Discrete-time integral terminal sliding mode based maximum power point controller for the PMSG-based wind energy system

This study proposes a discrete-time integral terminal sliding mode controller (DITSMC) integrated with a sensorless maximum power point tracking (MPPT) method for a permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS). The effects of the parameters of the proposed DITSMC on the convergence-time and the error-bound are investigated by the simulation studies. The dynamic performance of the DITSMC has been evaluated experimentally on a test bench for step-type wind changes. The optimum coefficient between the output voltage of the generator and the extracted power from the WECS is determined only for a wind speed by offline studies. Then, the MPPT can be provided using this coefficient for all wind speeds in the operating range of the WECS without any mechanical sensor. Additionally, the experimental studies show that DITSMC has better performance than the PI controller in terms of the settling time and thus the efficiency of the WECS

Glosarium Matematika

273 p.; 24 cm

Aeronautical engineering: A continuing bibliography with indexes (supplement 278)

This bibliography lists 414 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1992

AAS/GSFC 13th International Symposium on Space Flight Dynamics

This conference proceedings preprint includes papers and abstracts presented at the 13th International Symposium on Space Flight Dynamics. Cosponsored by American Astronautical Society and the Guidance, Navigation and Control Center of the Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude dynamics; and mission design

1999 Flight Mechanics Symposium

This conference publication includes papers and abstracts presented at the Flight Mechanics Symposium held on May 18-20, 1999. Sponsored by the Guidance, Navigation and Control Center of Goddard Space Flight Center, this symposium featured technical papers on a wide range of issues related to orbit-attitude prediction, determination, and control; attitude sensor calibration; attitude determination error analysis; attitude dynamics; and orbit decay and maneuver strategy. Government, industry, and the academic community participated in the preparation and presentation of these papers

Accelerometer calibration for NASA\u27s magnetospheric multiscale mission spacecraft

This thesis presents several methods for the on-board and/or ground-based calibration of accelerometers for the spacecraft (s/c) of the NASA Magnetospheric Multi-Scale (MMS) Mission during mission operation. A lumped bias is estimated to correct for the total effect of the MMS accelerometer sensor bias, orthogonal misalignment and the shift in the s/c\u27s center of mass. Various estimation techniques are evaluated and compared, including both dynamically driven real-time filters/observers and post processing batch algorithms. Both methods are shown to accurately determine lumped bias, so long as the s/c inertia tensor is well known. If, however, there is any uncertainty in the inertia tensor, only post processing methods yield accurate lumped bias estimates. Analytical simulations show that these methods are able to correct accelerometer readings to within 1 micro-g of true acceleration. Preliminary experimental verification also shows proof of concept

Tethered gravity laboratories study

The scope of the study is to investigate ways of controlling the microgravity environment of the International Space Station by means of a tethered system. Four main study tasks were performed. First, researchers analyzed the utilization of the tether systems to improve the lowest possible steady gravity level on the Space Station and the tether capability to actively control the center of gravity position in order to compensate for activities that would upset the mass distribution of the Station. The purpose of the second task was to evaluate the whole of the experiments performable in a variable gravity environment and the related beneficial residual accelerations, both for pure and applied research in the fields of fluid, materials, and life science, so as to assess the relevance of a variable g-level laboratory. The third task involves the Tethered Variable Gravity Laboratory. The use of the facility that would crawl along a deployed tether and expose experiments to varying intensities of reduced gravity is discussed. Last, a study performed on the Attitude Tether Stabilizer concept is discussed. The stabilization effect of ballast masses tethered to the Space Station was investigated as a means of assisting the attitude control system of the Station

Aeronautical engineering: A continuing bibliography with indexes (supplement 218)

This bibliography lists 469 reports, articles, and other documents introduced into the NASA scientific and technical information system in September, 1987

Flight Mechanics/Estimation Theory Symposium, 1989

Numerous topics in flight mechanics and estimation were discussed. Satellite attitude control, quaternion estimation, orbit and attitude determination, spacecraft maneuvers, spacecraft navigation, gyroscope calibration, spacecraft rendevous, and atmospheric drag model calculations for spacecraft lifetime prediction are among the topics covered