Bypass control structure of link unit of chain circuit active power filter and method

A bypass control structure of a link unit of a chain circuit active power filter, comprising a main controller (1), a chain circuit multilevel inverter (2) for generating a compensation voltage and controlling a link unit bypass thereof, and a reactor (3) for generating a compensation current and which is connected to an external electric network;

• wherein the chain circuit multilevel inverter (2) comprises two or more levels of link units (21);
• the link units (21) each have a unit controller (211), a fault detect circuit (212), a single-phase full-bridge inverter (213), a DC/DC power supply (214) and a DC coupling circuit (215);
• the unit controller (211) is connected to the main controller (1), the fault detect circuit (212) and the single-phase full-bridge inverter (213);
• an input end of the DC coupling circuit (215) is electrically connected to two DC voltage sides of the link unit (21) in which the DC coupling circuit (215) is located, and is connected to two DC voltage sides of an adjacent link unit (21);
• an input end of the DC/DC power supply (214) is electrically connected to an output end of the DC coupling circuit (215), and an output end of the DC/DC power supply (214) is electrically connected to the unit controller (211) for supplying power for each components.