An improved direct torque control strategy for induction motor drive

The object of this study is to study a new control structure for sensorless induction machine dedicated to electrical drives using a three-level Voltage Source Inverter (VSI). The major problem with DTC drives is the high torque ripple, to solve this problem two approaches are proposed to replace the conventional hysteresis-based controller. The output voltages of the three-level VSI can be represented by four groups: the zero voltage vectors, the small voltage vectors, the middle voltage vectors and the large voltage vectors in (d, q) plane. Then, the amplitude and the rotating velocity of the flux vector can be controlled freely. Both fast torque and optimal switching logic can be obtained. The selection is based on the value of the stator flux and the torque. Both approaches are simulated for a induction motor. The results obtained show superior performances over the conventional DTC one without need to any mechanical senso

A new algorithm applied to the evaluation of self excited induction generator performance

The paper presents the application of DIRECT algorithm to analyse the performances of the Self-excited induction generator. It is used to minimize the induction generator admittance yielding the solution which consists of the magnetizing reactance and the frequency. These parameters are the keys to find out the self excitation process requirements in terms of the prime mover speed, the capacitance and the load impedance and finally the output performances such as the voltage, output power, etc. A comparison with other powerful optimization algorithms is investigated to obtain DIRECT algorithm performance

Sigmoid function approximation for ANN implementation in FPGA devices

The objective of this work is the implementation of Artificial Neural Network on a FPGA board. This implementation aim is to contribute in the hardware integration solutions in the areas such as monitoring, diagnosis, maintenance and control of power system as well as industrial processes. Since the Simulink library provided by Xilinx, has all the blocks that are necessary for the design of Artificial Neural Networks except a few functions such as sigmoid function. In this work, an approximation of the sigmoid function in polynomial form has been proposed. Then, the sigmoid function approximation has been implemented on FPGA using the Xilinx library. Tests results are satisfactor

Sensorless speed field-oriented control of induction motor tacking core loss into account

In field-oriented controlled induction motor drives, the instantaneous rotor speed is measured using whether sensors or estimators. Since the basic Kalman filter is a state observer, its use in vector controlled schemes has received much attention. However, these schemes are based on the assumption that the existence of iron loss in the induction motor may be neglected. The paper shows the effect of iron loss on the extended Kalman filter performance that is designed on the basis of the classical dq model. Original simulation results are carried out to demonstrate this effect as well as the effectiveness of the suggested approach to minimise the speed estimation error without modifying the EKF's algorithm

Reliability assessment and improvement of medium power induction motor winding insulation protection system using predictive analysis

This chapter presents a reliability assessment of a widely used protection system of medium-power squirrel cage induction motors. In conjunction with published field induction motors reliability data, this assessment effort is based on a predictive analysis integrating three predictive techniques: (1) a fault tree analysis (FTA) that allows to identify and then quantify the initiating events weighting factors; (2) an event tree analysis (ETA) that allows to predict the protection system probability outcomes following an external disturbance; and (3) a failure mode effect and criticality analysis (FMECA) that will help set the stage to develop a preventive maintenance program fit to keep up the induction motor protection system reliability at the required level with particular attention given to aggressive environmental factors such as found in cement plant

A power Line communication control scheme for electrical energy management

In the present paper is described the scheme of a Power Line Communication (PLC) control system for energy management. The control system described is based on the Spread Spectrum Carrier Technology (SSCT) for the transmission of control information over the power line. This technique employs a series of short frequency swept chirps that act as carrier. The swept frequency chirps are generated by the implementation of a look up table stored in a ROM section. The choice of using a ROM is based on a hardware solution that allows the chirps generation under accurate timing. Another reason is the possibility to generate the chirps in their different modulated forms. Information data is converted to chirps according to the Consumer Electronics Bus (CEBus) standard that sets the transmission protocols and the modulation technique. Energy management to be achieved requires the control of various devices existing in buildings and houses and leading to the concept of Home Automatio

A scheme of EDTC control using a three-level voltage source inverter for an induction motor

The object of this paper is to study a new control structure for sensorless induction machine dedicated to electrical drives using a three-level voltage source inverter (VSI). The amplitude and the rotating speed of the flux vector can be controlled freely. Both fast torque response and optimal switching logic can be achieved; the selection is based on the value of the stator flux and the torque. A novel DTC scheme of induction motors is proposed in order to develop a suitable dynamic. We propose an approach; in wich we enhance the response of torque and flux with optimal switching strategies. However, the middle point voltage of the input DC voltages of the three-level NPC voltage source inverter presents serious problems caused by a fluctuation of the DC voltage sources UcU, UcL. As consequence to these problems, we obtain an output voltage of the inverter which is asymmetric and with an average value different from zero. In this paper, we will present one solution to minimise this fluctuation. This solution uses a clamping bridge to regulate the input voltages of a three-level inverter VSI NPC. A scheme of Enhanced direct torque control "EDTC" with complete cascade is simulated for an induction motor. The results obtained indicate superior performance over the FOC one without need to any mechanical senso