Electric propulsion with emphasis on switched reluctance motors and the motor optimum speed ratio.

摘要

This dissertation firstly proposes a straightforward approach for calculating the internal dimensions of a Switched Reluctance Motor (SRM) operating under multi-phase excitation. The SRM produces torque via the variation of the reluctance of the magnetic path. Thus, it is also called the variable reluctance motor and its design is based on this principle. The design approach benefits from the short flux paths mode to determine new design coefficients that extend previous single-phase design procedures to multi-phase excitation, taking into account the motor electric and magnetic constraints on the electric motor drive. The determination of the design coefficients uses 2D-FEA analysis as the basis for dimensionally sizing any SRM configuration under multi-phase excitation. A design program calculates the SRM geometry, total weight, peak current, current density and copper loss. A four-phase 8/6 SRM prototype designed and built based on the above approach demonstrates the feasibility of our ideas when comparing torque for different operating modes (e.g., single-phase, multi-phase short-flux and long-flux paths).; This dissertation secondly shows the need to establish the optimum speed ratio (i.e., rated frequency) for selecting and building the motor magnetic core and defines a new concept of operating efficiency, the average efficiency, that can be used as a comparing tool for different electric motor drives for Electric Vehicle and Hybrid Electric Vehicle (EV/HEV) traction.; Induction and Permanent Magnet Synchronous Motors are analyzed to demonstrate this idea for HEV traction applications. The IM and PMSM produce torque via the interaction of two magnetic fields, one in the stator and another in the rotor. That is, this principle is different to that of the SRM. Therefore, their designs are different and in the case of the PMSM, the procedure must take into account the dimensions of the space required for the permanent magnets. In other words, the design issues in IM and PMSM are different from those of the SRM. New scaling equations determine the outer dimensions, total weight, volume and loss components for motors operating at different speed ratios (i.e., rated speeds). Simulation results show improvements in the motor drive performance and flexibility to electric motor designers to tailor their designs to obtain certain performance specifications before the actual machine is designed.