Abstract: The paper proposes a new way to obtain pure sinusoidal based on DSP for the research and design of 400 Hz AC power supply.It gives the main circuit,control circuit and software design flow chart.A prototype is designed using the DSP as the master chip.The experimental result shows that this way not only can simplify the system structure by DSP and CPLD,but also can improve the power factor,reduce harmonics and enhance efficiency.

Key words: DSP, SPWM, invert, CPLD