Performance Analysis of Cascaded H-Bridge Multilevel Inverter with Variable Frequency ISPWM Technique

The multilevel inverter has applications in various areas. Now a days , multilevel inverters have wide scope in advancement of electric vehicles, static var compensators, photovoltaic purpose, interfacing with Renewable energy system.This paper proposes topology of multi level inverter with cascaded H-bridge which has several advantages over flying capacitor and neutral point clamped topology with the pulse width modulation (PWM) application. This topology can be used to increase number of level of output voltage by increasing number of input DC sources in appropriate manner. VFISPWM modulation method is proposed in this paper. In this switching method two signals are used with one is sinusoidal and other is inverted sine with variable frequency for reference and carrier signals respectively. The simulation results represents that the Total Harmonic Distortion (THD) for voltage is reduced with VFISPWM technique. The results of MATLAB simulation shows that fundamental voltage component gets improved with the significant reduction in THD as compared to Constant Frequency Inverted Sine PWM (CFISPWM)method.