Three-level ANPC inverter open-circuit fault tolerance method based on carrier modulation

The invention discloses a three-level ANPC inverter open-circuit fault tolerance method based on carrier modulation. When an open-circuit fault occurs in a single-phase switching device, the fault tolerance method comprises the steps of firstly, detecting a current direction Idir of a fault phase; defining the maximum value and the minimum value of the three-phase sine wave as Vmax and Vmin respectively and the zero sequence voltage as Zs, wherein according to the fault tolerance method, when Idir is equal to 1, Zs is equal to -0.5*(Vmax+Vmin+1), when Idir is equal to 0, Zs is equal to -0.5*(Vmax+Vmin-1), and Zs is injected into a three-phase sine wave to obtain a three-phase modulation wave during the open-circuit fault; comparing the three-phase modulation wave with a carrier wave to obtain a level state output by the three-level ANPC inverter; and determining a switching signal of each switching device of the three-level ANPC inverter according to the output level state and the typeof the switching device