Patent ID: 8717787

Claim:
A method for operating a converter circuit, wherein the converter circuit includes at least two phase modules, each phase module having a first subconverter system and a second subconverter system, the subconverter systems being connected in series with one another for each phase module, a node between the two subconverter systems forming an output connection, each subconverter system including an inductance and at least one two-pole switching cell, which is connected in series with the inductance, and each switching cell having two drivable bidirectional power semiconductor switches, which are connected in series with a controlled unidirectional current guidance direction and a capacitive energy store, which is connected in parallel with the power semiconductor switches connected in series, the power semiconductor switches of the switching cells of the first subconverter system being driven by means of a first drive signal, and the power semiconductor switches of the switching cells of the second subconverter system being driven by means of a second drive signal, the method comprising: for each phase module, forming the first drive signal from a voltage signal across the inductances and a first switching function for the power semiconductor switches of the switching cells of the first subconverter system, and forming the second drive signal from the voltage signal across the inductances and a second switching function for the power semiconductor switches of the switching cells of the second subconverter system; forming the switching functions by means of a voltage signal with respect to the voltage at an output connection of the corresponding phase module and a selectable reference signal, the voltage signals being selected so as to be in phase with the voltage at the output connections of the phase modules; forming, for each phase module, the voltage signal across the inductances from a current signal of the subconverter systems; forming, for each phase module, the current signal of the subconverter systems from a current signal amplitude value; and forming, for each phase module, the current signal amplitude value from an actual current value at the output connection and the reference signal according to the equation 1 2 ⁢ I 0 · M h 2 + A h · M h · cos ⁡ ( Δ ⁢ ⁢ φ ) - ( 1 + V ref ) · ( 1 - V ref ) · I 0 ≡ 0 , ⁢ with ⁢ ⁢ A h ≡ M h , wherein A h is the current signal amplitude value, V ref is the reference signal, I 0 is a DC com onent of the current at the output connection M h is a voltage signal amplitude value and Δφ is the phase difference between the current signal of the subconverter systems and the voltage at the output connection.