Novel individual voltage balancing control scheme for multilevel cascade active‐front‐end rectifier

In this study, a novel individual voltage balancing control scheme for multilevel cascade active‐front‐end rectifier is proposed to allow a different voltage setting capability among different dc outputs in series. First, the proportional resonant controller and admittance compensation controller are introduced for the active inner‐current control loop of cascade active‐front‐end rectifier to achieve better steady‐state and dynamic performance. Second, an assumption based on conservation of energy is proposed to decouple a series connected ac–dc system into several individual subsystems to facilitate the individual dc‐bus controller design. Both simulation and experimental results based on the cascade two‐unit cascade dual‐buck/boost‐type active‐front‐end rectifier proved the effectiveness of the proposed individual balancing control scheme, which also verified the proposed assumption.