Flexible Power Control for Extending Operating Range of PVBattery Hybrid Cascaded H-Bridge Converters Under Unbalanced Power Conditions

Due to the nonuniform solar irradiance, different temperature, and inconsistent module features, the output power among each photovoltaic (PV) module in a single-phase cascaded H-bridge (CHB) inverter is unequal. The H-bridge module with higher power generation faces the risk of overmodulation. To further extending the operating range of the CHB PV inverter under unity power factor condition, in this article, a battery module is connected with the system in series to form a PV-battery hybrid CHB converter. Meanwhile, the corresponding flexible power control strategy is proposed. The injected power of the battery module is controlled adaptively according to the maximum modulation index of all PV modules. With the proposed approach, all PV modules are free from overmodulation even with severe power imbalance, and thus, more energies are harvested. The effectiveness of the proposed control method is verified by experimental results.

Automated summary

Due to factors such as nonuniform solar irradiance and inconsistent module features, the output power among photovoltaic (PV) modules in a single-phase cascaded H-bridge (CHB) inverter is unequal. This article proposes a PV-battery hybrid CHB converter and a flexible power control strategy to extend the operating range under unity power factor condition. The control method adjusts the injected power of the battery module based on the maximum modulation index of all PV modules, preventing overmodulation and improving energy harvested.