A control method for voltage source inverter without dc link capacitor

Voltage source inverter plays an important role in modern industry. Conventional voltage source inverter has a large electrolytic capacitor as energy store element in order to keep the dc link voltage constant. However, a large electrolytic capacitor increases the input current distortion. Replacing the large electrolytic capacitor by a small film capacitor the input current quality is improved but the output currents are distorted by low order harmonics. This paper proposes a simple current control method for a voltage source inverter without the use of a large electrolytic capacitor in the dc link in order to compensate the low order harmonics in the output currents. The proposed current control scheme employs just one PI regulator and since that the space vector modulation is used in this control the switching frequency of the converter is kept constant.