Control of a three level converter used as a synchronous rectifier

We present an adaptive controller for a three level synchronous rectifier. The controller guarantees regulation and balance of the output capacitors voltages, as well as a close to unity power factor, simultaneously. The design is based on a model in αβγ-coordinates of the three level converter. Special attention is given to the γ-component of the control input, since it has direct influence in the balancing of the capacitors voltages, represented here as the arithmetic difference of voltages. Moreover, it is shown that this difference is polluted by a periodic disturbance, which is also compensated by the proposed controller by adding an adaptive term to the control law. After some transformations, this adaptive term is finally reduced to a bank of resonant filters. Simulations results are presented to asses the performance of the proposed controller.