• 대한전기학회논문지
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• 제38권6호
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• pp.431-440
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• 1989

This paper proposes a new PWM cycloconverter which can step up input voltage. With input reactors ac power supply acts as current source, and with output capacitors the balanced output voltage is build-up. The converter is modeled with fourth order state equation using dq transformation and the steady state characteristics are evaluated. It is shown that the proposed converter can generate the output voltage 2-5 times greater than input voltage. The output voltage and input current have sinusoidal and smooth waveforms and the converter is capable of voltage build-up. The characteristics of the proposed converter is verified simulation and experiment.

• Journal of Power Electronics
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• 제15권1호
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• pp.116-122
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• 2015

This paper presents a new current sharing control strategy for parallel-connected, synchronised three-phase DC-AC converters employing space vector pulse width modulation (SVPWM) without current sharing reactors. Unlike conventional control methods, the proposed method breaks the paths of the circulating current by dividing the switching cycle evenly between parallel connected equally rated converters. Accordingly, any inter-module reactors or circulating current control will be redundant, leading to reductions in system costs, size, and control algorithm complexity. Each converter in the new scheme employs a synchronous dq current regulator that uses only local information to attain a desired converter current. A stability analysis of the current controller is included together with a simulation of the converter and load current waveforms. Experimental results from a 2.5kVA test rig are included to verify the proposed control method.

• Journal of Power Electronics
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• 제16권3호
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• pp.1004-1011
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• 2016

The inaccurate model parameters in the predictive current control of surface-mounted permanent magnet synchronous motor (SMPMSM) affect the current dynamic response and steady-state error. This paper presents a model parameter correction algorithm based on the relationship between the errors of model parameters and the static errors of dq-axis current. In this correction algorithm, the errors of inductance and flux are corrected in two steps. Resistance is ignored. First, the proportional relations between inductance and d-axis static current errors are utilized to correct the error of model inductance. Second, the flux is corrected by utilizing the proportional relations between flux and q-axis static current errors under the condition that inductance is corrected. An experimental study with a 100 W SMPMSM is performed to validate the proposed algorithm.

• 한국전자파학회논문지
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• 제26권11호
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• pp.992-998
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• 2015

육군 항공기류의 UHF 대역 송수신기는 규격인 MIL-STD-461F Figure CE101-4를 만족해야 한다. 항공기에 장착되는 장비이므로, 소모전력 최소화 및 주파수 간섭 최소화에 중점을 두고 장비를 설계하였다. 장비 설계 후 CE101 시험을 진행하면서 문제가 발생되었던 부분은 30 Hz에서 1 kHz에서 100 dBuA 규격 이상의 신호가 발생하였고, 발생된 신호는 송수신기에서 방사되는 10 W, 20 ms 단위의 $T_{DD}$ 50 Hz 신호로 분석되었다. 규격 만족을 위해 전류변화량을 줄여야 한다는 시험 결과를 토대로 출력증폭기의 $I_{dq}$와 $I_d$ 값을 유사하게 수정하였고, 기존 설계의 소모 전력과 주파수 간섭과 크게 차이가 없게 설계 및 제작하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.231-231
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• 2000

It is proposed that a novel method which can compensate the time delay occurs in overall system, when voltage and current is measured, owing to LPF, hysteresis control inverter and microprocessor program computation time. The Proposed scheme estimates the time delay using the difference between Q-axis stator current command and time delayed Q-axis stator current in synchronous reference frame, and compensates the time delay of voltage and current using angular displacement of DQ transformation. The proposed scheme compensates accurately the time delay occurs in overall system. Therefore performance of vector control system is improved highly and it is verified by simulation and experiment.

• 전자공학회논문지B
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• 제32B권9호
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• pp.1239-1246
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• 1995

A forced commutated cycloconverter (FCC) is a direct ac-ac converter capable of providing simultaneous voltage and frequency transformations. In this paper, vector control of an induction motor controlling stator current with forced commutated cycloconverter is presented. The advantage of current control is that the stator dynamics are eliminated and high performance vector control can be achieved. A novel modulation method based on dq transformation techniques is presented. Proposed modulation strategy generates the low frequency modulation function by the instantaneous value of the desired output voltages not by the steady state values of output magnitude and output frequency. PI control and predictive control algorithm for current control are applied, and the validity of proposed method is confirmed through digital simulations. Simulation results of step response and torque distubance and current control are presented.

• Journal of Power Electronics
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• 제10권2호
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• pp.165-170
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• 2010

This paper presents a comparative study of P and PI controllers for a current source inverter (CSI) fed induction motor drive system. A dq model has been used which incorporates the induction motor and the inverter power supply with current feedback. The model is used first to generate the steady state curves to determine the operating point through computer simulations using the software package MATLAB. Then a transient analysis has been carried out for different values of the speed and current controller parameters. The controller value is adjusted by the Ziegler-Nichols method. It has been observed that the transient time to reach the steady state value is larger with the PI controller than with the P controller.

• 전력전자학회논문지
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• 제27권4호
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• pp.305-315
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• 2022

In this paper, phase current ripples and torque ripples of six-phase PM synchronous motor controlled by interleaved PWM are analyzed. The cause of the increase of phase current ripple in the interleaved PWM was mathematically analyzed based on the mutual inductance of stator windings and effective voltage vector. Simulation and experiment verified that the DQ current ripple and torque ripple can be reduced by interleaved PWM control. The FFT analysis of torque waveform confirmed that the magnitude of harmonic torque corresponding to double the PWM frequency was reduced.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.262-264
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• 1996

This paper presents a new dual loop control using novel vector phase locked loop(VP-PLL) for a high power static var compensator(SVC) with three-level GTO voltage source inverter(VSI). Through circuit DQ-transformation, a simple dq-axis equivalent circuit is obtained. From this, DC analysis is carried out to obtain maximum controllable phase angle ${\alpha}_{max}$ per unit current between the three phase source and the switching function of inverter, and AC open-loop transfer function is given. Because ${\alpha}_{max}$ becomes small in high power SVC, this paper proposes VP-PLL for more accurate $\alpha$-control. As a result, the overall control loop has dual loop structure, which consists of inner VP-PLL for synchronizing the phase angle with source and outer Q-loop for compensating reactive power of load. Finally, the validity of the proposed control method is verified through the experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.500-501
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• 2011

신재생 에너지를 계통과 효율적으로 연계하기 위해서는 일정한 DQ파형이 필요하다. 하지만 부하의 변동으로 전류가 작을 경우 노이즈의 영향으로 제어에 어려움을 겪게 된다. 따라서 본 논문에서는 효율적인 전류 제어를 하기 위해 DFT 기법을 사용하여 노이즈를 제거하고 기본파 전류 파형을 추출하여DQ 변환을 수행한다.