T.A. Nergaard

Publications (2)0 Total impact

• Conference Proceeding: Design considerations for a 48 V fuel cell to split single phase inverter system with ultracapacitor energy storage

  T.A. Nergaard, J.F. Ferrell, L.G. Leslie, Jih-Sheng Lai
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  ABSTRACT: Fuel cells are a versatile, renewable energy source that can be used in a wide range of applications. In this paper, topologies for a 10 kW inverter system with a low voltage fuel cell input are evaluated based on simplicity, performance, and cost. This particular fuel cell system is intended for household stand-alone power generation. The inverter proposed has a nominal fuel cell input of 48 VDC and is capable of two single phase 120 VAC outputs and one 240 Vac output. Different topology options are explored for the DC-DC converter and the inverter stages, and one combination is evaluated in detail. There is a clear topological choice for the DC-DC converter, but there are a couple of options that work well for the inverter stage. Different choices for energy storage also exist and a good alternative to batteries is presented. The chosen topology contains two modular units, which are supplemented with a set of ultracapacitors at the input for transient conditions. Each module consists of a full-bridge phase-shifted front-end and a half-bridge inverter. Experimental results are displayed for several load conditions
  Power Electronics Specialists Conference, 2002. pesc 02. 2002 IEEE 33rd Annual; 02/2002
• Conference Proceeding: Optimal system efficiency operation of an induction motor drive

  T.A. Nergaard, H.E. Kouns, Jih-Sheng Lai, C.E. Konrad
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  ABSTRACT: The efficiency of an induction motor drive can play an important role in energy conservation, especially for hybrid electric vehicle applications. This paper explores the optimal efficiency point of an inverter and induction motor system designed for an electric vehicle. Theoretically, it is shown that the maximum motor efficiency and maximum torque per ampere occur at different slips. Furthermore it is demonstrated that neither of these points is actually the maximum efficiency of the system during most operating conditions. The efficiency gain is not significant at low speed and low torque, but it can be significant at high speed and low torque. The theoretical results are compared with experimental data for a few operating points.
  Industry Applications Conference, 2002. 37th IAS Annual Meeting. Conference Record of the; 02/2002