Abstract: This paper proposes a novel three-phase current source SEPIC inverter,which is composed of traditional three-phase bridge circuit and SEPIC circuit. The inverter can achieve buck-boost comply with the characteristics of SEPIC circuit. Meanwhile,by means of the SPWM carrier amplitude adjustable strategy,the problem which traditional current source inverter has large inductance parameter in DC side is solved,and the output waveform quality is optimized. This paper first introduces the working mode and the corresponding modulation method of the inverter,afterwards gives the mathematical formula of the voltage gain. Moreover,based on the characteristics of the circuit,the corresponding mathematical model and the closed-loop control strategy is established. Finally,the corresponding digital control platform is built by TMS320F2812 and FPGA,and the corresponding experimental verification is carried out,which verifies the feasibility of the circuit.