Time Ratio Controlled Three-phase AC Chopper

A general switching method suitable to control three-phase AC chopper circuit is presented. Such a method can be used with different circuit configurations of the AC chopper. Detailed harmonic analysis of the AC chopper when controlled by the time ratio control (TRC) strategy is given. TRC has the advantages of linear control of the fundamental component of the output voltage and elimination of all harmonics of order less than the frequency ratio by two. Also, the control signal can be generated easily. Experimental results verifying the analysis are presented

Economic Modeling of Site-Specific Optimum Wind Turbine for Electrification Studies

A generalized approach for the economic selection of wind turbine for a given wind regime is proposed in this paper. It draws from the literature and standards being used in the field to arrive at an economic site specific wind turbine based on minimizing the annual cost of energy produced (AEP) while tracking the initial capital cost (ICC) of investment required. It is meant to provide an initial study to guide decision makers who are contemplating using wind energy as a power source to generate electricity in commercial quantity for community usage. It is a general estimation approach which does not require surfing for manufacture prices and wind turbine parameters. The input data consists of site specific wind data, hub height, rotor diameter and turbine power rating. The output gives a range of plots of feasible wind turbine ratings, rotor diameters, rated speed against initial capital cost (ICC) and also cost of energy produced (COE).</jats:p

Effect of short circuited DC link capacitor of an AC–DC–AC inverter on the performance of induction motor

AbstractInduction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition