• 조명전기설비학회논문지
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• 제14권3호
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• pp.29-37
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• 2000

본 논문에서는 TMS320C32 DSP를 사용하여 저속에서 구동되는 반송용 펀측식 전행 유도전동기의 슬립 각 주파수에 의한 벡터제어를 이용하여 추력제어하였다. 먼저, 반송용 편촉식 선형 유도전동기를 설계 및 제작하고, 이를 해석하였다. 저속에서 제풍의 운반시에 안정성있은 구동올 위해서 벡터제어에 의한 추력제어를 하였고, 정위치 제어를 하기 워해서 Ziegles- Nichols법을 이용하여 PiD제어기를 설계하였다. 저속에셔의 종량부하흘 갖는 반송용 선형기기에서 PID제어기에 추력제어가 가능한 벡터제어기법을 부가한 결과는 제품외 운반시에 안정성있는 구동을 하였으며, 정위치제어를 위한빠른 응답특쟁 및 soft start/stop을 이루었으며, 부하 변동시에도 제동시에 정위치제어를 위한 빠른 응탑 특성의 결과를 얻었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.95-97
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• 2018

The power quality of Single Phase Grid-Connected Inverters (GCIs) has received much attention with the increasing number of Distributed Generation (DG) systems. However, the performance of single phase GCIs get degraded due to several factors such as the grid voltage harmonics, the dead time effect, and the turn ON/OFF of the switches, which causes the harmonics at the output of GCIs. Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. To meet the harmonic standards a certain kind of harmonic controller needs to be added to the current control loop to effectively mitigate the low order harmonics. In this paper, the harmonic compensation is performed using a novel robust harmonic compensation method based on Digital Lock-in Amplifier (DLA). In the proposed technique, DLAs are used to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in the feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity, and implementation. The validity of the proposed harmonic compensation techniques for the single phase GCIs is verified through the experimental results with a 5kW single phase GCI. Index Terms -Single Phase Grid Connected Inverter (SPGCI), Harmonic Compensation Method, Total Harmonic Distortion (THD) and Harmonic Standard.

• 전력전자학회논문지
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• 제4권4호
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• pp.349-356
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• 1999

본 논문에서는 철도차량용 보조전원장치에 순시전압제어기법을 적용할 때 발생하는 문제들의 해결방안을 제시한다. 비선형부하나 과도상태에서 빠른 응답특성을 얻기 위해 순시전압제어기법을 사용할 때 LC 필터의 공진문제와 존재하는 정상상태 오차가 더욱 심각해진다. 인버터 출력측 LC 필터에 기인하는 공진현상을 억제하기 위해 전압전달함수의 제동비를 증가시키기 위한 방안으로 필터 커패시터 궤환제어기가 고려되었다. 그리고 교류전압 순시제어시 존재하는 정상상태 오차를 제거하기 위하여 고이득 전달함수를 기존의 PI 제어기에 첨가하였다. 이론적인 분석이 시뮬레이션 결과와 함께 잘 설명되어져 있다. 제안된 기법의 타당성을 5kVA급 시제품에 대한 시뮬레이션과 실험을 통하여 입증하였다.

• 전력전자학회논문지
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• 제7권2호
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• pp.205-213
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• 2002

본 논문에서는 직류모선에서 교류모선으로 회생되는 전력을 제어할 수 있는 3상 전압원 인버터 시스템을 구현하였다. 전체 시스템은 선간접압 및 선전류용 센서, d-q 변환방식을 사용한 실제전력 연산기. PI제어기법을 적용한 복소전력 제어기, 수정 ｑ도통방식을 구현하기 위한 게이팅신호 생성기, 주파수를 추종하기 위한 DPLL과 전력회로로 구성된다. 제어보드는 32비트 DSP인 TMS32C32, EFLD 2개, ACD 6개와 DAC로 구성하였다. 제안한 시스템의 성능을 검증하기 위해 교류 220V에서 5kVA 전력용량인 축소모델을 설계, 제작하였다. 실험결과, 회생 유효전력은 명령값으로 잘 제어되며 회생 무효전력은 운전동안 내내 거의 0의 값을 유지함을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제3권3호
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• pp.391-400
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• 2008

Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse ($6{\times}8$ pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the ${\pm}80MVAR$ compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse ${\pm}100MVAR$ STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.

• Journal of Power Electronics
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• 제13권3호
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• pp.369-380
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• 2013

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

• 전력전자학회논문지
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• 제12권1호
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• pp.65-73
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• 2007

본 논문은 1-Hz의 낮은 고정자 전류 주파수에서도 동작하는 순수적분 기반의 자속추정을 위한 온라인 전류측정 오차 보상방법을 제안한다. 오프셋 전류와 변환이득오차에 의한 역상분 전류 성분은 상태관측기를 이용하여 제거하고, 동시에 변환이득오차에 의한 역상분 전류는 동기좌표계에서 영구자석에 의하여 발생된 q축 자속을 기준모델에 의한 값과 추정된 자속에 의한 값 사이의 차이에 의하여 보상한다. 이 보상기는 PI제어기를 이용하여 두 값 사이의 오차가 0이 되도록 제어한다. 또한 적분기 초기값 오차 및 관측기의 전동기 상수 오차에 의한 잔여오차 보상방법도 제안하였다. 타당성을 입증하기 위하여 1.1-kW 영구자석형 동기전동기(PMSM)에 제안된 보상 방법을 구현하여 다양한 실험을 수행하였다.

• 전력전자학회논문지
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• 제21권5호
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• pp.396-403
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• 2016

Usually, large-sized buses and trucks have a very high load. In addition, frequent braking during downhill or long-distance driving, causes the conventional method using the brake friction to have a problem in safety because of brake fade and brake burst phenomenon. Auxiliary brakes dividing the braking load is essential. Hence, environment-friendly auxiliary brakes, such as contactless brake rather than the engine auxiliary brake system are needed. A study aimed at improving the energy efficiency by recharging electric energy with changing mechanical to electrical energy that occurs when braking is actively in progress. In this paper, the voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, the resonant L-C circuit is configured in the retarder. The voltage generated in the retarder is simply modeled as a transformer. However, retarder voltage control in this paper is simulated by modeling the induction generator because this induction generator modeling is more practical than transformer modeling. The changes in the voltage of the resonance circuit, which depends on the switch pulse duration of the control device, were analyzed. A PI controller algorithm to control this voltage is proposed. The feasibility of modeling retarder and voltage controller are shown by using MATLAB Simulink in this paper.

• 대한전기학회논문지
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• 제35권12호
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• pp.541-554
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• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.457-461
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• 2001

Advantages of switched reluctance motor(SRM) drives make it an attractive candidate for replacing adjustable speed ac and dc drives in both industrial and consumer applications. Furthermore, a simple, low cost and robust SRM drive can be efficiently operated in the hostile environment of an automobile. Generally, the speed control of SRM has a large step change or large torque reference, the output of its PI controller is often saturated. When this happens, the integral state is not consistent with the SRM input, while may give rise to the windup phenomenon. This paper proposes anti-windup control method for SRM speed control system by hysteresis current controlled asymmetry bridge converter. The experimental results show that the speed response has much improved performance, such as a small overshoot and fast settling time at the acceleration and particulary deceleration period with braking mode.