• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.239-241
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• 2001

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.

• Journal of Power Electronics
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• 제5권3호
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• pp.180-189
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• 2005

In this paper a DSP based control scheme for the interleaved boost converter is presented. The mathematical model for the interleaved boost converter operating in a continuous inductor current mode is developed. A state-space averaging technique is used for modeling the converter system. A fixed frequency sliding mode controller is designed to ensure current distribution between the two converter modules and to achieve the load voltage regulation simultaneously. Necessary and sufficient conditions, using variable structure theory, are derived for the sliding mode to exist. The range of sliding mode controller coefficients is also determined. The designed controller capability, load distribution among the individual boost cells and load voltage regulation against source and load disturbances, are demonstrated through PSIM simulation results. A real-time controller based on ADMC401 DSP is developed. Experimental results are provided to validate the proposed control scheme.

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

• 조명전기설비학회논문지
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• 제17권1호
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• pp.116-123
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• 2003

본 논문에서는 SMPS의 교류 입력측 역률을 개선시킬 수 있는 전치 레귤레이터로서 interleaved 승압형 컨버터를 관하여 연구하였다. Interleaved 승압형 역률보상 컨버터(IBPFC)는 입력전류를 두 개의 스위칭 소자에 의하여 50%씩 나누어져 흐르게 함으로써, 내부 전류제어 루프 얼이 전압제어 루프만으로 제어계를 구성하여 입력전류 리플을 줄일 수 있다. 즉, IBPFC를 구성하는 각각의 부스트 컨버터 cell을 불연속 전류모드로 동작시키더라도 전체적인 입력전류의 파형은 연속이 되어 입력전류 리플이 감소하게 된다. 불연속 전류모드로 동작하는 IBPFC를 해석하기 위하여 스위칭 상태에 따라서 6개의 모드로 구분하여 상태방정식을 구하였다. 또한, 각 상태방정식을 상태공간 평균화법을 이용하여 모델링하고, 미소변동분을 고려한 소신호 해석을 통하여 제어전달함수를 구할 수 있다. 또한, 제어전달함수를 이용하여 단일 전압제어 루프를 가지는 제어계를 설계하였으며, 이러한 해석 및 설계를 바탕으로 실험을 통하여 IBPFC의 역률개선 및 리플저감을 확인하였다.

• Journal of Power Electronics
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• 제17권5호
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• pp.1268-1277
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• 2017

Three-phase pulse width modulation (PWM) rectifiers are usually designed under the assumption of ideal ac power supply and input inductance. However, non-ideal circuit parameters may lead to a voltage collapse of PWM rectifiers. This paper investigates the mechanism of voltage collapse in three-phase PWM rectifiers. An analytical stability boundary expression is derived by analyzing the equilibrium point of the averaging state space model, which can not only accurately locate the voltage collapse boundary in the circuit parameter domain, but also reveal the essential characteristic of the voltage collapse. Results are obtained and compared with those of the trial-error method and the Jacobian method. Based on the analysis results, the system parameters can be divided into two categories. One of these categories affects the critical point, and other affects only the instability process. Furthermore, an effective control strategy is proposed to prevent a vulnerable system from being driven into the instability region. The analysis results are verified by the experiments.

• 전력전자학회논문지
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• 제13권1호
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• pp.1-8
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• 2008

상태 공간 평균화법을 이용하여 절연형 inverse-SEPIC(Isolated Inverse-SEPIC)의 동적 모델링을 정립하고, 그 제어특성을 해석한다. 정상 상태 해석을 통해 회로의 주요 소자들에 대한 설계식을 유도한다. 근 궤적과 주파수 해석을 통해 II-SEPIC의 동특성 및 제어 특성을 파악하여, 적절한 제어성능을 가지는 제어기를 설계한다. 본 논문에서 제시하는 방법에 따라 설계된 II-SEPIC의 회로파라미터 및 전압제어기를 포함한 전체 제어시스템의 시뮬레이션과 실험을 수행한다. 시뮬레이션과 실험결과는 논문에서 제시한 모델링 및 제어기 설계방법의 타당성 및 유용성을 확인시켜 주고 있다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.109-114
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• 2001

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method. In the future, properly designed controller for compensation will be constructed for maximum photovoltaic power tracking control.

• 전력전자학회논문지
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• 제19권5호
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• pp.422-430
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• 2014

This study proposes a small-signal model and control design for a two-stage DC-DC-AC converter to investigate its dynamic characteristics in relation to battery energy storage system. When the circuit analysis of the two-stage DC-DC-AC converter is attempted simultaneously, the mathematical procedure of deriving the dynamic equation is complex and difficult. The main idea of modeling the two-stage DC-DC-AC converter states that this topology is separated into a bidirectional DC-DC converter and a single-phase inverter with an equivalent current source corresponding to that of the inverter or converter. The dynamic equations for the separated converter and inverter are then derived using the state-space averaging technique. The procedures of building the small-signal model of the two-stage DC-DC-AC converter are described in detail. Based on the derived small-signal model, the individual controllers are designed through a frequency-domain analysis. The simulation and experimental results verify the validity of the proposed modeling approach and controller design.

• Journal of Power Electronics
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• 제17권3호
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• pp.686-694
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• 2017

Due to the wide use of electronic products, digitally controlled DC-DC converters are attracting more and more attention in recent years. However, digital control strategies may introduce undesirable Limit Cycle Oscillation (LCO) due to quantization effects in the Analog-to-Digital Converter (ADC) and Digital Pulse Width Modulator (DPWM). This results in decreases in the quality of the output voltage and the efficiency of the system. Meanwhile, even if the resolution of the DPWM is finer than that of the ADC, LCO may still exist due to improper parameters of the digital compensator. In order to discover how LCO is generated, the state space averaging model is applied to derive equilibrium equations of a digital PID controlled DC-DC converter in this paper. Furthermore, the influences of the parameters of the digital PID compensator, and the resolutions of the ADC and DPWM on LCO are studied in detail. The amplitude together with the period of LCO as well as the corresponding PID parameters are obtained. Finally, MATLAB/Simulink simulations and FPGA verifications are carried out and no-LCO conditions are obtained.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.25-26
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• 2014

배터리를 사용하는 하이브리드 시스템의 확장으로 인하여 2차 전지를 활용할 수 있는 양방향 컨버터의 사용이 증가하고 이에 대한 연구의 필요성 또한 증가하고 있다. 기존 비절연형 단방향 컨버터는 인덕터의 전류와 부하단 캐패시터의 전압을 변수로 지정하고 고정 전원과 고정부하를 대입하여 모델링에 적용했지만, 실제 사용되는 양방향 컨버터의 동작과는 차이가 있다. 또한 이상적인 전원과는 달리 배터리의 단자전압은 SOC 및 충방전 상태에 따라 전압 변동이 일어나고 컨버터의 스위칭 동작에 의해 전압 리플이 발생하기 때문에 제어기를 설계하기 위해서는 이를 반영하여 해석하는 것이 필요하다. 본 논문에서는 비절연형 양방향 컨버터의 양쪽에 부착된 캐패시터가 모두 변수로 적용된 전달함수와 이를 이용하여 설계된 제어기를 제안한다. 컨버터 모델링에 State-Space Averaging 방법을 사용하여 양방향 컨버터의 소신호 분석을 하였고, 충전 모드와 방전 모드 일때 전달함수를 각각 구하였다. 앞서 구한 전달함수를 이용하여 pole/zero 분석을 통해 PI 제어기 설계를 하였고, 주파수 분석을 통해 안정성을 확인하였다.