Overview of PI-based solutions for the control of the dc-buses of a single-phase H-bridge multilevel active rectifier

The H-bridge based multilevel active rectifier is an attractive topology that allows feeding of multiple dc loads. However the balancing of the dc buses often causes instability problems. The main control problem is to manage n+1 state variables (one current plus n dc voltages) with only n switching functions. In this paper several PI-based solutions are reviewed through simulations and experimental tests.