Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “power control”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Failure Detector for Power-Factor Controller

New protective circuits have been developed for power-factor ac motor controllers. Circuits prevent direct current and consequent motor heating that would normally result from failure of solid-state switch in controller. Single-phase power-factor controller with short detector compensates for short-circuit failure in either direction by applying full power to motor. Controller with open detector compensates for open-circuit failure in either direction by turning off power to motor.

Nola, F. J.↗
NASA NTRS2010

Closed Brayton Cycle Power Conversion Unit for Fission Surface Power Phase I Final Report

A Closed Brayton cycle power conversion system has been developed to support the NASA fission surface power program. The goal is to provide electricity from a small nuclear reactor heat source for surface power production for lunar and Mars environments. The selected media for a heat source is NaK 78 with water as a cooling source. The closed Brayton cycle power was selected to be 12 kWe output from the generator terminals. A heat source NaK temperature of 850 K plus or minus 25 K was selected. The cold source water was selected at 375 K plus or minus 25 K. A vacuum radiation environment of 200 K is specified for environmental operation. The major components of the system are the power converter, the power controller, and the top level data acquisition and control unit. The power converter with associated sensors resides in the vacuum radiation environment. The power controller and data acquisition system reside in an ambient laboratory environment. Signals and power are supplied across the pressure boundary electrically with hermetic connectors installed on the vacuum vessel. System level analyses were performed on working fluids, cycle design parameters, heater and cooling temperatures, and heat exchanger options that best meet the needs of the power converter specification. The goal is to provide a cost effective system that has high thermal-to-electric efficiency in a compact, lightweight package.

Fuller, Robert L.↗
NASA NTRS1977

Power factor control system for AC induction motors

A power factor control system for use with ac induction motors was designed which samples lines voltage and current through the motor and decreases power input to the motor proportional to the detected phase displacement between current and voltage. This system provides, less power to the motor, as it is less loaded.

Nola, F. J.↗
NASA NTRS1997

Evaluation of a Neural Adaptive Flight Controller

The objective of this paper is to present results from the evaluation of a direct adaptive tracking controller. The control architecture employs both pre-trained and an on-line neural networks to represent the non-linear aircraft dynamics in the model inversion portion of the controller. The aircraft model used for this evaluation is representative of the F-15 Advanced Control Technology for Integrated Vehicles (ACTIVE) aircraft. The controller was evaluated for three cases: (1) nominal conditions; (2) loss of control power; and (3) loss of control power in the presence of atmospheric turbulence. The results were compared with the existing F-15 ACTIVE conventional mode controller in all cases. The results indicate extremely desirable airframe stabilization characteristics for case (1) that do not degrade significantly for case (2) or (3) as does the conventional mode controller. It was concluded that this controller exhibits both stable and robust adaptive characteristics when subjected to mild and extreme loss of control power conditions. Integration of this neural adaptive flight controller into the full non-linear six degree-of-freedom F-15 ACTIVE simulation is recommended for evaluation in a real-time high fidelity piloted simulation environment.

Totah, Joseph J.↗
NASA NTRS1983

Advanced Control and Power System (ACAPS) Technology Program

The advanced control and power system (ACAPS) program is to establish the technology necessary to satisfy space station and related large space structures requirements for efficient, reliable, and cost effective energy storage and attitude control. Technology advances in the area of integrated flywheel systems capable of performing the dual functions of energy storage and attitude control are outlined.

Keckler, C. R.↗
NASA NTRS1983

Motor power factor controller with a reduced voltage starter

A power factor type motor controller in which the conventional power factor constant voltage command signal is replaced during a starting interval with a graduated control voltage. The present invention adds to the three-phase system of pending application Ser. No. 199,765, filed Oct. 23, 1980, means for modifying the operation of the system for a motor start-up interval of 5 to 30 seconds. The modification is that of providing via ramp generator 174 an initial ramp-like signal which replaces a constant power factor signal supplied by potentiometer 70. The ramp-like signal is applied to terminal 40 where it is summed with an operating power factor signal from phase detectors 32, 34, and 36 to thereby obtain a control signal for ultimately controlling SCR devices 12, 14, and 16 to effect a gradual turn-on of motor 10. The significant difference of the present invention over prior art is that the SCR devices are turned on at an advancing rate with time responsive to the combination signal described rather than simply a function of a ramp-like signal alone. The added signal, the operating power factor signal, enables the production of a control signal which effectively eliminates a prior problem with many motor starting circuits, which is that of accompanying motor instabilities.

Nola, Frank J.↗
NASA NTRS2008

Distributed solid state programmable thermostat/power controller

A self-contained power controller having a power driver switch, programmable controller, communication port, and environmental parameter measuring device coupled to a controllable device. The self-contained power controller needs only a single voltage source to power discrete devices, analog devices, and the controlled device. The programmable controller has a run mode which, when selected, upon the occurrence of a trigger event changes the state of a power driver switch and wherein the power driver switch is maintained by the programmable controller at the same state until the occurrence of a second event.

Alexander, Jane C.↗
NASA NTRS1983

Digital Single-Phase Power-Factor Controller

Digital circuit has faster response to load changes. Digital power-factor controller senses changing motor-load torques by sampling open-circuit voltage across gate-controlled silicon switch. Circuit responds more rapidly to hanging loads than analog power-factor controllers because no low-pass filter is in feedback loop.

Dabney, R. W.↗
NASA NTRS1980

Performance of a flight qualified, thermoelectrically temperature controlled QCM sensor with power supply, thermal controller and signal processor

A thermoelectrically temperature controlled quartz crystal microbalance (QCM) system was developed for the measurement of ion thrustor generated mercury contamination on spacecraft. Meaningful flux rate measurements dictated an accurately held sensing crystal temperature despite spacecraft surface temperature variations from -35 C to +60 C over the flight temperature range. An electronic control unit was developed with magentic amplifier transformer secondary power supply, thermal control electronics, crystal temperature analog conditioning and a multiplexed 16 bit frequency encoder.

Wallace, D. A.↗
NASA NTRS1981

Motor power factor controller with a reduced voltage starter

A power factor type motor controller is disclosed in which the conventional power factor constant voltage command signal is replaced during a starting interval with a graduated control voltage. This continuation-impart of a pending patent application (Serial No. 199, 765: Three Phase Factor Controller) provides a means for modifying the operation of the system for a motor start-up interval of 5 to 30 second. Using a ramp generators, an initial ramp-like signal replaces a constant power factor signal supplied by a potentiometer. The ramp-like signal is applied to a 15 terminal where it is summed with an operating power factor signal from phase detectors in order to obtain a control signal for ultimately controlling SCR devices. The SCR devices are turned on at an advancing rate with time responsive to the combination signal described rather than simply a function of a ramp-like signal alone.

Nola, F. J.↗
NASA NTRS1995

Improved Controllers For Heaters In Toxic-Gas Combustors

Commercial electronic proportional controllers installed in place of mechanical power controllers for electric heaters in toxic-gas combustors at NASA's Jet Propulsion Laboratory. Designed to maintain temperature of heater at preset value by turning power fully on or fully off when temperature falls below or rises above that value, respectively. Solid-state power controllers overcome deficiencies of mechanical power controllers.

Wishard, James↗
NASA NTRS1983

Power Factor Controller Avoids False Turnoff

Single-phase power-factor controller includes special inhibiting circuit to avoid false turnoff. If thyristor trigger signal occurs during flow of current from preceding half cycle, inhibiting signal delays application of trigger pulse until beginning of next current half cycle.

Nola, F. J.↗
NASA NTRS1984

Phase Detector for Power-Factor Controller

Positive feedback assures reliable switching. Three Phase Power Factor Controller includes three phase detectors, each produces rectangular waves of duration approximately equal to lag time between line voltage and motor current.

Nola, F. J.↗
NASA NTRS1984

Phase detector for three-phase power factor controller

A phase detector for the three phase power factor controller (PFC) is described. The phase detector for each phase includes an operational amplifier which senses the current phase angle for that phase by sensing the voltage across the phase thyristor. Common mode rejection is achieved by providing positive feedback between the input and output of the voltage sensing operational amplifier. this feedback preferably comprises a resistor connected between the output and input of the operational amplifier. The novelty of the invention resides in providing positive feedback such that switching of the operational amplifier is synchronized with switching of the voltage across the thyristor. The invention provides a solution to problems associated with high common mode voltage and enables use of lower cost components than would be required by other approaches.

Nola, F. J.↗
NASA NTRS1985

Power-Factor Controllers: How Safe?

Potential safety problems with power-factor controllers (PFC's) evaluated. Based on study of PFCs in use with appliances, report recommends measures to prevent consumers from misapplying these energy saving devices. Device used on such appliances as refrigerators, sewing machines, pumps, hair dryers, and food processors. When misused, they fail to save energy and may cause damage.

Long, K.↗
NASA NTRS1953

Review and investigation of unsatisfactory control characteristics involving in stability of pilot-airplane combination and methods for predicting these difficulties from ground tests

A number of examples are presented of control difficulties not completely covered by existing handling-qualities requirements. 520/3:*:These control difficulties appear to result from a tendency for dynamic instability of the combination of pilot, control system, and airplane. The unsatisfactory characteristics involved have been encountered most frequently with hydraulic-power control systems. The nature of the difficulties may range from a slight interference with the ability of the pilot to hold precisely straight and level flight to a dangerous tendency toward divergent short-period oscillations which require constant attention of the pilot to control. Tests of a bomber and a fighter airplane with experimental power control systems have been made to study this problem further. The results of the investigation show that control difficulties of the type considered have always been associated with a marked phase difference between the pilot's control force and the associated control-surface deflection. The presence of static friction in the control valves of hydraulic-power control systems was found to be the explanation for unsatisfactory characteristics in several airplanes equipped with such systems. The valve friction may cause a phase lag between the pilot's control force and the associated control-surface deflection approaching 180 degrees at small control deflections. Definite limits or simple rules for the tolerable amount of valve friction appear to be difficult to establish because of the large number of variables which may influence the problem.The control characteristics of the airplanes tested were strongly influenced by minor design details of the power control systems.

Phillips, William H↗