A Galvanic-Isolated Automatic Equalization Charging System for Series-Connected Cells or Battery Strings

Conventional battery equalization methods typically have high costs and complex control with a large number of switches. Therefore, a galvanic-isolated equalization charging system for series-connected cells or battery strings to equalize the battery voltage automatically during the charging process is proposed in this article. Based on the rate of change of the current passing through the inductor being directly proportional to the voltage drop across an inductor, the batteries under different initial voltage conditions can be charged to a desired uniform voltage level by supplying different corresponding continuous currents to batteries without the need for any sensor and any control. An experimental prototype for six series-connected battery strings was built to validate the balance performance of the proposed automatic equalization charging system.