This paper presents a variable-gain sliding-mode observer (VGSMO) based on active flux to achieve sensorless control for interior permanent magnet synchronous motor (IPMSM). A model of PMSM with the active flux concept is first described. Then, a sensorless control method is presented based on VGSMO and Fractional-Order Phase-Locked Loop (FO-PLL). The VGSMO is designed to estimate the active flux, and the FO-PLL is designed to estimate the rotor speed and position precisely. In particular, the variable of gain matrixes of VGSMO eliminates the chattering of sliding-mode successfully. The stability analysis of VGSMO is also given in detail. Finally, the results of the simulations are given to demonstrate the accuracy, validity of the proposed method. © 2020 IEEE.

To solve the problems such as poor anti-interference performance and more steady-state current harmonic components of a permanent magnet synchronous motor(PMSM) drive system based on traditional PI control, this paper presents a model predictive control method based on sliding-mode-controller (SMC-MPC). Firstly, a sliding mode speed controller based on exponential reaching law is designed to replace the traditional PI speed controller, and to reduce the influence of the load disturbance on system performance. Secondly, the model predictive current control is adopted based on the discrete model of PMSM to reduce current harmonics and improve the torque control accuracy. Then the cost function is designed by controlling the d- and q-axis current, and the optimal output voltage vector is obtained to drive the motor. Finally, compared with the traditional PI method, the simulation results show that the proposed method not only improves the robustness of the system to load disturbance effectively, but also decreases the ripples of current and torque. The presented method has good dynamic and static performance for PMSM drive system. © 2020 IEEE.

This paper presents a precise torque closed-loop control method by super-twisting algorithm based sliding mode observer (STA-SMO). A unified mathematical model of permanent magnet synchronous motor (PMSM) is first described. Then, a STA-SMO is designed to observe the PM flux linkage and to estimate the torque precisely. In particular, the STASMO eliminates the chattering of sliding mode successfully. Stability analysis of STA-SMO is also given in detail. Finally, the simulations results demonstrate the accuracy, validity of the proposed method. © 2020 IEEE.

To solve the problems such as poor anti-interference performance and more steady-state current harmonic components of a permanent magnet synchronous motor(PMSM) drive system based on traditional PI control, this paper presents a model predictive control method based on sliding-mode-controller (SMC-MPC). Firstly, a sliding mode speed controller based on exponential reaching law is designed to replace the traditional PI speed controller, and to reduce the influence of the load disturbance on system performance. Secondly, the model predictive current control is adopted based on the discrete model of PMSM to reduce current harmonics and improve the torque control accuracy. Then the cost function is designed by controlling the d- and q-axis current, and the optimal output voltage vector is obtained to drive the motor. Finally, compared with the traditional PI method, the simulation results show that the proposed method not only improves the robustness of the system to load disturbance effectively, but also decreases the ripples of current and torque. The presented method has good dynamic and static performance for PMSM drive system.
© 2020 IEEE.

High-speed rails are important tools for traveling across the country. Because wheel treads, which are the running parts of high-speed trains, are vulnerable to damage, their condition is vital to the safety of high-speed trains. Stains similar to defects can be found on the surfaces of wheels and rails, and images containing stains are easier to obtain than images containing defects. Therefore, a wheel tread defect detection method based on Faster R-CNN is proposed in this paper to detect defects and stains simultaneously in the case of imbalanced samples, thus reducing the difficulty of defect identification. Experimental results show that, when the ratio of total defects to stains on the image is 5:1 and 2.7:1, the detection accuracy of wheel tread defects can be respectively improved by 23.62% and 19.73% when the proposed algorithm is adopted. © 2020 The Institution of Engineering and Technology.

In the context of the increasing speed of high-speed trains, the safe and comfortable operation depends on the wheel-rail condition monitoring. First, this paper introduces the analysis of wheel-rail adhesion behavior from the aspects of rolling contact model and adhesion and wear. Second, this paper summarizes the research results related to the perception of wheel- rail condition information in recent years from the perspectives of wheel-rail force measurement and wheel-rail damage detection. Third, it focuses on the current situation of wheel-rail dynamic damage diagnosis and discusses the microdamage diagnosis around deep learning. Finally, the development trend of wheel-rail condition monitoring is stated from the perspectives of multicoupling wheel-rail dynamic contact system modeling, highly precise wheel-rail condition information perception, and wheel-rail dynamic microdamage diagnosis based on small sample. © 2020 The Institution of Engineering and Technology.

This study investigates the coordinated braking strategy integrated with sliding mode control for multiple high-speed trains, to solve the problem of non-linear couplers between trains and uncertainty during the braking process. First, a multiagent model with power between trains and uncertainty is established. Secondly, a sliding mode consistency tracking controller is designed. The consensus algorithm assures the consistency convergence of speed of each carriage. Sliding mode variable structure term is used to deal with the compound interference item consisting of non-linearity and uncertainty. Finally, it is demonstrated by a simulation experiment that, the algorithm can well deal with compound disturbance term so that high accuracy is obtained during the parking process.
© 2019 Institution of Engineering and Technology. All rights reserved.

This paper investigates a synchronous control method with variable proportion for multi-axis servo system based on sliding mode variable structure to solve the inherent shortcomings of parallel synchronous uncoupled control for multi-servo motors. The method is an improvement of the ring-coupled control strategy and is thus applicable to multi-axis proportional synchronous control. No-salient pole permanent magnet synchronous servo motors are taken as the controlled objects. A sliding mode controller is designed according to the state equation of the mathematical model. The rationality of the designed controller is proven by Lyapunov stability theory, and the method is compared with a parallel synchronous control strategy, which is widely used in the object of this research. Finally, the feasibility and superiority of the method in a multi-axis synchronous control system with variable proportion is confirmed by MATLAB simulation and experimental verification. The method is applied to a three-degree-of-freedom servo system, and makes the theoretical research have the corresponding practical engineering application value.
© 2019 IEEE.

To solve the problem of wheelset slip and effectively exert locomotive traction, a protection method of anti-slip control with integral sliding mode based on optimal slip ratio is proposed. First, a dynamic model of heavy-haul locomotives is established and a sliding mode observer is designed to observe the real-time adhesion coefficients of heavy-haul locomotives. An extremum seeking algorithm with sliding mode is used to monitor and search the optimal region of slip ratio. Then, a PID compound control is combined to weaken oscillations in the sliding mode extremum seeking. Finally, an integral sliding mode controller with new reaching law is designed to ensure the slip ratio of locomotives running on different rail surfaces are at optimal values, which maximise the utilisation of adhesion between wheels and rails. Simulation results also verify the feasibility and effectiveness of the integral sliding mode variable structure control method based on optimal slip ratio in the anti-slip traction system of vehicles.
© 2019 Institution of Engineering and Technology. All rights reserved.