Controller design, analysis and testing of a three‐phase VSI using IDA–PBC approach

Abstract

A voltage-source inverter (VSI) is a key component of a distributed generation unit and an uninterruptible power supply. In this study, a three-phase VSI control using interconnection and damping assignment passivity-based control (IDA-PBC) approach has been revisited and analysed on aspects such as voltage gain, output impedance, transient response, stability and steady-state error. It is shown that in the case of accurately known filter parameters and perfectly zero initial conditions, theoretically, the voltage controller would exhibit unity voltage gain and zero output impedance. It is also shown that the IDA-PBC-based voltage controller exhibits a second-order response to a step input. This property has been utilised to propose a novel systematic procedure for tuning of the IDA-PBC gains based on the transient response specifications. The tuning method reveals that the gains for the outer voltage and inner current loops are related to each other and should not be separately tuned. The presented analysis and the proposed tuning method for controller gain have been tested through simulation studies. The concepts were further validated on a laboratory scale prototype of a three-phase VSI for balanced, unbalanced and non-linear loads.