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  • 1
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    Integration issues of a plasma contactor Power Electronics Unit (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A hollow cathode-based plasma contactor is baselined on International Space Station Alpha (ISSA) for spacecraft charge control. The plasma contactor system consists of a hollow cathode assembly (HCA), a power electronics unit (PEU), and an expellant management unit (EMU). The plasma contactor has recently been required to operate in a cyclic mode to conserve xenon expellant and extend system life. Originally, a DC cathode heater converter was baselined for a continuous operation mode because only a few ignitions of the hollow cathode were expected. However, for cyclic operation, a DC heater supply can potentially result in hollow cathode heater component failure due to the DC electrostatic field. This can prevent the heater from attaining the proper cathode tip temperature for reliable ignition of the hollow cathode. To mitigate this problem, an AC cathode heater supply was therefore designed, fabricated, and installed into a modified PEU. The PEU was tested using resistive loads and then integrated with an engineering model hollow cathode to demonstrate stable steady-state operation. Integration issues such as the effect of line and load impedance on the output of the AC cathode heater supply and the characterization of the temperature profile of the heater under AC excitation were investigated.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-106977 , E-9739 , NAS 1.15:106977 , AIAA PAPER 95-362 , Intersociety Energy Conversion Engineering Conference; Jul 31, 1995 - Aug 04, 1995; Orlando, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Development Status of the NSTAR Ion Propulsion System Power Processor (1995)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A 0.5-2.3 kW xenon ion propulsion system is presently being developed under the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) program. This propulsion system includes a 30 cm diameter xenon ion thruster, a Digital Control Interface Unit, a xenon feed system, and a power processing unit (PPU). The PPU consists of the power supply assemblies which operate the thruster neutralizer, main discharge chamber, and ion optics. Also included are recycle logic and a digital microcontroller. The neutralizer and discharge power supplies employ a dual use configuration which combines the functions of two power supplies into one, significantly simplifying the PPU. Further simplification was realized by implementing a single thruster control loop which regulates the beam current via the discharge current. Continuous throttling is possible over a 0.5-2.3 kW output power range. All three power supplies have been fabricated and tested with resistive loads, and have been combined into a single breadboard unit with the recycle logic and microcontroller. All line and load regulation test results show the power supplies to be within the NSTAR flight PPU specified power output of 1.98 kW. The overall efficiency of the PPU, calculated as the combined efficiencies of the power supplies and controller, at 2.3 kW delivered to resistive loads was 0.90. The component was 6.16 kg. Integration testing of the neutralizer and discharge power supplies with a functional model thruster revealed no issues with discharge ignition or steady state operation.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-107037 , NAS 1.15:107037 , AIAA PAPER 95-2517 , E-9857 , NIPS-95-06124 , Joint Propulsion Conference and Exhibition; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 3
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    High Performance Power Module for Hall Effect Thrusters (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Previous efforts to develop power electronics for Hall thruster systems have targeted the 1 to 5 kW power range and an output voltage of approximately 300 V. New Hall thrusters are being developed for higher power, higher specific impulse, and multi-mode operation. These thrusters require up to 50 kW of power and a discharge voltage in excess of 600 V. Modular power supplies can process more power with higher efficiency at the expense of complexity. A 1 kW discharge power module was designed, built and integrated with a Hall thruster. The breadboard module has a power conversion efficiency in excess of 96 percent and weighs only 0.765 kg. This module will be used to develop a kW, multi-kW, and high voltage power processors.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2002-211874 , E-13556 , NAS 1.15:211874 , AIAA Paper 2002-3947 , 38th Joint Propulsion Conference and Exhibit; Jul 07, 2002 - Jul 10, 2002; Indianapolis, IN; United States
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    NASA TECHNICAL REPORTS
  • 4
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    Development of Power Electronics for a 0.2kW-Class Ion Thruster (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Applications that might benefit from low power ion propulsion systems include Earth-orbit magnetospheric mapping satellite constellations, low Earth-orbit satellites, geosynchronous Earth-orbit satellite north-south stationkeeping, and asteroid orbiters. These spacecraft are likely to have masses on the order of 50 to 500 kg with up to 0.5 kW of electrical power available. A power processing unit for a 0.2 kW-class ion thruster is currently under development for these applications. The first step in this effort is the development and testing of a 0.24 kW beam power supply. The design incorporates a 20 kHz full bridge topology with multiple secondaries connected in series to obtain outputs of up to 1200 V(sub DC). A current-mode control pulse width modulation circuit built using discrete components was selected for this application. An input voltage of 28 +/- 4 V(sub DC) was assumed, since the small spacecraft for which this system is targeted are anticipated to have unregulated low voltage busses. Efficiencies in excess of 91 percent were obtained at maximum output power. The total mass of the breadboard was less than 1.0 kg and the component mass was 0.53 kg. It is anticipated that a complete flight power processor could weigh about 2.0 kg.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA-TM-113180 , NAS 1.15:113180 , E-10947 , IEPC-97-099 , International Electric Propulsion Conference; Aug 24, 1997 - Aug 28, 1997; Cleveland, OH; United States
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    NASA TECHNICAL REPORTS
  • 5
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    Development Status of a Power Processing Unit for Low Power Ion Thrusters (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An advanced breadboard Power Processing Unit (PPU) for a low power ion propulsion system incorporating mass reduction techniques was designed and fabricated. As a result of similar output current requirements, the discharge supply was also used to provide the neutralizer heater and discharge heater functions by using three relays to switch the output connections. This multi-function supply reduces to four the number of power converters needed to produce the required six electrical outputs. Switching frequencies of 20 and 50 kHz were chosen as a compromise between the size of the magnetic components and switching losses. The advanced breadboard PPU is capable of a maximum total output power of 0.47 kW. Its component mass is 0.65 kg and its total mass 1.9 kg. The total efficiency at full power is 0.89.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2000-210383 , E-12440 , NAS 1.15:210383 , AIAA Paper 2000-3817 , Joint Propulsion; Jul 16, 2000 - Jul 19, 2000; Huntsville, AL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Power Electronics for a Miniaturized Arcjet (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A 0.3 kW Power Processing Unit (PPU) was designed, tested on resistive loads, and then integrated with a miniaturized arcjet. The main goal of the design was to minimize size and mass while maintaining reasonable efficiency. In order to obtain the desired reductions in mass, simple topologies and control methods were considered. The PPU design incorporates a 50 kHz, current-mode-control, pulse-width-modulated (PWM), push-pull topology. An input voltage of 28 +/- 4V was chosen for compatibility with typical unregulated low voltage busses anticipated for smallsats. An efficiency of 0.90 under nominal operating conditions was obtained. The component mass of the PPU was 0.475 kg and could be improved by optimization of the output filter design. The estimated mass for a flight PPU based on this design is less than a kilogram.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA-TM-107414 , NAS 1.15:107414 , AIAA Paper 96-2961 , E-10650 , Joint Propulsion; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
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    NASA TECHNICAL REPORTS
  • 7
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    NSTAR Ion Thruster and Breadboard Power Processor Functional Integration Test Results (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A 2.3 kW Breadboard Power Processing Unit (BBPPU) was developed as part of the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) Program. The NSTAR program will deliver an electric propulsion system based on a 30 cm xenon ion thruster to the New Millennium (NM) program for use as the primary propulsion system for the initial NM flight. The final development test for the BBPPU, the Functional Integration Test, was carried out to demonstrate all aspects of BBPPU operation with an Engineering Model Thruster. Test objectives included: (1) demonstration and validation of automated thruster start procedures, (2) demonstration of stable closed loop control of the thruster beam current, (3) successful response and recovery to thruster faults, and (4) successful safing of the system during simulated spacecraft faults. These objectives were met over the specified 80-120 VDC input voltage range and 0.5-2.3 output power capability of the BBPPU. Two minor anomalies were noted in discharge and neutralizer keeper current. These anomalies did not affect the stability of the system and were successfully corrected.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA-TM-107305 , E-10392 , NAS 1.15:107305 , AIAA Paper 96-2720 , Joint Propulsion Conference; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
    Format: application/pdf
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  • 8
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    Multi-Kilowatt Power Module for High-Power Hall Thrusters (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Future NASA missions will require high-performance electric propulsion systems. Hall thrusters are being developed at NASA Glenn for high-power, high-specific impulse operation. These thrusters operate at power levels up to 50 kW of power and discharge voltages in excess of 600 V. A parallel effort is being conducted to develop power electronics for these thrusters that push the technology beyond the 5kW state-of-the-art power level. A 10 kW power module was designed to produce an output of 500 V and 20 A from a nominal 100 V input. Resistive load tests revealed efficiencies in excess of 96 percent. Load current share and phase synchronization circuits were designed and tested that will allow connecting multiple modules in parallel to process higher power.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2005-213348 , AIAA Paper 2004-3973 , E-14816 , 40th Joint Propulsion Conference and Exhibit; Jul 11, 2004 - Jul 14, 2004; Fort Lauderdale, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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