The development and utilization of renewable energy has become an important measure to alleviate the contradiction of energy supply and cope with climate change. New energy sources typically operate at low-voltage DC sources, requiring two power conversion stages to achieve boost and inverter outputs. The differential Buck-Boost inverter has gained popularity in academia due to its ability to accomplish both boost and inverter operations in a single stage. In this research, the relationship between DC voltage utilization and voltage stress is discussed. A new modulation scheme based on third harmonic injection is proposed. This improved modulation scheme enhances differential inverter's boost capability and mitigates voltage stress on capacitors and switching devices. Moreover, the proposed scheme facilitates precise control through simple closed-loop control. Analysis and simulation results confirm the advantages and effectiveness of this method.