Comparison of Various Variable Amplitude Carrier Overlapping PWM Methods for Three Phase Five Level Cascaded Inverter

Vol. 1 No. 1

Year: 2013

 
Issue: Jan-Mar

Title : Comparison of Various Variable Amplitude Carrier Overlapping PWM Methods for Three Phase Five Level Cascaded Inverter

  

Author Name : R. Revathy, C.R.Balamurugan , S.P.Natarajan

  

Synopsis :  

This paper presents the comparison of various Carrier Overlapping Pulse Width Modulation (COPWM) Strategies for the three phase Cascaded Multi Level Inverter (CMLI). Various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase CMLI. A three phase CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference along with Carrier Overlapping (CO) techniques and simulation is performed using MATLAB-SIMULINK. The variation of fundamental RMS output voltage and total harmonic distortion is observed for various carrier overlapping techniques. Among the various equal amplitude carrier overlapping techniques such as COPDPWM, COPODPWM, COAPODPWM, COVFPWM and COPWM-D, it is observed that COAPOD provides less total harmonic distortion (THD) and COPWM-D provides higher RMS voltage. Among the various variable amplitude carrier overlapping techniques, such as VACOPDPWM, VACOPODPWM, VACOAPODPWM, VACOVFPWM and VACOPWM-D, it is recognised that VACOAPOD provides less THD and VACOPOD provides higher RMS voltage. By comparing the equal amplitude carrier overlapping techniques with the variable amplitude carrier overlapping techniques, it is observed that VACOVFPWM provides higher fundamental RMS output voltage with relatively low distortion.