Search

In order to solve the problems of low efficiency and large start-up shock of the belt conveyor main roller which is driven by an asynchronous motor with a hydraulic coupling, a direct drive roller control scheme of belt conveyor based on an external rotor permanent magnet synchronous motor(PMSM) is proposed. In order to realize low-speed high-torque control, a vector control strategy based on the rotating coordinate system with zero direct axis current is used. In order to solve the problem of small counter-electromotive force and low accuracy of rotor position and speed estimation during low-speed operation, the high frequency pulse signal injection method is applied to estimate the rotor position and speed. The experimental platform of direct-drive roller speed control system is established to conduct steady-state characteristic test, start-up characteristic test and load characteristic test. It is verified that the PMSM direct-drive roller control system has fast torque response and stable adjustable speed in the speed range of 0-90 r/min, which can meet the start-up speed regulation requirements of low-spreed high-torque belt conveyor.

A floating foundation vibration reduction system with an air spring as a vibration isolation element has been widely used in the foundation of large ultra-precision instruments. With the excellent vibration isolation performance of the air spring, its complex dynamic nonlinear behavior is always a research difficulty. In this paper, a dynamic model of a floating foundation vibration reduction system based on the restoring force of air spring is derived. The structure of the recurrent convolution neural network (RCNN) is proposed based on combining the working characteristics of a convolution neural network and a long short-term memory neural network, and the dynamic model of a floating foundation vibration reduction system is established with the restoring force of the air spring calculated by the RCNN as the input. Finally, a test experiment was designed to compare the dynamic characteristics of the traditional numerical model and three deep neural network models in the floating foundation. The results show that convolution neural network, long short-term memory, and RCNN models could predict the vibration response of floating foundation vibration reduction system, and the RCNN model had better performance for a floating foundation.

Steel plate concrete composite (SPCC) structure plays an essential role in modular construction, which has been widely applied in the floating foundation vibration reduction system. This study proposed a basis for designing an SPCC floating foundation vibration reduction system with an air spring as the main vibration isolation element. Based on the engineering thermodynamics and aerodynamics theories, the non-linear state equations and dynamic equations of each component of the air spring with auxiliary chamber were established, respectively. According to the operational characteristics of the air spring, the equations were linearized by using the small deviation linearization method under the condition of small amplitude, and the linearized model of the dynamic stiffness of the air spring with an auxiliary chamber was therefore proposed. The reliability of the proposed method was proved by a floating foundation vibration test, which was performed in a solid-state quantum laboratory. The constitutive equations of an air spring model and an SPCC floating foundation model were incorporated into the STERA_3D software. The simulation results showed good agreement with the low-frequency micro-vibration region test data.

In view of problems of low conversion efficiency, easy damage of switching devices and inapplicable to super capacitors of non-isolated converters currently used in mine electric locomotive, a parallel interleaved DC/DC converter applied to mine electric locomotive was introduced. At the low voltage side, a parallel interleaving structure is proposed to charge the capacitor and reduce current ripple; At the high voltage side, two capacitors are connected in series by adding a switch tube to increase buck-boost gain. Working process of the converter under boost drive mode and buck charging mode are described. The voltage/current double closed-loop step-up and constant current limit charging controller are designed. The experimental results show that the parallel interleaved DC/DC converter can effectively improve the performance of the electric locomotive in DC conversion.

In view of problems of low power quality, low cruising power, short service life of battery, separation between battery charging device and locomotive driving system existed in current charging system of mine-used electric locomotive with lead-acid battery, a new integrated on-board charging system was designed. The system is composed of the front-stage PWM rectifier circuit and the back-stage Buck circuit in series. When charging, the motor windings are reconstructed into the boost inductance of the PWM rectifier circuit to form an integrated on-board charging and discharging circuit. The supercapacitor is used to replace the battery as the energy storage element, which can realize quick on-board charging and discharging function. The simulation results show the system has shorter charging time and higher efficiency, and can realize functions such as power factor correction, ripple suppression, efficient and rapid charging and discharging compared with the traditional charging system.

In order to improve stability of sensorless control for interior permanent magnet synchronous motor of mine-used electric locomotive at low speed stage, an improved pulsating high-frequency voltage injection method was proposed. High-frequency sinusoidal voltage signal is injected into direct axis of estimated synchronous rotating coordinate, and high-frequency current of quadrature axis is processed through low pass filter, so as to obtain signal containing estimation error of rotor position angle. The signal is input into Luenberger observer to calculate estimated rotor position. The simulation and experimental results show that the method can estimate rotor position angle and speed accurately at low speed stage, so that electric locomotive can realize smooth starting, operation and stopping at low speed stage.

Traditional sliding mode control tends to generate big jitters and large control gains. In this paper, a sliding mode PI hybrid control strategy based on a new reaching law is proposed. Based on the traditional exponential reaching law, a hybrid control strategy based on a new reaching law to address the system jiUers is designed. As the motor starts, it works together with PI regulator to reduce the starting current. Since the salient pole effect and model error affect the performance of three-phase permanent magnet synchronous motor, the decoupled current PI control strategy is proposed. The feedforward decoupling compensation is introduced in the current loop, and the parameters of the current loop are adjusted by internal model control to improve the robustness and decoupling performance of the control system. The results of the simulation and experiment show the proposed control strategy improves the control precision and stability. [ABSTRACT FROM AUTHOR]