Synchronous reluctance generator with ferrite magnets for wind turbine

Synchronous reluctance generators with ferrite magnets in the rotor (PMSynRG) are a good alternative to synchronous generators (SG) with rare-earth magnets. The comparison between a SG with rare-earth magnets and a PMSynRG with ferrite magnets of the same diameter, stack length, power and speed is given in the paper. Twice as less magnets are required for the PMSynRG with ferrite magnets than for the SG with rare-earth magnets. The cost of the ferrite magnets is 4.4 times less than of the rare earth magnets. Also, the PMSynRG with ferrite magnets has much higher efficiency than the SG. The half-integer slot number per pole and phase is chosen to achieve rather low torque ripple without skewing the rotor. © 2018 Institute of Physics Publishing.All Rights Reserved

Gearless generator with magnets on the stator for wind turbine

In this work a new design of multi-pole gearless low-speed Generator with Magnets on the Stator (GMS) for wind turbine is described. Gearless GMS combines both high number of magnetic poles created by magnets and low-pole winding creating strong electromotive force. Therefore GMS has high efficiency and low operational speed. The GMS mathematical model has been developed. The low-speed gearless GMS was designed with the help of the developed mathematical model. Comparison of the designed GMS with a generator with magnets on the rotor (SG) is given. The GMS active material cost is 2.3 times less than that for the SG. The GMS mass is 1.3 times less. The GMS has higher efficiency at the rated speed. Also GMS maintain high efficiency in wide range of torques and speeds and GMS torque ripple is low. © 2018 Web Portal IOP. All rights reserved

Design optimization of a permanent-magnet flux-switching generator for direct-drive wind turbines

Due to the increasing need for direct-drive wind turbines, a large number of papers are dedicated to the optimization of low-speed wind generators. A permanent-magnet flux-switching machine can be a valuable option to use in such applications. This paper describes the optimization procedure of a direct-drive flux-switching wind generator. The average losses, the required converter power, and the cost of permanents magnets were chosen as the optimization objectives. To reduce the calculation efforts during the optimization, a method to construct the substituting load profiles is proposed. Two-mode and three-mode substituting profiles were constructed on the basis of the nine-mode initial profile. The losses calculated under the two-mode, three-mode, and nine-mode profiles accurately coincided, which supported the use of the low-mode substituting profiles instead of the initial one. During the optimization, the average losses decreased by 30%, which corresponded to an increase in the average efficiency by almost 6%. The required converter power was decreased by 10%. The total active material mass, cogging torque, and torque ripple were also slightly decreased. © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

Optimal design of gearless flux-switching generator with ferrite permanent magnets

In this paper, the optimal design of the Flux-Switching Generator with ferrite magnets based on a two-mode substituting load profile for a gearless wind generator is considered. A onecriterion Nelder-Mead method is used to optimize the generator design. The optimization function is constructed mainly so as to minimize the average losses in the generator and the required AC-DC converter power. Also, the Flux-Switching Generator torque-ripple and the ferrite magnets volume are minimized. Using substituting profiles instead of initial ones reduces the calculation efforts substantially. The paper contains the analysis of the optimal design of the Flux-Switching Generator with ferrite magnets. © 2020 by the authors.Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research was conducted on theme no. 8.9549.2017/8.9. within the frame of the government task of the Ministry of Education and Science of the Russian Federation in R&D. The authors thank the editors and reviewers for careful reading, and constructive comments

Optimum design of high-speed single-phase flux reversal motor with reduced torque ripple

Single-phase motors are used in low-power, cost-effective, variable-speed applications. As a replacement to traditional single-phase synchronous motors with magnets on the rotor, single-phase flux reversal motors (FRMs) with a rugged and reliable toothed rotor are considered for the high-speed applications. However, torque pulsations of single-phase motors are high. The aim of this work is to minimize the torque ripple and increase its minimum instantaneous value, as well as to reduce FRM losses. To solve this problem, an asymmetric rotor is used, and an objective function is proposed, which includes parameters characterizing the pulsations of the torque and the loss of FRM for two load conditions. To optimize the single-phase FRM and minimize the objective function, the Nelder-Mead method was applied. The optimization criterion was selected to maximize the efficiency, to reduce the torque ripple, and to the avoid the negative torque in a wide range of powers at the fan load (quadric dependence of torque on speed). Two operating loading modes are considered. After two stages of optimization, the peak-to-peak torque ripple in the FRM in the rated loading mode decreased by 1.7 times, and in the mode with reduced load by 2.7 times. In addition, in the FRM before optimization, the torque has sections with negative values, and in the FRM after optimization, the torque is positive over the entire period. Although losses in the rated mode increased by 4%, when underloaded, they decreased by 11%, which creates an additional advantage for applications that work most of the time with underload. © 2020 by the authors.Ministry of Science and Higher Education of the Russian Federation: FEUZ-2020-0060The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060). The authors thank the editors and reviewers for careful reading, and constructive comments

Life cycle energy cost assessment for pump units with various types of line-start operating motors including cable losses

The paper presents a comparative analysis of life-cycle energy consumption for three different types of 4 kW line-start motors used in a pump unit with throttling: the most widely used induction motor with IE3 efficiency class, line start permanent magnet synchronous motor with IE4 efficiency class and line start synchronous reluctance motor with IE4 efficiency class. The operating cycle for pump units with constant flow is considered for the above-mentioned types of motors taking into account not only the losses in the pump and motor, but also in the power supply cable. It is shown that the line start synchronous reluctance motor without magnets has the highest efficiency over the entire considered loading range. However, its power factor is lower than that of the synchronous motor with magnets and therefore it has more significant losses in power supply cable. Despite this disadvantage, the line-start reluctance motor is a good alternative to widespread induction motor since it allows saving of approximately 4000 euro more than the latter during the 20 years life cycle. It also provides similar savings in comparison to the permanent magnet synchronous motor, but unlike it, it does not have costly rare-earth materials in the rotor. © 2020 by the authors

Energy efficiency analysis of fixed-speed pump drives with various types of motors

The paper presents a comparative analysis of energy consumption by 2.2 kW electric motors of various types and energy efficiency classes in the electric drive of a pump unit with throttle control in a water supply system. Line-start permanent-magnet synchronous motors of the IE4 energy efficiency class and induction motors of the IE4 and IE3 energy efficiency classes of various manufacturers were considered (IE4 and IE3 are labels of energy efficiency classes of electric motors according to IEC 60034-30-1 standard). Energy consumption at a hydraulic load changing under a typical duty cycle was calculated based on the nameplate data of the pump and electric motors. The developed method shows that selecting an electric motor based on the IE energy efficiency class under the IEC 60034-30-1 standard (i.e., based on efficiency at a rated load) may not provide the minimum energy consumption of a variable flow pump unit over a typical duty cycle. In particular, the considered IE4 class line-start permanent-magnet synchronous motors do not provide significant advantages over IE4 class induction motors, and sometimes even over IE3 class induction motors when they are used in variable flow pump units. © 2019 by the authors.Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research was conducted as part of theme no. 8.9549.2017/8.9. within the frame of the government task of the Ministry of Education and Science of the Russian Federation regarding R&D

Optimal design of a high-speed flux reversal motor with bonded rare-earth permanent magnets

Single-phase flux reversal motors (FRMs) with sintered rare-earth permanent magnets on the stator for low-cost high-speed applications have a reliable rotor and a good specific power. However, to reduce eddy current loss, the sintered rare-earth magnets on the stator have to be segmented into several pieces and their cost increases with the number of magnet segments. An alternative to the sintered magnets can be bonded magnets, in which eddy current loss is almost absent. The remanence of bonded magnets is lower than that of sintered magnets, and they are prone to demagnetization. However, the cost of low-power motors with bonded magnets can be lower because of the simpler manufacturing technology and the lower material cost. This paper discusses various aspects of the optimal design of FRM with bonded magnets, applying the Nelder–Mead method. An objective function for optimizing an FRM with bonded magnets is designed to ensure the required efficiency, reduce torque oscillations, and prevent the bonded magnets from demagnetizing. As a result, it is shown that the FRM with bonded magnets has approximately the same efficiency as the FRM with sintered magnets. In addition, the peak-to-peak torque ripple is minimized and the minimal instantaneous torque is maximized. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Novel rotor design for high-speed flux reversal motor

A single-phase Flux Reversal Machine for high speed applications has a reliable rotor and a good specific power. This paper shows that eliminating the regions of negative torque of this machine can be reached if an asymmetric rotor is used. This machine with an asymmetric rotor was compared with that with a symmetric rotor. In the rated loading mode, the calculated torque ripple of the flux reversal machine with the symmetric rotor is 297%, while that of the one with the asymmetric rotor is 185% which is less by 1.6 times. The proposed high-speed flux reversal machine with the asymmetric rotor can be applied in low-cost drives of household appliances (vacuum cleaners, hand dryers, blenders, washing machines) and in electric power hand tools (angular grinders, miter saws, drills) to replace single-phase synchronous motors or single-phase Hybrid Switched Reluctance Motors. © 2020 The Author(s)The work was partially supported by the Ministry of Education and Science of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2020-0060)

Efficiency analysis of low electric power drives employing induction and synchronous reluctance motors in pump applications

Due to the rapid increase in the number of variable speed AC drives, the analysis of their energy efficiency has become highly essential. However, such an analysis requires consideration of a wide variety of factors. This includes considering the energy loss in the frequency converter, depending on the motor type. In this article, a computational comparison of the energy properties of variable frequency pump drive employing two types of electric machines, i.e. an induction and a synchronous reluctance motor, is presented. The effect of the motor type on the losses in a low-voltage two-stage frequency converter using analytical and numerical models, with a further comparison, is investigated. Furthermore, an alternative approach to determine the current magnitude and power factor of the load of the converter is suggested. Eventually, this study provides a quantitative estimate of the increase in losses in the converter caused by using the two different motor types. Several experimental tests are conducted on induction and synchronous 1.1 kW reluctance motors. © 2019 by the authors. Licensee MDPI, Basel, Switzerland