• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.3
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• pp.51-57
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• 1997

A new current controlled PWM technique with N.P.C structure is proposed in this paper. A current controlled PWM technique with neutral-point-clamped pulsewidth modulation inverter composed of main switching devices which operates as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential is described. This inverter output contains less harmonic content as compared with that of a conventional current controlled PWM type. In addition, the proposed current controlled PWM technique has lower switching frequency than that of conventional current controlled PWM technique at the same current limit. Two inverters are compared analytically. The improved voltage waveform of current controlled PWM with N.P.C structure is analyzed and the performance is investigated by the computer simulation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.259-266
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• 1987

In order to drive motor control system precisely, the motor is to be controlled by mmfs and current with sinusoidal waveforms. In this paper the Delta Modulation (DM) Technique is used for generating PWM pulse with sinusoidal waveform. However the motor currents yet contain odd harmonics due to leakage inductances, speed and exitation. To reduce harmonics, the parameter adaptive control method is introduced. That is, Req.C parameter of Delta Modulator is controlled adaptively by parameter adaptor. The adaptive signal is achieved by the difference between motor current and reference waveform, and this signal is converted to the voltage commend signal by adaptive mechanism. The test reslts show that this system is operated smoothly over a wide range of motor speed and motor current is controlled to be sinusoidal waveform adaptively.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.4
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• pp.305-315
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• 2022

In this paper, phase current ripples and torque ripples of six-phase PM synchronous motor controlled by interleaved PWM are analyzed. The cause of the increase of phase current ripple in the interleaved PWM was mathematically analyzed based on the mutual inductance of stator windings and effective voltage vector. Simulation and experiment verified that the DQ current ripple and torque ripple can be reduced by interleaved PWM control. The FFT analysis of torque waveform confirmed that the magnitude of harmonic torque corresponding to double the PWM frequency was reduced.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.3
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• pp.273-280
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• 1990

To prevent the shoot-through phenomena in a PWM inverter, a short dead time is usually provided between a pair of switching transistors in the same leg of the inverter. In this approach, the amount of the dead time is designed to meet the worst case condition of the inverter transistors and the base drive elements. So, in normal cases, relatively large portion of the dead time is unnecessary and it results in an undesirablecurrent waveform distortion and generates ripple torque on the motor shaft. In this paper, a new base drive method to remove the undesirable portion of the dead time is described. The method senses the transistor on/off states to interlock the other transistor of the leg without the external dead time. Also, for the transistors of large current rating, the Darlington drive circuit is combined to the proposed method and is tested to verify the effectiveness. The experimental results of the proposed method are described and compared with those of the conventional dead time method.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1107-1115
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• 2013

A new PWM technique for a two-phase BLDC motor fed by a two-phase eight-switch inverter is proposed in this paper. It is well known that a two-phase eight-switch inverter can significantly improve power output compared with a two-phase six-switch inverter in a two-phase motor drive. To drive the two-phase BLDC motor simply and effectively, two normal PWM strategies are investigated to manage speed regulation. However, under the conditions of low speed and light load, especially during the braking process, the current in a short time of one period is near zero, which is a discontinuous waveform every half period. To solve it, a novel PWM technique is investigated to improve the operational performance of normal technique. Using the new PWM scheme, the current continues every half period and the braking performance is improved. The effectiveness of the proposed PWM method is verified through the experiments.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.63-68
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• 2002

In a utility interactive photovoltaic generation system, a PWM inverter is used for the connection between the photovoltaic arrays and the utility. The do current becomes pulsated when the conventional inverter system operates in the continuous current mode and dc current pulsation causes the distortion of the ac current waveform. To reduce pulsation of dc input current, This paper presents a Buck-Boost PWM power inverter and its application for residential photovoltaic system. The PWM power inverter is realized by combining two sets of a high frequency Buck-Boost chopper and by making it operate in the discontinuous conduction mode. In this paper, we show the Buck-Boost PWM power inverter circuit, its equivalent circuit and basic differential equations and the power flow characteristics are clarified when the proposed Inverter is interconnected with the utility lines. In conclusion, the proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.426-428
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• 1997

This paper presents the linearized optimal PWM techniques for current source GTO converter. This proposed method is to linearize an optimal PWM modulation strategy so that the turn-on/off-periods of the GTO switches can be computed on-line in real-time for any modulation index. This allows the rapid and continuous regulation of the DC output current while producing the sinusoidal AC input current waveform and unit power factor.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.50-52
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• 2003

This paper presents characteristics analysis of brushless DC motor(BLDCM) which driven by two types of PWM mode. The phase current and torque ripples are generated differently at each PWM mode. So they have a different influence on motor characteristics. In this paper, we have analyzed characteristics of BLDCM using time-stepped voltage source finite element method. The effect of two types of PWM mode had been confirmed by comparing each phase current and torque ripple waveform. The compared simulation result is useful to select a better PWM mode.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.744-746
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• 2003

This paper presents characteristics analysis of brushless DC motor(BLDCM) which is driven by four types of PWM mode. The Phase current, radial forte and torque ripples are generated differently at each PWM mode. So they have different influences on motor characteristics. In this paper, we analyzed characteristics of BLDCM using time-stepped voltage source finite element method. The effect of four types of PWM mode had been confirmed by comparing each phase current and torque ripple waveform. The compared simulation result is useful to select a better PWM mode.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.5-9
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• 1998

In the high speed rail system, the distortion of the voltage and the current waveform of the input power line increases the power loss and make a several electro-magnetic problems such as EMI or the interference of the communication line. In this paper, the control scheme of the PWM converter to make a good power factor and to regulated the output voltage as well as to reduce the harmonic component of the input current is proposed. Also a control schem of the PWM converter in the parallel operation to reduce the harmonics of the input current is proposed