Performance Comparison of Field-oriented Control, Direct Torque Control, and Model-predictive Control for SynRMs

Simulation studies of three synchronous reluctance motor (SynRM) control strategies are presented: field-oriented control (FOC), direct torque control (DTC), and finite-set model-predictive control (FS-MPC). FOC uses linear controllers and pulse-width modulation to control the fundamental components of the load voltages vectors. In contrast, DTC and FS-MPC are nonlinear strategies wherein the voltage vectors are directly generated in the absence of a modulator. Theoretical operating principles and control structures of these control strategies are presented. Moreover, a comparative analysis of the static and dynamic performance of the control strategies is conducted using Matlab/Simulink to identify their advantages and limitations. It is confirmed that each of the control strategies has merits and that all three of them satisfy the requirements of modern high-performance drives.info:eu-repo/semantics/publishedVersio

Synchronous Reluctance Motor Performance Improvement Using MTPA Control Strategy and Five-Level Inverter Topology

An improved vector control method is presented in this study to enhance synchronous reluctance motor (SynRM) performance. The maximum torque per ampere (MTPA) technique has demonstrated good dynamic properties since the torque control is closely tied to the current control. The selection of the control approach is primarily influenced by how the reference current values will be defined. Additionally, a five-level neutral-point-clamped (NPC) inverter replaces the traditional two-level inverter. Only eight voltage vectors can be produced by a two-level inverter, whereas one hundred twenty-five voltage vectors can be generated by a five-level inverter. The goal is to produce an output voltage vector that closely resembles the reference voltage vector in order to ensure a quick response on the one hand and enhance dynamic performance on the other. An exact comparison of the suggested vector control strategy's properties is made once it has been simulated in MATLAB/Simulink. The acquired findings are satisfactory and high performance is attained in terms of response time, torque ripple reduction, and current waveform improvement

Design and Development of Novel Electric Drives for Synchronous Reluctance and PM Synchronous Machines

Permanent magnet synchronous machines (PMSMs) with rare-earth magnets are widely used by the hybrid electric and electric vehicle industry due to their high torque density and efficiency. However the increasing fluctuating prices of the rare earth magnets have triggered the search for other alternative electrical machines such as the induction machine (IM), synchronous reluctance machine (SynRM) and a variable flux machine (VFM). The SynRM and the variable flux machine have been identified as potential PMSMs replacement. This is because the control strategy for the SynRM is closer to the PMSM and that the VFM is a PMSM. Therefore the same hardware used for the PMSM drive can be used for the SynRM and the VFM. There has also been an increasing demand for higher dc bus voltage on the electric drive train for better performance. A three level inverter has been identified as the best candidate to meet this demand. Hence the thesis presents a three level inverter neutral point clamped SynRM drive for traction applications. A new space vector modulation scheme is also proposed for the three level inverter SynRM drive. A comparison between a three and two level inverter SynRM drives was also conducted. Due to high cost associated with EV/HEVs, a low cost high resolution position sensor is proposed for the SynRM and the variable flux machine drives. The low cost position sensor is also compared to the position sensor used in electric power steering (EPS) machine. The EPS machines are predominantly used in vehicles and the low cost position sensor is proposed as a best alternative for the position sensor used in the EPS machine due to their simpler algorithm for position information, higher resolution and cost reduction benefits. The effect of the three level inverter supply on the core losses of the SynRM was also conducted. The SynRM experienced lower core losses when supplied from a three level inverter. The reduction in the core losses is more significant in the stator tooth which is harder to cool as compared to the stator yoke. Hence the additional benefit of a three level inverter SynRM drive is that the burden of the cooling system will be reduced and hence a reduction in the cost associated with machine cooling. The thesis also presents a novel control strategy for a variable flux machine (VFM) which uses low cost aluminum-nickel-cobalt (AlNiCo) permanent magnets (PMs). The strategy implements field weakening for speed extension and takes into account the demagnetization characteristics of the AlNiCo magnets. The magnet flux is reduced from the armature current pulses thus eliminating the additional copper losses associated with the flux weakening current in conventional rare earth PMSMs. The performance of the core losses on the VFM are also evaluated and quantified

Field weakening and sensorless control solutions for synchronous machines applied to electric vehicles.

184 p.La polución es uno de los mayores problemas en los países industrializados. Por ello, la electrificación del transporte por carretera está en pleno auge, favoreciendo la investigación y el desarrollo industrial. El desarrollo de sistemas de propulsión eficientes, fiables, compactos y económicos juega un papel fundamental para la introducción del vehículo eléctrico en el mercado.Las máquinas síncronas de imanes permanentes son, a día de hoy la tecnología más empleada en vehículos eléctricos e híbridos por sus características. Sin embargo, al depender del uso de tierras raras, se están investigando alternativas a este tipo de máquina, tales como las máquinas de reluctancia síncrona asistidas por imanes. Para este tipo de máquinas síncronas es necesario desarrollar estrategias de control eficientes y robustas. Las desviaciones de parámetros son comunes en estas máquinas debido a la saturación magnética y a otra serie de factores, tales como tolerancias de fabricación, dependencias en función de la temperatura de operación o envejecimiento. Las técnicas de control convencionales, especialmente las estrategias de debilitamiento de campo dependen, en general, del conocimiento previo de dichos parámetros. Si no son lo suficientemente robustos, pueden producir problemas de control en las regiones de debilitamiento de campo y debilitamiento de campo profundo. En este sentido, esta tesis presenta dos nuevas estrategias de control de debilitamiento de campo híbridas basadas en LUTs y reguladores VCT.Por otro lado, otro requisito indispensable para la industria de la automoción es la detección de faltas y la tolerancia a fallos. En este sentido, se presenta una nueva estrategia de control sensorless basada en una estructura PLL/HFI híbrida que permite al vehículo continuar operando de forma pseudo-óptima ante roturas en el sensor de posición y velocidad de la máquina eléctrica. En esta tesis, ambas propuestas se validan experimentalmente en un sistema de propulsión real para vehículo eléctrico que cuenta con una máquina de reluctancia síncrona asistidas por imanes de 51 kW

Design and Control of Electrical Motor Drives

Dear Colleagues, I am very happy to have this Special Issue of the journal Energies on the topic of Design and Control of Electrical Motor Drives published. Electrical motor drives are widely used in the industry, automation, transportation, and home appliances. Indeed, rolling mills, machine tools, high-speed trains, subway systems, elevators, electric vehicles, air conditioners, all depend on electrical motor drives.However, the production of effective and practical motors and drives requires flexibility in the regulation of current, torque, flux, acceleration, position, and speed. Without proper modeling, drive, and control, these motor drive systems cannot function effectively.To address these issues, we need to focus on the design, modeling, drive, and control of different types of motors, such as induction motors, permanent magnet synchronous motors, brushless DC motors, DC motors, synchronous reluctance motors, switched reluctance motors, flux-switching motors, linear motors, and step motors.Therefore, relevant research topics in this field of study include modeling electrical motor drives, both in transient and in steady-state, and designing control methods based on novel control strategies (e.g., PI controllers, fuzzy logic controllers, neural network controllers, predictive controllers, adaptive controllers, nonlinear controllers, etc.), with particular attention to transient responses, load disturbances, fault tolerance, and multi-motor drive techniques. This Special Issue include original contributions regarding recent developments and ideas in motor design, motor drive, and motor control. The topics include motor design, field-oriented control, torque control, reliability improvement, advanced controllers for motor drive systems, DSP-based sensorless motor drive systems, high-performance motor drive systems, high-efficiency motor drive systems, and practical applications of motor drive systems. I want to sincerely thank authors, reviewers, and staff members for their time and efforts. Prof. Dr. Tian-Hua Liu Guest Edito

Feasibility and Energy Efficiency of Frequency Converter Driven Synchronous Reluctance Machine in Crane Application

Cranes can use frequency converter driven electrical machines to realize variable speed operations. This thesis discusses if industry favourite induction machine could be replaced by synchronous reluctance machine. Comparative tests have proposed that synchronous reluctance machine is more energy efficient than induction machine. Feasibility of this electrical machine for crane applications needs to be reviewed if this replacement is to be considered. Feasibility and energy efficiency is examined by presenting the operational principles of the compared electrical machines and conducting practical tests with synchronous reluctance machine against a load machine. Presented theory and comparative tests presented no objections against synchronous reluctance machine used for crane application. Practical tests display that synchronous reluctance machine can produce enough torque for crane applications. Tested motor handled zero-speed test cases remarkably well. The motor followed speed commands satisfactorily. Efficiency test results were too low with the tested motor. Efficiency tests faced difficulties, due to which the results are not accurate, but the results can be used to give an indicative view of the efficiency of the tested machine. Synchronous reluctance machine could be used instead of induction machine in cranes, but feasibility requires further research

Sensorless control strategy for light-duty EVs and efficiency loss evaluation of high frequency injection under standardized urban driving cycles

Sensorless control of Electric Vehicle (EV) drives is considered to be an effective approach to improve system reliability and to reduce component costs. In this paper, relevant aspects relating to the sensorless operation of EVs are reported. As an initial contribution, a hybrid sensorless control algorithm is presented that is suitable for a variety of synchronous machines. The proposed method is simple to implement and its relatively low computational cost is a desirable feature for automotive microprocessors with limited computational capabilities. An experimental validation of the proposal is performed on a full-scale automotive grade platform housing a 51¿kW Permanent Magnet assisted Synchronous Reluctance Machine (PM-assisted SynRM). Due to the operational requirements of EVs, both the strategy presented in this paper and other hybrid sensorless control strategies rely on High Frequency Injection (HFI) techniques, to determine the rotor position at standstill and at low speeds. The introduction of additional high frequency perturbations increases the power losses, thereby reducing the overall efficiency of the drive. Hence, a second contribution of this work is a simulation platform for the characterization of power losses in both synchronous machines and a Voltage Source Inverters (VSI). Finally, as a third contribution and considering the central concerns of efficiency and autonomy in EV applications, the impact of power losses are analyzed. The operational requirements of High Frequency Injection (HFI) are experimentally obtained and, using state-of-the-art digital simulation, a detailed loss analysis is performed during real automotive driving cycles. Based on the results, practical considerations are presented in the conclusions relating to EV sensorless control.Peer ReviewedPostprint (published version

Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine

Optimal performance of the electric machine/drive system is mandatory to improve the energy consumption and reliability. To achieve this goal, mathematical models of the electric machine/drive system are necessary. Hence, this motivated the editors to instigate the Special Issue “Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine”, aiming to collect novel publications that push the state-of-the art towards optimal performance for the electric machine/drive system. Seventeen papers have been published in this Special Issue. The published papers focus on several aspects of the electric machine/drive system with respect to the mathematical modelling. Novel optimization methods, control approaches, and comparative analysis for electric drive system based on various electric machines were discussed in the published papers

Torque Estimation of Synchronous Reluctance Machine using High Frequency Signal Injection

Il lavoro analizza due metodi per la stima della coppia prodotta da un motore sincrono a riluttanza, entrambi basati sull'iniezione di un segnale rotante di tensione ad alta frequenza sovrapposto al segnale sincrono alimentante il motore. A partire dal processo dei segnali ad alta frequenza si ottengono le induttanze ad alta freq e attraverso l'equazione di coppia si ottiene la sua stima. Sono state effettuate una simulazione in Simulink e un test sperimentale su un motore commerciale dell'ABB.ope

Design and Optimise Synchronous Reluctance Machines in Sensorless Control

This thesis researches the design and fabrication of axially laminated, anisotropic synchronous reluctance rotors with a high saliency ratio and low torque ripple for both three- and five-phase machines. One clear novelty of the research is the first method reported that allows skew to be incorporated in the axially laminated anisotropic (ALA) rotor. The designed rotor is then built with the help of the 3D printing technique which significantly reduces the complexity of the prototyping and fabrication process. The thesis then considers the control necessary including sensorless control schemes for the three- and five-phase synchronous reluctance motors with varying levels of skew. The performance and the effectiveness of the sensorless controllers are verified by experiments for all designed rotors under the three- and five-phase excitation. The three- and five-phase system of the synchronous reluctance motor is first discussed with the stator voltage equations and equivalent circuits. The d-and q-axis inductances are evaluated using finite element analysis. Finite element analysis (FEA) is a common used method in simulating and solving the electrical engineering problems. The FEA shows that for both three- and five-phase motors, the saliency ratio can reach around 10. Further detailed optimization is performed based on the rotor barrier dimensions such as shape, arc length, rib and bridge length, width, and the number of barriers. The final designed rotor in this research is an ALA rotor with 4 poles and 9 layers of magnetic segments. The barrier used is the round-type. The experimental inductances are shown to match the FEA predictions. The method of fabricating an ALA-type rotor with skew is a significant advance in this research. The FEA analysis for both three- and five-phase motor shows that torque ripple can be significantly reduced with the skew process: for instance, the 5.5° skewed rotor and the 9.5° skewed rotor are predicted to offer the best choice for the three- and five-phase stator designs from a parametric study of skew angles. Three skewed rotors are fabricated (5.5 o, 6 o and 9.5o). The experimental results of the torque ripple are compared. For the three-phase case, the rotors with skew shows a good reduction in torque ripple, the 6° skewed rotor performs better than the 5.5° skewed rotor. For the five-phase case, the 9.5° skewed rotor provides the best torque ripple reduction experimentally. The sensorless control is achieved for both three- and five-phase systems. According to the speed demand, the high-frequency injection sensorless control is used when the speed is below 500rpm. To further reduce the transient error, two different sliding mode observer methods are used for three and five-phase systems when the speed demand is above 500rpm. For both three- and five-phase synchronous reluctance motors with non-skewed and skewed rotors, the sensorless control can be successfully implemented. The transient and steady-state errors are all controlled in an acceptable range. By suddenly adding full load at rated and zero speed, the effectiveness of the sensorless control is also verified