Advances in dual-three-phase permanent magnet synchronous machines and control techniques

Multiphase electrical machines are advantageous for many industrial applications that require a high power rating, smooth torque, power/torque sharing capability, and fault-tolerant capability, compared with conventional single three-phase electrical machines. Consequently, a significant number of studies of multiphase machines has been published in recent years. This paper presents an overview of the recent advances in multiphase permanent magnet synchronous machines (PMSMs) and drive control techniques, with a focus on dual-three-phase PMSMs. It includes an extensive overview of the machine topologies, as well as their modelling methods, pulse-width-modulation techniques, field-oriented control, direct torque control, model predictive control, sensorless control, and fault-tolerant control, together with the newest control strategies for suppressing current harmonics and torque ripples, as well as carrier phase shift techniques, all with worked examples

Optimal Modeled Six-Phase Space Vector Pulse Width Modulation Method for Stator Voltage Harmonic Suppression

Dual Y shift 30 six-phase motors are expected to be extensively applied in high-power yet energy-effective fields, and a harmonic-suppressing control strategy plays a vital role in extending their prominent features of low losses and ultra-quiet operation. Aiming at the suppression of harmonic voltages, this paper proposes a six-phase space vector pulse width modulation method based on an optimization model, namely OM-SVPWM. First, four adjacent large vectors are employed in each of 12 sectors on a fundamental sub-plane. Second, the optimization model is constructed to intelligently determine activation durations of the four vectors, where its objective function aims to minimize the synthesis result on a harmonic sub-plane, and its constraint condition is that the synthesis result on the fundamental sub-plane satisfies a reference vector. Finally, to meet the real-time requirement, optimum solutions are obtained by using general central path following algorithm (GCPFA). Simulation and experiment results prove that, the OM-SVPWM performs around 37% better than a state-of-the-art competitive SVPWM in terms of harmonics suppression, which promise the proposed OM-SVPWM conforms to the energy-effective direction in actual engineering applications.Peer reviewe

A Novel Method Simulating Human Eye Recognition for Sector Judgement of SVPWM Algorithm

The conventional space vector pulse width modulation (SVPWM) algorithm is mature and widely used in the control of three-phase inverters. As we know, the position of the voltage vectors can be seen directly by human eyes, which can be used to replace the existing way for sector selection in the conventional SVPWM algorithm. Based on the fact, a novel method simulating human eye recognition for sector selection of SVPWM is proposed in this paper. In the real application, machine can replace human eyes, and it can `see' the sector step by step in which the voltage vector is located, and immediately give the switching time of the two non-zero voltage vectors. Theoretically, it can save the running time and complexity of the SVPWM algorithm reflected in the situation that multiple inverters are connected in parallel with the number of voltage vectors being increased. The feasibility of the proposed SVPWM algorithm has been validated by both simulation and experiments, which offers the possibility of the application in the multiple or multilevel converters

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

The investigation of electromagnetic radial force and associated vibration in permanent magnet synchronous machines

The rising public awareness of climate change and urban air pollution has been one of the key drivers for transport electrification. Such trend drastically accelerates the quest for high-power-and-torque-density electric drive systems. The rare-earth permanent magnet synchronous machine, with its excellent steady-state and dynamic characteristics, has been the ideal candidate for these applications. Specifically, the fractional-slot and concentrated-winding configuration is widely adopted due to its distinctive merits such as short end winding, low torque pulsation, and high efficiency. The vibration and the associated acoustic noise become one of the main parasitic issues of high-performance permanent magnet synchronous drives. These undesirable features mainly arise from mechanical connection failure, imperfect assembly, torque pulsation, and electromagnetic radial and axial force density waves. The high-power-and-torque-density requirement will only be ultimately fulfilled by the reduction of both electromagnetic active material and passive support structure. This results in inflated electromagnetic force density inside the electric machine. Besides, the sti.ness of the machine parts can be compromised and the resultant natural frequencies are significantly brought down. Therefore, the vibration and acoustic noise that are associated with the electromagnetic radial and axial force density waves become a burden for large deployment of these drives. This study is mainly dedicated to the investigation of the electromagnetic radial forced density and its associated vibration and acoustic noise in radial-flux permanent magnet synchronous machines. These machines are usually powered by voltage source inverter with pulse width modulation techniques and various control strategies. Consequently, the vibration problem not only lies on the permanent magnet synchronous machine but also highly relates to its drive and controller. Generally, the electromagnetic radial force density and its relevant vibration can be divided into low-frequency and high-frequency components based on their origins. The low-frequency electromagnetic radial force density waves stem from the magnetic field components by the permanent magnets and armature reaction of fundamental and phase-belt current harmonic components, while the high-frequency ones are introduced by the interactions between the main low-frequency and sideband highfrequency magnetic field components. Both permanent magnets and armature reaction current are the main sources of magnetic field in electric machines. Various drive-level modeling techniques are first reviewed, explored, and developed to evaluate the current harmonic components of the permanent magnet synchronous machine drive. Meanwhile, a simple yet e.ective analytical model is derived to promptly estimate the sideband current harmonic components in the drive with both sinusoidal and space-vector pulse width modulation techniques. An improved analytical method is also proposed to predict the magnetic field from permanent magnets in interior permanent magnet synchronous machines. Moreover, a universal permeance model is analytically developed to obtain the corresponding armature-reaction magnetic field components. With the permanent magnet and armature-reaction magnetic field components, the main electromagnetic radial force density components can be identified and estimated based on Maxwell stress tensor theory. The stator tooth structure has large impacts on both electromagnetic radial force density components and mechanical vibration behaviors. The stator tooth modulation e.ect has been comprehensively demonstrated and explained by both finite element analysis and experimental results. Analytical models of such e.ect are developed for prompt evaluation and insightful revelation. Based on the proposed models, multi-physics approaches are proposed to accurately predict low-frequency and high-frequency electromagnetic radial vibration. Such method is quite versatile and applicable for both integral-slot and fractional-slot concentrated-winding permanent magnet synchronous machines. Comprehensive experimental results are provided to underpin the validity of the proposed models and methods. This study commences on the derivations of the drive parameters such as torque angle, modulation index, and current harmonic components from circuit perspective and further progresses to evaluate and decouple the air-gap magnetic field components from field perspective. It carries on to dwell on the analytical estimations of the main critical electromagnetic radial force density components and stator tooth modulation e.ect. Based on the stator mechanical structure, the corresponding electromagnetic radial vibration and acoustic noise can be accurately predicted. Various analytical models have been developed throughout this study to provide a systematic tool for quick and e.ective investigation of electromagnetic radial force density, the associated vibration and acoustic noise in permanent magnet synchronous machine drive. They have all been rigorously validated by finite element analysis and experimental results. Besides, this study reveals not only a universal approach for electromagnetic radial vibration analysis but also insightful correlations from both machine and drive perspectives