• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.500-501
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• 2014

본 논문은 단상 3 레벨 NPC 인버터에서 스위칭 손실 저감을 위한 스위칭 방법을 제안한다. 기존의 유니폴라 스위칭 방법은 두 레그의 스위치가 독립적으로 제어되어 전압을 출력하며 모든 스위치가 계속해서 ON/OFF 동작을 수행 한다. 이는 스위치에서 발생하는 스위칭 손실을 증가 시킨다. 제안하는 스위칭 방법은 한 레그의 스위치의 동작을 고정시키고, 다른 한 레그의 스위치만을 ON/OFF 동작하여 전체적인 스위칭 손실을 감소 시킨다. PSIM을 이용한 시뮬레이션을 통해 제안하는 스위칭 방법과 유니폴라 스위칭 방법을 비교 분석하고 타당성을 확인한다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.427-428
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• 2020

본 논문에서는 최소손실 불연속 변조 기법에 따른 2레벨 3상 전압원 인버터의 DC 링크 전압 리플을 분석하고 이를 통해 DC 링크 커패시터 전기 용량을 선정하는 방법을 제시하였다. 커패시터 전기 용량은 클수록 전압 리플을 제한하는 데 유리하지만, 이는 인버터 제작비용을 증가시키고 전력 밀도를 낮춘다. 따라서 DC 링크 커패시터 전기 용량을 적절히 선정하는 것이 중요하다. PSIM을 이용한 매입형 영구자석 동기 전동기 구동모의실험으로 제시한 분석 방법의 타당성을 검증하였다.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.369-371
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• 1999

A torque ripple minimization technique is proposed for high power induction motors driven by 3-level inverters with switching frequency of inverter switching elements limited around 500Hz level. It is noted that conventional DTC algorithms with torque ripple minimization scheme are devised for applications with relatively high switching frequency above 2-3kHz. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation results show effectiveness of the proposed control algorithm, and associated experimental works will be presented in the final paper.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.84-93
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• 2000

In PWM voltage source inverters operated by conventional switching method, the dead time is inserted in switching signals to prevent tile short circuit of the DC voltage source. The dead time causes detrimental effects to the control performance of the inverter system. So we need to compensate the dead time effects. And the dead time minimization switching method can be considered as the best way to avoid the dead time effects fundamentally. In this paper, a new switching strategy is proposed which is a kind of dead time minimization switching methods. According to the proposed switching method, very short dead time is adopted in only once when the current polarity is changing. And the adopted dead time is equal to the turn off time of the swtiching device or shorter than it. As the proposed method can be done with the polarity information of the reference current in case that the output current of the inverter is controlled, it is easy to solve some problems in comparison with the case that the real current is used to get the polarity changing time； level detection difficulty, noise problem and so on

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2043-2046
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• 1997

GTO 소자의 최소 턴온 시간(minimum turn-on time, Tmin)때문에 발생된 지령전압 오차를 보상하는 기법을 제안한다. 공간백터전압$(V_1)$의 턴온시간이 Tmin보다 작을 경우에는 전압오차를 PI 제어기로 보상한다. 또한, 지령전압벡터의 크기가 특정한 값(Vmin)보다 작은 경우, 영벡터(zero vector)가 PWM 추기에서 중간에 매치가 되도록 스위칭 순서를 바꿔준다. 시뮬레이션을 통해 이러한 지령전압 오차의 보상으로 펄스 누락(pulse dropping) 영역에서 출력전압의 대칭성이 향상되고 고조파 함유량이 감소한다는 사실을 보인다.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.635-639
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• 2004

This paper presents a simple PWM method to control three phase four leg multilevel inverters, which have been developed for supplying electrical power to three phase unbalanced load and for related power active filters. The method is derived from a general correlation between space vector PWM (SVPWM) method and carrier based PWM (CPWM) method. As an advantage, the simplicity and flexibility of the proposed CPWM control can be obtained and the complicated calculations of the 3-D SVPWM concepts can be avoided. The method has been mathematical formulated and demonstrated by simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.490-495
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• 2020

The power loss of large-capacity systems using single-phase inverters has attracted considerable attention. In this study, optimal switching sequence model prediction control at a low switching frequency is proposed to reduce the power loss in a high-power inverter system, and a compensation method that can be utilized for model prediction control is developed to reduce errors in accordance with sampling values. When a three-level, single-phase inverter using a switching frequency of 600 Hz and a sampling frequency of 12 kHz is adopted, the power factor is improved from 0.95 to 0.99 through 3 kW active power control. The performance of the controller is also verified.

• ETRI Journal
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• v.44 no.3
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• pp.491-503
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• 2022

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are continuously scaling down in the nanoscale region to improve the functionality of integrated circuits. The scaling down of MOSFET devices causes short-channel effects in the nanoscale region. In nanoscale region, leakage current components are increasing, resulting in substantial power dissipation. Very large-scale integration designers are constantly exploring different effective methods of mitigating the power dissipation. In this study, a transistor-level input-controlled stacking (ICS) approach is proposed for minimizing significant power dissipation. A low-power ICS approach is extensively discussed to verify its importance in low-power applications. Circuit reliability is monitored for process and voltage and temperature variations. The ICS approach is designed and simulated using Cadence's tools and compared with existing low-power and high-speed techniques at a 22-nm technology node. The ICS approach decreases power dissipation by 84.95% at a cost of 5.89 times increase in propagation delay, and improves energy dissipation reliability by 82.54% compared with conventional circuit for a ring oscillator comprising 5-inverters.

• Journal of the Semiconductor & Display Technology
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• v.19 no.1
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• pp.42-48
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• 2020

As global warming accelerates, eco-friendly electric cars are being developed to reduce carbon dioxide emissions, and power conversion inverters are used to drive motors. Among inverter components, DC-link capacitor is heated by high current usage, which causes problems such as performance and life-saving of inverter. Although metal cases with good thermal performance have been used to solve this problem, it is difficult to apply them in practice due to insulation problems with other parts. In this paper, the Heat-Generation influence factor of DC-link capacitor is analyzed. Variables on heat-generation are set at 3 levels for film width, inductance, and film thickness. Box-Behnken to 13 tests using the design and minimal deviations, e.g. through the experiment three times by each level. The surface of the film k type by attaching the sensor current is measured temperature. Capacitance was set to a minimum level of 200 ㎌ and had a frequency of 16 kHz with Worst case, ambient temperature of 85℃ and a ripple current of 50 Ams was applied. The temperature at the measurement point was collected in the data logger after sampling at 1 minute intervals for 2 hours after saturation with the ambient temperature. This experiment confirmed that setup factors are correlated with heat-generation.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.304-315
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• 2013

In this paper, analysis of cascaded H-bridge multilevel inverter in DTC-SVM (Direct Torque Control-Space Vector Modulation) based induction motor drive for FCEV (Fuel Cell Electric Vehicle) is presented. Cascaded H-bridge multilevel inverter uses multiple series units of H-bridge power cells to achieve medium-voltage operation and low harmonic distortion. In FCEV, a fuel cell stack is used as the major source of electric power moreover the battery and/or ultra-capacitor is used to assist the fuel cell. These sources are suitable for utilizing in cascaded H-bridge multilevel inverter. The drive control strategy is based on DTC-SVM technique. In this scheme, first, stator voltage vector is calculated and then realized by SVM method. Contribution of multilevel inverter to the DTC-SVM scheme is led to achieve high performance motor drive. Simulations are carried out in Matlab-Simulink. Five-level and nine-level inverters are applied in 3hp FCEV induction motor drive for analysis the multilevel inverter. Each H-bridge is implemented using one fuel cell and battery. Good dynamic control and low ripple in the torque and the flux as well as distortion decrease in voltage and current profiles, demonstrate the great performance of multilevel inverter in DTC-SVM induction motor drive for vehicle application.