A　new　type　of　flat　top　quasi-sinusoidal　modulation　wave　was　designed　and　optimized　to　solve　the　complexity　issue　in　the　existing　pulse　width　modulation　(PWM)　overmodulation　algorithm.　The　technique　increase　fundamental　amplitude,　at　the　same　time　minimizes　the　low-order　harmonic　influence.　It　samples　the　modulating　wave　with　a　triangular　carrier　wave,　and　linearly　changes　PWM　fundamental　component　amplitude　through　changing　the　modulating　wave　height　in　the　linear　range.　In　the　overmodulation　range,　it　continuously　increases　the　fundamental　component　amplitude　till　approaching　a　square　wave　by　broadening　the　flat　top　width　of　modulating　wave　while　maintaining　the　maximum　height　as　a　constant.　To　maintain　linearity　between　fundamental　component　amplitude　and　modulation　index　M　in　overmoudulation　range,　a　lookup　table　including　the　flat　top　width　and　M　relationship　was　pre-programmed　into　a　microprocessor　for　real　time　implement.　The　new　PWM　algorithm　is　simple.　Compared　with　sinusoidal　pulse　width　modulation　(SPWM),　the　technique　produces　19%　higher　maximum　fundamental　component　amplitude　in　linear　modulation　range;　its　total　harmonic　current　distortion　is　lower　at　M∈[0.55,　1],　and　slightly　higher　at　M∈[0,　0.55]　but　the　increase　is　less　than　2.2%　under　the　same　carrier　wave　frequency　ratio　N=33　condition.　The　new　technique　was　validated　with　experiment　results.