System and method for controlling an energy storage device

Abstract

The invention relates to a method for controlling an energy storage device that comprises n output connections, wherein n≧2, for producing a supply voltage at each of the output connections, and n energy supply branches, which are each coupled to one of the output connections, wherein each of the energy supply branches comprises a plurality of series-connected energy storage modules that each comprise an energy storage cell module comprising at least one energy storage cell, and a coupling device having coupling elements in a full bridge circuit that is designed to connect or bridge the energy storage cell module selectively in the respective energy supply branch. The method according to the invention comprises the following steps: for a number k of energy storage modules of at least one first energy supply branch, generating a first pulse width modulated control signal for controlling the coupling devices of the respective energy storage modules by comparing a first target value signal with a number 2k first periodic reference signals having a pulse period T, which signals each have a phase shift of T/2k relative to the adjacent first reference signals; and, for a number k of energy storage modules of at least one second energy supply branch, generating a second pulse width modulated control signal for controlling the coupling devices of the respective energy storage modules by comparing a second target value signal with a number 2k of second periodic reference signals having the pulse period T, which each have a phase shift of T/2k relative to the adjacent second reference signals. The second reference signals each have a phase shift of T/4k relative to the first reference signals.