Active magnetic bearings (AMBs), pivotal in high-speed rotating machinery for their frictionless operation and precise control, demand power amplifiers with exceptional dynamic performance and minimal current ripple. However, conventional amplifier designs often overlook eddy current effects, a critical oversight given the high-frequency switching inherent to pulse-width modulation (PWM). These induced eddy currents distort output waveforms, amplify ripple, and degrade system bandwidth. This paper bridges this critical gap by proposing a comprehensive methodology to model, quantify, and mitigate eddy current impacts on three-level half-bridge power amplifiers. A novel mutual inductance-embedded circuit model was developed, integrating winding–eddy current interactions under PWM operations, while a discretized transfer function framework dissects frequency-dependent ripple amplification and phase hysteresis. A voltage selection criterion was analytically derived to suppress nonlinear distortions, ensuring stable operation in high-precision applications. A Simulink simulation model was established to verify the accuracy of the theoretical model. Experimental validation demonstrated a 212% surge in steady-state ripple (48 mA to 150 mA at 4 A DC bias) under a 20 kHz PWM operation, aligning with theoretical predictions. Dynamic load tests (400 Hz) showed a 6.28% current amplitude reduction at 80 V DC bus voltage compared to 40 V, highlighting bandwidth degradation. This research provides a paradigm for optimizing AMB power electronics, enhancing precision in next-generation high-speed systems.

Analyzing manufacturing tolerances is essential to ensure the high reliability design and cost optimization of magnetic bearings (MBs). This article employs an analytical method (AM) to establish the relationship between the output of a radial MB and various manufacturing tolerances. With this analysis, the key tolerances that significantly affect the magnetic force are identified. The accuracy of the analytical model is verified by finite element simulations and experiments. Subsequently, a sensitivity analysis is conducted using the mean suspension force, the force deviation, and the force ripple as quality objectives. The impact of the key tolerances on these quality objectives is quantitatively evaluated through linear regression modeling. The findings of this study provide a theoretical foundation for MB designers in selecting appropriate tolerance classes, thus enhancing the overall understanding of MB manufacturing.