• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.250-257
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• 2001

SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM drive. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a two stage commutation method during commutation period. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a tow stage commutation method during commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.79-83
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• 1997

The inverter fed BLDC(Brushless DC) motor has been increasingly applied to industry and home appliances due to the advance of power electronics and permanent magnet technology, and its high efficiency and good acoustic noise characteristics. The BLDC motor and drives, however, require the rotor position sensors that may cause some problems such as the high cost and space. In this paper, sensorless algorithm for an interior permanent magnet BLDC motor is proposed. The maximum torque per ampere operation with advance angle considering load torque and speed was simulated and verified through the experiment.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.9
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• pp.615-621
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• 2004

This paper describes the design of a 2-phase stepping motor driver using CPLD. The driver IC such as L297, which is mostly used has some difficulties in PWM current control because of the switching noise of power MOSFETs. The switching noise causes current ripple and acoustic noise. To reduce the switching noise, we designed a digital filter using VHDL. Also we designed constant current method for 1-2 phase(half step) excitation to reduce the torque ripple. Experimental results show the effectiveness of the proposed method. It is enabling further enhancements of stepping motor drive technology broadening the range of applications for the stepping motors.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.758-761
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• 2005

This paper describes the acoustic noise spectra of the pseudo-random carrier modulation technique according to the different PRBS(Pseudo Random Binary Sequence) bits. To confirm the validity of the proposed method, a 130v three-phase 5-level inverter motor drives was implemented. The harmonics spectra broadening effect of pseudo random carrier and the acoustic noise radiated from the inverter drives were discussed and verified according to the different bits of shift resister operating as PRBS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.39-45
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• 2001

As HDD moves into new emerging consumer markets, expectations on quietness, as well as performance, have increased. The acoustic noise of HDD seems to be closely related to excitation of the spindle motor system. Recently, as a simple approach to reduce disk vibration, thicker disk, which is 50 mil (1.27mm), starts to use in HDD industry. Noise spectrum of HDD with use of 50 mil disk shows the dominant peaks of 900 Hz, mainly caused by excitations of the disk due to air windage effect. In order to reduce noise at this specific frequency, squeeze air damping effect was investigated by extremely reducing the gap between the disk and the base platform.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.580-582
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• 2002

A major problems of Switched Reluctance Motor(SRM) is torque ripple which causes undesirable acoustic noise and vibration. To reduce the torque ripple two different approaches are used. One is to modify a motor geometry, the other is to manipulate motor current to improve performance. This paper presents modifications of the rotor pole shape which reduces the torque ripple.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.17-26
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• 2005

The random pulse width modulation(RPWM) in inverter-fed induction motor drive is presented. This paper describes a RPWM method based on space vector PWM strategy for shaping the switching noise spectrum in such a way it can merge with the natural system noise. To verify the validity of the proposed RPWM scheme, the experiment based on the DSP56F803 microprocessor was executed finally, the simulation and experimental results will be given to demonstrate the effectiveness of the unposed RPWM scheme.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.316-319
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• 1998

RPWM(Random Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics on the wide frequency area. Using randomly changed switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise cab be spread to the wide-band area. The wide-band noise is much more comfortable and less annoying than the narrow-band one. So RPWM have been attracting an interest as an excellent method for the reduction of acoustic noise on the inverter drive system. In this paper a new RPPWM (Random Position PWM) is proposed and implemented. Each of three pulses is located randomly in each switching interval. Along with the randomization of PWM pulses, the space vector modulation is executed in the C167 microcontroller also. The experimental results show that the voltage and current harmonics were spread to wide band area and that the audible switching noise was reduced by proposed RPPWM method.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.150-156
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• 2001

This paper describes an implementation of the DSP(Digital Signal Processor) based triangular carrier frequency modulated RPWM inverter drive system. The power spectrum of the noise emitted from the induction motor was measured in the anechoic chamber. The analysis of the sources for the acoustic noise and the effects of the noise reduction are confirmed by the measured spectra of the noise. Real-time RPWM along with the speed control was achieved by high speed DSP. By changing the center frequency and the bandwidth of the carrier, the proposed real-time RPWM scheme can be used as an efficient switching frequency band acoustic noise reduction method for the inverter drive system with variant load conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.9
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• pp.454-461
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• 2001

Acoustic noise and vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and electromagnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage, it is considered to influence the motor system characteristics. In this paper, the back electro motive force(BEMF) is analyzed by Finite Element Method(FEM) and verified by experiments for the SPM and IPM type motors. For magnetic field analysis, a FEM is used to account for the magnetic saturation. Using these results, the FEM is made to determine the appropriate electromagnetic field analysis in BLDC motors with rotor eccentricity ratio. A radial magnetic imbalance force of BLDC motor with rotor eccentricity is analyzed. Results demonstrate that the imbalance force is increased according to the degree of misalignment. An IPM motor, mostly chosen to realize high-speed operation, shows a worse effect on magnetic unbalanced forces and dynamic responses compared with SPM motor due to magnetic saturation when the rotor eccentricity exists.