Research On The Casade H-bridge DC Capacitor Voltage SAPF Balance Control

To solve the problem of control method is complicated and difficult to achieve for capacitor voltage unbalance in cascade H-bridge SAPF, this paper analyzes the capacitor voltage unbalance reason, the carrier phase shift modulation technology and cascade H-bridge SAPF soft-start method.This paper analyzes the reason of influence the DC voltage unbalance, and the shortage of the carrier phase shift modulation techniques, a suitable within phase capacitor voltage balance control carrier exchange modulation techniques were presented. Aim at the reason of the phase capacitor voltage unbalance, proposed a current phase output control mode based on the primitive ip, iq detection algorithm to maintain inter phase capacitor voltage balance for cascaded SAPF.This paper also analyzes the principle of soft-start the process of the two-level APF and boost charging stage, for cascaded SAPF topology, soft-start apply cascade SAPF were proposed, This manner without changing the topology cascaded SAPF, make the DC side capacitor of cascade SAPF charging voltage achieve the setting value.The simulation and experimental results show that the proposed carrier exchange modulation technique, ip, iq phase detection output algorithm and cascaded SAPF soft-start mode is effective, and has a certain practical significance.