DC-bus Voltage Controllers for a Three-Phase Voltage-Source Inverter for Distributed Generation

Abstract

An important function of the bus voltage controller of voltage-source inverters (VSI) for distributed generation (DG) applications is to control the balance between ac and dc power. Nevertheless is the bus voltage controller not the critical part of the control of the VSI. Therefore it is justified that little attention is paid to the design of this bus voltage controller what can be seen in literature. However, this controller can (negatively) influence the behaviour of the VSI. In three-phase systems a ripple can exist in the bus voltage due to unbalance or harmonics present in the grid voltage or current. This ripple can interact with the bus voltage controller which can have negative consequences on the injected current. Also the timing of updating the output of the bus voltage controller can have consequences on the waveform distortion which can result in oscillations. In this paper the focus is on the timing of updating. An overview of three possible bus voltage controllers is given. The response of the different implementations of dc-bus voltage controllers during a transient is simulated.