Modified SPWM control schemes for three-phase inverters

Two different modified SPWM control schemes, MPWM-S and MPWM-T, for three-phase inverters with nonconstant DC voltage sources are proposed in this paper. The proposed modified SPWM control schemes can achieve the desired fundamental amplitude and eliminate the low order harmonic components caused by the DC voltage source variation. The analysis of the inverter amplitude distortion and the developments of the proposed MPWM-S and MPWM-T control schemes are presented. Hardware implementation of the proposed control schemes can be easily accomplished by adding one or two analog components to the traditional SPWM control circuit. The performance of the two proposed modified SPWM control schemes is verified by experimental results.