Performance analysis of a three-phase induction motor with double-triple winding layout

Abstract: This paper presents the performance of threephase induction motor with a stator winding comprising of a combination of double and triple layer arrangements in slots, here simply referred to as double-triple stator winding layouts. The proposed layout provides a three-phase induction motor with high torque density and greater efficiency than the conventional machine with double winding layout. Field analysis technique is used to show that this winding arrangement has improved harmonic content and the machine performance is computed using Finite Element Method (FEM). Saturation is accounted for in the computation of the inductances. A 1500 W conventional three-phase induction machine with 36 stator slots is first wound as a four-pole double layer and then as a four-pole double-triple layer for the experimental study. Both windings are chorded with one slot with same number of turns per phase and use the same squirrel cage rotor

A study of improving the power factor of a three-phase induction motor using a static switched capacitor

Abstract: In this paper a static switched capacitor with an auxiliary three-phase stator winding, which is only magnetically coupled to the stator main winding, is explored for improving the starting and operating power factor of a three-phase induction motor. The scheme improves the power factor of the motor without compromising significantly on other performances. Important advantages of the scheme include preventing harmonics in the line current, and eliminating regeneration possibility as well as preventing high inrush currents at starting

Operating strategies and capacitor voltace balance strategies for a cascaded "3-5-9" hybrid inverter for grid interface application

Abstract: The paper presents a novel phase shifted SPWM control scheme for cascading two cells to form a “3-5-9 hybrid inverter with improved harmonic suppression. Modeling of the hybrid inverter from first principle is introduced and a standard control law is derived for further analysis and development of the model. A new balance circuit for DC link voltage control is designed and tested. Combined with individual voltage control, a complete control scheme is developed. Detailed MATLAB simulation and experimental results are obtained for further validation of the adopted topology and the control schem

Zero voltage switching used for a reversible DC-DC converter

Abstract A novel bi-directional dc-dc converter with Zero Voltage Switching (ZVS) and interleaving for dual voltage systems in automobiles is presented. A variable frequency extended band hysteretic current control method is proposed. In comparison with classical fixed frequency current control PWM, the reverse polarity peak current needed for ZVS operation is kept constant. Inductor current ripple decreases with load reduction. Automatic changes in operation between buck and boost modes are accomplished without transient currents. Converter simulations are carried out using Matlab/Simulink platform

Flat control of industrial robotic manipulators

Published ArticleA new approach to tracking control of industrial robot manipulators is presented in this paper. The highly coupled nonlinear dynamics of a six degrees of freedom (6-DOF) serial robot is decoupled by expressing its variables as a function of a flat output and a finite number of its derivatives. Hence the derivation of the flat output for the 6-DOF robot is presented. With the flat output, trajectories for each of the generalized coordinates are easily designed and open loop control is made possible. Using MATLAB/Simulink Sfunctions combined with the differential flatness property of the robot, trajectory tracking is carried out in closed loop by using a linear flat controller. The merit of this approach reduces the computational complexity of the robot dynamics by allowing online computation of a high order system at a lower computational cost. Using the same processor, the run time for tracking arbitrary trajectories is reduced significantly to about 10 s as compared to 30 min in the original study (Hoifodt, 2011). The design is taken further by including a Jacobian transformation for tracking of trajectories in cartesian space. Simulations using the ABB IRB140 industrial robot with full dynamics are used to validate the study

LV and MV distribution networks reconfiguration for minimum losses

Abstract: The reconfiguration of the distribution network feeders can be defined as the restructuring of the feeders through the changing of the open/close states of the sectionalizing and tie switches. This creation of a new distribution network topology is normally required to improve the performance of the network, and thus sometimes the efficiency of the electricity supply. For optimum loss reduction, feeder reconfiguration is often considered as an option. This, however, requires the implementation of an appropriate switching control strategy. It would be desirable for the switching to be automatic, that is to follow the connected load situation of the feeder. The proposed optimal reconfiguration of the phase balancing using the heuristic method proves to be robust compared to neural network method, to turn ON and OFF the different switches, allowing the three phases supply of the transformer to the end-users to be balanced. This paper presents the application examples of the proposed method using the real data

Forecasting model for energy consumption in South Africa correlated with the income

Abstract This paper presents a mathematical model that forecasts the energy consumption in South Africa. The model is correlated to the income of the consumers. The study made use of the real energy consumption audit in South Africa. The mathematical model in this work is developed around the variables identified from the survey. The model can be applied to other utilities worldwide with some modifications in the influencing parameter values. The model developed was used to study the effect of certain indices; such as society, personality, and fixed contribution index on the electricity consumption. Different results obtained and presented in this work clearly show that the income is a major determinant of energy consumption

Performance analysis of induction machines with unconventional winding configurations

Abstract: This paper presents the performance of fractional slots distributed windings (FSDW) and fractional slots concentrated windings (FSCW) of three-phase squirrel cage induction machines. The different windings have been designed and modeled using the same machine physical and electrical parameters. The Finite Element Model (FEM) of the machine for the different windings has been carried out. The results for the machine with FSDW and FSCW are compared to the results of the conventional double layer (CDL) with 8/9 chorded coil