• 전력전자학회논문지
• /
• 제14권1호
• /
• pp.46-53
• /
• 2009

본 논문은 다중출력 전원 시스템을 위한 새로운 구조의 영전류 스위칭(ZCS, Zero Current Switching) LLC 공진형 Post-regulator를 제안한다. 기존의 LLC 공진형 컨버터는 정밀한 다중 출력을 얻기 위해 추가의 비 절연형 DC/DC 컨버터가 요구되었고, 이는 전력 변환 효율 감소 및 제조 원가 상승의 단점을 갖고 있다. 제안된 Post-regulator는 각 정류 다이오드 및 전력 스위치의 내압 및 전류 스트레스가 작고, 부피가 큰 고가의 비 절연형 DC/DC 컨버터의 추가 대신 1 개의 보조 스위치만으로 구현되므로 구조가 간단하고, 저가격화에 유리하다. 또한, 제안된 Post-regulator의 모든 전력 스위치는 영전류 스위칭이 가능하므로 EMI 특성이 우수하며 스위칭 손실을 최소화 할 수 있다. 최종적으로 본 논문에서 제안된 전원 시스템의 동작 원리 및 타당성을 검증하기 위하여, 영전류 스위칭 LLC 공진형 Post-regulator의 실험 결과를 제시한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.987_988
• /
• 2009

견인용 시스템에 있어서 구동모터의 효율증대를 위해서는 고압전원이 필수적이며 이를 위해 일반적으로 승압 DC/DC 컨버터 사용하고 있으나, Hard Switching 방식의 PWM 컨버터로는 효율향상에 한계가 있으며 동특성이 저하되는 단점이 있다. 본 논문에서는 새로운 방식의 절연된 차량용 고압 DC/DC 컨버터를 이용하여 효율 및 동특성을 개선하기위해 Full-bridge 컨버터와 Double-half-bridge 컨버터를 이용한 소프트 스위칭방식으로 고효율화를 달성하고 컨버터의 동특성을 향상시켰다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2010년도 하계학술대회 논문집
• /
• pp.23-24
• /
• 2010

본 논문에서 설계한 3kW급 절연형 DC/DC 컨버터는 전기 버스의 주 동력원인 고전압 배터리로부터 차량의 전장시스템에 저전압 전원을 공급한다. 이 전력변환에는 고전압 배터리측과 저전압 배터리측의 절연이 반드시 필요하기 때문에 고주파 변압기를 사용한 절연형 DC/DC 컨버터가 일반적으로 사용된다. 따라서 ZVS 동작이 가능한 위상천이 방식의 풀-브리지 컨버터를 선정하였다. 본 논문에서 사용된 전력변환장치는 차량시스템에 적용하기 적합한 프리스케일사의 32-Bit DSP인 MPC5553 기반의 제어기를 이용한 실험을 통해 타당성을 검증하였다.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제3권2호
• /
• pp.215-221
• /
• 2014

To satisfy the high voltage direct current (HVDC) grid connection demand for wind power generation system, a novel topology and control strategy of HVDC grid connection for open-winding permanent magnet synchronous generator (PMSG) based wind power generation system is proposed, in which two generator-side converter and two isolated DC/DC converters are used to transmit the wind energy captured by open winding PMSG to HVDC grid. By deducing the mathematic model of open winding PMSG, the vector control technique, position sensorless operation, and space vector modulation strategy is applied to implement the stable generation operation of PMSG. Finally, the simulation model based on MATLAB is built to validate the availability of the proposed control strategy.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
• /
• pp.365-367
• /
• 2000

Recently, the power supply equipments have tendency to take multiple feedback loop paths. In this paper, the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the gurantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test results. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency $f_c$ is nearly 1/5 of switching frequency $f_s$ from the experimental result with frequency response analyzer.

• 전력전자학회논문지
• /
• 제22권6호
• /
• pp.517-526
• /
• 2017

In this paper, we propose an LLC resonant converter that operates over a wide controllable output voltage ($50V_{DC}$ to $800V_{DC}$) and shows high efficiency characteristics under all load conditions and output voltages. Two 3.3kW prototypes are designed for an experimental comparison between the variable frequency control (control scheme 1) and the variable input voltage($V_{IN}$) control (control scheme 2) mechanisms. The experimental results show that the variable input control mechanism demonstrates high efficiency under all loads and output voltages.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1997년도 전력전자학술대회 논문집
• /
• pp.413-416
• /
• 1997

In this paper, we propose a new single-stage isolated switching power supply. The proposed converter reduces the diode conduction loss and offer both the high input Power factor and the direction conversion from the ac line to a dc output voltage. This paper present the Operational principle, analysis and control and experimental results of a 100W prototype.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2019년도 전력전자학술대회
• /
• pp.153-155
• /
• 2019

This paper proposes a two-phase interleaved bridgeless single-stage ac-dc converter with magnetic integration that can achieve CCM power factor correction without input current sensing. All switches achieve ZVS turn-on and all diodes achieve ZCS turn-on for the whole grid cycle. SDAB-based modulation strategy is applied which results in simple power control and wide range output voltage. A flux cancellation method to integrate the interleaved transformer is firstly proposed in this paper to reduce the core size and loss. Experimental results on a 1.7-kW, 50kHz prototype are given to verify the principle and advantages of the proposed ac-dc converter.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2011년도 전력전자학술대회
• /
• pp.429-430
• /
• 2011

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology with coupled inductors. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charging mode, constant-current mode, and constant-voltage mode. The pre-charging mode employs the staircase shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is able to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 67A. The optimal discharging algorithm for Vehicle to the Grid (V2G) operation has been adopted to maintain the discharging current of 1C. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Journal of Power Electronics
• /
• 제16권5호
• /
• pp.1629-1638
• /
• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.