Abstract: A method is provided for determining a control scheme for a voltage source converter (VSC) with a topology of three bridge legs between each of three phases of a grid and a neutral point. The method includes: analyzing the waveform of the grid and/or a load voltage and determining an allowed period for no-swilching of the corresponding bridge leg; operating the VSC with different clamping carrier modulator frequencies, and then analyzing the balance in the operating junction temperatures and/or power losses across the active switches and also analyzing the total losses of the VSC; comparing the balance and the total losses of different clamping carrier modulator frequencies and selecting the clamping carrier modulator frequency; operating the VSC with the selected clamping carrier modulator frequency, and optimizing the balance in the operating junction temperatures and/or power losses across the active switches and the total losses of the VSC.

Abstract: A method is provided for determining a control scheme for a neutral point clamped (NPC) voltage source converter (VSC) with at least 3 levels and a topology of three bridge legs between each of three phases of a grid and a neutral point. Each leg includes at least four active switches, and a clamping carrier modulator synchronized with the grid is provided for the control of no-switching intervals.