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Synchronous reluctance motors (SynRMs) with four layers of flux barriers are currently in practical use as high-efficiency motors for industrial applications. While SynRMs have higher efficiency than induction motors, they have a high torque ripple. In this study, an asymmetric rotor structure was designed to reduce the torque ripple of the four-layer SynRM, considering the mechanical strength. Two rotor structures with different flux barrier angles were combined in the stacking direction, and the ratio of the combination was optimized by finite element analysis. In addition, prototypes of the initial structure and proposed asymmetric structure were manufactured, and their torque and efficiency characteristics were measured. The experimental results show that the proposed asymmetric structure can reduce the torque ripple while maintaining the basic characteristics such as average torque and efficiency. [ABSTRACT FROM AUTHOR]

SUMMARY Recently, the use of permanent magnet (PM) motors has risen markedly because of improvements in the performance of rare earth PM motors. However, the use of rare earth materials, which is an important aspect of the high-performance PM motor, should be reduced because of the high cost and unpredictability associated with procuring such materials. The performance of motors that use rare earth materials has reached a very high level, one that will not be easy to match without such materials. In this paper, we propose a structure for a high-power-density PM-assisted synchronous reluctance motor involving the use of a ferrite PM. The structure prevents irreversible demagnetization of the PM even in the presence of heavy flux-weakening excitation or an inverter fault. It is shown that the proposed structure achieves high-power and high-efficiency performance. © 2014 Wiley Periodicals, Inc. Electr Eng Jpn, 187(1): 42-50, 2014; Published online in Wiley Online Library (). DOI 10.1002/eej.22362 [ABSTRACT FROM AUTHOR]

Although motors that use rare-earth permanent magnets (PMs) typically exhibit high performance, high costs and concerns about the stability of raw material supplies are leading to their decreased production. However, the performance of such motors is not easily matched without the use of rare-earth PMs. This paper proposes and examines a PM-assisted synchronous reluctance motor with ferrite magnets that has the same power density as rare-earth PM synchronous motors. A suitable rotor structure for high torque and high power is discussed with respect to the demagnetization of ferrite magnets and the mechanical strength. [ABSTRACT FROM PUBLISHER]

The importance of reducing the amount of rare earth materials used in high-performance permanent magnets has been established. However, the performance of such motors will not be easy to match without the use of rare earth materials. Although the torque characteristic of the motor can be improved by shortening the air gap length of the motor, there is a mechanical limitation on the gap length. In this paper, a 3-D air gap structure of the motor is proposed to improve the torque characteristics without shortening the gap length. The 3-D air gap structure is demonstrated to be equivalent to shortening the actual gap length to approximately 70% of the original length. Some disadvantages in the 3-D air gap structure are also described. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel control scheme for maximum power operation of synchronous reluctance motors. The proposed scheme consists of a combination of maximum torque per ampere control, maximum torque per flux control, flux-weakening control, and torque limiting. The first three control methods are based on a mathematical model in a rotating reference frame that is synchronized with the stator flux linkage. The final method utilizes a reactive torque calculated as the inner product of the flux and current vectors. The proposed control scheme is suitable for direct torque control (DTC) or flux-oriented control. In this paper, the scheme is applied to a DTC-based motor-drive system. The validity of the control scheme is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

A synchronous reluctance motor has many advantages because it has no permanent magnet, such as low back emf in high-speed operation, maintaining performance in a high-temperature environment, and so on. Therefore, many rotor constructions have been studied and developed. The rotor with multiflux barrier structure has the merit of easy construction and high performance. The linear synchronous reluctance motor has been developed. It is necessary to improve the performance of the mover design for industrial use, because of its low power factor. In this paper, we propose a novel configuration of mover for the linear synchronous reluctance motor, and examine the static characteristics of the motor with reluctance equalization design by means of the finite element method. From analytical results, it is demonstrated that the static characteristics of the linear synchronous reluctance motor are greatly improved by the reluctance equalization design at the iron layer in the mover. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 61–69, 2002; DOI 10.1002/eej.1139 [ABSTRACT FROM AUTHOR]

Presents a study which examined the design and the performances of a permanent-magnet assisted synchronous reluctance motor (PMASRM) for wide constant-power operation. Discussion on the flux-weakening performance and the efficiency characteristics of the proposed PMASRM; Description of the prototype PMASRM; Operating performance.

Permanent magnet synchronous motors (PMSMs) are widely used in many applications as high-performance variable-speed drives. In traction drives, such as those used for electric vehicles or for the compressor drives of air conditioners, a wide constant-power speed range and high-efficiency operation are desired. The aim of this paper is to develop a high-performance PMSM that offers high-efficiency performance in the high-speed region, including light-load conditions, as well as a wide constant-power speed range. Simulations show that the proposed interior PMSM, which produces chiefly reluctance torque and in which the permanent magnet flux assists torque production, is capable of meeting the above performance requirements. A prototype PMSM is designed in accordance with this new design concept and several drive tests are carried out. The saliency ratio of the prototype IPMSM is about 5, and, as a result, reluctance torque is the principal torque component, representing more than 70% of total torque. The prototype IPMSM can attain a constant-power speed range of up to 5:1 with high-efficiency drive in the high-speed, constant-power region. The proposed IPMSM is suitable for variable-speed drives requiring high-speed, constant-power operation. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 60–68, 2001 [ABSTRACT FROM AUTHOR]