Conversores estáticos multiníveis obtidos a partir da interconexão de módulos de dois e três braços em série e paralelo.

Abstract

Static converters are a valuable tool when seeking to improve the power quality of power systems. This work presents conventional and proposed converters, all composed by AC-DC (or DC-AC) and AC-DC-AC modules with two or three legs without isolation transformer. We studied two types of converters: fourteen single-phase converters, derived from series and/or parallel connection of AC-DC modules with two legs, and eight AC-DC-AC converters obtained from AC-DC-AC modules with three legs. The following aspects are discussed for each topology: (i) dynamic modelling; (ii) PWM strategy; (iii) control of several variables of the system, i.e., input grid current (waveform and power factor), DC-link voltage, load voltage and low frequency of the circulating current (when it exist); (iv) characterization

of the converters based on harmonic distortion of voltages and currents, losses of the DC- link capacitors, and conduction and switching losses of the semiconductor switches. The

series connection is advantageous because they allow the reduction of the DC-link voltage, the harmonics generated by the converters, witch reduce the rating of the semiconductor switches. The parallel connection is advantageous because they reduce the currents, power and harmonics of leg converters. In order to reduce voltage and current of the semiconductor switches, this work to propose building static converter by series and parallel connections. In order to validate the results, simulation and experimental results are presented.