DC bus current harmonics of a three-phase PWM inverter with the zero sequence injection

Power electronic converters connected to a dc bus are sources of undesirable harmonics towards the dc side due to an inherent high-frequency switching used for the power processing. Three-phase inverters are widely used in many applications like motor drives and active rectifiers. With a SPWM control the dc bus voltage is not fully utilized, so a zero sequence injection method is commonly used to increase the maximum fundamental voltage output. The inverter dc side current harmonics are investigated for a three-phase SPWM inverter with and without zero sequence injection. The results show that the injection of the third harmonic and Min/Max zero sequence will not increase the dc side harmonics. The RMS value of the inverter dc side current is increased less than 1% when the zero sequence is injected.