Effect of digital SPWM on system delay

The time delay caused by SPWM(Sinusoidal Pulse Width Modulation) with symmetrical or asymmetrical sampling is analyzed and three improved SPWM methods are introduced:improved asymmetrical sampling,multiple sampling fixed updating and multiple sampling immediate updating.The time delay caused by each improved SPWM method is also analyzed.DSP and FPGA are used to simultaneously generate the SPWM waveforms by five SPWM methods with a common sinusoidal reference signal.The phase difference of each SPWM method between its fundamental and reference is obtained and the time delay caused by each SPWM method is derived,which confirms the effectiveness of theoretical analysis and shows that three improved SPWM methods can reduce the time delay effectively.