A novel PWM control method to eliminate the effect of dead time on the output waveform for hybrid clamped multilevel inverters

A novel PWM control method called AHPWM (Alternative Hybrid PWM) is proposed in this paper. By applying the AHPWM method to the hybrid clamped multilevel inverter, the unexpected levels in the output voltage waveform with the traditional PDPWM method can be eliminated. The analyses on the switching modes conversions, the reason causing the unexpected output levels, the effect of the PWM carrier waveforms on the switching modes conversions and the principle of the AHPWM method are given. Simulations and experiments show the unexpected output levels caused by the dead time can be effectively eliminated by applying the AHPWM method to the hybrid clamped multilevel inverter within broad modulation index range. The analysis on the output voltage spectrum shows the energy of lower harmonics can be remarkably reduced, which can simplify the design of the output filter and reduce its size.