• Journal of Magnetics
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• v.21 no.3
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• pp.399-404
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• 2016

This paper presents a new permanent magnet (PM) assisted topology for a recently introduced brushless wound rotor synchronous machine (BL-WRSM) [1]. The BL-WRSM had a dual-inverter configuration for generating a composite magneto motive force (MMF) with a fundamental component and a subharmonic component. The subharmonic component of the MMF is used for brushless excitation of the rotor. In this paper, additional PMs were introduced on the rotor of the BL-WRSM, making it a hybrid BL-WRSM. We also discussed the flux weakening operation for the hybrid BL-WRSM. The hybrid BL-WRSM offered advantages for starting the machine and provided better performance under full-load conditions. The finite element method (FEM) was used to analyze the performance of the hybrid BL-WRSM, and we compared its performance with BL-WRSM. Finally, prototypes were built with and without the PM-assistance, and experiments were conducted to demonstrate their performance.

• Proceedings of the KIEE Conference
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• summer
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• pp.866-868
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• 2004

The flux-reversal machine(FRM) is a new brushless doubly-salient permanent-magnet machine combining the advantages of the switched-reluctance machine(SRM) and the permanent-magnet machine(PMM) into one machine. FRM has a naturally low inductance, therefore, a low electrical time constant. This feature, combined with its simple construction and low rotor inertia appear to make the FRM attractive as a low-cost high-speed machine. For high-speed applications, two alternative commutation strategies are studied, one using the phase commutation advancing technique and another using the conducting pulse-width control. This paper describes the techniques and reports the corresponding simulated and experimented performance

• Journal of Magnetics
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• v.21 no.4
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• pp.537-543
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• 2016

Currently, an interest in electric vehicles (EVs) exhibited by automakers, government agencies and customers make it as more attractive research. This is due to carbon dioxide emitted by conventional combustion engine that worsens the greenhouse effect nowadays. Since electric motors are the core of EVs, it is a pressing need for researchers to develop advanced electric motors. As one of the candidates, switched flux machine (SFM) is initiated in order to cope with the requirement. This paper proposes a new alternate circumferential and radial flux (AlCiRaF) of permanent magnet switched flux machines (PMSFM) for light weight electric vehicles. Firstly, AlCiRaF PMSFM is compared with the conventional PMSFM based on some design restrictions and specifications. Then the design refinements techniques are conducted by using deterministic optimization method in order to improve preliminary performance of machine. Finally the optimized machine design has achieved maximum torque and power of 47.43 Nm and 12.85 kW, respectively, slightly better than that of conventional PMSFM.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.68-70
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• 2002

Important category of brushless ac machine design is emerging in which the fundamental component of the stator MMF has fewer poles than the rotor. the torque being developed by a higher order MMF harmonic. The fundamental and lower order MMF harmonics can then give rise to significant rotor eddy currents. An analytical model is developed to predict rotor-induced eddy currents in such machines, and to quantify the effectiveness of circumferentially segmenting the permanent magnets in reducing the rotor loss.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.9-12
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• 2003

Brushless do motors have been replacing brush type motors in machine tool and robotics applications over the last number of years This Paper deals with the design and application of the slot-less permanent magnet synchronous motor (PMSM). The slot-less PMSM eliminates rotational cogging torque due to permanent magnet preferred positions decreases core loss and thus increases efficiency, provides excellent torque-to-volume and power-to-volume ratios, and has a linear current versus torque relation. The PMSM with slot-less stator is designed and manufactured, which will be used for high speed and high efficiency application such a medical instruments.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.356-363
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• 2011

Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other [1, 4]. The characteristics of these forces depend on the air gap flux density, which is also influenced by other factors, such as stator slots and poles, saturation level, winding type, and certain faults. The aim of this work is to investigate the effect of eccentricity and demagnetization faults on electromagnetic noise generated by the external surface of Permanent Magnet Synchronous Machine [PMSM]. For this purpose, an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity and demagnetization fault in generating some low modes radial forces.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.315-322
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• 2001

High speed brushless permanent magnet(PM) machines need a key technology to minimize the iron core losses in stator and the eddy current losses in the retained sleeve and magnets caused by slotting harmonics. Thus, slotless or iron-coreless brushless PM machines have been applied for a very high rotational speed and/or the ripple-free torque. Unfortunately, slotless or coreless PM machines have lower open-circuit field than slotted and/or iron-cored types, which cause to reduce power density. Fortunately, Halbach array can generate the strong magnetic field systems without additional magnetic materials. In this paper, the 4-pole Halbach array is applied to the high speed machine and is compared with the radial magnetized PM array in field system. The iron-/air-cored stator of PM machine is constructed with/without winding slots. Open circuit magnetic fields of each type are presented from the analytical method and finite element method. Consequently, it is confirmed that the Halbach array field system with slotless stator is more suitable to the high speed motor because it has high flux density, sinusoidal flux distribution than others.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.39-42
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• 1994

The application of speed or position control technique in AC drives demands accurate position and velocity feedback information. Generally, resolver and absolute encoders are used as a velocity or position sensor. But they increase cost and when the sampling frequency is faster than sensoer's output frequency we can't Set exact information. In order to solve this problem this thesis proposes a speed and a position observer design for Permanent-Magnet Synchronous Motors(PMSM) specialty in low speed drives. Most literatures on this topic design the observer based on the field_oriented d_q model. But in this thesis, a new approach to machine dynamics is proposed. Since it is difficult to design the observer using the nonlinear model, the machine model is here linearlized at the operating point. The observer designed is implemented by software using Intel's 8097 microprocessor and verifies the proper performance of observer by simulation and experiment.

• Journal of the Korean Magnetics Society
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• v.25 no.6
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• pp.189-197
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• 2015

As enforced the regulation of fuel efficiency, the electrification of automotive components in internal combustion vehicle has been applied instead of hydraulic pressure. A typical example of such parts is the EPS (electric power steering), and it is applied to most automotive at present. In electric power steering system, the core component is motor. The reduction of cogging torque and torque ripple is required to improve steering feeling and reduce NVH (Noise Vibration Harshness) in EPS. Generally the skewed design of stator or rotor is applied in order to reduce cogging torque and torque ripple. This paper propose the design and analysis methodology of Brusheless PMSM (Permanent Magnet Synchronous Motor) which is applied to skewed stator. The proposed methodology is as follows: First Intial Design PMSM with skewed stator for EPS, Second Optimal design using RSM (Response surface method), Third Performance Analysis such as Phase Back EMF, Inductance, Load torque using FEA (Finite Element Method). Finally, the reliability of proposed design methodology will be verified through the experiments of prototype sample.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.170-172
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• 2003

Among low power servo applications, classical DC motors are very popular because they are reasonably cheap and easy to control. The main disadvantage is the mechanical collector which has only a limited life period. Also, brush sparking can destroy the rotor coil, generate EMC problems. So permanent magnet brushless do motors and drives are being used increasingly in a wide range of applications. This has been made possible with the advantages of high performance permanent magnets with high coercively and residual magnetic, which make it possible for the PM to have superior power density, torque to inertia ratio and efficiency, when compared to an induction or conventional dc machine. This paper presents the design of a PM brushless dc motor drive simplistically operates as a classical dc motor. The BLDC motor drive system for this paper composes to the power integrated circuits, the one chip device. And several simple semiconductors add to drive system for a motor drive system simplistically operates as a conventional dc motor. Test results confirmed the feasibility of the proposed motor drive system design.