General Electric Company

Ge Energy Power Conversion Technology Gmbh

Qingyun Chen

Stefan Schroeder

Jie Shen

Zhihui Yuan

Nora Cheng-Huei Han

A method of operating a multilevel power converter includes using, through a processing device, a model of an electrical circuit that includes a plurality of switching devices, a plurality of flying capacitors, and an AC terminal. The method also includes regulating a voltage level of the AC terminal through selecting, at least partially based on the model, a possible charging state of the electrical circuit. Each possible switching state has a voltage level that at least partially corresponds to a commanded voltage level for the AC terminal. The method further includes selecting, at least partially based on the model of the electrical circuit and at least partially based on the selected possible switching state, a charging state from a plurality of possible charging states. The method also includes setting the switching state of the electrical circuit at least partially based on the selected charging state of the electrical circuit.

System and method for operating power converters

An electrical circuit for a power converter includes a first switching device proximate an AC source. The circuit also includes a voltage measurement device proximate a DC link and extends between the AC source and the DC link. The circuit further includes a DC voltage source and a first capacitive device. The first capacitive device is positioned between the first switching device and the voltage measurement device. The circuit further includes a second switching device positioned between the first capacitive device and the voltage measurement device. The circuit also includes a controller operatively coupled to the DC voltage source, the voltage measurement device, and the switching devices. The controller is configured to open the second switching device when a measured voltage signal generated by the voltage measurement device is substantially representative of a reference voltage value.

A method of operating a flying capacitor multilevel converter having a direct current link and a plurality of phase legs each having a plurality of flying capacitors includes employing redundant states to balance flying capacitor voltages by charging or discharging flying capacitors. The redundant states are employed by obtaining a load current of the flying capacitor multilevel converter. If a load current value is lower than a threshold value then a capacitor current of a phase terminal capacitor is utilized to determine redundant states else a load current direction is utilized to determine the redundant states.

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Bavaria, Germany

Qingyun Chen