Design and development of a controller for a brushless doubly-fed automotive alternator system

approved : Rene Spee The loads on the electrical systems of automobiles are projected to increase significantly in the near future. This will result in a requirement for improved efficiency over the present-day car alternators. An alternative scheme proposed at Oregon State University employs a Brushless Doubly-Fed Machine (BDFM) as an alternator. This thesis begins with a study and characterization of the existing car alternator system. The configuration of the proposed scheme is discussed. In the proposed configuration, the power winding of the machine generates the bulk of the power and the control winding provides the excitation. The power winding feeds a power rectifier, which in turn charges the battery in an automobile. The control winding is supplied through an inverter. Issues related to inverter and rectifier design are discussed. A 3-phase pulse width modulated inverter and a bridge rectifier were developed and tested for performance. A PSPICE simulation model for the rectifier was developed and results are compared with laboratory tests. A Voltage Regulator Circuit (VRC) and an Efficiency Maximizer Unit (EMU) for the system are designed and developed. A prototype alternator system is tested and the principle of efficiency maximization is verified. Finally, the comparative performance of the the existing and the proposed system is discussed and some recommendations for further improvements in the prototype system are made. Design and Development of a Controller for a Brushless Doubly-Fed Automotive Alternator System by Virendra S. Javadekar A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed January 31, 1992 Commencement June 1992 APPROVED: Redacted for Privacy Assistant Professor of Electrical and Computer Engineering in charge of major Redacted for Privacy Head of ent of Electrical and Computer Engineering Redacted for Privacy Dean of Graduaryhool d Date thesis is presented January 31. 1992 Typed by Virendra S. Javadekar