복소 벡터 동기좌표계 비례 적분 전류 제어기의 안티 와인드업 이득 설정

유현재,정유석,설승기 전력전자학회 2006 전력전자학회 논문지 Vol.11 No.5

This paper presents an anti-windup gain selection method for a complex vector synchronous frame PI current controller. The complex vector PI current controller is more robust to the parameter variation than the state feedback decoupling PI current controller. The complex vector PI current controller also includes an integral term, which can results in windup problem when the controller is saturated due to physical limitation of the system. Furthermore, even an anti-windup is utilized, inappropriate gain can deteriorate the performance of the current controller. Therefore, appropriate anti-windup gain selection method for a complex vector current controller has been proposed based on the mathematical description of the current control system. The superior performance of the current control system with the proposed anti-windup gain has been verified by the experimental results. 본 논문에서는 복소 벡터 동기 좌표계 비례 적분(PI) 전류 제어기의 안티 와인드업(anti-windup)이득 설정에 대해 논의한다. 복소 벡터 동기 좌표계 비례 적분 전류 제어기는 시스템 제정수 변동에 기존의 비례 적분 전류 제어기 보다 더 강인한 특성을 보인다. 복소 벡터 전류 제어기 역시 적분기를 포함하고 있으며, 엑츄에이터(actuator)의 물리적인 한계로 전압이 포화되는 경우에는 안티 와인드업이 필요하게 되고, 적절치 못한 안티 와인드업 이득 설정은 제어 시스템의 동특성을 저하시킬 수 있다. 따라서 복소 벡터 동기 좌표계 비례 적분 전류 제어기에 적합한 안티 와인드업 이득을 제안하였고, 제안된 알고리즘의 유효성은 실험을 통하여 검증하였다.

Research on a Multi-Objective Control Strategy for Current-source PWM Rectifiers under Unbalanced and Harmonic Grid Voltage Conditions

Geng, Yi-Wen,Liu, Hai-Wei,Deng, Ren-Xiong,Tian, Fang-Fang,Bai, Hao-Feng,Wang, Kai The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current $2^{nd}$ order fluctuations, and 3) elimination of the DC-current $2^{nd}$ and $6^{th}$ order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

Research on a Multi-Objective Control Strategy for Current-source PWM Rectifiers under Unbalanced and Harmonic Grid Voltage Conditions

Yi-Wen Geng,Hai-Wei Liu,Ren-Xiong Deng,Fang-Fang Tian,Hao-Feng Bai,Kai Wang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, 5th and 7th order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current 2nd order fluctuations, and 3) elimination of the DC-current 2nd and 6th order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, 5th and 7th order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

Improved Deadbeat Current Controller with a Repetitive-Control-Based Observer for PWM Rectifiers

Jilei Gao,Trillion Q. Zheng,Fei Lin 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.1

The stability of PWM rectifiers with a deadbeat current controller is seriously influenced by computation time delays and lowpass filters inserted into the current-sampling circuit. Predictive current control is often adopted to solve this problem. However, grid current predictive precision is affected by many factors such as grid voltage estimated errors, plant model mismatches, dead time and so on. In addition, the predictive current error aggravates the grid current distortion. To improve the grid current predictive precision, an improved deadbeat current controller with a repetitive-control-based observer to predict the grid current is proposed in this paper. The design principle of the proposed observer is given and its stability is discussed. The predictive performance of the observer is also analyzed in the frequency domain. It is shown that the grid predictive error can be decreased with the proposed method in the related bode diagrams. Experimental results show that the proposed method can minimize the current predictive error, improve the current loop robustness and reduce the grid current THD of PWM rectifiers.

Y 결선된 7상 BLDC 전동기의 구형파 전류 제어를 위한 새로운 전류 제어방식에 관한 연구

문종주(Jong-Joo Moon),이원(Won Lee),김장목(Jang-Mok Kim) 대한전기학회 2016 전기학회논문지 Vol.65 No.4

The current control methods of Y-connected 7 Phase BLDC motor are sine wave current control and square wave control. The sine wave current control method needs dq axis transformation of 7x7 matrix for current control and very complex. Also this method is not suitable for multi Phase BLDC motor of trapezoidal back emf wave. Therefore, in Y connected multi phase BLDC motor, the square wave current control methods are required. Generally, in the 3Phase BLDC system, Average current control method is used for current control. The average current is obtained that the summation of absolute value of each phase current magnitude is divided by the number of conduction phase. However, if average current control method is applied to multi-phase system, there is a problem that each phase currents are different. This problem affects unbalance of each phase torque and fluctuation of total torque. This paper proposed each phase current control method of Y connected 7Phase BLDC system. Proposed method is used for PI controller of each phase for each phase current control. This method can perfect square wave current control. Also, configuration of the method is easier than DQ axis transformation. Proposed method is verified through simulation and experiments.

Predictive current controller and compensator‑based discrete current controller for single‑phase bridge inverters

Jinghua Zhou,Shuang Xu,Riming Shao,Liuchen Chang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9

Transfer efficiency and power quality are two critical factors when it comes to grid-connected distributed generation systems. Single-phase inverters are commonly used in distributed generation systems under 10 kilowatts as the connection between the gird and renewable energy sources (RESs). In this application, grid current distortion plays a pivotal role in determining inverter performance. In this article, an improved current control strategy based on a predictive current controller (PCC) and a compensator is presented to decrease current harmonic distortion and increase power quality. The controller design method inspects a single-phase inverter system as a digital platform, and designs the controller in discrete time in order to obtain a more precise and effective controller than that in continuous time. The discretization procedures using sampling and hold (S&H) are taken into consideration in the design process. The improved current controller is a DSP-based digital current controller for grid-connected single-phase bridge inverters, whose performance is optimized by considering the time delay caused by analog–digital conversion (ADC) and computations. A comparison has been made to analyze the performance of the single-phase grid-connected inverter system with PCC and ICC. Experimental results are shown to validate the effectiveness of the designed current controller.

트랙터 전후진 자동변속기용 비례 제어 밸브의 전류 제어 모델 개발

안다빈,김경대,유지훈,김수철,이진웅,박영준 경상국립대학교 농업생명과학연구원 2020 농업생명과학연구 Vol.54 No.3

본 연구의 목적은 전후진 자동변속기가 장착된 트랙터의 변속 충격을 모사하기 위한 시뮬레이션 모델에 적용될 비례 제어 밸브의 전류 제어 모델을개발하는 것이다. 전류 제어 모델을 개발하기 위하여 시험 장치를 구성하여 밸브의 정특성 시험과 계단 응답 시험을 수행하였으며, 시험 결과를 토대로전류 제어 모델을 검증하였다. 비례 제어 밸브의 전류 제어 모델은 밸브의 전류-압력 선도, PID 제어기, 펄스폭변조 신호 발생기와 밸브 모델로구성하였다. 전류 제어 모델에 사용된 데이터는 시험을 통하여 도출된 값과 대상 트랙터에 적용된 값을 사용하였다. 전류 제어 모델 검증을 위해계단 입력 신호에 대하여 전류 특성 시험을 수행하였고, 실제 전류 시험 결과와 시뮬레이션 결과를 비교하였다. 시험 결과와 시뮬레이션 결과에 대한전류 특성을 비교해 보면, 상승 시간 오차는 0.0074초, 첨두치 시간의 오차는 0.0065초, 오버슈트 오차는 0.06%로 나타났다. 따라서 개발된 비례제어 밸브의 전류 제어 모델은 실제 제어기의 전류 제어 특성을 제대로 반영할 수 있으며, 추후 변속 충격 모사를 위한 트랙터 시뮬레이션 모델에서비례 제어 밸브의 전류 제어 모델로 사용될 수 있을 것으로 판단된다. This study has developed the current control model for proportional control valve (PCV) to be applied in simulation models for simulating the shift impact of tractor with power shuttle transmission. In order to develop the current control model, the test equipment was constructed to perform a static characteristic test and step response test of the PCV, and compared to the simulation results using current control model to validate the model. The current control model of the proportional control valve consists of the current-pressure curve of the PCV, PID controller, pulse width modulation signal generator and PCV model. The data used in the current control model were derived from the test and used values applied to the target tractor. The current characteristics test was performed on the step input signal, and the actual current test results were compared the simulation results to validate the current control model. The rise time error was 0.0074 seconds, the peak time error was 0.0065 seconds, and the overshoot error was 0.06%. Thus, the PCV current control model developed in this study can be confidently used to predict the current control characteristics of the actual controller, and it can be used as a current control model of the PCV in a tractor simulation model for simulating the shift impact in the future.

단상 부스트 PFC 컨버터의 제어 기법 리뷰: 평균 전류 모드 제어, 예측 전류 모드 제어 및 모델 기반 예측 전류 제어

고현준(Hyeon-Joon Ko),최영준(Yeong-Jun Choi) 한국컴퓨터정보학회 2023 韓國컴퓨터情報學會論文誌 Vol.28 No.12

부스트 PFC (Power Factor Correction)컨버터는 AC 입력 전류의 단일 역률과 낮은 THD (Total Harmonic Distortion)를 달성하기 위해 다양한 제어기법들이 연구되고 있다. 그중 인덕터 전류의 평균값을 전류지령에 추종하도록 제어하는 평균전류 모드 제어가 있으며 가장 널리 사용되고 있다. 하지만, 오늘날 디지털 프로세서의 발달로 고도화된 디지털 제어가 가능해지면서 부스트 PFC 컨버터의 예측제어가 관심을 받고 있다. 예측제어에는 예측 알고리즘으로 듀티를 미리 생성하는 예측전류 모드 제어 및 모델을 기반으로 한 비용함수를 선정하여 스위칭 동작을 하는 모델예측제어로 분류된다. 따라서 본 논문에서는 부스트 PFC 컨버터의 평균전류 모드 제어, 예측전류 모드 제어, 모델예측 전류 제어를 간단히 설명한다. 또한, 시뮬레이션을 통해 전체 부하 및 다양한 외란 조건에서의 전류 제어를 비교 분석한다. For boost PFC (Power Factor Correction) converters, various control methods are being studied to achieve unity power factor and low THD (Total Harmonic Distortion) of AC input current. Among them, average current mode control, which controls the average value of the inductor current to follow the current reference, is the most widely used. However, nowadays, as advanced digital control becomes possible with the development of digital processors, predictive control of boost PFC converters is receiving attention. Predictive control is classified into predictive current mode control, which generates duty in advance using a predictive algorithm, and model predictive current control, which performs switching operations by selecting a cost function based on a model. Therefore, this paper simply explains the average current mode control, predictive current mode control, and model predictive current control of the boost PFC converter. In addition, current control under entire load and disturbance conditions is compared and analyzed through simulation.

Current Decoupling Scheme of Three-Phase Inverter with Complex Coefficient Controller

Zheng Xinxin,Xu Jianjun,Shi Jingkui,Huang Wenxin,Li Qiyue 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

In the control of three-phase system, AC signals are always changed into DC signals by synchronous coordinate transformation. A decoupling control scheme in the dq synchronous reference frame (SRF) is proposed to realize active and reactive current decoupling of three-phase inverter. The complex vector control model is established in SRF. Diff erent from the model established in static reference frame, the SRF control model can refl ect the coupling characteristic of the active and reactive current. As a result, the PI controller with complex coeffi cient can be applied to realize current decoupling. In this paper, the coupling characteristic of three-phase system is analyzed. A novel complex PI controller design method is proposed based on the SRF control model and the coeffi cients are calculated. And its implementation in the control loop is given. Compared with existing PI controllers with real or complex coeffi cients, the proposed complex PI controller can realize completely the decoupling of the active and reactive current in three-phase system. Besides, the control scheme can make current loop fulfi ll the expected symmetrical bandwidth, so as to realize a higher eff ective set-off frequency. As a result, the inverter can achieve well dynamic performance. Finally, the simulation and experimental results are given to verify the theoretical analysis.

Current Harmonics Rejection and Improvement of Inverter-Side Current Control for the LCL Filters in Grid-Connected Applications

Jinming Xu,Shaojun Xie,Binfeng Zhang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

For grid-connected LCL-filtered inverters, the inverter-side current can be used as the control object with one current sensor for both LCL resonance damping and over-current protection, while the grid-voltage feedforward or harmonic resonant compensator is used for suppressing low-order grid current harmonics. However, it was found that the grid current harmonics were high and often beyond the standard limitations with this control. The limitations of the inverter-side current control in suppressing low-order grid current harmonics are analyzed through inverter output impedance modeling. No matter which compensator is used, the maximum magnitudes of the inverter output impedance at lower frequencies are closely related to the LCL parameters and are decreased by increasing the control delay. Then, to improve the grid current quality without complicating the control or design, this study proposes designing the filter capacitance considering the current harmonic constraint and using a PWM mode with a short control delay. Test results have confirmed the limitation and verified the performance of the improved approaches.