• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.52-60
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• 2005

Generally, a voltage difference or voltage distortion exists between the reference voltage and the practical voltage applied to a motor in a pulse width modulated(PWM) voltage source inverter(VSI). This voltage distortion varies with the operating conditions such as the temperature, DC link voltage, and phase current level. Also the voltage distortion affects the machine current distortion, torque pulsations, and control performance. In this paper, the voltage distortion in a PWM VSI is analyzed and a new on-line estimation method based on the model reference adaptive system(MRAS) is proposed to compensate the time varying voltage distortion, while considering the parameter variations for a permanent magnet synchronous motor (PMSM). The simulation and experimental results show the effectiveness of the proposed voltage difference observer and the compensation method.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1729-1750
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• 2018

Voltage source inverters (VSIs) are widely used to drive induction motors in industry applications. The quality of output waveforms depends on the switching sequences used in pulse width modulation (PWM). In this work, all existing optimal space vector pulse width modulation (SVPWM) switching strategies are studied. The performance of existing SVPWM switching strategies is optimized to realize a tradeoff between quality of output waveforms and switching losses. This study generalizes the existing optimal switching sequences for total harmonic distortions (THDs) and switching losses for different modulation indexes and reference angles with a parameter called quality factor. This factor provides a common platform in which the THDs and switching losses of different SVPWM techniques can be compared. The optimal spatial distribution of each sequence is derived on the basis of the quality factor to minimize harmonic current distortions and switching losses in a sector; the result is the minimum ripple loss SVPWM (MRSLPWM). By employing the sequences from optimized switching maps, the proposed method can simultaneously reduce THDs and switching losses. Two hybrid SVPWM techniques are proposed to reduce line current distortions and switching losses in motor drives. The proposed hybrid SVPWM strategies are MRSLPWM 30 and MRSLPWM 90. With a low-cost PIC microcontroller (PIC18F452), the proposed hybrid SVPWM techniques and the quality of output waveforms are experimentally validated on a 2 kVA VSI based on a three-phase two-level insulated gate bipolar transistor.

• Journal of Power Electronics
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• v.13 no.6
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• pp.1016-1023
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• 2013

Predictive current control offers the potential for achieving more precise current control with a minimum of distortion and harmonic noise. However, the predictive method is difficult to implement and has a greater computational burden. This paper introduces a theoretical analysis and experimental verification for an improved predictive current control technique applied to single phase grid connected voltage source inverters (VSI). The proposed technique has simple calculations. An ATmega1280 microcontroller board is used to implement the proposed technique for a simpler and cheaper control system. To enhance the current performance and to obtain a minimum of current THD, an improved tri-level PWM switching strategy is proposed. The proposed switching strategy uses six operation modes instead of four as in the traditional strategy. Simulation results are presented to demonstrate the system performance with the improved switching strategy and its effect on current performance. The presented experimental results verify that the proposed technique can be implemented using fixed point 8-bit microcontroller to obtain excellent results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.09a
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• pp.34-37
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• 2001

This research suggested the new algorithm controlled by micro processor which is already stored by various PWM form of output voltage by using fundamental data of the carrier and signal. The determined PWM pattern is not concerned with the signal wave form and the new algorithm can obtain the desired pulse width by synchronous of carrier. The PWM wave can be controlled with real time by using extra hardware and digital software and to speed up program processing, the control signals to switch the power semi-conductor of three phase PWM inverter, simultaneously use the output signal by microprocessor and extra hardware, and control signal by software. In the end, this method was proved by applying to Three phase voltage source inverter.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1016-1019
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• 1993

A low-pass L-C filter has been adopted for conversion of frequency variable 3 phase PWM waveform to a grid power line and it is used for attenuation of harmonics in the VSI PWM Inverter. A optimum design of the L, C parameters was derived. The result of the study show that the inductor L seems to have a certain air gap for linear I-V characteristics and the resonant frequency of the filter must be set below the 5th harmonics of the grid power line. Further, the voltage drop in L must be within a adequate limit compared to grid power voltage.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.186-190
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• 2000

This paper propose a "Active common-mode voltage damper circuit" that capable of a suppression of a common-mode voltage produced in the PWM VSI. The four level half-bridge PWM inverter circuit and common-mode transformer are incorporated into the "Active common-mode voltage damper" the design method of which is presented Effect of "Active common-mode voltage damper" in this paper verifies a propriety and effectiveness in 2.2[kW] induction motor drive using IGBT inverter. Experimental results show that "common-mode voltage damper" makes contributions to reducing a high frequency leakage current and common-mode voltage.leakage current and common-mode voltage.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.373-376
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• 1999

This paper propose a "common mode voltage damper" that is capable of reducing the common mode voltage produced in the PWM VSI. An push-pull circuits and high frequency leakage current damper[1] are incorporated into the "common mode voltage damper", the design method of which is presented. Effect of "common mode voltage damper" is simulated in this paper verifies the viability and effectiveness in 2.2kW induction motor drive using IGBT inverter. Simulated results show that "common mode voltage damper" makes significant contributions to reducing a high frequency leakage current.ducing a high frequency leakage current.

• Journal of Industrial Technology
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• v.18
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• pp.323-328
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• 1998

A current controlled VSI-PWM rectifier and inverter with capacitor dc link is regarded as one of the most promising structures for three-phase to three-phase to three-phase power conversion. This type of converter normally requires twelve switches for a rectifier and inverter composed of self turn-off switch such as a bi-polar transistor or IGBT with an anti-parallel diode. In this paper, a new three-phase to three-phase converter for ac motor drives is proposed. The proposed converter employs only eight switches and has the capability of delivering sinusoidal input currents with unity power factor and bidirectional power flow. This paper describes the feasibility and the operational limitations of the proposed structure. A mathematical model of the system is derived using generalized modulation theory and experimental results for steady state and dynamic behavior are presented to verify the developed model.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.413-414
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• 2017

영구자석 동기전동기 구동 인버터 시스템 내 스위치 고장은 다양한 조합으로 발생한다. 특히 스위치 개방고장의 경우 다른 전기 부품에 과전류를 유발하여 전체 시스템에 심각한 2차 손상을 초래한다. 본 논문에서는 개방고장 진단 알고리즘의 복잡성을 완화하기 위해 고장 그룹을 분류하여 고장 발생 시 false alarm의 영향을 받지 않고 간단하고 체계적인 방식으로 고장을 식별할 수 있는 기법을 제안한다. 스위치의 개방 고장으로 영구자석 동기전동기 구동 시스템 내 PWM 전압원 인버터의 신뢰성을 향상시키기 위해 3중 스위치 개방고장 진단 및 검출 기법을 제시한다. 제안된 기법은 기존의 개방고장 진단방법과 달리 정보처리를 위해 Moving Filter를 사용함으로써 연산부하를 증가시키지 않고 신속한 고장 검출이 가능하며 별도의 하드웨어 구성없이 구현이 가능하다. 제안된 기법의 안정성과 유효성이 시뮬레이션을 통해 입증된다.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.455-460
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• 2003

The a PWM VSI, the voltage distortion exists between the reference and output voltage. This distortion is caused by the intended blanking time and the inherent characteristics of the switching devices which are function of the operating condition. In this paper, the dead-time effects are analysed and a new on-line estimation method for a PMSM is proposed to compensate time varying dead-time effects