuit that controls its gate. This switch is associated with an optimized self-powered driver, which is a very efficient solution to handle the perturbations associated with the HV and high-frequency operation. Experimental application of this device for DBD excimer lamp supply is proposed

Analysis of electric propulsion electrical power conditioning component technology. Volume 1 - Data bank Final report

Analysis of electric propulsion electric power conditioning component technology - data revie

Modeling and Analysis of Power Processing Systems

The feasibility of formulating a methodology for the modeling and analysis of aerospace electrical power processing systems is investigated. It is shown that a digital computer may be used in an interactive mode for the design, modeling, analysis, and comparison of power processing systems

Resonant Behaviour of Pulse Generators for the Efficient Drive of Optical Radiation Sources Based on Dielectric Barrier Discharges

Excimer-Lampen basierend auf Dielektrisch Behinderten Entladungen (DBD) sind effiziente Quellen ultravioletter Strahlung. Diese Arbeit verbindet theoretische Betrachtungen mit der praktischen Verifikation neu entwickelter Topologien und Betriebsmodi, um DBEs effizient mit kurzen Hochspannungspulsen zu betreiben. Durch transformatorlose Topologien und Nutzung von SiC Leistungshalbleitern konnten Effizienzen von bis zu 92 % und Pulsfrequenzen von bis zu 3.1 MHz erreicht werden

A novel RGBW pixel for LED displays

In this work, a novel pixel configuration RGBW, consisting of red (R), green (G), blue (B), and white (W) LEDs, is employed and investigated for color generation. Energy consumption and various hues of new pixels are compared to standard pixels consisting of RGB LEDs. Human perception experiments are conducted in order to study the perceptual difference between the two architectures when the same colors are generated using RGBW vs. RGB. Power measurements for an 8x8 pixel LED display has demonstrated up to 49% power savings for gray scale, over 30% power savings for low saturated colors, and up to 12% for high saturated colors using RGBW as an alternative. Furthermore, human perception studies has shown that vast majority of test subjects could not distinguish between most colors displayed using RGB and RGBW showing that RGBW is an excellent substitute for RGB. Statistics has shown that 44% of test subjects found the colors in gray scale to be the same, whereas 82% and 95% of test subject found low saturated colors and high saturated colors, respectively, to be identical

Portable Computer Technology (PCT) Research and Development Program Phase 2

The subject of this project report, focused on: (1) Design and development of two Advanced Portable Workstation 2 (APW 2) units. These units incorporate advanced technology features such as a low power Pentium processor, a high resolution color display, National Television Standards Committee (NTSC) video handling capabilities, a Personal Computer Memory Card International Association (PCMCIA) interface, and Small Computer System Interface (SCSI) and ethernet interfaces. (2) Use these units to integrate and demonstrate advanced wireless network and portable video capabilities. (3) Qualification of the APW 2 systems for use in specific experiments aboard the Mir Space Station. A major objective of the PCT Phase 2 program was to help guide future choices in computing platforms and techniques for meeting National Aeronautics and Space Administration (NASA) mission objectives. The focus being on the development of optimal configurations of computing hardware, software applications, and network technologies for use on NASA missions