Synchronous Reluctance Motor for Household Applications

This thesis has been done in the Electromechanics group of Department of Electrical Engineering, Aalto University as part of the motor design and electromechanics research. The project is centered on the design of synchronous reluctance motors and study on how this motor can be used for household applications. The design and simulation were carried out by using extensive finite element analysis with FCSMEK developed in the Helsinki University of Technology. The purpose was to create a motor with cheaper cost and having good performance parameters. The main concentration in the work was on the design part, especially the rotor design, as minute design elements have considerable effect on the performance of the motor. The optimization process of the rotor design has given results on the effect of some geometrical parameters in the motor design technology. A 300 W motor is designed and a thermal model was prepared using Lumped Thermal Networking method. The motor has good efficiency and low losses with good torque characteristics. A study on the comparison of the synchronous reluctance motor with induction motor has been done in order to justify the performance of the motor and the feasibility of using this type of motor for household applications

Design of non conventional Synchronous Reluctance machine

Synchronous reluctance (SyR) and Permanent magnet Synchronous Reluctance (PM-SyR) machines represent an answer to the growing emphasis on higher efficiency, higher torque density and overload capability of ac machines for variable-speed applications. Their high performance is particularly attractive in electric traction and industry applications. The SyR technology represents a convenient solution to obtain high efficiency machines at reduced cost and high reliability. The manufacturing costs are comparable to other existing technologies such as induction motors. Different SyR and PM-SyR machines with different ratings and applications were designed, for comparison with induction motors having equal frame. An accurate comparison between Induction motors, SyR and PM-SyR machines is reported, with reference to the IE4 and IE5 efficiency specifications that could become mandatory in the next years. Three studies are classified under the term ”Non-Conventional” machines: Line-Start SyR motor: is a special SyR machine designed for constant speed applications, line supplied. The rotor flux barriers are filled with aluminum, to obtain a squirrel cage that resembles the one of an induction motor. The manufacturing costs are comparable to those of the induction motor, and the efficiency is higher. Two prototypes were realized and tested. FSW-SyR: tooth-wound coils and fractional slot per pole combinations were investigated. They are of interest because they permit a simplification and higher degree of automatization of the manufacturing process. However, FSW-SyR machines are known for their high torque ripple, low specific torque and power factor. The number of slots per pole was optimized to maximize the torque density. Dealing with the torque ripple, a lumped parameters model was used together with optimization in SyRE. A design with minimized ripple was obtained, comparable to a distributed winding machine in this respect. This design was prototyped and tested. Mild Overlapped SyR: this study shows a new winding configuration applied to SyR and PM-SyR machines. The proposed case is in the direction to find a hybrid solution between distributed winding and tooth winding motors, that permits to reduce costs and improve performances. One limitation of this solution is that only number of pole pairs equal to five or higher are feasible, and this reduces the applicability of the solution to classical industry applications, where one to three pole pairs are normally used

Torque prediction using the flux-MMF diagram in AC, DC, and reluctance motors

This paper uses the flux-MMF diagram to compare and contrast the torque production mechanism in seven common types of electric motor. The flux-MMF diagram is a generalized version of the flux-linkage versus current (ψ-i) diagram for switched-reluctance motors. It is illustrated for switched-reluctance, synchronous-reluctance, induction, brushless AC, brushless DC, interior PM and commutator motors. The calculated flux-MMF diagrams for motors with the same electromagnetic volume, airgap, slotfill, and total copper loss are shown and are used to compare the low-speed torque and torque ripple performance. The motor designs used were reasonably optimized using a combination of commercially available motor CAD packages and finite-element analysis

Performance evaluation of synchronous reluctance motors with and without permanent magnets

Nowadays, a growing interest in the efficiency and the cost of electrical machines has been noticed. Therefore, Synchronous Reluctance Motors (SynRMs) have become more attractive, thanks to their higher efficiency and nevertheless acceptable cost compared to induction machines. The rotor design of SynRMs with or without permanent magnets (PMs) has a huge effect on the motor efficiency, torque density and power factor. This paper introduces an evaluation for the performance of SynRMs with and without PMs in terms of efficiency, torque and power factor maps. Three different rotor designs for the same machine have been compared. For one machine, the experimental measurements have been obtained and the validation of the simulation results have been confirme

Sensored and sensorless speed control methods for brushless doubly fed reluctance motors

The study considers aspects of scalar V/f control, vector control and direct torque (and flux) control (DTC) of the brushless doubly fed reluctance machine (BDFRM) as a promising cost-effective alternative to the existing technological solutions for applications with restricted variable speed capability such as large pumps and wind turbine generators. Apart from providing a comprehensive literature review and analysis of these control methods, the development and results of experimental verification, of an angular velocity observerbased DTC scheme for sensorless speed control of the BDFRM which, unlike most of the other DTC-concept applications, can perform well down to zero supply frequency of the inverter-fed winding, have also been presented in the study

Detection of inter-turn faults in multi-phase ferrite-PM assisted synchronous reluctance machine

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currentsPeer ReviewedPostprint (published version

Solar array fed synchronous reluctance motor driven water pump : an improved performance under partial shading conditions

An improved performance of a photovoltaic (PV) pumping system employing a synchronous reluctance motor (SynRM) under partial shading conditions is proposed. The system does not include the dc-dc converter that is predominantly being utilized for maximizing the output power of the PV array. In addition, storage batteries are also not contained. A conventional inverter connected directly to the PV array is used to drive the SynRM. Further, a control strategy is proposed to drive the inverter so that the maximum output power of the PV array is achieved while the SynRM is working at the maximum torque per Ampere condition. Consequently, this results in an improved system efficiency and cost. Moreover, two maximum power point tracking (MPPT) techniques are compared under uniform and partial shadow irradiation conditions. The first MPPT algorithm is based on the conventional perturbation and observation (P&O) method and the second one uses a differential evolution (DE) optimization technique. It is found that the DE optimization method leads to a higher PV output power than using the P&O method under the partial shadow condition. Hence, the pump flow rate is much higher. However, under a uniform irradiation level, the PV system provides the available maximum power using both MPPT techniques. The experimental measurements are obtained to validate the theoretical work

Hybrid photovoltaic-thermoelectric generator powered synchronous reluctance motor for pumping applications

The interest in photovoltaic (PV) pumping systems has increased, particularly in rural areas where there is no grid supply available. However, both the performance and the cost of the whole system are still an obstacle for a wide spread of this technology. In this article, a hybrid photovoltaic (PV)-thermoelectric generator (TEG) is investigated for pumping applications. The electric drivetrain comprises a synchronous reluctance motor and an inverter. A control strategy for the drivetrain is employed to execute two main tasks: 1) driving the motor properly to achieve a maximum torque per Ampere condition and 2) maximizing the output power of the PV system at different weather conditions. This means that the conventional DC-DC converter is not used in the proposed system. Moreover, batteries, which are characterized by short life expectancy and high replacement cost, are also not used. It is found that the motor output power and the pump flow rate are increased by about 9.5% and 12% respectively when the hybrid PV-TEG array is used compared to only using PV array. Accordingly, the performance, cost and complexity of the system are improved. Measurements on an experimental laboratory setup are constructed to validate the theoretical results of this work