Engineering topics

Tam, Kwa-Sur

Publications and source records attributed to Tam, Kwa-Sur.

6 records

NASA NTRS1991

An EMTP system level model of the PMAD DC test bed

A power management and distribution direct current (PMAD DC) test bed was set up at the NASA Lewis Research Center to investigate Space Station Freedom Electric Power Systems issues. Efficiency of test bed operation significantly improves with a computer simulation model of the test bed as an adjunct tool of investigation. Such a model is developed using the Electromagnetic Transients Program (EMTP) and is available to the test bed developers and experimenters. The computer model is assembled on a modular basis. Device models of different types can be incorporated into the system model with only a few lines of code. A library of the various model types is created for this purpose. Simulation results and corresponding test bed results are presented to demonstrate model validity.

Dravid, Narayan V.↗

NASA NTRS1991

Functional models of power electronic components for system studies

A novel approach to model power electronic circuits has been developed to facilitate simulation studies of system-level issues. The underlying concept for this approach is to develop an equivalent circuit, the functional model, that performs the same functions as the actual circuit but whose operation can be simulated by using larger time step size and the reduction in model complexity, the computation time required by a functional model is significantly shorter than that required by alternative approaches. The authors present this novel modeling approach and discuss the functional models of two major power electronic components, the DC/DC converter unit and the load converter, that are being considered by NASA for use in the Space Station Freedom electric power system. The validity of these models is established by comparing the simulation results with available experimental data and other simulation results obtained by using a more established modeling approach. The usefulness of this approach is demonstrated by incorporating these models into a power system model and simulating the system responses and interactions between components under various conditions.

Tam, Kwa-Sur↗

NASA NTRS1991

Modeling of Space Station power system components and their interactions

The authors demonstrate that the functional modeling approach is feasible in modeling large-scale spacecraft power systems such as the Space Station electric power system (EPS). The functional models for the solar array sequential shunt unit and the battery charging/discharging unit are presented. The functional modeling approach has also been applied to simulate other major EPS components. The usefulness of this approach in system-level studies has been demonstrated by incorporating these models into a power system model and simulating the system behavior under various conditions. The simulation results are consistent with those obtained experimentally. With larger time step size and reduced model complexity, the computation time required by the functional modeling approach is short. Functional models are effective in simulation studies of system-level issues, especially for large-scale power systems including many power electronic components.

Tam, Kwa-Sur↗

NASA NTRS1991

An EMTP system level model of the PMAD DC test bed

A power management and distribution direct current (PMAD DC) test bed was set up at the NASA Lewis Research Center to investigate Space Station Freedom Eelectric Power Systems issues. Efficiency of test bed operation significantly improves with a computer simulation model of the test bed as an adjunct tool of investigation. Such a model is developed using the Electromagnetic Transients Program (EMTP) and is available to the test bed developers and experimenters. The computer model is assembled on a modular basis. Device models of different types can be incorporated into the system model with only a few lines of code. A library of the various model types is created for this purpose. Simulation results and corresponding test bed results are presented to demonstrate model validity.

Dravid, Narayan V.↗

NASA NTRS1990

Modeling of Space Station electric power system with EMTP

The authors provide an introduction to using the electromagnetic transients (EMTP) program to model aerospace power system components. A brief general overview of EMTP is presented. The modeling of the dc/dc converter unit in the space station electric power system is described as an illustration.

Tam, Kwa-Sur↗

NASA NTRS1989

Modeling of power electronic systems with EMTP

In view of the potential impact of power electronics on power systems, there is need for a computer modeling/analysis tool to perform simulation studies on power systems with power electronic components as well as to educate engineering students about such systems. The modeling of the major power electronic components of the NASA Space Station Freedom Electric Power System is described along with ElectroMagnetic Transients Program (EMTP) and it is demonstrated that EMTP can serve as a very useful tool for teaching, design, analysis, and research in the area of power systems with power electronic components. EMTP modeling of power electronic circuits is described and simulation results are presented.

Tam, Kwa-Sur↗