Novel Active Magnetic Bearing Power Amplifiers Based on the Single DC-Link Current Sensor

With the development of active magnetic bearings (AMBs), power electronics amplifiers have become a key area of research in electromechanical systems. Current sensors are connected in series with each coil in traditional power amplifiers, resulting in suboptimal utilization efficiency. This paper proposes an innovative single-current-sensor architecture. The current sensor is positioned in the DC bus loop, allowing comprehensive current measurement across all coils. The proposed scheme introduces two key innovations: a switching-state-modulated current sampling strategy for coil current decoupling and a model predictive feedback current reconstruction strategy to overcome sampling frequency limitations. These strategies ensure that the performance of the single-current-sensor system is comparable to that of conventional configurations with multiple current sensors. For four-degree-of-freedom AMBs, the proposed scheme reduces the number of current sensors by 87.5% to lower costs and enhance the reliability of power amplifiers. The effectiveness of the proposed single-current-sensor scheme is validated through experimentation.