• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1088-1091
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• 1992

Programmed PWM(Pulse Width Modulated) generation techniques eliminating several low order harmonics have been widely used in the inverter circuit which produces minimum current ripple, reduced torque pulsation and thereby improves overall system performance. However, the applications of the programmed PWM technique are limited to CVCF(Constant Voltage Constant Frequency) applications and various motor drives. Although the programmed PWM produces a lower harmonic distorted waveform than the carrier modulated PWM, real-time programming is not possible because of the complicated calculation required for the gating signal. In this paper, a new programmed PWM technique named TAM (time averaging model) is developed to compensate for the demerits of the conventional programmed PWM technique with moderate harmonic distortion. Computer simulations are performed to verify the performance of the proposed algorithm.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1914-1920
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• 2014

In this paper, characteristics of blushless direct current (BLDC) motor including core loss are analyzed considering pulse width modulation (PWM) of inverter. Input voltage of BLDC motor due to PWM is calculated considering duty ratio and carrier frequency of inverter in order to control torque or speed of BLDC motor. For the calculation of core loss, the input current with harmonics due to PWM voltage is calculated by using equivalent circuit model of BLDC motor according to switching pattern and carrier frequency. Next, core loss is analyzed by inputting the currents as a source of BLDC motor for FEM. Characteristics including core loss are compared with ones without PWM waveform according to reference speed.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.25-27
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• 2007

Brushless DC Motor (BLDCM) is DC motor and Interior PM Synchronous Motor (IPMSM) is AC motor. Besides their way of control is different. But it is similar that both motors rotate synchronous velocity and use the permanent magnet. So, it is an objective to grasp a tendency of motor design and efficiency of motor through a characteristic comparison of BLDCM and IPMSM with the same power, rotation velocity, torque and input voltage.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.660-662
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• 2001

This paper describes the problems generated with the use of PWM ASDs with induction motors. The major effect of harmonic voltages and currents in induction motors is increased the heating due to iron and copper losses at harmonic frequencies. The harmonic components thus affect the motor efficiency and developed the torque. In order to investigate the effect of harmonics which is caused by using of nonlinear load at the low voltage system, we set up simple load system and measured the voltage and current. Measurement results show that additional operation of induction motor at the parallel bus in using nonlinear load such as ASD is helpful to the reduction of harmonic current.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.42-47
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• 2012

Construction equipment is heavily loaded during normal operation. In recent years, there is a trend that lower gear noise levels are demanded for drivers to avoid annoyance and fatigue during operation. For articulated hauler's final drive, meshing transmission error(T.E.) is the excitation that leads the tonal noise known as gear whine, and radiated gear whine is also the dominant source of noise in the whole gearbox. This paper presents a method for the analysis of the tooth profile modification, and the prediction of transmission error under the loaded torques for the spur gear pair of the articulated hauler's final drive. And the transmission error, transmission error harmonics and contact stress are also calculated and compared before and after tooth modification under one torque. The simulation result shows that the transmission error and contact stress under the loads can be minimized by the appropriate tooth profile modification.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.52-54
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• 1997

This paper deals with investigating some characteristics of the inverter-driven tractive induction motor according to the various rotor slot number. 2-D time-stepped finite element method considering the inverter voltage waveform is utilized for electromagnetic field analysis. As a result, harmonics spectra of torque and bar loss are compared in each case.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.134-137
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• 1998

In this paper, a hybrid maximum power tracker for a photovoltaic/wind hybrid power system is proposed. In the hybrid system, a direct interfacing the wind power system to the photovoltaic system gives the problems of voltage fluctuations, poor maximum power tracking, and harmonics generation associated with the random wind speed, the random solar irradiation and the pulsating torque came from the wind turbine synchronous generator and photovoltaic. To overcome these problems, a wind side DC/DC converter are proposed employing a star/delta transformer interconnected between the wind turbine side and the photovoltaic side. The control objective for each dc/dc converter is to extract maximum power from each different photovoltaic system and wind system, and transfer two different powers to the inverter and load.

• 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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• 1988.07a
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• pp.93-97
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• 1988

The sliding mode control is an effective method to establish robustness against parameter variations and disturbance. But, in sliding mode strategy, the control function is discontinuous on the hyperplane. Consequently, the control input chatters at high frequency. When we apply such a control to the induction motor drive system, that causes a torque ripple and current harmonics, which are harmful to the system. In this paper, we introduce a low pass filter between sliding mode control output and driver input to overcome that problem. The band-width of this filter is varied according to the error funtion to improve transient responses.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.59-64
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• 2000

Especially, demands for the noise reduction of mold transformer has been becoming an common issue because it has been used mainly at the residence area such as building and ship. So, this paper investigates the noise source and countermeasure of mold transformer radiated high noise abnormally. The result of impact hammering test for core of transformer ascertains the core resonance by harmonics of line frequency and high noise can be reduced to avoid core resonance by changing torque strength of tie rod. Magnetic field analysis is performed to identify the reason that noise of V-phase is higher than U and W-phase in the normal condition. It is the cause that flux density and magnetic force of V-phase is higher than the other phase respectively.