The Feasibility Study of an Isolated Induction Motor / Induction Generator Power Conversion System Based upon a 20 kHz Parallel Resonant AC Link
Tez Türü: Doktora
Tezin Yürütüldüğü Kurum: The University of Wisconsin Madison, Graduate School, Electrical Engineering, Amerika Birleşik Devletleri
Tez Danışmanı: Prof. Thomas A. Lipo
Tezin Onay Tarihi: 1993
Özet:
Two squirrel cage induction machines interconnected via a 20 kHz parallel resonant high frequency AC link and associated switching Pulse Density Modulated (PDM) converters are investigated. Both theoretical and experimental background investigation leading to the realization of such a system capable of operating at 10 Hp has been carried out. Theoretical analysis, formulation of the system required for the software simulations and experimental realization has been developed. The feasibility of operation of such a system has been fully demonstrated by means of both computer simulations as well as experimental results. Both induction machines have been shown to be in need of no excitation capacitors at their terminals when they are operated from a 20 kHz HF AC link via associated PDM converters. Initial excitation of the generator by means of an initial charging circuit used to build-up the link voltage at the same time has been shown. The real power of the generator has been shown to be controlled well enough to maintain the proper link voltage and match the power between the input and output. A fast way of average power estimation technique for the current fed field oriented induction machine has been outlined along with a review of induction machine field orientation dynamics. The effectiveness of this fast average active power estimation technique based upon the dc reference quantities of field orientation controller, speed information and machine parameters has been demonstrated. Competent performance of power estimation techniqe for the link, converter and machine losses based upon some prior knowledge of operational losses, measured and command quantities has been illustrated. The regulation of the HF peak link voltage has been shown to be achievable within the desired limits with the proper selection of resonant tank circuit. The induction generator at the input has been shown to be capable of operating in two quadrants of operation while the motor at the output in all four quadrants because of the control techniques utilized and the bidirectional power flow capability of the overall converter structure. A zero voltage switching technique is utilized with the associated PDM converters. Low harmonic distortion waveforms has been obtained both at the input and output due to the 40 kHz high switching frequency. It has also been shown via software simulation results that a total end to end system efficiency in the range of 50-55%, link efficiency of about 85%, a combined converter and link efficiency in the range of 75-80% and a combined generator and motor efficiency of about 75-80% could be achieved in such a system. Such a system lends itself easily to typical aerospace utility applications as a means of obtaining high power densities [Watts/kg] and flexibility in accomplishing voltage level changes.