Md. Zakirul Islam

Obtaining optimized designs of multi-phase PMa-SynRM using lumped parameter model based optimizer

This paper focuses on multi-objective optimization of multi-phase Permanent Magnet Assisted Synchronous Reluctance Motor (PMa-SynRM) using Lumped Parameter Model based Optimizer (LPO). Optimized PMa-SynRM are cost efficient compared to Interior Permanent Magnet Motor (IPM). Five-phase PMa-SynRMs offer lower torque ripple and higher fault tolerant capability. Depending on various industry application and their application environment, PMa-SynRMs should be customized with appropriate design specification including different current rating, torque ripple, converter cost, magnet cost and overall machine cost. The developed LPO can efficiently extract optimized multi-phase PMa-SynRM models from different design families through defined Objective Functions (OFs). To prove the accuracy of developed LPO for different OFs, four PMa-SynRM models have been obtained while minimizing torque ripple, phase current, machine cost, and magnet costs respectively. Finally, Finite Element Analysis (FEA) of these models has been performed to validate accuracy of the LPO by comparing predicted performances through LPO and FEA.

Design of five-phase ferrite magnet assisted synchronous reluctance motor using lumped parameter model based optimizer and FEA

This paper proposes an efficient and reliable five-phase ferrite magnet assisted synchronous reluctance motor (Fa-SynRM) which exhibits comparable performance to a five-phase rare-earth permanent magnet based PMa-SynRM. Five-phase PMa-SynRM offers higher reliability and lower torque ripple compared to conventional three phase PMa-SynRMs, and low-cost ferrite magnet potentially decrease the manufacturing cost. However, lower strength of ferrite magnets require more magnet composition and increase stress towards the edges of flux barriers. Demagnetization of ferrite magnets is another factor to be considered in designing the Fa-SynRM. Initially, to develop an optimal and sustainable design, a lumped parameter model (LPM) based optimizer and a finite element model (FEA) has been used to extract an optimal model. The designs are further optimized to reduce the cost and develop more robust models to stress and demagnetization. Finally, the performance and cost of the developed models have been compared to those of benchmark model and initial LPM model.

Design of rare-earth free five-phase outer-rotor IPM motor drive for electric bicycle

This paper presents the design considerations of a five-phase outer rotor interior permanent magnet motor (IPM) for an electric bicycle (e-bicycle). Conventional e-bicycles employ three phase outer rotor surface permanent magnet motors which are less reliable compared to the five-phase IPM motors. Moreover, the traditional electric motors use rare-earth permanent magnet materials such as neodymium which are expensive. Ferrite based magnets can be a better substitute to rare earth materials to make the motor more affordable. In this study, the design of a highly reliable and economical five-phase ferrite based IPM motor to be accommodated in a hub motor drive (HMD) for an e-bicycle is presented. The proposed motor design is optimized using a lumped parameter model (LPM) based optimizer. Detailed analysis on the design parameters and constraints considered for optimization is discussed. Thorough finite element simulations in terms of torque developed, cogging torque, back-EMF, and mechanical stress have been conducted to verify the effectiveness of the proposed motor design.

Optimal design of five phase permanent magnet assisted synchronous reluctance motor for integrated starter generator application

This paper presents the design of optimal five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) for integrated starter generator (ISG) application. PMa-SynRM is the hybrid structure of interior permanent magnet (IPM) motor and synchronous reluctance motor (SynRM). In this study, an optimized 15kW five-phase PMa-SynRM has been proposed as a better substitute for three-phase IPM motor for ISG operation in Honda Civic Hybrid car. A new reverse engineering technique (RET) has been applied to model the Honda IPM ISG. In order to develop a better PMa-SynRM ISG, the model developed using RET has been used as reference. Thorough analytical and finite element analysis have been performed to obtain the optimal PMa-SynRM design which has better performance characteristics compared to the Honda IPM ISG. Lumped parameter modeling (LPM) has been utilized with differential evolution (DE) optimizer to extract the best optimal design for the five-phase PMa-SynRM ISG. For the same power and volume, five-phase PMa-SynRM design has shown better performance characteristics in terms of cogging torque and torque developed.

Eccentricity fault detection in multiphase permanent magnet assisted synchronous reluctance motor

This paper presents fault detection and its analysis for permanent magnet assisted synchronous reluctance motor (PMa-SynRM). The PMa-SynRM has been increasingly studied for critical service application where high efficiency and reliability is required in industry. However, the research on the fault in a PMa-SynRM has been limitedly studied, and no study on the eccentricity fault diagnosis for multiphase PMa-SynRM has been documented so far. The three-phase and five-phase PMa-SynRM has been comparatively analyzed under eccentricity condition to identify a fault diagnosis index which is independent from phase numbers. The simulation model for PMa-SynRM has been developed using finite element method (FEM). Through FEM, static eccentricity (SE), dynamic eccentricity (DE) and mixed eccentricity (ME) are designed to evaluate the performance of the multiphase PMa-SynRM motors under faulty conditions. The fault features have been extracted through average torque, torque ripple, and back-EMF harmonics. Theoretical analysis with designed motors has been done to evaluate extracted features under eccentricity condition.

Design optimization of rare-earth free PM-assisted synchronous reluctance motor to improve demagnetization prevention capability

This paper presents the design optimization of rare-earth-free permanent magnet assisted synchronous reluctance motor (PMSynRM) with an objective to improve the demagnetization prevention capability. Ferrite magnet is a common rare-earth-free permanent magnet (PM) which is attracting the manufacturers with its lower price and abundant supply compared to rare-earth materials such as Neodymium, Samarium, and Cerium based PMs. However, due to lower coercive force, Ferrite magnets have a higher risk of getting demagnetized than rare-earth magnets. Therefore, Ferrite based motor should be carefully designed so that the magnets do not get demagnetized at any desired operating condition. This study proposes a Ferrite magnet based PMSynRM (F-PMSynRM) with non-conventional flux-barrier structures to improve its demagnetization prevention capability while maintaining the same output power as a conventional F-PMSynRM. The equivalent magnetic circuit (EMC) has been used to obtain and justify the proposed motor of improved demagnetization prevention capability. Besides, finite element analysis (FEA) results have been presented to compare the proposed motor and conventional motor in terms of their electromagnetic torque, back-emf, stress and demagnetization preventive capability. Experimental results of the no-load induced voltage have been provided to validate the analytical and simulation results.

Design of a rare earth free external rotor permanent magnet assisted synchornous reluctance motor

This paper presents the design of a low-cost rare-earth free external rotor permanent magnet assisted synchronous reluctance motor (EFa-SynRM) for traction motor applications. In recent design innovations, rare-earth free permanent magnet (PM) motors have been proposed as an alternative to the rare-earth based PM motors. However, rare-earth free PM motors exhibit lower power density, lower torque, lower efficiency, and higher prone to demagnetization issues. With proper design of flux barrier and PM shapes, the Fe PM based electric motor design can be optimized to overcome the above mentioned drawbacks. In this study, an optimal five-phase ferrite PM based EFa-SynRM is developed to achieve high power density and no demagnetization effect. Extensive finite element simulations are carried out to depict the higher average torque developed, lower torque pulsations, and higher efficiency. The proposed EFa-SynRM design has shown no demagnetization effect at three times of rated input current. A 3.7kW design prototype is fabricated and experimentally tested under no load conditions. Results are compared with a same size five-phase internal rotor 3kW Fa-SynRM.

Comparison of two different winding topologies for external-rotor five-phase PM-assisted synchronous reluctance motor in vehicle applications

This paper compares the performance of five-phase external rotor permanent magnet assisted synchronous reluctance motor (PMaSynRMs) for two different winding configurations. In vehicle applications, five-phase winding improves power density, fault tolerant capability and reduces torque pulsation compared to a conventional three-phase winding whereas the adoption of external rotor architecture increases the power density. However, the degree of freedom reduces in selecting winding configuration for multiphase motors which is very critical for performance of PMaSynRM. Therefore, for the design external rotor PMaSynRM, the winding topology like slot/pole combination and coil-distribution should be carefully selected to obtain higher power density with higher efficiency and lower cost. This paper compares the electromagnetic performance of two motors having two different winding topologies, one has fractional-slot concentrated winding (FSCW) with 15slot/12pole and the other one has fractional-slot distributed winding with 25slot/12pole. The analytical modeling and optimization procedure to obtain these motors have been discussed briefly followed by thorough finite element analysis to compare the performance of the motors. Finally, the experimental results have been presented to verify the induced voltage of one motor at no load condition.

Performance comparison between three-phase and five-phase ferrite permanent magnet assisted synchronous reluctance motor

This paper provides a performance comparison between three-phase and five-phase ferrite-based permanent magnet assisted synchronous reluctance motor (PMa-SynRM). Recently, research on PMa-SynRM has got significant attention, especially in vehicular applications. They can meet the performance requirements of electric vehicles with reduced or no use of rare-earth-based permanent magnets (PMs). However, these motors face the challenges of lower torque density, irreversible demagnetization tendency, and intolerance to the augmented stress due to the relatively higher amount of PM. These challenges can be mitigated by employing five-phase winding which can develop higher power density with lower torque pulsation compared to the conventional three-phase motor. This paper compares the electromagnetic performance of a three-phase and five-phase Ferrite magnet based PMa-SynRM. A thorough finite element analysis (FEA) has been presented to validate the superior demagnetization preventing capability, and stress tolerance capability of the five-phase PMa-SynRM over the three-phase PMa-SynRM. Experimental results of the induced voltage for fabricated three-phase and five-phase PMa-SynRMs will be provided to validate the FEA results.

Five-phase external rotor permanent magnet assisted synchronous reluctance motor for in-wheel applications

This paper presents a five-phase external rotor permanent magnet assisted synchronous reluctance motor (PMa-SynRM) with low torque ripple and cogging torque for in-wheel applications. Multi-phase internal rotor electric motors have been proposed for vehicular applications as they possess low torque ripple and low back-EMF harmonics. However, increase in the power density while maintaining the same size and amount of PMs has been a challenging issue. In comparison to the internal rotor motors, external rotor motors can be optimally designed to produce higher torque density with low torque ripple. In this study, the design technique to develop an optimal five-phase external rotor PMa-SynRM model is discussed in detail. Detailed finite element simulations are conducted on the optimally designed 3.8kW five-phase external rotor PMa-SynRM and the results are compared with five-phase internal rotor PMa-SynRM. With the same size, volume, and lower PM composition, the 3.8kW five-phase external rotor PMa-SynRM is capable of generating higher torque density with lower torque pulsation and almost negligible cogging torque in comparison to the 3kW five-phase internal rotor PMa-SynRM. Experimental results are compared between five-phase internal and external rotor PMa-SynRMs to validate the simulation results.