• Journal of Power Electronics
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• 제11권2호
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• pp.202-210
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• 2011

Polymer electrolyte membrane (PEM) fuel cell is one of the popular renewable energy sources and widely used in commercial medium power areas from portable electronic devices to electric vehicles. In addition, the increased integration of the PEM fuel cell with power electronics, dynamic loads, and control systems requires accurate electrical models and simulation methods to emulate their electrical behaviors. Advancement in parallel computation techniques, various real-time simulation tools, and smart power hardware have allowed the prototyping of novel apparatus to be investigated in a virtual system under a wide range of realistic conditions repeatedly, safely, and economically. This paper builds up advancements of optimized model constructions for a fuel cell stack system on a real-time simulator in the view points of improving dynamic model accuracy and boosting computation speed. In addition, several considerations for a power hardware-in-the-loop (PHIL) simulation are provided to electrically emulate the PEM fuel cell stack system with power facilities. The effectiveness of the proposed PHIL simulation method developed on Opal RT's RT-Lab Matlab/Simulink based real-time engineering simulator and a programmable power supply is verified using experimental results of the proposed PHIL simulation system with a Ballard Nexa fuel cell stack.

• 한국산학기술학회논문지
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• 제18권9호
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• pp.444-453
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• 2017

기존 RTDS를 이용한 PV PHIL(Power-Hardware-In-Loop) Simulator는 확장성과 유연성의 문제로 인하여 일반 DC Amplifier를 이용한 많은 연구가 진행되었으나, PV Inverter와 연계할 경우에 과도 상태의 출력이 발생하여 안정성과 PV Inverter의 성능 개선이 불가능하였다. 따라서, 이러한 문제점을 해결하기 위하여 본 논문에서는 PV PHILS의 출력 성능 향상과 안정적인 운영이 이루어질 수 있는 제어 알고리즘을 제안한다. 즉, 이 제어 알고리즘은 DC Amplifier의 전기적 출력 특성을 극복하기 위해 정전압(CV), 정전류(CC) 상태에 따라 전압, 전류의 목표 값을 제어하고 각 장치별 특성 고려한 Multi-rate 기반의 특성을 갖는다. 먼저, PV Array의 수학적인 모델링과 DC Amplifier 그리고 DC 전력측정용 Isolated 장치와 통합하여 실시간 처리 기반의 장치로 구성하였고, 제안한 알고리즘이 적용된 PV PHILS와 실제 계통에 연계된 PV Inverter를 이용한 성능시험을 통해서, 그 결과가 기존 방법에 대비해 우수성 및 유용성을 입증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.296-297
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• 2017

태양광 발전에 있어서 실제 태양광 셀 특성은 날씨와 같은 환경 요인에 의존적이기 때문에 다양한 동작 조건에 대한 태양광 셀의 특성을 전력변환장치를 통해 테스트하기 위해 많은 시간과 비용이 소요된다. 이러한 문제를 해결하기 위해 Power Hardware-In-the-Loop Simulation (PHILS) 기술을 이용해 태양광 발전용 전력변환장치 시제품의 테스트 시간 및 비용을 단축할 수 있다. PHILS는 실시간 모의시험장치와 외부 입력이 가능한 전력변환장치로 구성되며, 해당 장치에서 모델의 동특성을 실시간으로 연산하기 때문에 모델이 복잡할수록 고성능 모의시험장치가 요구된다. 태양광 셀 모델의 출력 전압은 수치해석 기법을 통해 계산되고, 수치해석 기법의 종류와 초기 값에 따라 연산 시간 등의 성능이 변화하므로 적절한 기법을 선정하여 모델의 연산시간을 감소시킬 수 있다. 본 논문에서는 수치 해법 분석을 통한 태양광 발전의 PHILS를 위한 태양광 셀 모델의 연산 성능향상 기법을 제시하고, 실제 태양광 발전용 PHILS를 구현하여 실험적으로 제안하는 기법의 성능을 검증한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.121-123
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• 2019

본 논문에서는 실시간 시뮬레이터를 이용하여 DC 전력시스템의 모델링하고, Power Hardware-in-the-Loop (PHIL) 모의 테스트를 통해 DC 마이크로그리드에 적용 가능한 컨버터의 전력제어 알고리즘의 실효성을 검증하고자 한다. PHIL 모의시험 테스트 기법을 이용해 DC 마이크로그리드의 자율운전을 모사할 수 있는 Test-Bed를 제안하고자 한다. 이를 통해 부하 변화에 따른 운전 모드, 사고 상황 대처 알고리즘 등 DC 마이크로그리드에 연계된 전력변환장치의 전력제어 방법 및 실효성을 검증을 하고자 한다. 모의시험과 3 kW급 컨버터 시작품을 이용하여 제안하는 DC 마이크로그리드의 시험환경을 검증하고 전력제어 알고리즘의 신뢰성 및 안정성을 검증한다.

• Journal of Power Electronics
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• 제11권4호
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• pp.471-478
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• 2011

This paper addresses the establishment of a kVA-range plug-in hybrid electrical vehicle (PHEV) integration test platform and associated issues. Advancements in battery and power electronic technology, hybrid vehicles are becoming increasingly dependent on the electrical energy provided by the batteries. Minimal or no support by the internal combustion engine may result in the vehicle being occasionally unable to recharge the batteries during highly dynamic driving that occurs in urban areas. The inability to sustain its own energy source creates a situation where the vehicle must connect to the electrical grid in order to recharge its batteries. The effects of a large penetration of electric vehicles connected into the grid are still relatively unknown. This paper presents a novel methodology that will be utilized to study the effects of PHEV charging at the sub-transmission level. The proposed test platform utilizes the power hardware-in-the-loop (PHIL) concept in conjunction with high-fidelity PHEV energy system simulation models. The battery, in particular, is simulated utilizing a real-time digital simulator ($RTDS^{TM}$) which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces via a LC-LC-type filter to a power grid. In addition, the PHEV impact is evaluated via another power electronic converter controlled through $dSPACE^{TM}$, a rapid control systems prototyping software.

• Journal of Power Electronics
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• 제11권4호
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• pp.479-489
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• 2011

The bidirectional dc-dc converter, being the interface between Energy Storage Element (ESE) and DC bus, is an essential component of the power management system for vehicle applications including electric vehicle (EV), hybrid electric vehicle (HEV), and fuel cell vehicle (FCV). In this paper, a novel multiphase bidirectional dc-dc converter interfacing with battery to supply and absorb the electric energy in the FCV system was studied with the help of real time digital simulator (RTDS). The mathematical models of fuel cell, battery and dc-dc converter were derived. A power management strategy was developed and first simulated in RTDS. A Power Hardware-In-the-Loop (PHIL) simulation using RTDS is then presented. The main challenge of this PHIL is the requirement for a highly dynamic bidirectional Simulation-Stimulation (Sim-Stim) interface. This paper describes three different interface algorithms. The closed-loop stability of the resulting PHIL system is analyzed in terms of time delay and sampling rate. A prototype bidirectional Sim-Stim interface is designed to implement the PHIL simulation.

• 전력전자학회논문지
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• 제26권2호
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• pp.150-157
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• 2021

Nowadays, a DC microgrid that can link various distributed power sources is gaining much attention. Accordingly, research on fault situations, such as line-to-line and line-to-ground faults of the DC microgrid, has been conducted to improve grid reliability. However, the blackout of an AC system and the oscillation of a DC bus voltage have not been reported or have not been sufficiently verified by previous research. In this study, a 20 kW DC microgrid testbed using a power HIL simulation technique is proposed. This testbed can simulate various fault conditions without any additional grid facilities and dangerous experiments. It includes the blackout of the DC microgrid caused by the AC utility grid's blackout, a drastic load increment, and the DC bus voltage oscillation caused by the LCL filter of the voltage source converter. The effectiveness of the proposed testbed is verified by using Opal-RT's OP5707 real-time simulator with a 3 kW prototype three-port dual-active-bridge converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.245-247
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• 2020

본 논문에서는 DUT(Device Under Test) 및 PHIL(Power Hardware-in-the-Loop) 시뮬레이터의 스위칭 주파수 비 및 PWM 위상차에 의하여 발생할 수 있는 문제를 분석하였다. 또한, DUT 인버터의 PWM 특성을 고려한 디지털 필터를 적용하여 PHIL 시뮬레이터의 운전 영역을 확대하였다. 디지털 필터는 DUT 스위칭 주파수의 고조파 성분만을 선택적으로 제거하여 PHIL 스위칭 주파수에 무관하게 일정한 시뮬레이션 결과를 생성할 수 있다. 분석한 내용과 디지털 필터의 변경으로 인한 PHIL 시뮬레이터의 특성은 다양한 조건에서 시행된 실험을 통하여 검증하였다.

• Journal of Power Electronics
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• 제14권2호
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• pp.402-412
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• 2014

This paper proposes a novel electric propulsion system for naval ships, which consists of Active Front End (AFE) converters directly connected to battery Energy Storage Modules (ESMs). Employing the proposed AFE converters with ESMs in the power systems of naval ships can enhance the reliability and quality of the electric power. Furthermore, the fuel-efficiency of the generator can be improved by a higher loading factor of the generator and its prime movers. The proposed AFE configuration does not require an additional dedicated DC/AC converter for the ESMs. Instead of that, the AFE converter itself can control the DC link voltage and the discharging and/or charging of the ESMs. A control scheme to achieve these control objectives is also presented in this paper. The overall power system, including the generators and electrical loads of a naval ship, is implemented by a small scaled Power Hardware-In-the-Loop (PHIL) simulator. Through this experimental setup, the proposed system configuration and the power control strategies are verified. It is shown that the fuel-efficiency and transient dynamics can be improved in the normal and contingency operation modes.

• 전기학회논문지
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• 제64권11호
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• pp.1564-1570
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• 2015

This paper intends to suggest a sensing circuit of PWM voltage for a motor emulator operated in the inverter. In the emulation of the motor using a power converter, it is necessary to measure instantaneous voltage at the PWM voltage loaded from the inverter. Using a filter can generate instantaneous voltage, while it is difficult to follow the rapidly changing inverter voltage caused by the propagation delay and signal attenuation. The method of measuring the duty of PWM using FPGA can generate output voltage from the one-cycle delay of PWM, while the cost of hardware is increasing in order to acquire high precision. This paper suggests a PWM voltage sensing circuit using the analogue system that shows high precision, one-cycle delay of PWM and low-cost hardware. The PWM voltage sensing circuit works in the process of integrating input voltage for valid time by comparing levels of three-phase PWM input voltage, and produce the output value integrated at zero vector. As a result of PSIM simulation and the experiment with the produced hardware, it was verified that the suggested circuit in this paper is valid.