Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems res...Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.展开更多
A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient...A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient is controlled by estimating the load torque of motor, thereby traction motor is not rotated after stop. In addition, coasting operation and brake test are performed from normal-opposite operation and start using a small-scale model comprising the inertial load equipment and the power converter. Further, traction motor is made to be equipped with a suspension torque. Pure electric braking that makes traction motor stop by an air brake at the time of stop is also implemented. Constant torque range and constant power range are expanded during braking so that braking force is secured with the electric brakes even in high speed region. Therefore, vehicle reduction effect can be expected by reducing parts related with an air brake which is not used frequently by using a pure electric brake in the M car in wide speed region. Further, maintenance of brake system can be reduced. Besides, ride comfort of passenger in the electric rail car, energy efficiency improvement, and noise reduction effect can be additionally expected. Further, an improved brake method that uses only an electric brake till motor stop is proposed by comparing those in the blending brake that uses an air brake while reducing brake torque at vehicle stop.展开更多
For a permanent magnet synchronous motor(PMSM)model predictive current control(MPCC)system,when the speed loop adopts proportional-integral(PI)control,speed regulation is easily affected by motor parameters,resulting ...For a permanent magnet synchronous motor(PMSM)model predictive current control(MPCC)system,when the speed loop adopts proportional-integral(PI)control,speed regulation is easily affected by motor parameters,resulting in the inability to balance the system robustness and dynamic performance.A PMSM optimal control strategy combining linear active disturbance rejection control(LADRC)and two-vector MPCC(TV-MPCC)is proposed.Firstly,a mathematical model of a PMSM is presented,and the PMSM TV-MPCC model is developed in the synchronous rotation coordinate system.Secondly,a first-order LADRC controller composed of a linear extended state observer and linear state error feedback is designed to reduce the complexity of parameter tuning while linearly simplifying the traditional active disturbance rejection control(ADRC)structure.Finally,the conventional PI speed regulator in the motor speed control system is replaced by the designed LADRC controller.The simulation results show that the speed control system using LADRC can effectively deal with the changes in motor parameters and has better robustness and dynamic performance than PI control and similar methods.The system has a fast motor speed response,small overshoot,strong anti-interference,and no steady-state error,and the total harmonic distortion is reduced.展开更多
A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can main...A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can maintain the original features of ADRC and make the parameters of ADRC transition smoothly.The proposed control scheme also ensures speed control accuracy and improves the robustness and anti-load disturbance ability of the system.Moreover,through the analysis of a d-axis current output equation,a novel current-loop SM-ADRC is presented to improve the system’s dynamic performance and inner ability of anti-load disturbance.Results of a simulation and experiments show that the improved sliding-mode ADRC system has the advantages of fast response,small overshoot,small steady-state error,wide speed range and high control accuracy.It shows that the system has strong anti-interference ability to reduce the influence of variations in rotational inertia,load and internal parameters.展开更多
In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be complet...In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be completelymeasured.We theoretically prove that each agent can follow the leader with estimable track errors.Finally,somenumerical simulations are presented to illustrate our theoretical results.展开更多
文摘Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.
文摘A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient is controlled by estimating the load torque of motor, thereby traction motor is not rotated after stop. In addition, coasting operation and brake test are performed from normal-opposite operation and start using a small-scale model comprising the inertial load equipment and the power converter. Further, traction motor is made to be equipped with a suspension torque. Pure electric braking that makes traction motor stop by an air brake at the time of stop is also implemented. Constant torque range and constant power range are expanded during braking so that braking force is secured with the electric brakes even in high speed region. Therefore, vehicle reduction effect can be expected by reducing parts related with an air brake which is not used frequently by using a pure electric brake in the M car in wide speed region. Further, maintenance of brake system can be reduced. Besides, ride comfort of passenger in the electric rail car, energy efficiency improvement, and noise reduction effect can be additionally expected. Further, an improved brake method that uses only an electric brake till motor stop is proposed by comparing those in the blending brake that uses an air brake while reducing brake torque at vehicle stop.
文摘For a permanent magnet synchronous motor(PMSM)model predictive current control(MPCC)system,when the speed loop adopts proportional-integral(PI)control,speed regulation is easily affected by motor parameters,resulting in the inability to balance the system robustness and dynamic performance.A PMSM optimal control strategy combining linear active disturbance rejection control(LADRC)and two-vector MPCC(TV-MPCC)is proposed.Firstly,a mathematical model of a PMSM is presented,and the PMSM TV-MPCC model is developed in the synchronous rotation coordinate system.Secondly,a first-order LADRC controller composed of a linear extended state observer and linear state error feedback is designed to reduce the complexity of parameter tuning while linearly simplifying the traditional active disturbance rejection control(ADRC)structure.Finally,the conventional PI speed regulator in the motor speed control system is replaced by the designed LADRC controller.The simulation results show that the speed control system using LADRC can effectively deal with the changes in motor parameters and has better robustness and dynamic performance than PI control and similar methods.The system has a fast motor speed response,small overshoot,strong anti-interference,and no steady-state error,and the total harmonic distortion is reduced.
基金Project(2011AA11A10102) supported by the High-tech Research and Development Program of China
文摘A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can maintain the original features of ADRC and make the parameters of ADRC transition smoothly.The proposed control scheme also ensures speed control accuracy and improves the robustness and anti-load disturbance ability of the system.Moreover,through the analysis of a d-axis current output equation,a novel current-loop SM-ADRC is presented to improve the system’s dynamic performance and inner ability of anti-load disturbance.Results of a simulation and experiments show that the improved sliding-mode ADRC system has the advantages of fast response,small overshoot,small steady-state error,wide speed range and high control accuracy.It shows that the system has strong anti-interference ability to reduce the influence of variations in rotational inertia,load and internal parameters.
基金Supported by the National Science Foundation of China under Grant Nos.10702023,10832006,and 60704041the Research Fund for the Doctoral Program of Higher Education under Grant No.20070487090
文摘In this paper,we investigate a leader-following tracking problem for multi-agent systems with boundedinputs.We propose a distributed bounded protocol for each follower to track a leader whose states may not be completelymeasured.We theoretically prove that each agent can follow the leader with estimable track errors.Finally,somenumerical simulations are presented to illustrate our theoretical results.
