Induction machine based flywheel speed estimation at stand-by mode

This paper presents an novel approach for stand-by mode sensorless speed estimation scheme for flywheel energy storage system (FESS). The proposed scheme eliminates the sensors required for flywheel speed monitoring, and estimates rotor speed in very short duration without affecting FESS in standby mode. This proposed algorithm only needs minimal change to the existing sensorless-based field orientation control(FOC) scheme of the flywheel. The algorithm is evaluated by simulation and experiment with short duration of excitation to the flywheel. The results also shows this method can estimate the speed without affecting the energy stored in the flywheel.