710 research outputs found
High Performance Direct Torque Control of Induction Motor Drives: Problems and Improvements
This paper presents some of the main problems, as well as their root causes, of Direct Torque Control (DTC) 3-phase induction motor drive. The high torque ripple in DTC drive due to the hysteresis controller inevitably becomes worst with the discrete implementation of the drive system. The hysteresis controller also causes variable switching frequency that depends on operating conditions, especially the speed. The simplification used in stator flux expression for voltage vectors selection in flux control results in a poor flux regulation at low speed. To overcome these problems, techniques that have been implemented at UTM- PROTON Future Drive Laboratory (UPFDL) are presented and described. Some experimental results obtained from the previous works are also presented and discussed.
Torque Control
This book is the result of inspirations and contributions from many researchers, a collection of 9 works, which are, in majority, focalised around the Direct Torque Control and may be comprised of three sections: different techniques for the control of asynchronous motors and double feed or double star induction machines, oriented approach of recent developments relating to the control of the Permanent Magnet Synchronous Motors, and special controller design and torque control of switched reluctance machine
Multiphase induction motor drives - a technology status review
The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio
Hybrid Cascaded H-Bridge Multilevel-Inverter Induction-Motor-Drive Direct Torque Control for Automotive Applications
International audienceThis paper presents a hybrid cascaded H-bridge multilevel motor drive direct torque control (DTC) scheme for electric vehicles (EVs) or hybrid EVs. The control method is based on DTC operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a hybrid cascaded H-bridge multilevel inverter, where each phase of the inverter can be implemented using a dc source, which would be available from fuel cells, batteries, or ultracapacitors. This inverter provides nearly sinusoidal voltages with very low distortion, even without filtering, using fewer switching devices. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with fewer switching losses, since only the small power cells of the inverter operate at a high switching rate. Therefore, a high performance and also efficient torque and flux controllers are obtained, enabling a DTC solution for multilevel-inverter-powered motor drives
Hybrid Cascaded H-Bridge Multilevel Inverter Motor Drive DTC Control for Electric Vehicles
International audienceThis paper presents a hybrid cascaded H-bridge multilevel motor drive DTC control scheme for Electric (EV) or Hybrid Electric Vehicles (HEV). The control method is based on Direct Torque Control operating principles. The stator voltage vector reference is computed from the stator flux and torque errors imposed by the flux and torque controllers. This voltage reference is then generated using a hybrid cascaded H-bridge multilevel inverter, where each phase of the inverter can be implemented using a DC source, which would be available from fuel cells, batteries, or ultracapacitors. This inverter provides nearly sinusoidal voltages with very low distortion, using less switching devices. Due to the small dv/dt's, torque ripple is greatly reduced. In addition, the multilevel inverter can generate a high and fixed switching frequency output voltage with less switching losses, since only the small power cells of the inverter operate at high switching rate. Therefore a high performance and also efficient torque and flux controller is obtained, enabling a DTC solution for multilevel inverter powered motor drives
High-Speed Computation using FPGA for Excellent Performance of Direct Torque Control of Induction Machines
The major problems in hysteresis-based DTC are high torque ripple and variable switching frequency. In order to minimize the torque ripple, high sampling time and fast digital realization should be applied. The high sampling and fast digital realization time can be achieved by utilizing high-speed processor where the operation of the discrete hysteresis regulator is becoming similar to the operation of analog-based comparator. This can be achieved by utilizing field programmable gate array (FPGA) which can perform a sampling at a very high speed, compared to the fact that developing an ASIC chip is expensive and laborious
Predictive current control in electrical drives: an illustrated review with case examples using a five-phase induction motor drive with distributed windings
The industrial application of electric machines in variable-speed drives has grown in the last decades thanks to the
development of microprocessors and power converters. Although three-phase machines constitute the most common case, the
interest of the research community has been recently focused on machines with more than three phases, known as multiphase
machines. The principal reason lies in the exploitation of their advantages like reliability, better current distribution among phases
or lower current harmonic production in the power converter than conventional three-phase ones, to name a few. Nevertheless,
multiphase drives applications require the development of complex controllers to regulate the torque (or speed) and flux of the
machine. In this regard, predictive current controllers have recently appeared as a viable alternative due to an easy formulation
and a high flexibility to incorporate different control objectives. It is found however that these controllers face some peculiarities
and limitations in their use that require attention. This work attempts to tackle the predictive current control technique as a viable
alternative for the regulation of multiphase drives, paying special attention to the development of the control technique and the
discussion of the benefits and limitations. Case examples with experimental results in a symmetrical five-phase induction machine
with distributed windings in motoring mode of operation are used to this end
Model Predictive Control based on Dynamic Voltage Vectors for Six-phase Induction Machines
Model predictive control (MPC) has been recently
suggested as an interesting alternative for the regulation of
multiphase electric drives because it easily exploits the inherent
advantages of multiphase machines. However, the standard
MPC applies a single switching state during the whole sampling
period, inevitably leading to an undesired x y voltage production.
Consequently, its performance can be highly degraded when the
stator leakage inductance is low. This shortcoming has been,
however, mitigated in recent work with the implementation
of virtual/synthetic voltage vectors (VVs) in MPC strategies.
Their implementation reduces the phase current harmonic
distortion since the average x y voltage production becomes
null. Nevertheless, VVs have a static nature because they are
generally estimated offline, and this implies that the flux/torque
regulation is suboptimal. Moreover, these static VVs also present
some limitations from the point of view of the dc-link voltage
exploitation. Based on these previous limitations, this article
proposes the implementation of dynamic virtual voltage vectors
(DVVs), where VVs are created online within the MPC strategy.
This new concept provides an online optimization of the output
voltage production depending on the operating point, resulting
in an enhanced flux/torque regulation and a better use of the
dc-link voltage. Experimental results have been employed to
assess the goodness of the proposed MPC based on DVVs.Ministerio de Ciencia, InnovaciĂłn y Universidades RTI2018-096151-B-100
Simple and robust predictive direct control of DFIG with low constant switching frequency and reduced torque and flux ripples
For conventional direct torque control (CDTC) methods, there are usually undesired torque and flux ripples mainly for two reasons. First, the vectors selected are not necessary the best. Secondly, one-step delay influence in digital implementation causes additional torque and flux ripples. This paper proposes a novel predictive direct torque control (PDTC) strategy of the doubly fed induction generator (DFIG). The proposed strategy aims to reduce torque and flux ripples effectively at low constant switching frequency by appropriately arranging two active vectors followed by one zero vector within one control period. Furthermore, one-step delay is compensated using a mode-based prediction scheme. Finally, the control system is simplified through further analysis of the transient slope of torque and flux without performance degradation. Simulation results validate the proposed strategy with excellent steady-state and transient performance, which makes it very suitable for wind power generation. © 2011 IEEE
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