Permanent Magnet Assisted Synchronous Reluctance Motor Research Articles

Performance evaluation of a permanent magnet-assisted synchronous reluctance machine with hybrid magnets of ferrite magnets and rare-earth PMs

In this paper, a novel permanent magnet-assisted synchronous reluctance machine (PMASynRM) with rare-earth PMs and ferrite magnets is proposed. The performance of PMASynRM is discussed with respected to the different magnet ratio of rare-earth PMs and ferrite magnets. Some characteristics including the flux density, output torque, cogging torque, output power, power factor, torque ripple, loss, efficiency, and demagnetization are calculated by 2-D finite element analysis (FEA). The analysis results show that the excellent performance can be obtained by using hybrid magnet of rare-earth PMs and ferrite magnets with the suitable magnet ratio, and provide some desirable cost-performance trade-off.

Influence of Stator MMF Harmonics on the Utilization of Reluctance Torque in Six-Phase PMA-SynRM with FSCW

Although fractional-slot concentrated winding (FSCW) offers many significant advantages, such as short end-turn windings, high slot filling factor, and low cogging torque, it is frequently limited by excessive stator magnetomotive force (MMF) harmonics which will induce high eddy losses in the permanent magnets (PMs). What is more, in the literature, it can be observed that the reluctance torque of the salient-pole machine with FSCW is usually much lower than that obtained with integral slot winding. To explore the underlying reason why the reluctance torque in a salient machine with FSCW significantly decreases, a new six-phase FSCW with 24 slots and 10 poles, which can significantly reduce the undesirable stator MMF harmonics, is obtained by using the concept of stator shifting. Then, two permanent-magnet-assisted synchronous reluctance machines (PMA-SynRMs) with the proposed winding layout and conventional asymmetric 12-slot/10-pole six-phase winding layout are designed and simulated by the finite-element method (FEM). The reluctance torque, total torque, and d/q-axis inductances with different current phase angles are also compared under different loaded conditions. The results show that a reduction in stator MMF harmonics can indeed lead to a significant enhancement in reluctance torque under heavy loaded conditions, while the dominance will diminish under light loaded conditions.

Adaptive Backstepping Based MTPA Sensorless Control of PM-Assisted SynRM with Fully Uncertain Parameters

A nonlinear and robust adaptive backstepping based maximum torque per ampere speed sensorless control scheme with fully uncertain parameters is proposed for a permanent magnet-assisted synchronous reluctance motor. In the design of the controller, the relation to d-q-axis currents constrained by maximum torque per ampere control is firstly derived. Then, a fully adaptive backstepping control method is employed to design control scenario and the stability of the proposed control scenario is proven through a proper Lyapunov function candidate. The derived controller guarantees tracking the reference signals of change asymptotically and has good robustness against the uncertainties of motor parameters and the perturbation of load torque. Moreover, in allusion to the strong nonlinearity of permanent magnet-assisted synchronous reluctance motor, an active flux based improved reduced-order Luenberger speed observer is presented to estimate the speed. Digital simulations testify the feasibility and applicability of the presented control scheme.

Sensorless Control of a Ferrite PM Assisted-Synchronous Reluctance Machines by Using Sliding Mode Observer and High Frequency Signal Injection

Sensorless Control of a Ferrite PM Assisted-Synchronous Reluctance Machines by Using Sliding Mode Observer and High Frequency Signal Injection

Comparative Study of PM-Assisted SynRM and IPMSM on Constant Power Speed Range for EV Applications

This work analyzes and compares the performances of permanent-magnet-assisted synchronous reluctance machines (PMa-SynRM) and interior permanent magnet synchronous machine (IPMSM) on their constant power speed range (CPSR) capability for electric vehicle (EV) applications. The CPSR is a key performance index for traction motors to achieve wide speed range where the IPMSM is known to be an excellent candidate. However, a recent trend for traction motor development is to reduce the amount of rare earth magnet used due to its high cost and possible supply uncertainty. As an alternative, the PMa-SynRM possesses a higher saliency (thus higher reluctance torque) and lower PM quantity (thus lower PM torque) compared to IPMSMs. With the same power or torque output, the major distinction between these two types of machines would be the proportions of different torque components (PM and reluctance torques) due to rotor designs. The distinctive rotor designs would significantly affect the CPSR and this needs to be investigated for traction motor designs and various EV applications. Five 10 kW-30 Nm/L designs, with three IPMSMs and two PMa-SynRMs are studied. The analysis results show that the PMa-SynRMs can achieve higher peak speed despite the torque and power are lower at high speed. In contrast, the IPMSM can maintain the power beyond the base speed to achieve superior CPSR but the power drops quickly to zero at high speed. The high efficiency region appears at the mid speed range for the IPMSM but at high speed region for the PMa-SynRM due to their different PM and reluctance torque profiles. Two prototypes were tested, one being IPMSM and the other PMa-SynRM to validate the analysis results.

PM-Assisted Synchronous Reluctance Machine Flux Weakening Control for EV and HEV Applications

In this paper, a novel robust torque control strategy for permanent magnet assisted synchronous reluctance machine drives applied to electric vehicles and hybrid electric vehicles is presented. Conventional control techniques can highly depend on machine electrical parameters, leading to poor regulation under electrical parameters deviations or, in more serious cases, instabilities. Additionally, machine control can be lost if field weakening is not properly controlled and, as a consequence, uncontrolled regeneration is produced. Thus, advanced control techniques are desirable to guarantee electric vehicle drive controllability in the whole speed/torque operation range and during the whole propulsion system lifetime. In order to achieve these goals, a combination of a robust second-order current-based sliding mode control and a look-up table/voltage constraint tracking based hybrid field weakening control is proposed, improving the overall control algorithm robustness under parameter deviations. The proposed strategy has been validated experimentally in a full-scale automotive test bench (51-kW prototype) for being further implemented in real hybrid and electric vehicles.

Open-Phase Fault Detection of a Five-Phase Permanent Magnet Assisted Synchronous Reluctance Motor Based on Symmetrical Components Theory

This paper presents a novel approach for open-phase fault detection of a five-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM). Under faults, the five-phase PMa-SynRM is expected to run at fault-tolerant control (FTC) mode, otherwise it draws a large amount of current with a significant reduction in the reluctance torque. To successfully achieve FTC operation of five-phase PMa-SynRM, the accurate detection of a fault condition has to be preceded. With the best of these authors knowledge, the detection of faults has been limitedly studied for five-phase motors. The analysis of open-phase fault in five-phase machine involves complicated conditions including single-phase open fault, two-phase adjacent fault, and two-phase nonadjacent fault. To perform the timely fault-tolerant operation, those faults have to be accurately analyzed and detected. In this paper, a novel symmetrical components (SCs) analysis is utilized to extract the feature of those fault conditions. This analysis will provide the types of faults by logically analyzing the pattern of magnitude and phase angle changes of the fundamental signal in the SCs. The proposed method has been comprehensively analyzed through theoretical derivation, finite-element simulations, and experimental testing through a 5 hp PMa-SynRM controlled by TI-DSP F28335.

Optimized design of a high-power-density PM-assisted synchronous reluctance machine with ferrite magnets for electric vehicles

AbstractThis paper proposes a permanent magnet (PM)-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rareearth PM synchronous motors employed in Toyota Prius 2010. A suitable rotor structure for high torque density and high power density is discussed with respect to the demagnetization of ferrite magnets, mechanical strength and torque ripple. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2-D finite element analysis (FEA). The analysis results show that a high power density and high efficiency of PMASynRM are obtained by using ferrite magnets.

Design and Analysis of a Novel PM-Assisted Synchronous Reluctance Machine With Axially Integrated Magnets by the Finite-Element Method

This paper presents the design and analysis of a novel permanent-magnet (PM)-assisted synchronous reluctance machine (PMA-SynRM) with axially integrated magnets for improving machine performance by using a finite-element method (FEM). The proposed PMA-SynRM features a simple structure with high performance by incorporating the advantages of a SynRM and a surface-mounted PM machine (SPMM). In particular, the rotor parts of the SynRM and SPMM are assembled to make the “q-axis” located 45° (elec.) from the d-axis. Thus, the magnetic torque and reluctance torque of the proposed PMA-SynRM reach the maximum values at the same current phase angle, for efficient production of the total torque. To highlight the advantages of the proposed PMA-SynRM, a conventional PMA-SynRM is adopted for comparison under the same operating conditions. The FEM analysis results finally demonstrate that the proposed PMA-SynRM has a higher total torque and power factor, as well as greatly reduced torque ripple, when compared to the conventional PMA-SynRM with the same magnet amounts. In addition, the Mises stress analysis indicates that the configuration of the proposed PMA-SynRM exhibits the advantage of avoiding stress deterioration in the rotor ribs.

Study on the Optimal Design of PMa-SynRM Loading Ratio for Achievement of Ultrapremium Efficiency

Globally, the efficiency of industrial motors is regulated through minimum energy performance standards (MEPS) to reduce energy consumption and CO2 emission. Induction motor, used as a representative industrial motor, has a limit to efficiency improvement as the result of the additional copper loss of the rotor. To replace the induction motor, design of synchronous reluctance motor (SynRM) and permanent magnet assisted synchronous reluctance motor (PMa-SynRM), and the application of a small amount of permanent magnet, is actively studied in the industry. However, it is necessary to develop an ultrapremium efficiency motor beyond the superpremium efficiency to fulfill MEPS, which will be strengthened in the future. Therefore, this paper presents the optimal design method of SynRM by using the finite element method and response surface method to achieve superpremium efficiency. Furthermore, the redefinition of the loading ratio with shape parameters, and the design method of PMa-SynRM, using the loading ratio, is proposed to meet the ultrapremium efficiency. It is an effective design method that can shorten the time and process when designing ultrapremium efficiency PMa-SynRM from the existing SynRM, which is already mass-produced.

Design of Permanent Magnet-Assisted Synchronous Reluctance Motor for Maximized Back-EMF and Torque Ripple Reduction

This paper proposes the optimization of the shape and size of a ferrite magnet and the arrangements necessary to reduce torque ripple and maximize back electromotive force (B-EMF) in a permanent-magnet-assisted synchronous reluctance motor. First, four different models of general magnet arrangements were selected, and analysis using the finite-element method was performed under open circuit and load operations for each of the four models. Next, the relationship between the cogging torque and the torque ripple was analyzed, considering the segment saturation phenomenon. Then, based on the initial model, the design was optimized for maximum B-EMF and minimum torque ripple, and the total harmonic distortion was measured. Finally, the validity and superiority of the optimized design were confirmed by manufacturing a prototype motor and performing the experiment.

Robust Speed Sensorless Control to Estimated Error for PMa-SynRM

Recently, the permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) that can replace induction motor has been more studying because of the needs of the high efficiency motor development for minimum energy performance standard. PMa-SynRM requires the speed and position information of rotor to control motor correctly. However, sensor for rotor information has many problems such as mounting space shortage and the additional system cost. Therefore, in this paper, the speed-sensorless control based on reference model adaptive control is introduced to eliminate the sensor. And mechanical design is improved for control. The proposed method is verified by simulation.

A Computational Study of Efficiency Map Calculation for Synchronous AC Motor Drives Including Cross-Coupling and Saturation Effects

After designing and optimizing an electric machine, efficiency maps are needed to predict a vehicle's performance in a dynamic simulation. Calculating efficiencies at various torque and speed points, however, requires prior knowledge of the input excitation conditions, such as the current magnitude and advance angle, in an electromagnetic finite-element analysis simulation. Hence, this paper derives and uses nonlinear motor control equations (MTPA, FW, MTPV) in the study of efficiency map calculation while accounting for both saturation and cross-coupling effects. Two synchronous ac motors are considered in this paper, including the 2010 Prius IPM and a PM-assisted synchronous reluctance machine, with all procedure steps outlined in detail.

Quantitative comparison of electromagnetic performance of electrical machines for HEVs/EVs

In this paper, various types of sinusoidal-fed electrical machines, i.e. induction machines (IMs), permanent magnet (PM) machines, synchronous reluctance machines, variable flux machines, wound field machines, are comprehensively reviewed in terms of basic features, merits and demerits, and compared for HEV/EV traction applications. Their latest developments are highlighted while their electromagnetic performance are quantitatively compared based on the same specification as the Prius 2010 interior PM (IPM) machine, including the torque/power-speed characteristics, power factor, efficiency map, and drive cycle based overall efficiency. It is found that PM-assisted synchronous reluctance machines are the most promising alternatives to IPM machines with lower cost and potentially higher overall efficiency. Although IMs are cheaper and have better overload capability, they exhibit lower efficiency and power factor. Other electrical machines, such as synchronous reluctance machines, wound field machines, as well as many other newly developed machines, are currently less attractive due to lower torque density and efficiency.

Characteristic analysis of a less-rare-earth hybrid PM-assisted synchronous reluctance motor for EVs application

Low-energy permanent magnet (PM) such as ferrite is usually adopted in a PM-assisted reluctance (PMAREL) motor to enhance the output torque and reduce costs. However, the relatively low magnetic energy product and remanence in such PMs may lead to the risk of demagnetization. By using two types of materials of rare-earth NdFeB and non-rare-earth ferrite PM, a new less-rare-earth hybrid PMAREL motor is proposed in this paper, where the output torque and the power factor can be improved obviously, and meanwhile the risk of irreversible demagnetization in ferrite PMs can be reduced significantly due to the existence of NdFeB PMs. To verify the validity of the proposed motor, the operating principles of the motor and the positive interaction influences between the two involved types of PMs are analyzed. Moreover, by using the finite element method, the torque characteristics and anti-demagnetization capabilities are also investigated in details. Both the theoretical analysis and simulated results confirm the advantages of the proposed motor.

Optimum design and operation analysis of permanent magnet-assisted synchronous reluctance motor

Optimum design and operation analysis of permanent magnet-assisted synchronous reluctance motor

Analysis and design of a high power density permanent magnet-assisted synchronous reluctance machine with low-cost ferrite magnets for EVs/HEVs

Purpose The purpose of this paper is to propose a permanent magnet-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rare-earth PM synchronous motors used in Toyota Prius 2010. Design/methodology/approach A novel rotor structure with rectangular PMs is discussed with respect to the demagnetization of ferrite magnets and mechanical strength. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2D finite element analysis. Findings The results of the analysis show that a high power density and high efficiency for PMASynRM can be achieved using ferrite magnets. Originality/value This paper proposes a novel rotor structure of PMASynRM with low-cost ferrite magnets that achieves high power density as permanent machines with rare-earth PMs.

Recent technical trends in permanent magnet synchronous motors

This paper presents an overview of the recent technical trends in permanent magnet synchronous motors (PMSMs), especially the rare earth (RE)‐less PMSMs that have been developed in Japan. The RE‐less PMSMs, along with PMSMs with reduced RE permanent magnets (PMs), PM‐assisted synchronous reluctance motors (PMASynRM) with ferrite PMs, spoke‐type interior PMSMs (IPMSMs) with ferrite PMs, and axial‐gap PMSMs with ferrite PMs, are reviewed. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Sensorless Control of a Ferrite PM Assisted-Synchronous Reluctance Machines by Using Sliding Mode Observer and High Frequency Signal Injection

This paper presents sensorless control of ferrite permanent magnet-assisted synchronous reluctance machines (FPMA-SynRM) over wide speed range by using sliding mode observer (SMO) and high frequency signal injection. The basic equation of sliding mode observer will be derived based on dynamic model of PMSynRM. In the study, the equivalent of EMF-based SMO is proposed to estimate rotor position at medium and high speed range. The principles of high frequency signal injection, digital signal processing and rotor polarity identification is also analysed. Finally, the theoretical analysis have been verified with the experiments and the results obtained show that the resolution of estimated position signal can meet requirements of some industrial drive applications.DOI: http://dx.doi.org/10.5755/j01.eie.22.4.15906

Comparisons of three‐phase and five‐phase permanent magnet assisted synchronous reluctance motors

This paper presents the comparison of three-phase and five-phase permanent magnet assisted synchronous reluctance motors (PMa-SynRM) in terms of their design and performance characteristics. With higher fault tolerant capability, efficiency, and reliability, the five-phase PMa-SynRM can be a better substitute when compared with the three-phase PMa-SynRM in critical applications where safety is top priority. In this study, for a fair comparison, same design procedure using in lumped parameter modelling is followed in developing the three-phase and five-phase PMa-SynRMs. The models are optimised to minimise cost and maximise efficiency. For further detailed comparison of the three-phase and five-phase PMa-SynRMs, two-dimensional finite element analysis (FEA) is utilised. Performance characteristics such as torque pulsation, back electromotive force, flux linkage, d- and q-axis inductances versus their respective currents, cogging torque, efficiency plot, and torque-speed characteristics are intensively simulated through FEA. The optimised three-phase and five-phase PMa-SynRMs are fabricated with the same power rating (3 kW) and same volume. Experimental tests are conducted on the prototypes to validate the simulation results.