Finite-Time Stabilization for Constrained Discrete-time Systems by Using Model Predictive Control

In this paper, a model predictive control(MPC)framework is proposed for finite-time stabilization of linear and nonlinear discrete-time systems subject to state and control constraints. The proposed MPC framework guarantees the finite-time convergence property by assigning the control horizon equal to the dimension of the overall system, and only penalizing the terminal cost in the optimization, where the stage costs are not penalized explicitly. A terminal inequality constraint is added to guarantee the feasibility and stability of the closed-loop system.Initial feasibility can be improved via augmentation. The finite-time convergence of the proposed MPC is proved theoretically,and is supported by simulation examples.

广义预测控制的deadbeat性质研究

本文利用广义预测控制中对象与闭环特征多项式之间的系数映射关系，分析了闭环系统特征多项式系数为零的条件，导出了GPC闭环系统deadbeat性质完善而新颖的理论结果，并提供了一种基于系数空间映射的新思路来研究GPC的性质。

广义预测控制性质研究

研究了带有纯滞后系统的广义预测控制的deadbeat性质,通过系数映射关系,分析闭环系统特征多项式系数为零的条件,给出了带有纯滞后的GPC闭环系统具有deadbeat性质所要满足的条件,为研究有纯滞后的GPC的性质提供了一种基于系数空间映射的新思路.

当今美国大学生常用部分俚语汇释

笔者在海外教学中,收集了美国中部一大学学生中不少最新的语言材料.这些语言材料的内容范围,明显地反映当今美国大学生中的一些突出问题;反映他们的思想个性和生活习俗.在做一道普通语言学课程的习题时,每个学生都要列举一些他们日常生活中常用的学生俚语.一个在念硕士学位的美国女学生,与丈夫离了婚,成了自己带着一个两岁孩子的single mother.她提供的例子,就反映了她的思想情绪和生活现实:

Generalized synchronization between different chaotic maps via dead-beat control

This paper presents a new scheme to achieve generalized synchronization（GS） between different discrete-time chaotic（hyperchaotic） systems.The approach is based on a theorem,which assures that GS is achieved when a structural condition on the considered class of response systems is satisfied.The method presents some useful features：it enables exact GS to be achieved in finite time（i.e.,dead-beat synchronization）;it is rigorous,systematic,and straightforward in checking GS;it can be applied to a wide class of chaotic maps.Some examples of GS,including the Grassi-Miller map and a recently introduced minimal 2-D quadratic map,are illustrated.

A novel digital control strategy of three-phase shunt active power filter under non-ideal mains voltages

A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.

Novel control scheme for 3-phase PWM current-source converters under unbalanced source voltage conditions

Under unbalanced source voltage supply, considerable output second harmonics and input low-order harmonics in 3-phase PWM current-source converters (PWM-CSC) are generated. This paper proposes a new deadbeat controller based on compensation for unbalanced source voltage and current. With the proposed scheme, the second harmonics of the output current are eliminated and low-order harmonics of the source current are reduced effectively. Simulation and experimental results con- firmed the feasibility of the proposed method.

Research and simulation of two-level grid-connected photovoltaic inverter system

The photovoltaic cell can achieve the optimal state, and the solar energy is converted into electrical energy suffi- ciently in the two-level PV power system by using the method of MPPT which is based on the front stage Boost converter. The back stage network side inverter adopts the method of deadbeat control and the grid power factor turns to be 1. The maximum power point tracking is realized, and the grid current has the same frequency and phase with the grid voltage through simulation. Therefore, efficiency of the solar module is improved and the sine AC wave of the inverter control circuit is high-quality. Each converter can achieve relatively independent function in the two-level PV power system by the method of Matlab/Simulink software simulation. The simulation shows that it is very conducive to the modular design and integration of the system.

基于状态空间的有约束稳定广义预测控制

针对一类有约束的稳定广义预测控制问题,提出一种基于状态空间的稳定广义预测控制算法。首先通过传递函数的状态空间实现,得到被控对象的离散状态空间形式;然后引入Deadbeat状态反馈矩阵并给出约束条件的等价性定理,实现了约束条件的等价转化;最后通过等价约束条件优化性能指标函数求解控制律。仿真实例表明该方法具有良好的稳定性。

DEADBEAT COVARIANCE CONTROLLER DESIGN FOR SAMPLED-DATA SYSTEMS

The problem of deadbeat covariance controller design for sampled data feedback systems is considered. The purpose of considering this problem is to design linear discrete controllers such that the state covariance of the closed loop system achieves its steady state value which is equal to a prespecified positive definite matrix during finite beats. This problem is reduced to the similar one for equivalent discrete time systems by taking intersample behaviour into account. Both the existence conditions and the explicit expression of the desired controllers are given.

An Improved Deadbeat Predictive Current Control Method for SPMSM Drives with a Novel Adaptive Disturbance Observer

To improve the dynamic performance of conventional deadbeat predictive current control(DPCC)under parameter mismatch,especially eliminate the current overshoot and oscillation during torque mutation,it is necessary to enhance the robustness of DPCC against various working conditions.However,the disturbance from parameter mismatch can deteriorate the dynamic performance.To deal with the above problem,firstly,traditional DPCC and the parameter sensitivity of DPCC are introduced and analyzed.Secondly,an extended state observer(ESO)combined with DPCC method is proposed,which can observe and suppress the disturbance due to various parameter mismatch.Thirdly,to improve the accuracy and stability of ESO,an adaptive extended state observer(AESO)using fuzzy controller based on ESO,is presented,and combined with DPCC method.The improved DPCC-AESO can switch the value of gain coefficients with fuzzy control,accelerating the current response speed and avoid the overshoot and oscillation,which improves the robustness and stability performance of SPMSM.Finally,the three methods,as well as conventional DPCC method,DPCC-ESO method,DPCC-AESO method,are comparatively analyzed in this paper.The effectiveness of the proposed two methods are verified by simulation and experimental results.

Fault-tolerant Deadbeat Model Predictive Current Control for a Five-phase PMSM with Improved SVPWM

The main drawbacks of traditional finite set model predictive control are high computational load,large torque ripple,and variable switching frequency.A less complex deadbeat(DB)model predictive current control(MPCC)with improved space vector pulse-width modulation(SVPWM)under a single-phase open-circuit fault is proposed.The proposed method predicts the reference voltage vector in the a-β subspace by employing the deadbeat control principle on the machine predictive model;thus,the exhaustive exploration procedure is avoided to relieve the computational load.To perform the constant switching frequency operation and achieve better steady-state performance,a modified SVPWM strategy is developed with the same conventional structure,which modulates the reference voltage vector.This new approach is based on a redesigned and adjusted post-fault virtual voltage vector space distribution that eliminates the y-axis harmonic components in the x-y subspace and ensures the generation of symmetrical PWM pulses.Meanwhile,the combined merits of the DB,MPCC,and SVPWM methods are realized.To verify the effectiveness of the proposed control scheme,comparative experiments are performed on a five-phase permanent magnet synchronous motor(PMSM)drive system.

Study on the closed-loop properties of GPC

Based on the coefficient mapping of eigenpolynomial from plant to GPC closed-loop system in the IMC structure, the solvability of the optimal control law of GPC and some properties of GPC in relationship with tun ing parameters are discussed Theorems on GPC resulting in deadbeat control are given by properly choosing the design parameters. Furthermore, new result about reducing GPC closed-loop system is derived, which extends the former conclusions. It also provides a new way to study the properties of GPC system based on coefficient mapping

Sagittal SLIP-anchored task space control for a monopode robot traversing irregular terrain

As a well-explored template that captures the essential dynamical behaviors of legged locomotion on sagittal plane,the spring-loaded inverted pendulum(SLIP)model has been extensively employed in both biomechanical study and robotics research.Aiming at fully leveraging the merits of the SLIP model to generate the adaptive trajectories of the center of mass(CoM)with maneuverability,this study presents a novel two-layered sagittal SLIP-anchored(SSA)task space control for a monopode robot to deal with terrain irregularity.This work begins with an analytical investigation of sagittal SLIP dynamics by deriving an approximate solution with satisfactory apex prediction accuracy,and a two-layered SSA task space controller is subsequently developed for the monopode robot.The higher layer employs an analytical approximate representation of the sagittal SLIP model to form a deadbeat controller,which generates an adaptive reference trajectory for the CoM.The lower layer enforces the monopode robot to reproduce a generated CoM movement by using a task space controller to transfer the reference CoM commands into joint torques of the multi-degree of freedom monopode robot.Consequently,an adaptive hopping behavior is exhibited by the robot when traversing irregular terrain.Simulation results have demonstrated the effectiveness of the proposed method.

An Improved Deadbeat Predictive Current Control of PMSM Drives Based on the Ultra-local Model

Deadbeat predictive current control(DPCC)has been widely applied in permanent magnet synchronous motor(PMSM)drives due to its fast dynamic response and good steady-state performance.However,the control accuracy of DPCC is dependent on the machine parameters’accuracy.In practical applications,the machine parameters may vary with working conditions due to temperature,saturation,skin effect,and so on.As a result,the performance of DPCC may degrade when there are parameter mismatches between the actual value and the one used in the controller.To solve the problem of parameter dependence for DPCC,this study proposes an improved model-free predictive current control method for PMSM drives.The accurate model of the PMSM is replaced by a first-order ultra-local model.This model is dynamically updated by online estimation of the gain of the input voltage and the other parts describing the system dynamics.After obtaining this ultra-local model from the information on the measured stator currents and applied stator voltages in past control periods,the reference voltage value can be calculated based on the principle of DPCC,which is subsequently synthesized by space vector modulation(SVM).This method is compared with conventional DPCC and field-oriented control(FOC),and its superiority is verified by the presented experimental results.

Short-circuit fault-tolerant control for five-phase fault-tolerant permanent magnet motors with trapezoidal back-EMF

When a short-circuit fault occurs in a phase,the faulty phase needs to be removed artificially from the system because of the loss of the capability to generate torque.In this case,both the short-circuit current and phase-loss fault would generate additional torque ripples.In this study,a novel fault-tolerant control strategy is introduced to achieve low torque ripple operation of five-phase fault-tolerant permanent magnet synchronous motors with trapezoidal back electromotive force(FTPMSM-TEMF)in the event of a short-circuit fault.The key concept of this method is to compensate for the torque ripples caused by the short-circuit current and the adverse effect of the phase-loss.Based on the torque expression under fault conditions,the torque ripple caused by the short-circuit current can be offset by injecting a certain pulsating component into the torque expression in the phase-loss condition.This would result in smooth operation under fault conditions.Moreover,to track the fault-tolerant alternating currents,the model of the deadbeat current predictive control is extended and restructured for the fault condition.The effectiveness and feasibility of the proposed fault-tolerant strategy are verified by experimental results.

A Power Allocation Method for Grid-Connected MMC Inverter Based on Droop Control

Droop control has been widely used for controlling distributed generators.As capacity of the MMC inverter may be insufficient,a power allocation method for grid-connected MMC inverter based on droop control is presented to improve the stability of the power system.As there is potential for large disturbances in the power grid,an equal speed regulation strategy is adopted to make the speed of the voltage collapse be the same as the frequency collapse.With obtaining the active and reactive power references of MMC inverter according to equal speed regulation strategy,the deadbeat control method is calculated using these power references and adopted to track the reference currents.The Routh criterion is used to analyze the influence of the inductance measurement error on the control system.Additionally,a simulation model is established with Matlab and Simulink.The simulation results show that the stability of the power grid has been improved with the proposed control method.