Power Equalization Circuits for Modular Cascaded DC–DC Converters in Distributed PV

As an interface form of DC boosting and collection system of PV power plants, the input-independent output-series (IIOS) connected modular dc-dc converter is suitable for distributed PV, which has the advantage of high voltage gain and independent maximum power point tracking (MPPT) control. However, the problem of power mismatch may cause the IIOS DC boosting and collection system run in an unstable state. This paper proposed a power equalization circuit(PEC) for DC boosting and collection system of Distributed PV to solve the power mismatch problem. Compared with the existing topology, the number of switching devices is reduced. By adding additional balancing branches, the "point-to-point" balance of power between the sub-modules(SMs) of the collection system can be realized. Simulation and down-scaled experiment are provided to verify the effectiveness and advantages of the proposed topology.