No abstract

Since the AC-DC conversion is widely spread in power sources, this work proposes a novel strategy of multi-pu[se topologies, associated to the ha[f-controlled boost-based rectifier, which has the follows main advantages: [ow Total Harmonic Distortion of the line current (THDi), below 2%; Power Factor (PF) close to unit; simple gate drive circuit, since all active switches are connected to the same reference; robustness given that the DCM operation results the peaks of the current naturally follow the voltage waveform. The control circuit becomes very simplified because all the switches are synchronized and only one basic voltage loop should be used to regulate the DC output, without current sensors. In addition, the commutation process occurs after the current in the diode becomes zero (DCM), without losses and current stresses due to the diode reverse recovery. The simulation analysis shows a significant improvement of PF once the THDi is lower than 2% while the conventional 12-pu[se topologies have about 14%. Each conventional three-phase bridge rectifier is replaced by a three-phase ha[f-controlled boost based topology, also called of bridge[ess rectifiers. A 2.5 kW prototype is being built and its feature is a strong candidate for More Electric Aircraft (MEA) and Adjustab[e Speed Drive (ASD) applications.

This paper presents the analysis of the integration of two three-phase half-controlled boost converters, operating in discontinuous conduction mode (DCM), to the auto-connected 12-pulse rectifier. The proposed structure shows a reduced current harmonic content compared to the traditional 12-pulse rectifiers, being a simpler and effective alternative to using rectifiers with higher pulse numbers. It also presents a greater range of possibilities for regulating the output voltage, without the use of synchronization algorithms or rigorous control techniques, being possible to send to all controlled switches, the same command signal, resulting in a simpler logic. Another advantage of using the proposed technique is the employment of a single-loop voltage control scheme, reducing the computational and financial cost by eliminating some elements such as current sensors. Moreover, the proposed strategy provides soft commutations (Zero-Current-Switching -ZCS). In this work, a small-scale prototype was implemented, aiming to obtain a structure capable to operate in a wide range of line frequencies, without requiring any additional complex techniques. In this regard, the developed structure is capable to work as a Power Factor Correction (PFC) stage in a wide range of input frequencies (30Hz -120Hz) with a Total Harmonic Distortion of the input current (THD i ) of less than 2.19%.

Since harmonics in power systems have a substantial influence in the energy supply quality, a variety of topologies are used to reduce those effects. The twelve-pulse converter is one of these topologies. It will be observed the flux in a core, which has an intermediary yoke. The analysis will be a comparison of practical results with theoretical modeling, showing that the area of the intermediate yoke can be optimized when comparing to the use of two separate three-phase cores.I.

No abstract