Control method for DC-link voltage ripple cancellation in voltage source inverter under unbalanced three-phase voltage supply conditions

A control method for the compensation of unbalanced voltage supply that eliminates pulsating current in the DC bus of a voltage source inverter is investigated and analysed. Such a pulsating current can have detrimental effects on operating properties of the drive as well as on the quality of power supply in the electrical vicinity of the inverter. A feasible range of control parameters is determined based on the required level of immunity against unbalanced voltage supply and on the parameters of the system. The impact of the control method on the power factors and current amplitudes in individual input phases for the available range of control parameters is analysed and discussed. In particular, achievable power factor and current unbalance at the input of the front-end rectifier are addressed. Examples of numerical simulations and experimental measurements illustrate operation of the system under investigation, both with and without the use of the compensation method.