Square wave modulation midpoint voltage control method and system and related components

The invention discloses a square wave modulation neutral-point voltage control method and system and related components, which are applied to a three-level inverter and comprise the following steps: acquiring the value of a current three-phase modulation wave; determining the type of the output voltage vector according to the value of the current three-phase modulation wave; judging whether the output voltage vector type is a preset output voltage vector type or not; if yes, determining a zero-sequence component according to a vector flag bit and the value of the current three-phase modulation wave; and determining a target three-phase modulation wave according to the zero-sequence component so as to control neutral-point voltage balance of the three-level inverter. The method is used for controlling the three-level inverter, the output voltage vector type is determined to be the preset output voltage vector type, the zero-sequence component is determined according to the vector flag bit and the value of the