Accurate and fast-response magnetically suspended flywheel torque control

The run-out of a magnetically suspended flywheel (MSFW) rotor invokes speed fluctuation. It is found that the fluctuation alters sinusoidally and synchronously with the rotor rotational frequency, and its amplitude is proportional to the value of the rotor speed, which is different from conventional disturbance. A real-time speed correction method is proposed in this paper to suppress the fluctuation. In addition, the general disturbances in MSFWs have been suppressed by the designed acceleration-based disturbance observer (DOB). It is worth noting that the DOB developed here does not contain a pure derivative, although it is a common problem in the realization of most DOBs. Furthermore, system transient performance is improved by the designed command feedforward controller (FFC). Finally, accurate and fast-response flywheel torque can be obtained.