Suspension Force Performance of Bearingless BLDC Motor in Generator Mode for Flywheel Batteries

The traditional suspension force analysis of bearingless motors is mainly based on electromotor mode. However, the generator mode is also an important component in energy conversion for flywheel batteries, and the stable suspension of rotor is beneficial to reduce the loss and improve the power quality. Therefore, suspension force performance in generator mode need to be analyzed deeply. In this paper, a new bearingless brushless DC (BLDC) motor with 12-slot and 4-pole structure is proposed for flywheel batteries. Firstly, the principle of suspension force generation in generator mode is introduced. Then, the mathematical model of the suspension force is deduced and the finite element analysis is carried out to prove the validity of the mathematical model. Finally, the control system of the bearingless BLDC motor is established and the experiment is carried out through the bearingless BLDC motor digital control platform. The experiment results show the reliability of bearingless BLDC motor in generator mode.