基于脉幅调制的超高速无刷直流电机过零点检测补偿策略

超高速无刷直流电机广泛应用于超高速空压机、晶圆切割、飞轮储能等系统。针对超高速无刷直流电机控制中的三相绕组不完全对称和参考零点不确定偏移导致的失步问题,该文以脉幅调制控制器为基础,通过对非理想电机的研究,建立过零点抗扰动的模型,提出一种综合考虑不平衡过零点和不对称过零点补偿的改进控制策略,建立适用于三种非理想过零点模型的基础延迟时间择优策略的数学模型和换向时间补偿函数。同时,在不平衡不对称过零点扰动存在的前提下,考虑负载变化等因素引起的换相误差并提出相应的变速误差补偿策略。实验结果表明,改进控制策略可以有效减小无刷直流电机的换相误差,显著地提高电机换相的精度进而提高其运行速度上限,为无速度传感器超高速无刷直流电机稳定运行提供了一定的理论基础。

冠状动脉粥样硬化的超高速CT检测与病理学对照:II-钙化参数与管腔狭窄之间的关系

目的 :为探讨超高速 CT检测的冠状动脉钙化与冠状动脉管腔狭窄之间的关系。方法 :从 8例压力灌注固定后的心脏标本中分离出 2 0支冠状动脉 ,拉直后 ,超高速 CT扫描 ;每支冠状动脉分成相应的 3mm血管段 ,组织切片 ,地衣红染色 ,L eica图像分析仪上计算冠状动脉管腔面积狭窄率。结果 :在 4 84个血管段中 ,无粥样病变血管段的钙化率、钙化面积、钙化积分 (0 ,0 ,0 )明显低于有粥样病变的血管段 (2 8% ,1.74 %和 6 .73,P<0 .0 1)和管腔狭窄≥ 75%的血管段 (54.4 % ,5.8和 2 2 .7,P<0 .0 1) ;狭窄程度越大 ,钙化率越高 ;尽管冠状动脉钙化阴性的血管段可能有粥样硬化存在 ,但是只有 8.4 %的血管段属于管腔面积狭窄≥ 75% ;超高速 CT检测管腔面积狭窄≥ 75%的血管段敏感性、特异性分别为 54.4 %、81.5%。结论 :冠状动脉狭窄程度越重 ,粥样硬化内钙化发生率越高 ;冠状动脉钙化阴性有着重要的临床意义 ;CT阈值≥ 130

Trigonometric Regularization and Continuation Method Based Time-Optimal Control of Hypersonic Vehicles

Aiming at the time-optimal control problem of hypersonic vehicles(HSV)in ascending stage,a trigonometric regularization method(TRM)is introduced based on the indirect method of optimal control.This method avoids analyzing the switching function and distinguishing between singular control and bang-bang control,where the singular control problem is more complicated.While in bang-bang control,the costate variables are unsmooth due to the control jumping,resulting in difficulty in solving the two-point boundary value problem(TPBVP)induced by the indirect method.Aiming at the easy divergence when solving the TPBVP,the continuation method is introduced.This method uses the solution of the simplified problem as the initial value of the iteration.Then through solving a series of TPBVP,it approximates to the solution of the original complex problem.The calculation results show that through the above two methods,the time-optimal control problem of HSV in ascending stage under the complex model can be solved conveniently.

Design and Simulation of Controller for Hyper Velocity Kinetic Energy Missile

The controller design and digital simulation for the hyper velocity kinetic energy missile is investigated. A mathematical model of the trajectory deviation from the line of sight was established, the guidance closed loop was compensated with a phase advance lag corrective network, a selecting algorithm of the attitude control motors used to steer the missile's attitude was presented. In the presence of a wide variety of disturbances the results of digital simulation are satisfactory to circular error probability(CEP) being less than 0 5?m. The steering scheme utilizing attitude control motors as actuators to control the attitude of the missile is feasible.

ADRC FRACTIONAL ORDER PID CONTROLLER DESIGN OF HYPERSONIC FLIGHT VEHICLE

Active disturbance rejection controller（ADRC）uses tracking-differentiator（TD）to solve the contradiction between the overshoot and the rapid nature.Fractional order proportion integral derivative（PID）controller improves the control quality and expands the stable region of the system parameters.ADRC fractional order（ADRFO）PID controller is designed by combining ADRC with the fractional order PID and applied to reentry attitude control of hypersonic vehicle.Simulation results show that ADRFO PID controller has better control effect and greater stable region for the strong nonlinear model of hypersonic flight vehicle under the influence of external disturbance,and has stronger robustness against the perturbation in system parameters.

STRATEGY AND IMPLEMENTATION FOR HIGH-SPEED TORQUE ENHANCEMENT OF BRUSHLESS DC MOTOR

Serious commutation lag occurs when a Brushless DC Motor(BLDCM) operates at high speeds,and this leads to torque decline with ripple.In this paper,an advanced conduction control scheme is proposed which can accelerate the commutation and enhance the torque production remarkably.Besides,an on line adjusting algorithm based on the Golden Section Method is adopted to search the optimal advanced conduction angle.Simulation and experimental results verify the feasibility and effectivity of the scheme proposed.

Robust tracking control design for a flexible air-breathing hypersonic vehicle

A nonlinear robust controller was presented to improve the tracking control performance of a flexible air-breathing hypersonic vehicle(AHV) which is subjected to system parametric uncertainties and unknown additive time-varying disturbances.The longitudinal dynamic model for the flexible AHV was used for the control development.High-gain observers were designed to compensate for the system uncertainties and additive disturbances.Small gain theorem and Lyapunov based stability analysis were utilized to prove the stability of the closed loop system.Locally uniformly ultimately bounded tracking of the vehicle's velocity,altitude and attack angle were achieved under aeroelastic effects,system parametric uncertainties and unknown additive disturbances.Matlab/Simulink simulation results were provided to validate the robustness of the proposed control design.The simulation results demonstrate that the tracking errors stay in a small region around zero.

Discussion of the target-missile control scheme with supersonic speed at minimum altitude

An antiship missile with supersonic speed at minimum altitude is an effective weapon to break through a defense line. The former Soviet Union was a leader in this field since it had developed several kinds of antiship missiles which obtained supersonic speed at minimum altitudes. To counter this kind of missile, many countries have been developing corresponding antimissiles. For the purpose of verifing the antimissile missile′s effectiveness in intercepting antiship missiles, a target-missile is needed. A target-missle is cheaper and can imitate the main characteristics of antiship missiles with supersonic speed at minimum altitude. In this paper, the control scheme of a target missile flying with supersonic speed at minimum altitude is studied. To counter the problem of hedgehopping over the sea, a control scheme utilizing a SINS+altimeter was proposed. In this scheme, both the quick response ability of altitude control and the anti-jamming problem were considered. A simulation experiment shows that when an integrated altitude control system is used, the anti-disturbance ability of the integrated altitude is good and the response speed of altitude control system can be dramatically improved.

Robust parametric approach for tracking control of an air-breathing hypersonic cruise vehicle

To realize the stabilization and the tracking of flight control for an air-breathing hypersonic cruise vehicle, the linearization of the longitudinal model under trimmed cruise condition is processed firstly. Furthermore, the flight control problem is formulated as a robust model tracking control problem. And then, based on the robust parametric approach, eigenstructure assignment and reference model tracking theory, a parametric optimization method for robust controller design is presented. The simulation results show the effectiveness of the proposed approach.

Progress in control approaches for hypersonic vehicle

The controller design for hypersonic vehicle is critical and challenging because of the inherent couplings between the propulsion system and the airframe dynamics,as well as the presence of strong flexibility effects.Many researchers have investigated various strategies to mitigate the coupling by means of robust design methods.This paper reviews the recent research efforts to promote the capability of control design for hypersonic vehicle.Methodologies such as robust control,adaptive control,sliding mode control and other hybrid methods have made significant progresses in hypersonic control.Then,the main challenges of control approaches for hypersonic vehicle are systematically analyzed in detail.

Nonlinear hierarchy-structured predictive control design for a generic hypersonic vehicle

A hierarchy-structured predictive controller is designed and analyzed for rotation motion dynamics of a generic hypersonic vehicle(GHV).This vehicle model has fast variability,is highly nonlinear,and includes uncertain parameters.The controller contains two subsystems,the inner-fast-loop nonlinear generable predictive controller(NGPC)and the outer-slow-loop NGPC,both of which are designed by the closed-form optimal generable predictive control method.Thus,the heavy on-line computational burden in the classical predictive control method is avoided.The hierarchy structure of the control system decreases the relative degree of each subsystem and helps increase the dynamic response speed of the attitude controller.In order to improve the robustness of the control system,a feedback correction algorithm is proposed that corrects the calculation error between the predictive model and the real dynamic model.Simulation studies are conducted for the trimmed cruise conditions of an altitude of 33.5 km and Mach 15 to investigate the responses of the vehicle to the step commands of angle of attack,sideslip angle,and bank angle.The simulation studies demonstrate that the proposed controller is robust with respect to the parametric uncertainties and atmospheric disturbance,and meets the performance requirements of GHV with acceptable control inputs.

Three-dimensional nonlinear coupling guidance for hypersonic vehicle in dive phase

Three-dimensional(3D)nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper.It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly,and converts it into linear state space equation with the same relative degree by feedback linearization.With the linear equation,slide mode control with strong robustness is employed to design the guidance law,and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system.Besides,regarding lateral overload as the standard,hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn(BTT)and skid-to-turn(STT)controls is designed to improve the guidance accuracy further.Finally,the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists,and has strong robustness to the path disturbances and navigation errors as well.