There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Multiphase variable-speed drives and generation systems (systems with more than three phases) have become one of the mainstream research areas during the last decade. The main driving forces are the specific applications, predominantly related to the green agenda, such as electric and hybrid electric vehicles (EVs), locomotive traction, ship propulsion, “more-electric” aircraft, remote offshore wind farms for electric energy generation, and general high-power industrial applications. As a result, produced body of significant work is substantial, making it impossible to review all the major developments in a single paper. This paper therefore surveys the recent progress in two specific areas associated with multiphase systems, namely power electronic supply control and innovative ways of using the additional degrees of freedom in multiphase machines for various nontraditional purposes.

/pdf/advances-in-converter-control-and-innovative-exploitation-of-3nc3l7z4ta.pdf

Advances in Converter Control and Innovative Exploitation of Additional Degrees of Freedom for Multiphase Machines

A position sensorless control strategy of an interior permanent magnet synchronous motor (IPMSM) drive based on a digital signal processor (DSP) is proposed. To achieve sensorless wide-speed-range operation, a hybrid position estimation strategy combining the high frequency (HF) signal injection method with the electromotive force (EMF)-based method is presented. At low-speed range, an HF voltage signal is injected, and a rotor position observer is designed to improve the robustness to the load disturbance. At middle- and high-speed ranges, a sliding-mode observer based on the extended EMF of IPMSM is designed for sensorless operation. Moreover, during the switch-over area, the two position estimation methods are both enabled for the sensorless control. A software phase-locked loop and a dead-time compensation strategy are adopted to improve the position estimation accuracy. The experimental results demonstrate the feasibility of the control strategy with a sensorless IPMSM drive based on a DSP.

DSP-Based Control of Sensorless IPMSM Drives for Wide-Speed-Range Operation

Permanent-magnet (PM) motors with both magnets and armature windings on the stator (stator PM motors) have attracted considerable attention due to their simple structure, robust configuration, high power density, easy heat dissipation, and suitability for high-speed operations. However, current PM motors in industrial, residential, and automotive applications are still dominated by interior permanent-magnet motors (IPM) because the claimed advantages of stator PM motors have not been fully investigated and validated. Hence, this paper will perform a comparative study between a stator-PM motor, namely, a flux switching PM motor (FSPM), and an IPM which has been used in the 2004 Prius hybrid electric vehicle (HEV). For a fair comparison, the two motors are designed at the same phase current, current density, and dimensions including the stator outer diameter and stack length. First, the Prius-IPM is investigated by means of finite-element method (FEM). The FEM results are then verified by experimental results to confirm the validity of the methods used in this study. Second, the FSPM design is optimized and investigated based on the same method used for the Prius-IPM. Third, the electromagnetic performance and the material mass of the two motors are compared. It is concluded that FSPM has more sinusoidal back-EMF hence is more suitable for BLAC control. It also offers the advantage of smaller torque ripple and better mechanical integrity for safer and smoother operations. But the FSPM has disadvantages such as low magnet utilization ratio and high cost. It may not be able to compete with IPM in automotive and other applications where cost constraints are tight.

Quantitative Comparison of Flux-Switching Permanent-Magnet Motors With Interior Permanent Magnet Motor for EV, HEV, and PHEV Applications

Although the concept of a multiphase drive system dates back to the middle of the 20th century, the initial pace of development was rather slow, as witnessed by the first two surveys of the area published in the beginning of this century. However, considerably new developments have resulted in the last decade of the 20th century and the beginning of this century, leading to an authoritative survey of the asymmetrical six-phase drive control and subsequently of the review of the complete area. This also initiated the organization and subsequent publication of the first IEEE Transactions on Industrial Electronics "Special Section on Multiphase Machines and Drives" in May 2008, which commenced with another survey paper, and that contained 12 original research papers. Since the publication of this Special Section in May 2008, the level of interest and pace of developments in the area have further accelerated and substantial new knowledge has been generatedwith an ever-increasing number of published research papers and reported new industrial applications. Such a trend has been emphasized in a recent paper. It therefore seemed appropriate to revisit the area and organize this Special Section as a sequel to the first one. The call for the Special Section papers resulted in 51 submissions, almost twice as many as the total back in 2008, thus confirming a substantial growth of the area. Indeed, the amount of new knowledge acquired since the publication of the first Special Section in 2008 has meant that it was not possible to provide a complete and thorough survey of the field in a single review paper.

/pdf/multiphase-machines-and-drives-revisited-2kmbx8a5nm.pdf

Multiphase machines and drives - Revisited

The interior permanent-magnet (IPM) machine is used in many industrial drives. In order to analyze performance and to design efficient and fast controllers, accurate knowledge of machine parameters such as d- and q-axes inductances is essential. Although there are a number of methods available to calculate these inductances, none of them is considered standard. Accuracy levels of all these methods are also not consistent, and some of the measurement methods require complicated arrangements. Among these test methods, the ac standstill test and a newly developed test method that uses vector current control technique are ideal for a laboratory environment. In this paper, these two methods are compared by applying them to a prototype IPM machine. The paper analyzes the test results of the methods and their differences in detail with the help of finite-element analysis

A Comparative Analysis of Two Test Methods of Measuring $d$ - and $q$ -Axes Inductances of Interior Permanent-Magnet Machine

This paper evaluates the design of a new segmented interior permanent magnet (SIPM) machine with very wide constant power operation range. The machine uses segmentation of the rotor magnets with the help of iron bridges between magnet segments. This provides for an inherent flux-weakening capability to the interior permanent magnet (IPM) machine. A very wide flux-weakening range has been achieved by using a standard distributed stator winding only. The flux-weakening capability of the proposed SIPM motor was compared to a conventional IPM machine. The same stator was used in both machines for direct comparison. The paper also presents the design optimization process and experimental verification of the performance of the proposed machine as a case study of a 42 V alternator operation in which the speed range is from 600 to 6000 r/min.

Design and Analysis of an Interior Permanent Magnet (IPM) Machine With Very Wide Constant Power Operation Range

This paper investigates inductance characteristics of a novel 14 pole/18 slot, fractional-slot concentrated-winding (FSCW) IPM machine. The variations of the self and mutual inductances were calculated analytically and also obtained from the finite element model. These results were compared with experimentally measured values of the self and mutual inductances of the prototype machine. Study of the inductance characteristics reveals that both self and mutual inductances vary with rotor positions nonsinusoidally. Presence of harmonics in the magnetomotive force (MMF) is responsible for this nonsinusoidal variation of inductances. The conventional distributed winding machine does not have these harmonics. This paper analyses the contribution of these harmonics in the Ld and Lq parameters in a dq-model of the prototype FSCW machine constructed. The self and mutual inductances were represented by a Fourier series in the inductance matrix of the machine for dq-transformation. It was seen that the difference between d- and q-axis inductance is mainly contributed by the harmonic terms of the mutual inductance.

Winding Inductances of an Interior Permanent Magnet (IPM) Machine With Fractional Slot Concentrated Winding

This paper presents the design and the experimental verification of an 18-slot/14-pole fractional-slot concentrated winding interior permanent magnet machine. The prototype machine was optimized for wide constant power speed range (7:1) and very low cogging torque, two of the most important requirements for traction machines. Measured performance of the constructed prototype machine has confirmed the finite-element modeling results. Experience gained from this study has led to develop a set of design rules for the concentrated winding (CW)- interior permanent magnet (IPM) machine. Scaling up of the prototype design based on these rules is also discussed in this paper.

Design and Experimental Verification of an 18-Slot/14-pole Fractional-Slot Concentrated Winding Interior Permanent Magnet Machine

In this paper, design of a new interior permanent magnet (IPM) machine with very wide constant power operation range is presented It has been seen that segmentation of the pole magnets and presence of iron bridges between magnet segments provide an inherent flux-weakening capability to the IPM rotor Consequently, a very wide flux-weakening range is achievable with standard distributed stator winding The flux-weakening capability of the new rotor was compared to a conventional IPM rotor using the same stator The paper also presents the design optimization process and experimental verification of performance characteristic of the proposed machine as a case study of a 42 V alternator operation in which the constant power speed range is from 600 to 6000 r/min

Rukmi Dutta

Papers

A Comparative Analysis of Two Test Methods of Measuring $d$ - and $q$ -Axes Inductances of Interior Permanent-Magnet Machine

Design and Analysis of an Interior Permanent Magnet (IPM) Machine With Very Wide Constant Power Operation Range

Winding Inductances of an Interior Permanent Magnet (IPM) Machine With Fractional Slot Concentrated Winding

Design and Experimental Verification of an 18-Slot/14-pole Fractional-Slot Concentrated Winding Interior Permanent Magnet Machine

Design and Analysis of an Interior Permanent Magnet (IPM) Machine with Very Wide Constant Power Operation Range