In power generation systems based on distributed renewable energy, the topology of a Y-source inverter(YSI) has been applied to realize a flexible buck-boost function. However, the mutually constrained disadvantage of the modulation factor and boost duty cycle of the YSI leads to a significant reduction in voltage quality and DC bus utilization when a high voltage gain is required by the system. In addition, when considering the effect of leakage inductance, the YSI will generate voltage spikes caused by sudden changes in the induced current. In view of these problems, an improved split Y-source inverter(ISYSI) is proposed. By combining a split-source structure with a Y-source impedance network and incorporating a voltage clamp unit, the above-mentioned problems are solved effectively, and the system's voltage gain is significantly improved while eliminating the voltage oscillations caused by the resonance of the diode parasitic capacitance and the leakage inductance of the Y-source impedance network. A detailed theoretical analysis of ISYSI is carried out, and the corresponding simulation and experimental results are provided to verify the feasibility of the proposed inverter.