Abstract: The cascaded H-bridge inverter power supply has the advantages of input voltage equalization and low output harmonic content, and has been widely used in the high power range. Firstly, the harmonic generation mechanism of the output voltage of single-phase cascaded H-bridge carrier amplitude-shift modulation is analyzed, and an improved triangular carrier and modulating wave are adopted for carrier amplitude-shift modulation to reduce the content of carrier harmonics and sideband harmonics. In view of the high THD and large steady-state error of the nonlinear load output voltage of the traditional control method, the reactive voltage is virtualized by FFT transformation, and the vector controller is designed and simplified, and the voltage loop q-axis control is omitted. The design of the controller achieves faster convergence speed, higher stability and less oscillation. Simulation and experimental results verify that the proposed modulation algorithm and control strategy have stronger anti-disturbance performance, can adapt to different types of load changes and voltage fluctuations on the DC voltage side, and achieve fast dynamic response and no steady-state error of the inverter power supply control.