Chapter 3 - Modeling and analysis of induction machines

Abstract

Simplified and complete fundamental and harmonic equivalent circuits of three-phase induction machines are discussed. Detailed magnetic fields under steady-state, transient, starting, and short-circuit conditions based on finite-difference (FD) method are presented. Operating point-dependent saturation is introduced. Such calculated magnetic field solutions are novel and not published to date in power quality books. Time and spatial harmonics, interharmonics, and subharmonic losses of three-phase induction machines are calculated and measured, greatly influencing induction machine performance. Fundamental and harmonic torque measurements and resulting operating characteristics for single-phase and three-phase induction machines are presented and explained. The interaction of space and time harmonics is analyzed. The winding stress caused by pulse-width-modulated (PWM), current-controlled voltage-source inverters plays an important role in the design of machines, transformers, variable-speed drives, and power system components. A three-phase induction machine operating within a single-phase power system is important from an electric noise development approach and for providing increased torque within a (rural) single-phase distribution system. The concept of compensation of flux weakening (CFW) leads to increased torques at flux-weakening (FW) operation, which is very important for power-electronic drives employed by electric automobiles at high speed and permits the deployment of batteries with reduced DC output voltages.