Conversores estáticos a partir de retificadores monofásicos mistos.

Abstract

Static converters are a very useful tool when there is interest in improving the power quality of power systems and power generation, especially in renewable energy. This work deals with converters presented in the technical literature and proposes also new converters, being the proposed converters mixed, which means it uses legs with controlled switches and legs with diodes. For each topology presented the following aspects are evaluated: (i) dynamic modeling, (ii) PWM strategy, (iii) control systems of the DC-Link voltages and the synchronization method of the grid current, (iv) performance analysis of the converter following the criteria of harmonic distortion and conduction and switching losses in semiconductor switches. The mixed converters, which use legs with diodes, are useful as regards the cost of the converter, due the leg with the diode to be cheaper than a leg with controlled semiconductor switches. As legs with diodes are used, these converters can be used in wind energy conversion systems, with the advantage of having unidirectional power flow. The proposed method of synchronization aims to reduce the zero-crossing distortion in the grid current caused by the diode leg. Despite not seeking unity power factor, it is possible to achieve high power factor.