• 전력전자학회논문지
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• 제20권4호
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• pp.356-362
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• 2015

This paper presents a current control strategy in the synchronous reference frame for a single-phase PWM converter, which ensures sinusoidal input current control under the distorted source voltage and frequency condition. Given that the distorted source voltage distorts the phase angle for PWM converter control, the input current contains the same harmonics as the source voltage. Aside from the distorted voltage, the variation in source frequency reduces the performance of input current control. To achieve sinusoidal input current control under the distorted source voltage and frequency condition, this paper proposes a compensation strategy of current reference with the distortion component extracted from the phase angle and a detection strategy of frequency variation from the output of a synchronous reference frame phase-lock loop. The experimental results confirm the validity of the proposed method under the distorted source voltage and frequency condition.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1746-1752
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• 2014

This paper presents an application of proportional-resonant (PR) current controllers in modular multilevel converter-high voltage direct current (MMC-HVDC) system under unbalanced voltage conditions. The ac currents are transformed and controlled in the stationary reference frame (${\alpha}{\beta}$-frame). Thus, the complex analysis of the positive and negative sequence components in the synchronous rotating reference frame (dq-frame) is not necessary. With this control method, the ac currents are kept balanced and the dc-link voltage is constant under the unbalanced voltage fault conditions. The simulation results based on a detailed PSCAD/EMTDC model confirm the effectiveness of the proposed control method.

• 전력전자학회논문지
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• 제20권6호
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• pp.517-525
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• 2015

A grid connected inverter must be operated as the main electricity source under an isolated condition caused by the grid problem. Conventionally, the dual loop controller is used for the grid inverter, and the controller is used for control under the stand-alone mode. Generally, the PI(Proportional - Integral) controller is highly efficient under a synchronous reference frame, and stable control can be available. However, in this synchronous frame-based control, high-quality DSP is required because many sinusoidal calculations are necessary. When the PI control is conducted under a stationary frame, the controller constructions are made simple so that they work even with a low-price micro controller. However, given the characteristics of the PI controller, it should be designed with the phase of reference voltage considered. Otherwise, the phase delay of the output voltage can occur. Although the current controller also has a higher bandwidth than the voltage controller, distortion of the voltage is difficult to avoid only by the rapid response of the PI controller, as a sudden load change can occur in the nonlinear load. In this study, a new control method that solves the voltage controller bandwidth problem and rapidly copes with it even in the nonlinear load situation is proposed. The validity of the proposed method is proved by simulation and experimental results.

• Journal of Power Electronics
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• 제8권4호
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• pp.317-324
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• 2008

This paper proposes a Multiband Shunt Hybrid Active Filter (SHAF) with sensorless control. A plant is modeled in the discrete- time domain and a controller is designed using the Pole shifting law in the polynomial domain. This control approach is very useful for filtering the load harmonics with reduced sensor counts where a low cost solution like SHAF is required. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure the $5^{th}$ and $7^{th}$ harmonic components separately from the load and filter currents. Individual current controllers are designed for the $5^{th}$ and $7^{th}$ harmonic currents. Control is realized in the stationary, three-phase (abc) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models, as well as experimentally on a full-scale distribution system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.411-412
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• 2020

본 논문은 단상 영구자석 동기 전동기의 센서리스 제어방법을 제안한다. 단상 전류와 그에 직교하는 가상의 전류성분을 이용하여 dq 회전 좌표계에서 전류제어를 하고, d축 전류제어기의 출력을 이용하여 회전각을 추정한다. 제안된 방법은 구현이 매우 간단하다는 장점이 있다. 실험을 통해 제안된 방법의 성능을 확인하였다.

• 전자공학회논문지
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• 제51권6호
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• pp.271-275
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• 2014

회전하는 동기 좌표계 d-q 변환을 이용한 단상 능동 전력 필터의 새로운 제어기를 제안하였다. 힐버트 변환기를 사용하여 $90{\circ}$의 위상차를 가지는 두 개의 교류 신호를 만든다. 이 신호들을 회전하는 동기 좌표계 d-q 변환을 이용하여 기본파 성분을 직류로 변환할 수 있고 따라서 고조파 검출이 용이하다. 순시 유효 전력의 평균값을 구한다. 역률 보상을 하므로 전원 전류는 전원 전압과 동위상이다. 단상에서의 전력 공식으로부터 전원 전류의 크기를 알 수 있다. 능동 전력 필터의 보상 전류의 기준 신호는 전원 전류의 기준신호에서 부하 전류를 빼주면 구할 수 있다. 새롭게 제안된 제어기에 히스테리시스 전류 제어기를 적용하여 시뮬레이션 하였다. 능동 전력 필터가 부하전류의 고조파와 무효전력을 보상하여 전원 전류가 전원전압과 동위상이 되고 전원전류가 정현파에 가깝게 되는 것을 확인하였다. 힐버트 변환기는 전대역 여파기를 사용하여 구현하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.245-248
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• 2000

In this paper a novel method for voltage disturbance detection is presented. This is a instantaneous detection method using normalized error get in synchronous reference frame and also it is implemented in digital. Feedback noise the problem of digital implementation is removed by a digital filter of which the time delay is compensated through numerical analysis.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.532-540
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• 2014

It is necessary to measure the current of rotor for controlling the active and reactive power generated by the stator side of the doubly fed induction generator (DFIG) system. There are offset and scaling errors in the current measurement. The offset and scaling errors cause one and two times current ripples of slip frequency in the synchronous reference frame of vector control, respectively. This paper proposes a compensation method to reduce their ripples. The stator current is variable according to the wind force but the rotor current is almost constant. Therefore input of the rotor current is more useful for a compensation method. The proposed method adopts the synchronous d-axis current of the rotor as the input signal for compensation. The ripples of the measurement errors can be calculated by integrating the synchronous d-axis stator current. The calculated errors are added to the reference current of rotor as input of the current regulator, then the ripples are reduced. Experimental results show the effectiveness of the proposed method.

• Journal of Power Electronics
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• 제2권1호
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• pp.55-66
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• 2002

A new on-line dead-time compensation method for a permanent magnet (PM) synchronous motor drive is proposed. Using a simple disturbance observer without any additional circuit and off-line experimental measurement, disturbance voltages in the synchronous reference dq frame caused by the dead time and non-ideal switching characteristics of power devices are estimated in an on-line manner and fed to voltage references in order to compensate the dead-time effects. The proposed method is applied to a PM synchronous motor drive system and implemented by using software of a digital signal processor (DSP) TMS320C31. Simulations and experiments are carried out for this system and the results well demonstrate the effectiveness of the proposed method.

• 전력전자학회논문지
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• 제22권6호
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• pp.543-546
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• 2017

This paper presents a simple approach for improving the performance of back-electromotive force (back-EMF)-estimation-based sensorless drives for surface-mounted permanent magnet synchronous motors (SPMSM). Similar to conventional approaches, a hypothetical d-q synchronous reference frame model of SPMSM is employed in the proposed approach to estimate the back-EMFs. This approach also employs a dual phase locked loop structure to compensate for the effect of the dead time and parameter uncertainty of the inverter on the estimated back-EMFs. The proposed algorithm is validated by conducting experiments.