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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]

A sensorless-control technique for improving the performance of interior permanent-magnet synchronous-motor control such as the operating speed range and position estimation accuracy is proposed herein. The method presented is based on the estimation of an extended electromotive force in a rotating reference frame. The difference between the reference voltage and the actual voltage of the inverter is modeled and compensated for in order to improve the accuracy and the stability of the sensorless drive system. Moreover, an online parameter-identification technique is applied in order to improve the accuracy of position estimation. The effects of the proposed scheme are evaluated by the experimental results. Index Terms--Interior permanent-magnet synchronous motors (IPMSMs), online parameter identification, sensorless control, voltage error compensation.

The influence of rotor configuration on sensorless control for interior permanent-magnet synchronous motors (IPMSM) with concentrated windings is evaluated. Sensorless control that gives estimated angle with simple integration procedure and the biased convergent point observer is applied. Two types of rotors are analyzed and their robustness for an offset value of the observer is compared. To analyze the influence of magnetic saturation, nonlinear motor voltage equation is solved. Finite-element analysis plays an important role to realize high-speed and precise analysis. Analyzed results show that the rotor which has salient poles on the side of permanent magnets is insensitive to the offset value of the observer. And the sensitivity to the offset value of the observer with these two types of rotors is confirmed by experimental results. Index Terms--Concentrated windings, finite-element method, interior permanent-magnet synchronous motors (IPMSM), magnetic saturation, sensorless control.

This paper proposes a variable-speed wind generation system using an interior permanent-magnet synchronous generator (IPMSG). The armature current vector of the IPMSG is optimally controlled according to the generator speed in order to maximize the generated power from the wind turbine. The IPMSG is controlled by the loss-minimization control with maximum power point tracking below the base speed, which corresponds to low and medium wind speed, and the maximum energy can be captured from the wind. Above the base speed corresponding to the high wind speed region, the current- and voltage-limited maximum output control is applied, where the current vector is optimally controlled so that the output may become the maximum in consideration of the constraints of current and voltage. The proposed output maximization control is achieved without mechanical sensors such as wind speed sensor and position sensor. The control system has been developed and several experimental results show the effectiveness of the proposed wind generation system. Index Terms--Interior permanent-magnet synchronous generator (IPMSG), maximum power point tracking (MPPT) control, sensorless control, variable-speed generation, wind generation.

An interior permanent-magnet synchronous motor (IPMSM) is a highly efficient motor and operates in a wide speed range; therefore, it is used in many industrial and home appliance applications. However, the torque ripple of synchronous motors such as the IPMSM and synchronous reluctance motor is very large. The variation of magnetic resistance between the flux barriers and teeth causes the torque ripple. In this paper, flux barriers are asymmetrically designed so that the relative positions between the outer edges of the flux barriers and the teeth do not correspond. As a result, torque ripple can be reduced dramatically. Index Terms--Asymmetric flux barrier, permanent-magnet synchronous motor, synchronous reluctance motor (SynRM).

Iron loss prediction is an important issue in both design and analysis of electrical machines. Because of their complicated structure, flux distribution, and rotational variation of flux, it is difficult to predict the iron loss in a machine exactly. This paper studies the iron loss in the core of rotating machines in which the rotational field is dominant, using the finite-element method. For electrical machines in practical operation, additional iron losses due to the appearance of rotation of flux vectors and harmonic flux densities make the calculation results deviate from the measured data. We have revised the method to account for these excess iron losses by considering both the influences of flux vector rotations and flux density harmonics. Calculation and experiments on two kinds of interior permanent-magnet synchronous motors have verified that our method produces results that agree well with the experimental ones. Index Terms--Electric machines and transformers, magnetic losses.

This paper proposes the current-sensorless drive system with only low-resolution position sensor in order to simplify the synchronous motor drive system. The high-performance current vector control can be achieved in the proposed drive system, where the current sensors are eliminated but the simulated currents based on motor model are used for current control. The low-resolution position sensor, which has a resolution of only 60 electrical degrees, is used instead of a conventional high-resolution position sensor, and the position information with higher resolution is estimated. The steady-state performance and dynamic performance are examined by several drive tests with respect to the interior permanent-magnet synchronous motor and the synchronous reluctance motor. The effectiveness of the proposed drive system is clarified from several experimental results. Index Terms--Current-sensorless drive, low-resolution position sensor, permanent-magnet synchronous motor (PMSM), synchronous reluctance motor (SynRM), vector control.

This paper presents a novel sensorless control strategy for a salient-pole permanent-magnet synchronous motor (PMSM). A new model of a salient-pole PMSM using an extended electromotive force (EMF) in the rotating reference frame is utilized to estimate both position and speed. The extended EMF is estimated by a least-order observer, and the estimation position error is obtained from the extended EMF. Both estimated position and speed are corrected so that the position error becomes zero. The proposed system is very simple and the design procedure is easy and clear. Several experimental drive tests are demonstrated and the experimental results show the effectiveness of the proposed sensorless control system. Index Terms--Extended electromotive force, interior permanent-magnet synchronous motor, observer, salient-pole permanent-magnet synchronous motor, sensorless control.

Permanent magnet linear synchronous motors have been developed for factory automation, transportation applications, and so on. In the rotary-type permanent magnet synchronous machines, the wide speed and constant power operation are realized by using the reluctance torque due to the saliency and the flux-weakening control. In this paper, we examine the effect of the interior permanent magnet arrangement for wide speed operation and the end effect in the linear structure. Index Terms - End effect, flux weakening, IPM-LSM, reluctance thrust.

Permanent magnet synchronous (PM) motors can be applied to applications requiring constant power operation, such as traction and spindle drives by means of flux-weakening control. In a PM motor drive system with flux-weakening control, the motor parameters are used to produce the current vector command. The motor parameters vary because of magnetic saturation and as a result, the control performances are affected by the magnetic saturation. In this paper, the effects of magnetic saturation are examined and the control system considering the magnetic saturation is proposed. The performances of the proposed control system are examined by simulations and the experimental results with respect to the prototype interior permanent magnet synchronous motor.

Interior permanent magnet synchronous motors can be applied to applications requiring wide-speed operation. The current vector control algorithm of an interior permanent magnet synchronous (IPM) motor for constant power operation over the base speed is proposed. As the available voltage controlling the armature current vector is small in the flux-weakening constant power region, the current vector sometimes becomes uncontrollable in transient operations because of the current regulator saturation. The high-performance current regulator is also proposed to improve the current responses in the flux-weakening region, which includes the decoupling current controller and the voltage command compensator. The control performances are confirmed by several drive tests with respect to the prototype IPM motor.

The advantages of the conventional cylindrical linear pulse motor (C-LPM), which has a ring permanent magnet between the A- and B-phase stators, are its simple magnet shape and small motor diameter; the disadvantages are the thrust imbalance resulting from the magnetic flux path of the outer poles being longer than that of the inner poles. This thrust imbalance decreases the pull-in thrust and increases the positioning error. In this paper a new C-LPM with an interior permanent magnet mover which reduces this thrust imbalance is proposed. Steady and dynamic thrust are also examined and magnetic equivalent circuit is discussed. It is shown that a C-LPM with an interior permanent magnet mover effectively improves the thrust imbalance and the dynamic thrust.