APPARATUS AND METHOD FOR STATE OF CHARGE COMPENSATION OF AN ENERGY STORAGE SYSTEM

1 . An apparatus for state of charge compensation, comprising

at least two energy storage modules, each energy storage module having an energy storage module voltage,

at least two voltage converter modules, with each voltage converter module being electrically connected to a respective one of the at least two energy storage modules in one-to-one correspondence and forming a corresponding submodule,

an electrical machine electrically connected to the at least two submodules, and

a control device configured to control a flow of electrical energy between at least one of the submodules and the electrical machine.

2 . The apparatus of claim 1 , wherein the control device is configured to control at least one of the at least two submodules and the electrical machine such that the electrical energy flows from a first of the at least two energy storage modules to the electrical machine and from the electrical machine to a second of the at least two energy storage modules.

3 . The apparatus of claim 1 , wherein the electrical machine comprises at least two independent three-phase windings and wherein the at least two three-phase windings are electrically connected to a respective one of the at least two submodules in one-to-one correspondence.

4 . The apparatus of claim 3 , wherein the control device is configured to control at least one of the at least two submodules and the electrical machine such that at least a portion of the electrical energy flows from a first of the at least two submodules to a second of the at least two submodules via a first of the at least two three-phase windings and a second of the at least two three-phase windings.

5 . The apparatus of claim 1 , wherein the control device is configured to control the flow of electrical energy such that the electrical machine removes electrical energy from or supplies electrical energy to an energy storage module having a first energy storage module charge state and supplies or removes at least a portion of the previously removed/supplied energy to/from an energy storage module having a second energy storage module charge state that is different from the first energy storage module charge state according to a predetermined operating strategy.

6 . The apparatus of claim 1 , further comprising a switching device disposed between two respective energy storage modules and configured to at least one of electrically connect and isolate the energy storage modules from one another.

7 . The apparatus of claim 1 , further comprising a heating device configured to provide the power dissipated during energy flow between the at least two submodules as a heat output.

8 . The apparatus of claim 1 , wherein the control device is configured to control at least one of the at least two submodules and the electrical machine such that an amount of electrical energy removed from an energy storage module having a first energy storage module charge state for driving the electrical machine is greater than an amount of electrical energy removed from an energy storage module having a second energy storage module charge state that is lower than the first energy storage module charge state.

9 . The apparatus of claim 1 , wherein the control device is configured to control at least one of the at least two submodules and the electrical machine such that an amount of electrical energy removed from the electrical machine and supplied to a battery storage module having a first battery storage module charge state is greater than an amount supplied to a battery storage module having a second battery storage module charge state that is different from the first battery storage module charge state.

10 . A method for state of charge compensation, comprising:

providing at least two energy storage module voltages, each representing a voltage drop across a corresponding energy storage module,

connecting each of the at least two energy storage modules to a corresponding voltage converter module to form at least two submodules,

connecting an electrical machine to the at least two submodules, and

controlling an electrical energy flow between at least one of the at least two submodules and the electrical machine.