Browsing by Author "L. Moran"
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- ItemDC link fuzzy control for an active power filter, sensing the line current only(IEEE, 1997) Dixon Rojas, Juan, 1948-; Contardo Guevara, Jaime; L. MoranA different approach for controlling a shunt active power filter is presented. The DC link is controlled with fuzzy logic, and the current generated for the filter to compensate harmonics and power factor is not sensed. The sensors acts directly on the mains line currents, forcing them to be sinusoidal, and in phase with the mains voltage supply. The amplitude of the current is controlled by the fuzzy system, which operates through the error between the DC link voltage of the PWM modulator (active power filter), and a pre-established reference voltage, Vref. The main advantages of this approach are the following: (a) the control block becomes simpler because there is no need to evaluate the current template for the filter currents; (b) the DC link fuzzy control has better dynamic behavior than conventional PI control; and (c) the filter can operate simultaneously as a power factor compensator, and as a four quadrant rectifier-inverter system.
- ItemHigh-level multistep inverter optimization using a minimum number of power transistors(2006) Dixon Rojas, Juan; L. MoranMultilevel inverters with a large number of steps (more than 50 levels) can generate high quality voltage waveforms, good enough to be considered as suitable voltage template generators. Many levels or steps can follow a voltage reference with accuracy, and with the advantage that the generated voltage can be modulated in amplitude instead of pulse-width modulation. The main disadvantage of this type of topology is the large number of power supplies and semiconductors required to obtain these multistep voltage waveforms. This paper is focussed on minimizing the number of power supplies and semiconductors for a given number of levels. Different combinations of topologies are presented, and the corresponding mathematical relations have been derived. This paper shows optimized curves to obtain the relation between a minimum number of power semiconductors required for a given number of levels. Experimental results obtained from an optimized prototype, capable of generatng 81 levels of voltage with only four power supplies and 16 transistors per phase, are shown.