An adaptive control strategy for single-phase cascaded H-bridge multilevel inverter under distorted load conditions

This paper investigates an adaptive combined control strategy for single-phase cascaded H-bridge multilevel converter under distorted load conditions. The nonlinear loads cause harmonic distortion and affect the quality of output voltage. An adaptive voltage control strategy is suggested to compensate for the harmonic distortion caused by the nonlinear loads. The suggested control strategy enables the output voltage to track the reference according to the load-side disturbances. The DC links of the multilevel converter generate low-frequency ripples which also cause output voltage distortion under nonlinear load conditions. To compensate this, an adaptive DC link ripple control strategy is also suggested. Detailed analysis has been conducted to verify the effectiveness of the suggested system and is compared to the conventional control strategies. Fast dynamic response and lower distortion in output voltage are obtained with the suggested strategy compared to the conventional control strategies. Experimental and simulation results are provided to validate the suggested control scheme.