Weight-transducerless control strategy based on active disturbance rejection theory for gearless elevator drives

Direct-drive traction systems applying the permanent magnet synchronous motor have become the trend of modern gearless elevators. To estimate and reject the non-linear and uncertain load disturbance effectively during the elevator startup, a novel active disturbance rejection control (ADRC) strategy adopting extended state observer (ESO) and non-linear error feedback (NLEF) controller is proposed to attenuate the elevator car sliding without using weight-transducer. By using the weight-transducerless control strategy, the sliding distance and speed can be suppressed to the extent that it could ensure the riding comfort. The proposed ADRC scheme will also accelerate the dynamic response and enhance the system robustness. Both the parameter selection and the stability of ESO are analysed according to the application requirements, and the contrastive analysis of the functions selected in NLEF controller is performed via Lyapunov theory. The feasibility of the proposed strategy is verified by the experimental results on an 11.7 kW elevator traction machine.