• 산업기술연구
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• 제30권B호
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• pp.109-112
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• 2010

Unlike the general lighting systems, stage lighting system requires accurate dimming control and reduction of flicker phenomenon. In this paper, we studied PWM dimming control and linear voltage level control methods. PWM Dimming is easy control and flicker phenomenon of linear voltage level dimming does not happen by experiment result. We concluded that stage lighting dimming system required to combine two techniques of the PWM and linear voltage level dimming control method.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권10호
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• pp.544-554
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• 1999

Multi-level inverters are now receiving widespread interest form the industrial drives for high power variable speed applications. Especially, for the high power variable speed applications, a diode clamped multi-level inverter has been widely used. However, it has the inherent problem that the voltage of the link capacitors fluctuates. This paper describes a voltage control scheme effectively to suppress the DC-link potential fluctuation for a diode clamped four-level inverter. The current to flow from/into the each link capacitor is analyzed and the operation limit is obtained when a conventional SVPWM is used. To overcome the operation limit, a modified carrier-based SVPWM is proposed. Various simulation and experiment results are presented to verify the proposed voltage control scheme for DC-link voltage balancing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.294-296
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• 2000

Energy recovery in the regenerative region is very important when SRM(Switched Reluctance Motor) is used in traction drive. This is because that to reduce energy loss during mechanical braking and/or to have a high efficiency drive during braking. To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation in SRM.

• Journal of Power Electronics
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• 제19권1호
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• pp.108-118
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• 2019

This paper proposes a DC-link voltage balance controller using the fourth-phase of a three-level neutral-point clamped (NPC) PWM converter with medium vector selection (MVS) PWM for common-mode voltage reduction. MVS PWM makes the voltage reference by synthesizing the voltage vectors that cannot generate common-mode voltage. This PWM method is effective for reducing the EMI noise emitted from converter systems. However, the DC-link voltage imbalance problem is caused by the use of limited voltage vectors. Therefore, in this paper, the effect of MVS PWM on the DC-link voltage of a three-level NPC converter is analyzed. Then a proportional-derivative (PD) controller for the DC-link voltage balance is designed from the DC-link modeling. In addition, feedforward compensation of the neutral point current is included in the proposed PD controller. The effectiveness of the proposed controller is verified by experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권3호
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• pp.64-69
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• 2001

Energy recovery in the regenerative region is very important when SRM is used in traction drive, This is to reduce en-ergy loss during mechanical braking and/or to have a high efficiency drive during braking To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM multi-level voltage control is effective The paper sug-gests multi-level inverter which is useful for motoring and regenerative operation in SRM

• Journal of Power Electronics
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• 제15권5호
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• pp.1207-1216
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• 2015

In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

• 반도체디스플레이기술학회지
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• 제14권4호
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• pp.72-77
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• 2015

Three-level diode clamped multilevel inverter, generally known as neutral point clamped (NPC) inverter, has an inherent problem causing neutral point (NP) potential variation. Until now, the NP potential problem of variation has been investigated and lots of solutions have also been proposed. This paper presents a neutral point voltage control technology using the anti-windup PI controller and offset technology of PWM (Pulse Width Modulation) to control the variation of NPC 3-phase three-level inverter neutral point voltage. And the proposed algorithm is tested and verified using a PLL (Phase Locked Loop) in order to synchronize the phase voltage from the line voltage of grid. It significantly improves the voltage balancing under a solar fluctuation conditions of the inverter. Experimental results show the good performance and effectiveness of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.403-405
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• 2007

This paper presents the over-modulation strategy and indirect vector control drive of NPC type PWM inverter. NPC inverter has three level phase voltage output.It can perform in high voltage through assembling switching components. It has less harmonics and surge voltage stress at motor terminals than the 2 level inverter in same switching frequency through 3 level voltage. The conventional railway vehicle has used the vector control to MI=0.907 and the slip-frequency control from MI=0.907 to six-step mode. The slip-frequency control has bad motive power and slow torque control response. But vector control has good motive power and can instant torque control. In this paper, output voltage is controlled linearly from linear region to six-step mode by using over-modulation strategy. And NPC inverter is used.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.29-32
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• 2001

The application of SRM(Switched Reluctance Motor) is dramatically increasing due to a simple mechanical structure, high efficiency and a good high speed characteristics. To control high conduction ratio in motor operation and regenerative voltage in the generator operation multi-level voltage control is effective. This paper proposes multi-level inverter to have a maximum conduction ratio of SRM. The proposed method is verified by experiments.

• 전기학회논문지
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• 제67권7호
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• pp.846-853
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• 2018

In this paper, an improved model predictive control (MPC) method is proposed, which reduces the amount of calculations caused by the increased number of candidate voltage vectors with the increased voltage level in multi-level inverters. When the conventional MPC method is used for multi-level inverters, all candidate voltage vectors are considered to predict the next-step current value. However, in the case that the sampling time is short, increased voltage level makes it difficult to consider the all candidate voltage vectors. In this paper, the improved MPC method which can get a fast transient response is proposed with a small amount of the computation by adding new candidate voltage vectors that are set to find the optimal vector. As a result, the proposed method shows faster transient response than the method that considers the adjacent vectors and reduces the computational burden compared to the method that considers the whole voltage vector. the performance of the proposed method is verified through simulations and experiments.