A High-Frequency AC-Linked Active Multicell Balancing Topology for Series-Connected Batteries

A novel multicell balancing topology based on series input parallel output configuration with a high-frequency AC bus is proposed in this paper to provide flexibility in handling battery voltage imbalance in an time-efficient way. It has the advantage over traditional balance systems as the multicell balance for inconsecutive cells can be achieved. The hardware designed for a four-cell module verifies its operations and evaluates the performance of different operation modes. Automatic balancing was achieved with efficiency from 77.36% to 88.58% and with a minimum final voltage difference of 23mV. With an additional phase shift, the final voltage difference can be further reduced to 1mV and the balancing time by 69.8%.