Power control of individual batteries by exchanging switching patterns for battery energy storage system using multilevel cascade converter

Abstract

This paper focuses on a battery energy storage system (BESS) that uses a multilevel cascade converter. This converter can individually manage each state of the battery connected to the DC side of each bridge cell by controlling the power of each bridge cell. However, this converter needs to cooperatively control the switching patterns of multiple bridge cells. PWM control method can solve this issue. One of the main PWM control methods employs a level-shifting carrier PWM technology. This method effectively controls bridge cells cooperatively, but it is difficult to change the power of each bridge cell intentionally for a short period, for example, a half cycle. We propose a control method based on level-shifting carrier PWM technology for a multilevel cascade converter. The proposed method can control the power of each bridge cell individually for a short period by exchanging switching patterns in multiple bridge cells. The validity of the proposed method is verified using an experimental single-phase battery energy storage system. © 2013 The Institute of Electrical Engineers of Japan.