Voltage sensorless control of the three-level three-switch Vienna rectifier with programmable input power factor

The three-level, three-switch Vienna rectifier is fast emerging as the preferred topology for the high-power factor front end converter in many applications. Conventional control algorithms for the Vienna rectifier requires sensing of both the supply voltage and the line current. However, in many applications, where an electrical generator feeds the rectifier, the `supply voltage´ is not available for measurement. Even for grid-connected applications the supply voltage may contain significant harmonic distortion which, in turn, increases the harmonic distortion of the rectifier input current. To mitigate these disadvantages, this study presents a novel voltage sensorless control algorithm for the Vienna rectifier. Voltage sensorless control algorithms reported in the literature for this rectifier, so far permit only unity rectifier terminal power factor operation. In contrast, the proposed control algorithm can operate the rectifier at programmable power factor. For the verification of the algorithm, experiments were conducted on a laboratory prototype of the Vienna rectifier using both voltage sensorless and sensor-based control algorithms. Performances of both these algorithms were found to be similar under transient conditions. The voltage sensorless controller achieved better input line current total harmonic distortion in steady state.