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A direct self control (DSC) strategy is applied to an induction motor with two three-phase stator winding sets. A remarkable reduction in the electromagnetic torque harmonics, as well as a meaningful minimization of the machine current distortion, are evidenced with respect to a conventional induction motor. In traction applications, electromagneti...
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... this paper an inverter-fed induction machine with two three-phase stator wind- ing sets (Nelson and Krause, 1974;Morando, 1987) is considered. The two stator winding sets have magnetic axes spatially shifted of an angle ², as shown in Fig- ure 1, while a wound or squirrel-caged rotor structure can be indiOE erently chosen. In traction applications, a fast torque control is required and can be obtained by using two vector control strategies; i.e., eld orientation schemes (FO) (Blasckhe, 1972) and DSC (Depenbrock, 1988). ...
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Citations
The strong ability of controlling torque and tolerated fault operation are demanded for multiphase permanent magnet synchronous motor drive system applied in such as locomotive traction, shipping-push, and so on. A tolerated fault direct torque control (DTC) strategy is proposed for six-phase symmetrical winding shifted-phase 60 degree permanent magnet synchronous motor in this paper. Firstly, the relationship between the flux linkage and torque based on the restructured fictitious variables is researched under the condition of one opened phase. Secondly, the optimal control strategy of fictitious flux linkage, torque and zero-sequence current error is proposed with different switching combination of five-phase invert bridge according to the fictitious voltage vector on αβ plane used to convert the mechanic-electric energy and zero-sequence voltage vector on z1z2 plane. The experimental results show that the presented DTC has fast response of torque, the five-phase stator currents are sinusoidal and the magnitudes of five-phase current are the same.
There may be serious distortion in stator currents of multi-phase permanent magnet synchronous motor with direct torque control (DTC) because of the nonlinear factors such as inverter dead-zone, power switch voltage drop and switching transition. A novel DTC was proposed for six-phase symmetric winding phase-shifted by a 60 degree permanent magnet synchronous motor. Firstly, the synthesized voltage vectors were determined to achieve the zero-sequence current, and the ideal DTC strategy was proposed based on the synthesized vectors. Secondly, the factual voltage vector operating time was compensated according to the principle of dead-zone compensation. At last, the voltage vector operating time was regulated continuously by a proportion-integral controller aiming at zero zero-sequence current. The experimental results show that the presented DTC has fast response of torque and the total harmonics is very small due to very lower zero-sequence current.
This paper gives an overview of the topological variations of multi-winding induction machines (IMs) and drives. The study is restricted to IMs having two distributed windings on the stator and a brushless rotor. The mathematical modeling techniques and control algorithms available in the literature are highlighted. Being magnetless and brushless, a Dual Stator Winding IM is highly reliable, maintenance free, and economic. Thus, it possesses the necessary potential to become a part of ac and dc microgrids. Recent research trend shows growth in the application of such generators for off-grid and grid-connected systems.
The paper deals with the analysis, design and implementation of a field-oriented vector control system for a dual-three-phase induction motor for low DC link voltage applications. The issues addressed in this paper include: the advantages of dual-three-phase induction motors, the modeling of dual-three-phase induction motor, Pulse-Width Modulation (PWM) techniques for Voltage Source Inverters (VSI); Field Oriented Control (FOC) and Direct Torque Control (DTC) strategies for dual-three-phase induction motors. The experimental results, obtained for a dual-three-phase induction motor drive in a test laboratory, are included in the paper.
The paper aims to perform an overview on the state-of-the-art in the control of multi-phase drives employing dual-three phase induction machines. In particular, the paper is focused on modeling aspects, Pulse-Width Modulation (PWM) techniques for Voltage Source Inverters (VSI), Field Oriented Control (FOC) and Direct Torque Control (DTC) strategies for dual-three phase induction machines. Furthermore, the paper briefly presents the advantages of dual-three phase induction motor drives over the conventional three-phase drives and the different applications reported in the literature.
A Direct Torque Control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.
A Direct Stator Flux and Torque Control (DSFTC) scheme for asymmetrical six-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is very simple and it is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. The advantages of the discussed control strategy are: constant inverter switching frequency, inherent current limitation, good transient and steady-state performance, maximum torque capability at field weakening even with large variations of the inverter DC link voltage and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Simulation results are presented for a low voltage/high current 10 kW asymmetrical six-phase induction motor drive prototype designed for light traction.
This paper proposes a method to analyze the speed ripple of a six-phase squirrel cage induction machine based on the non-stationary stator current characteristics. Some frequency components associated with the machine space harmonics are present in the stator current spectrum and depend on the rotor slip. The time evolution of these frequencies can be examined to evaluate the effect of torque ripple generated by the negative sequence components when one or several stator phases are lost. The information on the time evolution can be obtained using the spectrogram for time-frequency analysis or several consecutive simple fast Fourier transforms (FFT) as well. A six-phase squirrel-cage induction machine of 90 W, 20 V, 2-poles in normal operation and in faulted mode with two lost phases has been used to validate the proposed method.
