Power Electronic Converter-Based Induction Motor Emulator Including Main and Leakage Flux Saturation

Different electric machines are considered for electrified transportation systems. A failure in the control algorithm can result in damage to both the drive and the connected machine. In this paper, an induction motor emulator based on a power electronic converter is developed to allow detailed testing the converter and controller. A proportional-resonant current controller in the abc-frame and pulsewidth modulation is employed. The conventional model of the induction machine with constant parameters does not represent accurately the machine's performance for severe transients specifically during starting and loading conditions. Magnetic saturation effects should be considered. Hence, experimental procedures to determine the flux saturation characteristics in the main and both stator and rotor leakage flux paths are achieved. An approach that utilizes finite-element modeling to separate the leakage reactance at rated current and when the machine is deeply saturated is discussed and verified experimentally. Machine models that consider or neglect the main and leakage flux saturation are compared with experimental results. The model, which considers the magnetic saturation effect in both flux paths, results in more accurate transient responses. Likewise, the dynamic response of the induction motor emulator during startup and loading transients shows the effectiveness of using the developed emulator to resemble closely a real motor.