Comparison of Voltage Balancing Methods for Supercapacitor-Based Elevator Energy Storage

This paper specifies the requirements for voltage balancing methods for supercapacitor-based Elevator Energy Storage Systems (EESS) and analyses the suitability of existing voltage balancing methods for use in EESS. Application-specific requirements for supercapacitors in EESS are given, focusing on the balancing current and the balancing speed. The existing five groups of active balancing methods: adjacent cell to cell, direct cell to cell, cell to bank, bank to cell and any cell to any cell are analysed and their suitability for application in EESS based on supercapacitors is verified by simulation tests. The simulation tests are performed for a supercapacitor bank consisting of 100 cells. The methods are tested for two cases: when the balancing takes place after charging the supercapacitor bank and when the balancing takes place during the charging process of the SC bank. The advantages and disadvantages of each method are discussed as well as their suitability for supercapacitor-based EESS.