Abstract: A power control system includes a current sensor and a control unit. The current sensor is coupled to a permanent magnet synchronous motor (PMSM) and is configured to monitor a current profile of the PMSM. The control unit is coupled to the PMSM and a magnetic bearing system. The control unit receives signals associated with the current profile of the PMSM and controls power provided by a main power supply to the PMSM in a first operating mode. In response to detecting a power failure of the main power supply, the control unit determines an estimated rotation speed of the PMSM according to the current profile of the PMSM and generates a first output voltage to power the magnetic bearing system in a second operating mode different from the first operating mode. A value of the first output voltage is generated based on the estimated rotation speed of the PMSM.