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This paper proposes the use of a 3-level Cascaded H-Bridge Multilevel Inverter (CHMI) topology which results in further torque ripple minimization compared to the 2-level inverter-based Direct Torque Control (DTC). This is due to the increase in the inverter switching voltage vectors that allows minimization of the torque error. This in turn can reduce the Total Harmonic Distortion (THD) of the output...
Predictive direct torque control for a three-level neutral point clamped inverter is proposed. The main differences between standard direct torque control and the proposed approach are the flexibility and simple algorithm implementation, which does not require complex predefined switching tables nor logic to select among them, as standard direct torque control requires. The dynamic performance is...
This paper presents a simple dynamic overmodulation method to obtain a fast dynamic torque response in DTC of induction machines with constant switching frequency controller. A fast dynamic torque response can be obtained by switching only the most optimized voltage vector during torque dynamic condition. The optimized voltage vector can be identified by comparing the rate of change of torque produced...
In this paper, a new speed identification method is presented based on a stator magnetic field oriented and neuron theory in direct torque control (DTC) system. Compared with the deficiencies of the previous traditional speed identification method, in the suggested method the speed could be fleetly estimated and transferred backward to adjust controller parameters in order to make the desired speed...
Electric vehicles pose specific challenges to the drive system and the control scheme. Safety-relevant features like slip-slide control, electronic stability programs or emergency-brake assistance require fast torque control in the whole speed range at limited voltage control margin. Stator-flux-oriented Indirect Stator-Quantities Control (ISC) is limited only by the physical bounds of available voltage...
Multiphase electric drives have been recently proposed for applications where the highest overall system reliability and power distribution per phase are required. The propulsion drive of an Electric Vehicle (EV) is one of these applications. Direct Torque Control (DTC) methods are normally used in conventional AC drives when fast electrical dynamic performance is required, like in electric propulsion...
A novel sensor-less algorithm for decoupled control of torque and reactive power of a class of doubly-fed machines like the conventional wound rotor induction machine (DFIM) or the emerging brushless reluctance machine (BDFRM), has been proposed in this paper. The control concept has been derived from the first principles of torque production and magnetisation of the machines and requires only the...
In this work, a duty ratio control scheme for inverter fed six-phase induction machines using the direct torque control method based on a fuzzy inference system is presented. A six-phase induction machine has six windings spatially phase shifted by sixty electrical degrees. An improved steady state torque response has been achieved by using the duty ratio control and it has shown less torque ripple...
Multiphase electric drives have been recently proposed for applications where the highest overall system reliability and power distribution per phase are required. The propulsion drive of an Electric Vehicle (EV) is one of these applications. This paper deals with the use of a five-phase induction machine in the propulsion module of EVs, where the viability of a Predictive Torque Control method (PTC)...
Direct torque and flux control of induction machines, fed by matrix converters, is part of academic research since about ten years. Improvements have been achieved and published for the main drawbacks of the control method, high torque and current ripples as well as the variable switching frequency, in particular. However, grid side control of the matrix converter is not yet fully explained. The aim...
Squirrel-cage induction motors are replacing DC motors in variable speed applications due to the availability of advanced control techniques such as Direct Torque Control and Field Oriented Control. At part-load operation of an induction machine, the core losses and, to some extent, copper losses can be minimized, if the machine is operated at a reduced value of flux rather than at the rated value...
A novel technique that improves the low-speed performance of a 5-phase induction machine driven by a 2-level inverter using the classic DTC technique is presented. Demagnetization of the stator flux using DTC is investigated when the induction machine runs at lower speeds and a solution is provided to overcome this phenomenon. The proposed technique reduces the demagnetization phenomenon by using...
A predictive torque and flux control method for an induction machine fed by an indirect matrix converter is presented in this paper. The control scheme selects the switching state that minimizes the error in the torque and flux predictions according to their reference values and, at the same time, the control scheme is enhanced by including a reactive power minimization strategy with the goal to have...
This article contributes a torque control based on hysteresis for Brushless Doubly Fed Induction Machine (BDFM) through machine analysis and extracting the d-q parameters that influence on the machine behavior. In this research, a Direct Torque Control (DTC) based on stator flux-oriented vectors and machine's relation and equations with voltage and current of both stators have been introduced. The...
This paper analyses operation of an indirect rotor field oriented controlled five-phase induction machine with current control in the synchronous reference frame. Artificial Neural network (ANN) based Space vector PWM (SVPWM) technique is utilized to control the five-phase voltage source inverter feeding the five-phase induction machine. Performance, obtainable with ANN based space vector PWM and...
In this paper, Direct Torque Control (DTC) algorithms for dual three-phase induction motor fed by six phases Voltage Source Inverter (VSI) is described. The induction machine has two sets of three-phase stator windings spatially shifted by arbitrary angle. The machine dynamic model is based on the vector space decomposition theory. Optimal switching strategies to control the machine for different...
The present paper treats the effects that arise from an unsymmetrical rotor on an induction machine that is controlled with a predictive direct torque control technique. The influence of a single rotor broken bar can be clearly noticed on the simulation results presented. The electromagnetic torque and consequently the angular speed are considerably affected by a disturbance that is directly related...
A predictive torque and flux control method for an induction machine fed by an indirect matrix converter is presented in this paper. Simple discrete models of the induction machine and the converter are used to predict the behavior of torque and flux. The control scheme selects the switching state that minimizes the error in the torque and flux predictions according to their reference values. The...
To reduce the electromagnetic torque ripple of induction machines under conventional direct torque control, a improved direct torque control based on predictive algorithm is proposed. The control strategy predicts the change of electromagnetic torque and stator flux magnitude for each output voltage vector of inverter in several steps using a discrete-time model of an induction machine. An objective...
This paper presents a simple overmodulation method employed in direct torque control (DTC)-constant switching frequency (CSF) controller of induction machines. The proposed overmodulation method is utilized to extend a constant torque region and hence produces high torque capability in field weakening region with six-step operation. It will be shown that the overmodulation operation using the DTC-CSF...
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