Browsing by Author "Pontt, J."
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- ItemHigh-Power Machine Drive, Using Nonredundant 27-Level Inverters and Active Front End Rectifiers(2007) Dixon Rojas, Juan; Bretón, A. A.; Ríos, F. E.|Rodríguez, J.; Pontt, J.; Pérez, M. A.A nonredundant 27-level inverter using ldquoHrdquo converters is being analyzed for high power machine drive applications. The main advantage of this kind of converter is the minimum harmonic distortion obtained at the machine side. The drawbacks are the large number of isolated dc power supplies required for each one of the three stages of the multistage converter. In this paper this problem has been overcome in two ways: 1) by using independent windings for each phase of the motor and 2) by using independent input transformers. Special configurations and combinations of diode rectifiers and active front end rectifiers for one of the stages of the drive are used to eliminate input harmonics. The topology can also keep high power factor at the input terminals. Simulation results are shown and some experiments with small three-stage prototype are displayed. The control of this multiconverter is being implemented using DSP controllers, which give flexibility to the system.
- ItemNew Methodology for Analysis and Diagnosis of Sympathetic Interaction of Inrush Currents in Power Transformers for Detecting Abnormal Operating Conditions(IEEE, 2007) Martin, J. S.; Pontt, J.; Rodríguez, J.; Dixon Rojas, JuanThis paper presents a methodology for fast detection and identification of abnormal conditions in electrical systems. Modeling and simulation of most common operations of the system are simulated to create a database containing several patterns of performance under different abnormal operation conditions. The methodology has been tested to identify abnormal operating condition caused by sympathetic interaction of inrush currents in power transformers. Experimental validation of this method was allowing good current pattern identification and a good performance of the methodology was reached.
- ItemPWM regenerative rectifiers: state of the art(IEEE, 2005) Rodriguez, J.R.; Dixon Rojas, Juan, 1948-; Espinoza, J.R.; Pontt, J.; Lezana, P.New regulations impose more stringent limits on current harmonics injected by power converters that are achieved with pulsewidth-modulated (PWM) rectifiers. In addition, several applications demand the capability of power regeneration to the power supply. This work presents the state of the art in the field of regenerative rectifiers with reduced input harmonics and improved power factor. Regenerative rectifiers are able to deliver energy back from the dc side to the ac power supply. Topologies for single- and three-phase power supplies are considered with their corresponding control strategies. Special attention is given to the application of voltage- and current-source PWM rectifiers in different processes with a power range from a few kilowatts up to several megawatts. This paper shows that PWM regenerative rectifiers are a highly developed and mature technology with a wide industrial acceptance.