Multilevel Inverter based Battery System Operation using a Decentralized Controller

Intensive research is currently being carried out on multilevel inverter based battery systems because of their wide range of possible applications and their promising results in efficiency. Since the communication within such a system is increasingly difficult with a rising number of modules, a new concept of module operation is necessary. This paper introduces the operation of an electric vehicle’s battery pack based on a multilevel inverter using a decentralized controller. Thereby, the necessary information transmitted within the system can be minimized. By using an individual current controller on each of the system’s modules, the distinct switching states for each module do not need to be transmitted via the data connection. A simulation model describing the system is implemented in Matlab/Simulink. It is used for parameter estimation of the individual controllers. Additionally, the decentralized controller’s functionality can be verified. The results show that the operation is fast enough for charging via the AC power grid and for the control of an electric motor. Furthermore, the regulations for grid-parallel operation can be complied with. It can also be shown that the system is enabled for battery balancing, defect monitoring and troubleshooting during operation.