Supercapacitor-Based Energy Recovery System With Improved Power Control and Energy Management for Elevator Applications

This paper proposes a supercapacitor-based energy recovery system (ERS) with improved power control and energy management (PC&EM) capability for elevator applications. The ERS is connected to the dc link of the elevator motor drive through a bidirectional dc-dc converter for storing and then recovering the braking energy. The proposed PC&EM technique provides improved cost effectiveness and exploitation of the ERS capability, by adjusting the elevator power requirements with the ERS power capability through cabin speed regulation within predefined limits. The proposed control system can be easily installed without requiring modifications in the elevator motor drive, and thus, it can be easily applied to any existing elevator applications. Also, an experimental procedure is proposed in order to online determine and periodically fine-tune the parameters of the suggested PC&EM controller. In this paper, the proposed control technique has been applied in an ERS with a nonisolated dc-dc converter; however, it can as well be used in the isolated counterpart. Selective experimental results are presented in order to verify the effectiveness of the proposed control technique and demonstrate the resulting operational improvements.