• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.714-716
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• 2003

This paper deals with the characteristic analysis of a brushless DC motor (BLDC) and taking into consideration the freewheeling diodes and DC link voltage ripple using a time-stepped voltage source finite element method. By comparing with the experimental results, we show that the proposed computational method is useful for the analysis and design of a BLDC motor. We also examine the influence of freewheeling diodes and DC link voltage ripples on the performance of a BLDC motor such as torque ripples and radial force on the surface of the teeth.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.114-121
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• 2016

This paper is Instant space vector PWM(Pulse Width Modulation)power conversion devices in switching power semiconductors from my generation to losses and switching when the voltage surge and current surge of electronic noise(EMI: Electro Magnetic Interference / RFI: Radio Frequency Interference)to effectively minimize the power soft-switching power conversion circuit topologies of auxiliary resonant DC tank for the purpose of high performance realization of the electric power conversion system by the high-speed switching of a semiconductor device(AQRDCT simultaneously : an active auxiliary resonance using auxiliary Quasi-resonant DC tank)DC link snubber switch has adopted a three-phase voltage inverter. AQRDCL proposed in this paper can reduce the effective and current peak stress of the power semiconductors of the auxiliary resonant snubber circuit compared to the conventional active-resonant DC link snubber, it is not necessary to install the clamp switch of the auxiliary resonant DC link, DC the peak current and power loss of the bus line can be reduced.

• Journal of IKEEE
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• v.23 no.1
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• pp.99-106
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• 2019

This paper propose a new form of UPQC (Unified Power Quality Compensator) to compensate the current and voltage quality problems of nonlinear loads. The conventional UPQC system consists of a series inverter, a parallel inverter, and a common DC link. A new type of UPQC proposed is a parallel compensator with SVC (Static Var Compensator) added to compensate for the wide compensation range and low DC link voltage. The parallel inverter compensates the reactive power generated by the nonlinear load, and the series inverter compensates the sag and swell generated at the power supply side.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.381-383
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• 2006

A novel online capacitance estimation method for a DC-link capacitor in a three-phase AC/DC/AC PWM converter is proposed. A controlled AC voltage with a lower frequency than the line frequency is Injected into the DC-link voltage, which then causes AC power ripples at the DC output side. By extracting the AC voltage and power components on the DC output side using digital filters, the capacitance can then be calculated using the recursive least squares method. The proposed method can be simply implemented with only software and no additional hardware. Experimental results confirm that the estimation error is less than 0.2%.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.192-198
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• 2012

Switch losses directly affect the efficiency of power conversion systems and those have big differences according to the power consumed by load systems and the structures of power conversion circuits. In this paper, analyses for switch losses in DC link converter are performed based on the circuit structures of the DC/DC converter in photovoltaic generation system whose output power is varied according to the amount of solar radiation, temperature and partial shade on the solar modules. Boost converter is adopted as a DC link converter topology of the photovoltaic generation system and the loss analyses for the switches used in the boost converters are performed according to the circuit structures. Analyses like the things performed in this paper will be a prerequisite to designing the photovoltaic generation system whose output power is changed according to the environmental variations.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.102-103
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• 2013

화석 연료의 고갈과 유가 급등으로 인해 자동차 업체에서는 친환경 차량 개발에 힘쓰고 있다. FCEV는 차량 구동용 전동기에 필요한 에너지를 연료전지를 통해 공급받게 된다. 하지만 연료전지의 특성상 연료전지와 배터리를 같이 사용하게 된다. 본 논문에서는 일반적인 Half-bridge 타입의 양방향 컨버터에 스위치를 추가하여 양방향 buck, boost가 가능한 컨버터를 설계하였다. 전동기 구동용 인버터는 전압형 인버터가 사용되는데 전압형 인버터에서 발생하는 출력은 데드타임과 스위칭 소자의 전압 강하에 의해 왜곡된 전압과 전류를 출력하게 되고 이러한 출력은 토크와 속도에 나쁜 영향을 끼치게 된다. 이러한 문제를 해결하기 위해 전동기의 속도에 따라 DC-link 전압을 가변하여 공급한다.

• Journal of Power Electronics
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• v.8 no.3
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• pp.239-247
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• 2008

This paper presents the design of 1 kW prototype high frequency link boost half bridge inverter-fed DC-DC power converters with bridge voltage-doublers suitable for small scale PEM fuel cell systems and associated control schemes. The operation principle of this converter is described using fuel cell modeling and some operating waveforms. The switching mode equivalent circuits are based on simulation results and a detailed circuit operation analysis at soft-switching conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.49-56
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• 2006

The bi-directional converter interfaces the low voltage battery to the inverter do link of FC generation system. When power flows from the low voltage side(battery: 48[V]) to the high voltage side(dc link: 380[V]), the circuit works in discharge mode (boost) to power the high voltage side load; otherwise, it works in charge mode (buck) to charge the low voltage side battery. In this paper, the 1.5[kW] active clamp current-fed full bridge converter employing MOSFETs is operated to discharge the battery whereas a voltage-fed half bridge converter employing IGBTs is operated to charge the battery.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.752-759
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• 2013

This paper proposes a method for fault diagnosis and fault-tolerant control of DC-link voltage sensor for two-stage three-phase grid-connected PV inverters. Generally, the front-end DC-DC boost converter tracks the maximum power point (MPP) of PV array and the rear-end DC-AC inverter is used to generate a sinusoidal output current and keep the DC-link voltage constant. In this system, a sensor is essential for power conversion. A sensor fault is detected when there is an error between the sensed and estimated values, which are obtained from a DC-link voltage sensorless algorithm. Fault-tolerant control is achieved by using the estimated values. A deadbeat current controller is used to meet the dynamic characteristic of the proposed algorithm. The proposed algorithm is validated by simulation and experiment results.

• Journal of Power Electronics
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• v.10 no.1
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• pp.27-33
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• 2010

This paper presents a bidirectional DC-DC converter suitable for low-voltage super capacitor-based electric energy storage systems. The DC-DC converter presented here consists of a full-bridge circuit and a current-fed push-pull circuit with a high frequency (HF) transformer-link. In order to reduce the device-conduction losses due to the large current of the super capacitor as well as unnecessary ringing, synchronous rectification is employed in the super capacitor-charging mode. A wide range of voltage regulation between the battery and the super capacitor can be realized by employing a Phase-Shifting (PS) Pulse Width Modulation (PWM) scheme in the full-bridge circuit for the super capacitor charging mode as well as the overlapping PWM scheme of the gate signals to the active power devices in the push-pull circuit for the super capacitor discharging mode. Essential performance of the bidirectional DC-DC converter is demonstrated with simulation and experiment results, and the practical effectiveness of the DC-DC converter is discussed.