Multilevel SPWM Inverter with Variable Carrier Synchronization
Keywords:
SPWM-Sinusoidal Pulse Width Modulation, Multilevel Inverter, THD%, FilterAbstract
Multilevel inverter generates stepped AC signal. Based on sequence of switching and duration of each
step we can minimize the output Voltage THD. Sinusoidal Pulse Width Modulation (SPWM) is a very popular
control method and widely used in power electronics inverter circuits to reduce lower level Harmonics. We
connect several SPWM inverters in cascade and receive multilevel SPWM output.There are different SPWM
methods to receive multilevel SPWM output voltage. And there are: (a) In Phase Disposition PWM (PH
Disposition) (b) Phase Opposition Disposition PWM (PO Disposition) (c) Alternative opposition Disposition
PWM (APO Disposition) (d) 90˚ Phase Shifted Disposition PWM (90˚ PS Disposition). From all these methods
there are creates an many triangular carrier waveforms which are phase shifted or level shifted from main
triangular carrier signal and they all compared with reference Sine Wave signal to generates switching pulse
which gives Sinusoidal output voltage with different harmonics level.