Discontinuous mode sparse Dyna-C rectifier for efficient AC/DC power conversion

The paper investigates a soft-switching buck-boost AC/DC converter. The proposed converter uses 4 active switches and overcomes the various shortcomings of conventional rectifiers. The proposed controller facilitates discontinuous mode of operation that leads to zero current turn on and turn off. A nonlinear average phase charge based controller is presented which ensures zero harmonic current in the input phases. The switching scheme has been so arranged that the diodes always turn off at zero voltage thereby reducing the reverse recovery stress and losses. These modifications lead to a considerable reduction of switching loss and device stress as compared to the conventional control scheme of Dyna-C. Owing to soft switching states, the frequency of operation can be pushed even higher thereby reducing the size of the passive components. An alternate switching pattern has also been discussed which enables soft switched turn off of active switches. Design guidelines to construct an optimized inductor has also been discussed. Simulation and initial experimental results are presented to validate operation of the control scheme. A comparison study has been carried out to choose the appropriate set of devices for this application. The research shows that SiC-MOS with low cost Si-PiN Diode results in impressive reduction in overall losses. The topology is expected to offer compact, fast, efficient and inexpensive solution to the present AC/DC power conversion requirements.