A multilevel front-end stage for traction systems with a passivity-based controller

This work addresses the control of a high voltage, high power single phase rectifier suitable for traction applications. A multilevel H-bridge single phase configuration has been considered. Such a converter often presents instability problems making difficult its design and uncertain its behaviour. This paper proposes a new controller based on the passivity-based approach. Such a controller allows stability, unity-power factor, good balancing of the two dc links and a satisfactory transient behaviour even in presence of sudden load changes. A different choice of the damping parameters allows fulfilling the system requirements in terms of reduced dc link voltage error or low grid current distortion or to find an optimum trade-off between them. The better performance in comparison with a PI are demonstrated.