Power Hardware-in-the-Loop-Based Emulation of Induction Machines With Static Eccentricity

This article presents a power hardware-in-the-loop (PHIL)-based emulation testing method for investigating eccentricity faults in wound-rotor induction machines (WRIMs). Due to the smaller per-unit air-gap length and high-power ratings of WRIMs, even minor eccentricities can be hazardous, yet inclined eccentricity, which is more prevalent in practical scenarios, has been underexplored. Conventional fault studies rely on physical prototypes and large test benches, leading to high cost and prototyping delays. The proposed PHIL approach integrates a high-fidelity analytical model to replicate complex inclined eccentricity fault behaviors in real time. This method provides substantial cost reductions over conventional dynamometer-driven setups by replacing expensive mechanical test-bed components and single-use custom motors with power electronic-based setups, while eliminating assembly delays and mitigating the physical risks of direct fault testing. The analytical model for the inclined eccentricity fault is developed using the modified winding function method, accounting for the complexity arising from air-gap variations that change circumferentially and axially in a motor. The emulation results are validated against experimental measurements from a scaled-down 2.5 MW WRIM test rig, demonstrating strong correlation and confirming the accuracy of the approach. Linear amplifier and switched converter-based emulation results are compared with the actual machine.