A Novel Point-to-Point Energy Transmission Voltage Equalizer for Series-Connected Supercapacitors

In view of the nonuniform voltage of series-connected supercapacitors (SCs), a new voltage equalizer was designed. This voltage equalizer is composed of a switching network circuit and an isolated dc/dc converter. A switching network greatly simplifies the circuit over a traditional switch driver by using electrical potential difference between series-connected SCs to drive switches. It provides pathways for all SCs that are series connected. Each SC can be connected to an isolated dc/dc converter individually by the use of a switching network. Energy will be transmitted between any two cells directly; thus, it is also called point-to-point energy transmission. Detailed operation analyses and an equalizing strategy were presented for the voltage equalizer. A prototype for 12 SCs that are series connected was built based on the new voltage equalizer, and an experiment was performed for series-connected SCs with a nonuniform initial voltage. The experimental results showed that the voltage equalizer has the ability to eliminate nonuniform voltage of the series-connected SCs effectively. Furthermore, this voltage equalizer not only can be used for SCs but can be used for traditional secondary batteries as well.