A Current Harmonics Detection Method Based on Input Observer Theory

基于输入观测器理论,对电流谐波在线检测问题进行了研究,得到了一种能够快速准确地提取电流信号中各频率分量的方法。首先,将被测电流信号和其各频率的分量作为状态量,构建线性时变的状态空间模型。然后,设计基于状态空间模型的观测器对未知状态变量进行在线观测,从而实现各频率分量的信息提取。所设计的观测器是时变的,其稳定性和收敛性由Lyapunov定理及Lasalle不变集原理所证明。最后,搭建仿真和实验平台对该方法进行验证,结果表明其具备检测速度快、精度高、动态跟踪性能和抗干扰性好等优点。Based on the input observer theory,the online current harmonics detection method is proposed,which can detect all the frequency components within the current signal accurately and rapidly. Firstly,by setting the state variables as the value and each frequency component of the measured current,a linear time-varying state space model is established. Then,based on the proposed model,a time-varying observer is constructed to estimate the unknown states in order to achieve the extraction of each frequency component. The stability and convergence of the observer are proved by the Lyapunov theorem and the Lasalle invariant set principle. Finally,the simulation and experimental results show that the proposed method has advantages in detection speed,accuracy,dynamic tracking performance,and robustness.中央高校基本科研业务费资助项目(20720150088

A Novel Method of Space Vector Pulse Width Modulation With Constraints

为解决传统调制方法中的最小脉宽问题,提出了一种带约束的电压空间矢量脉宽调制(SPACE VECTOr PulSE WIdTH MOdulATIOn,SVPWM)方法。首先,建立新的三相桥臂坐标,取消了扇区的划分和判断;其次,将基本电压空间矢量由8个减小为3个,并将其作用时间与三相桥臂的导通时间一一对应;再次,通过增加约束条件,将传统SVPWM方法的调制过程及其结果离散化,从而避免了窄脉宽的出现;最后,给出了一种快速的计算策略,其计算量仅与SVPWM方法一个扇区的计算量基本相同。相对于SVPWM方法,所提方法调制的基波与杂波在频谱上的分布更清晰,低次谐波较少,有利于进行低通滤波处理,更适合较高电压和较大电流的逆变要求。仿真及实验结果均验证了该方法的可行性。To solve the problem of the minimum pulse width in traditional modulation methods, a space vector pulse width modulation(SVPWM) method with constraints is proposed.Firstly, a three-phase bridge-arm coordinate is established to cancel the traditional sector division and the judgment; secondly, the number of basic voltage space vectors is reduced from 8 to 3, and their actuation durations correspond to the on-times of three-phase bridge-arms respectively; thirdly, by means of adding constraint conditions the modulation process of traditional SVPWM and modulation results are discretized to prevent the appearance of narrow pulse width; finally a fast computational strategy is given and its calculated amount is basically same as to the calculated amount for one sector by SVPWM method.Relative to SVPWM method, the distribution of the fundamental wave and clutters modulated by the proposed method on the frequency spectrum is more clear and there are less low-order harmonics, so it is favorable to implement low-pass filtering, thus the proposed method is more suitable for PV inverters with higher voltage and larger current.The feasibility of the proposed method is verified by results of simulation and experiments.国家自然科学基金(51177141); 中央高校基本科研业务费专项资金资助项目(0620ZK1007); 福建省自然科学基金(2010J01310)~

基于真空继电器的选相分合闸控制系统的设计与实现

为减少电力系统中断路器投切开关的分闸燃弧和合闸涌流,设计了一种永磁机构断路器的选相分合闸控制系统.系统通过真空继电器的二级驱动方式保证了机械动作时间可控且离散性小,解决了单级接触器驱动方式的机械动作时间离散性大和单级晶闸管驱动方式的驱动电路复杂性的问题.系统以STM32单片机为控制核心,通过电流突变捕捉时刻算法准确捕捉到分合闸动作完成时刻,进而计算出上一次的分合闸机械动作过程时间,预测出下一次的分合闸机械动作时刻,实现了控制系统根据设定的分合闸相角对断路器准确地进行分相投切控制的功能.控制系统在35kV永磁机构断路器上进行了实验,结果表明分合闸相角最大误差在±3°以内,达到了选相分合闸的精度要求.福建省科技计划项目(2016H6022

Voltage tracking modulation method using FCS-MPC

提出了一种利用有限集模型预测控制(fCS-MPC)策略的电压跟踪调制新方法,不使用常规策略中的基本电压矢量,而是直接将桥臂功率器件的开关时间作为主要控制量。通过一个开关时间约束条件,将控制模型转换为约束优化问题,并在此特殊的约束下,控制模型的解满足“有限集“条件。以期望的连续电压矢量为预测模型的控制目标,电压控制误差为价值函数,该优化问题可通过fCS-MPC策略进行求解,得到电压跟踪调制结果。该跟踪调制方法的调制度可达到1,其PWM输出的总谐波畸变率显著减小。仿真和实验结果验证了所提方法的有效性和正确性。A method of voltage tracking modulation based on FCS-MPC(Finite Control Set-Model Predictive Control) strategy is proposed,which directly takes the acting time of bridge-arm power component,instead of the basic voltage vector of conventional strategy,as the main control variable.A constraint condition is defined for the acting time to transfer the control model into the constrained optimization and in this special constraint condition,the solutions of the model become a "finite control set".The FCS-MPC strategy with the expected continuous voltage vectors as the control objective of prediction model and the voltage control error as the evaluation function is applied to solve the optimization problem for achieving the results of voltage tracking modulation.Its modulation index is up to 1 and the THD of its PWM output is greatly reduced.Its feasibility and correctness are verified by the simulative and experimental results.国家自然科学基金资助项目(51177141); 中央高校基本科研业务费专项资金资助项目(2010121041); 航空基金资助项目(2012-ZD68003)~

Individual air-fuel ratio balancing control for multi-cylinder si engines: Modeling and validation

Conference Name:18th IFAC World Congress. Conference Address: Milano, Italy. Time:August 28, 2011 - September 2, 2011.The three phase catalyst is popularly employed in modern engines for exhaust control and its catalytic efficiency is determined by the Air-Fuel ratio (A/F). In this paper, individual A/F control problem is addressed for a multi-cylinder SI engine, of which one exhaust pipe is shared by many cylinders. Firstly, an overlap model to describe the dynamics from individual fuel injection to A/F value of mixing point at the exhaust pipe is introduced. In this model, the imbalance between cylinders in A/F is presented by unknown offsets in individual fuel injection. Then the unknown offset free Model Predictive Control (MPC) scheme is designed based on this model. Finally, both the model and the controller are validated by a car-used six-cylinder SI engine. ? 2011 IFAC

The analysis between two different methods of power plant boiler thermal efficiency

Conference Name:2014 2nd International Conference on Mechatronics, Robotics and Automation, ICMRA 2014. Conference Address: Zhuhai, China. Time:March 8, 2014 - March 9, 2014.Hong Kong Industrial Technology Research Centre; Inha University; Korea Maritime UniversityThe power plant boiler is one of the most important facilities in thermal power plants. The thermal efficiency of power plant boilers is the index. This paper discusses the relationship between the boiler thermal efficiency and the coefficient of excess air via two methods, one is called the simplified calculating formula and the other is the calculating formula according to the "The People's Republic of China national standard power plant boiler performance test procedures". According to the proposed methods, by solving the same optimal problem, optimum excess air coefficients are obtained. Then a comparative analysis is given. Moreover, an improved way for saving calculation time to get the coefficients of the mixed coal in the so called simplified calculating formula is developed. ? (2014) Trans Tech Publications, Switzerland

Idle speed performance improvement via torque balancing control in ignition-event scale for SI engines with multi-cylinders

Imbalance in torque generation leads to engine speed fluctuation. To improve the idle engine speed performance, the torque balancing control problem is addressed in this paper for multi-cylinder SI engines. To evaluate cylinder-to-cylinder imbalance, the average torque in ignition-event scale is introduced as controlled output, which enables a feedback control to be performed without measurement of instantaneous torque, and the individual spark advances are chosen as control inputs. A linear discrete time model with single input and single output is proposed to represent the dynamics of the imbalance, where a sequentially switching function is introduced to describe the spark advance signals delivered to each cylinder and the differences in torque generation caused by the individual cylinder characteristics are equivalently modelled as unknown offset in the inputs. An estimation algorithm with the proof of convergence is presented to provide on-line estimation of the unknown offset under the passivity assumption of the system. Furthermore, a feedback control law which combines the unknown offset estimation and the model predictive control is proposed. Finally, the unknown offset estimation and the feedback control approach are validated based on the experimental results carried out on a six-cylinder gasoline engine test bench. 漏 Authors 2011

A current harmonic detection method via input observer

Conference Name:3rd International Conference on Manufacturing Engineering and Process, ICMEP 2014. Conference Address: Seoul, Korea, Republic of. Time:April 10, 2014 - April 11, 2014.Carleton University; Science and Engineering Institute; University of Ontario Institute of Technology (UOIT)The current harmonic detection method is an important part in the control of active power filters used in power systems, since inaccuracy in harmonic detection yields to incorrect compensation. In this paper, an input observer for current harmonic detection is proposed. Firstly, a integral unit of the measured current signal is introduced to establish an augment function,then based on the augment system an observer is deduced. By constructing a Lyapunov function, the stabilization of the error system between the augment system and its observer is proved, which means the observed current harmonic approaches their real values. Finally, the proposed method is validated by Matlab simulation. ? (2014) Trans Tech Publications, Switzerland

A Novel Passive Control Strategy for Transformerless Shunt Hybrid Active Power Filter

无变压器并联混合型有源电力滤波器(TlS-HAPf)是一种新颖的具有较强实用性的拓扑,特别适用于高压大功率系统。文中在分析该拓扑结构主电路构成和工作原理的基础上,提出将无源性理论应用到该拓扑的控制中以获取更好的静态和动态性能。首先在固定AbC坐标系下建立了TlS-HAPf模型,为简化模型将其变换到同步旋转dQ坐标系下;继而通过注入阻尼获得原系统的伴随系统及跟踪偏差的动态方程;然后通过选取存储函数并对其求导证明系统的严格无源性;最后通过伴随系统得到系统的无源控制器,给出了控制框图并将其应用到系统控制中。仿真和实验结果验证了所提出的无源性控制的正确性。Transformerless shunt hybrid active power filter(TLS-HAPF) is a novel topology for active power filters with great practicality,especially suitable for high-voltage high-power system.Based on the analysis of the topological structure and working principle of TLS-HAPF,a novel passive control topology is proposed to enhance its static and dynamic compensation effect.First,the shunt hybrid power filter is modeled in the stationary abc frame and then the model is transformed to the rotating dq frame with the aim of reducing the control complexity.Then by means of injecting adjustable damping into the system to establish its associated system and get the tracking error dynamic equation.The storage function of the closed-loop system is established and derived to prove its strict passivity.Finally,the dynamic controller is derived from the associated system and the control graph is given.The simulation performed in MATLAB and experimental results verify the new approach.福建省科技计划重大项目(2012H6023)~

A model predictive control method for bidirectional DC-DC converter in the ZVS condition

Conference Name:3rd International Conference on Manufacturing Engineering and Process, ICMEP 2014. Conference Address: Seoul, Korea, Republic of. Time:April 10, 2014 - April 11, 2014.Carleton University; Science and Engineering Institute; University of Ontario Institute of Technology (UOIT)The bidirectional DC-DC converter can achieve energy storage and transfer by adjusting the magnitude and direction of the current, which is widely used in the DC interconnect micro-grid system and battery energy management system. In the current tracking control of the bidirectional DC-DC converter, the switching loss can be significantly reduced under the Zero Voltage Switching (ZVS) condition. In this situation, the paper firstly establishes the model of switching progress. Considering the ZVS constraints, the model can be described as piecewise linear equations. Secondly, based on the piecewise model, the model predictive controller is constructed. By solving a constrained optimal problem, the switching time forecast in the ZVS condition is obtained to realize the current tracking. Moreover, the derivation of boundary conditions is presented. Finally, a simulation is presented to validate the proposed model and control method. ? (2014) Trans Tech Publications, Switzerland