• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
• /
• pp.174-178
• /
• 2001

An improved stationary frame-based digital current control technique for a permanent magnet (PM) synchronous motor is presented. Generally, the stationary frame current controller is known to provide the advantage of a simple implementation. However, there are some unavoidable limitations such as a steady-state error and a phase delay in the steady-state. On the other hand, in the synchronous frame current regulator, the regulated currents are dc quantities and a zero steady-state error can be obtained through the integral control. However, the need to transform the signals between the stationary and synchronous frames makes the implementation of a synchronous frame regulator complex. Although the PI controller in the stationary frame gives a steady-state error and a phase delay, the control performance can be greatly improved by employing the exact decoupling control inputs for the back EMF, resulting in an ideal steady-state control characteristics irrespective of an operating condition as in the synchronous PI decoupling controller. However, its steady-state response may be degraded due to the inexact cancellation inputs under the parameter variations. To improve the control performance in the stationary frame, the disturbance is estimated using the time delay control. The proposed scheme is implemented on a PM synchronous motor using DSP TMS320C31 and the effectiveness is verified through the comparative simulations and experiments.

• Journal of Power Electronics
• /
• 제1권2호
• /
• pp.88-98
• /
• 2001

An improved stationary frame-based digital current control technique for a permanent magnet(PM) synchronous motor is presented. Generally, the stationary frame current controller is known to provide the advantage of a simple implementation. However, there are some unavoidable limitations such as a steady-state error and a phase delay in the steady-state. On the other hand, in the synchronous frame current regulator the regulated currents are dc quantities and a zero steady-state error can be obtained through the integral control. However, the need to transform the signals between the stationary and synchronous frames makes the implementation of a synchronous frame regulator complex. Although the PI controller in the stationary frame gives a steady-state error and a phase delay, the control performance can be greatly improved by employing the exact decoupling control inputs for the back EMF., resulting in an ideal steady-state control characteristics irrespective of an operating condition as in the synchronous PI decoupling controller. However, its steady-state response may be degraded due to the inexact cancellation inputs under the parameter variations. To improve the control performance in the stationary frame, the disturbance is estimated using the time delay control. The proposed scheme is implemented on a PM synchronous motor using DSP TMS320C31 and the effectiveness is verified through the comparative simulations and experiments.

• Journal of Power Electronics
• /
• 제8권1호
• /
• pp.91-100
• /
• 2008

The d-q harmonic detecting algorithms are dominant methods to generate current references for active power filters (APF). They are often implemented in the synchronous frame and time domain. This paper researches the frequency characteristics of d-q synchronous transformations, which are closely related to the analysis and design issues of control system. Intuitively, the synchronous transformation is explained with amplitude modulation (AM) in this paper. Then, the synchronous filter is proven to be a time-invariant and linear system, and its transfer function matrix is derived in the stationary frames. These frequency-domain models imply that the synchronous transformation has an equivalent effect of frequency transformation. It is because of this feature, the d-q method achieves band-pass characteristics with the low pass filters in the synchronous frame at run time. To simplify these analytical models, an instantaneous positive-negative sequence frame is proposed as expansion of traditional symmetrical components theory. Furthermore, the synchronous filter is compared with the traditional bind-pass filters based on these frequency-domain analytical models. The d-q harmonic detection methods are also improved to eliminate the inherent coupling effect of synchronous transformation. Typical examples are given to verify previous analysis and comparison. Simulation and experimental results are also provided for verification.

• Journal of Electrical Engineering and Technology
• /
• 제11권2호
• /
• pp.405-415
• /
• 2016

This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집
• /
• pp.1951-1958
• /
• 2009

This paper presents a synchronous-rotating-frame-based control of single-phase UPQC(Unified Power Quality Conditioner) to improve power quality in ac electrified railway systems. The simulation results show that the UPQC can compensate the harmonic supply voltages, the harmonic load currents, and the reactive power in electrified railway systems. Validity of the proposed UPQC control method based on the synchronous rotating frame is illustrated through the simulation results.

• 전력전자학회논문지
• /
• 제21권3호
• /
• pp.215-223
• /
• 2016

In this study, a novel rotor position sensorless estimation method of an interior permanent-magnet synchronous motor is proposed. A square-wave pulsating voltage signal is injected in the estimated synchronous reference frame. This signal is interpreted in the stationary reference frame regardless of the estimated rotor position. Thus, assuming that the position error is nearly zero is unnecessary because the variables in the estimated synchronous reference frame are not used. The rotor position can be exactly calculated from two voltage references and three sampled current feedbacks in the stationary reference frame. The proposed method is easy to implement and helps enhance the bandwidth of the current controller. The validity of the proposed method is verified by simulations and experiments.

• 한국통신학회논문지
• /
• 제30권12B
• /
• pp.838-846
• /
• 2005

본 논문은 동기식 이더넷 시스템의 구현 시 고려해야 할 다음과 같은 두 가지의 사항에 대한 해결방안을 제시한 것이다. 첫째, 실시간 및 비실시간 트래픽을 모두 지원하기 위하여 일정주기의 사이클 기반으로 동작하는 동기식 이더넷 시스템은 이미 송신이 진행 중인 비실시간 프레임 때문에, 사이클의 시작 시점이 지연됨으로서 실시간 트래픽의 전송이 지연되는 문제점을 가지고 있다. 이 점에 착안하여, 기존 방식의 지터 성능을 분석한 후, 다음 사이클의 시작 시점을 참조하여 비실시간 프레임을 여러 사이클에 분할하여 전송함으로써 실시간 트래픽에 대하여 지터가 전혀 없는 엄격한 전송을 보장하는 방법을 제안하고, 또 다른 지터 억제 방식인 전송보류(hold) 방식과의 프레임 전송지연 특성을 비교 분석하였다. 두 번째는 한 사이클 내의 실시간 트래픽 전송 구간에는 비실시간 프레임을 전승할 수 없기 때문에, 신속히 송신되어야 할 링크 계층에서의 흐름제어용 IEEE 802.3x 중지(pause) 프레임의 전송이 지연됨으로써 과도한 비실시간 프레임의 손실을 초래하는 문제점이 있다. 이 점에 착안하여 실시간 트래픽 전송 구간에서도 흐름제어용 프레임의 전송을 허용하도록 하는 새로운 흐름제어 방법을 제안하고 이에 따른 비실시간 트래픽의 손실률을 분석하였다.

• ETRI Journal
• /
• 제37권4호
• /
• pp.657-666
• /
• 2015

We propose a two-stage resource allocation algorithm for the high link utilization of an orthogonal frequency-division multiplexing passive optical network (OFDM-PON). An OFDM-PON is assumed to use a synchronous frame structure in supporting service differentiation. In distributing resources, the proposed algorithm first allocates a time window for each optical network unit (ONU), and then it arranges a subchannel, which is a group of subcarriers. This algorithm needs to satisfy two constraints. First, computations for the resource allocation should be done using a frame unit. Second, an ONU has to use a single subchannel to send upstream data for multiple services within a frame duration. We show through a computer simulation that the proposed algorithm improves the link utilization.

• 전력전자학회논문지
• /
• 제25권6호
• /
• pp.477-483
• /
• 2020

This study proposes a DQ synchronous reference frame model of a series-parallel tuned inductive power transfer (SP-IPT) system. The wireless power transmission system experiences control difficulty because the transmitter-side controller cannot directly measure the receiver-side load voltages and currents. Therefore, a control-oriented circuit model that shows the dynamics of the IPT system is required to achieve a well-behaved controller. In this study, an equivalent circuit model of the SP-IPT system in a synchronously rotating reference frame is proposed using the single-phase DQ transformation technique. The proposed circuit model is helpful in modeling the dynamics of the voltages and currents of the transmitter- and receiver-side resonant tanks and loads. The proposed circuit model is evaluated using frequency- and time-domain simulation results.

• 한국철도학회논문집
• /
• 제12권5호
• /
• pp.694-699
• /
• 2009

교류 전기철도 급전시스템의 전압, 전류의 왜곡 및 전압 sag과 무효전력을 보상하기 위한 단상 UPQC의 동기좌표계를 이용한 제어 방법을 제안한다. 단상 UPQC의 동기좌표계를 이용한 제어를 통해 단상인버터 형태인 UPQC의 직렬보상기와 병렬보상기를 순시적으로 제어한다. 시뮬레이션을 통해 단상 UPQC를 이용하여 비선형 단상 부하인 차량으로 인해 급전시스템에 생길 수 있는 전압, 전류의 왜곡 및 전압 sag과 무효전력의 보상이 가능함을 증명하고, 단상 UPQC의 동기좌표계를 이용한 제어 방법이 타당함을 확인한다.