• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.116-118
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• 2006

Recently more attention is paid to the development of high-speed permanent magnet (PM) synchronous generators driven by gas-turbine, since they are conductive to high efficiency, high power density, small size, low weight, simple mechanical construction, easy maintenance and good reliability. In this paper, the performance analysis of a high-speed PM synchronous generator for military power application considering the min-max operating speed is presented. The output current and power versus DC-link voltage loci can obtained by solving the PM machine's steady-state equations for variable resistive load.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.243-250
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• 2015

This paper proposes a novel skewed-type iron slot wedge that can improve both the cogging torque and the output power of a permanent magnet synchronous generator (PMSG). Generally the open slot structure is adopted in a PMSG due to its convenient winding work, but the high cogging torque is undesired. Firstly, an iron slot wedge was utilized to reduce the cogging torque of an open slot type PMSG. However, the output power of the machine decreased rapidly with this method. Thus, a proposed skewed type iron slot wedge is presented to improve the output power as well as the cogging torque as compared to the open slot type. Shape optimization of the skewed-type iron slot wedge is performed to simultaneously maximize the output power and reduce the cogging torque. The Kriging model based on the Halton sequence method and a genetic algorithm are used to optimize the design.

• Journal of Power Electronics
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• v.14 no.1
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• pp.92-104
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• 2014

To insure stable operation and eliminate twice torque ripple, a topology for a six phase permanent magnet synchronous generator (SP-PMSG) with a neutral point connected together was analyzed in this paper. By adopting an extended transformation matrix, the mathematic model of the space vector control was established. The voltage and torque equations were deduced while considering the third harmonic flux and inductance. In addition, the suppression third harmonic method and the closed loop control strategy were proposed. A comparison analysis indicates that the cooper loss minimum method and the current magnitude minimum method can meet different application requirements. The voltage compensation amount for each of the methods was deduced which also takes into account the third harmonic effect. A simulation and experimental result comparison validates the consistency through theoretical derivation. It can be seen that all of the two control strategies can meet the requirements of post-fault.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.3
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• pp.378-386
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• 2012

For reduction of the amount of CO2 emitted from ships, power generation characteristics of two power generation systems consisting of a high-efficiency permanent magnet synchronous generator and diode bridge rictifiers are discussed in this paper. One of the discussed systems has three-phase stator windings, and the other has two sets of three-phase (six-phase) stator windings to reduce pulsation in the electromagnetic torque and DC current. Experimental results reveal that the power generation efficiency of the system having six-phase stator windings is higher than that of the system having three-phase stator windings for a light load. The maximum power generation efficiency of the system having six-phase stator windings is almost the same as that of the system having three-phase stator windings. For the electromagnetic torque of the system having six-phase stator windings, the width of pulsation is about one-fifth compared to the system having three-phase stator windings.

• Journal of Power Electronics
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• v.8 no.2
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• pp.156-162
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• 2008

This paper proposes a low-cost power converter for micro wind turbine systems using permanent magnet synchronous generators (PMSG). The proposed converter consists of a two-leg three-phase PWM inverter for the generator control and a single-phase half-bridge PWM converter which is connected to the utility grid. For the two separate DC-link voltages, a balancing control is added and the adverse effect of the DC-link voltage ripples on the inverter output voltage is compensated. The control performance of the proposed converter topology for the micro wind turbine system is shown by the simulation results using PSIM software.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.443-443
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• 2009

Cogging Torque is induced by the magnetic attraction between the rotor mounted permanent magnet(PM) and the stator teeth. This torque is an unwanted effect causing shaft vibration, noises, metal fatigues and increased stator length. A variety of techniques exist to reduce the cogging torque of PM generator. Even though the cogging torque can be vanished by skewing the stator slots by one slot pitch or rotor magnets, manufacturing cost becomes high due to the complicated structure and increased material costs. This paper introduces a new cogging torque reduction technique for PM generators that adjusts the azimuthal positions of the magnets along the circumference. A 900 kW class PMSG model is simulated using a three dimensional finite element method and the resulting cogging torques is analyzed using the Maxwell tensor stress tensor. Using the 3D simulation, the end contribution of the cogging torque is accurately calculated.

• New & Renewable Energy
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• v.6 no.4
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• pp.41-49
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• 2010

Over the last decade, wind turbine industry has rapidly increased around world. These days many parts of the wind generators are induction generator. But it has some problems such as gearbox failure, rotor excitation and maintenance. Thus many manufacturers are considered permanent magnet synchronous generator named PMSG and direct drive. PMSG uses NdFeB magnet has many the advantage compare with induction generator. In this study, 3MW class outer rotor type PMSG for wind turbine is proposed. The generator features 2.6m stator outer radius, 1200mm stator length, 81 pole pairs, 14 rated rpm, 42kN/$m^2$ shear force density and 94.2% efficiency. Design and analysis generator using FEM program. Then calculate and derivate no load voltage, losses, conductor temperature. To reduce total harmonic distortion and cogging torque, the stator is applied the stator skewing. And to evaluate the designed generator, compare with other generators by active mass per rating torque and torque density.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1111-1112
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• 2011

This paper investigated application of fractional-slot concentrated-winding axial flux permanent magnet machines for wind turbines. Design criteria of cogging torque and voltage regulation was firstly proposed for this kind of application. Fractional winding has small cogging torque which is highlight for wind turbines, but slot leakage inductance would increase voltage regulation, which is an important performance index of generators. By varying slot opening, cogging torque and slot leakage inductance could be adjusted. In this paper, cogging torque and inductances were calculated by both analytical and finite element methods. Voltage regulation was studied by two-axis model under unity-power-factor load and verified by transient finite element analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2109-2115
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• 2007

The wind generators have been installed with high output power to increase the energy production and efficiency. Hence, Optimal design of the direct-driven PM wind generator, coupled with F.E.M(Finite Element Method) and Genetic Algorithm(GA), has been performed to maximize the Annual Energy Production(AEP) over the whole wind speed characterized by the statistical model of wind speed distribution. Particularly, the parallel computing via internet web service has been applied to loose excessive computing times for optimization. The results of the optimal design of Surface-Mounted Permanent Magnet Synchronous Generator(SPMSG) are compared with each other candidates to verify the usefulness of the maximizing AEP model.

• Proceedings of the KIEE Conference
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• summer
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• pp.752-754
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• 2004

Super high speed motors and generators are increasing in various applications such as air compressor, gas turbine and fuel cell systems because of small size and light weight at the same power level. This paper presents an experiment and simulation for a permanent magnet synchronous motor(PMSM) in super high speed applications.