Yongming Bian

Regenerative braking strategy for motor hoist by ultracapacitor

Rising concern in environmental issues on global scale has made energy saving in powered equipment a very important subject. In order to improve the energy efficiency and driving range of a motor hoist, a regenerative braking system is designed and discussed. The system takes a unique ultracapacitor-only approach to energy storage system. The bi-directional bride DC/DC converter which regulates current flow to and from the ultracapacitor operates in two modes: boost and buck, depending on the direction of the flow. In order to provide constant input and output current at the ultracapacitor, this system uses a double proportional-integral (PI) control strategy in regulating the duty cycle of PWM to the DC/DC converter. The permanent magnet synchronous motor (PWSM) drive system is also studied. The space vector pulse width modulation (SVPWM) technique, along with a two-closed-loop vector control model, is adopted after detailed analysis of PMSM characteristics. The overall model and control strategy for this regenerative braking system is ultimately built and simulated under the MATLAB and Simulink environment. A test platform is built to obtain experimental results. Analysis of the results reveals that more than half of the gravitational potential energy can be recovered by this system. Simulation and experimentation results testify the validity of the double PI control strategy for interface circuit of ultracapacitor and SVPWM strategy for PMSM.

Design and Application of Hydraulic-Walking Incremental Launching Equipment

This work designs a novel hydraulic-walking incremental launching equipment. The working principle of the equipment is proposed. Considering that the contact in incremental launching construction is a typical elastic contact problem, and changes in contact state will directly affect the stability of the incremental launching, this work proposes the equilibrium equations of computational contact mechanics and numerical analysis method for the incremental launching equipment through analyzing the working process of the equipments. The proposed model and method are applied in the analysis of typical working conditions of the incremental launching of Donghua Bridge. The structural characteristics in the construction process are analyzed and discussed. The analysis results show that the strength and stability of the steel box girder can meet the construction requirements. The incremental launching of Donghua Bridge was completed suc- cessfully. The proposed model and method can be used to predict and analyze the structural performance in incremental launching construction as well as provide theoretical reference and analysis method for similar constructions.

Development of a path following control model for an unmanned vibratory roller in vibration compaction

To achieve automatic rolling of an unmanned vibratory roller, the path following control model of the vibratory roller was built and the influence of drum vibration is considered since the roller always works in the vibration condition. The vibration dynamic model was first established. The dynamic model of the vibratory roller under the influence of exciting force was then developed. The heading following control algorithm based on preview strategy was designed to control the path following errors in unmanned automatic rolling. The control performance of the algorithm was analyzed by simulation based on the vibration dynamic model and the dynamic and kinematic models of the vibratory roller. The control performance was also verified by the field automatic rolling experiments. Experimental results show that the maximum absolute lateral error of line path following is 24.5 cm in vibration rolling and 19.5 cm in non-vibration rolling at the traveling speed of 0.83 m/s. The average absolute lateral errors in vibration and non-vibration rolling are both less than 10 cm. The experimental results verify the effectiveness and achievability of the control algorithm for unmanned vibration rolling. Besides, the ratio of completely compacted area to the whole set area is 97.28% in the field automatic rolling experiment, which meets the requirements for practical use.To achieve automatic rolling of an unmanned vibratory roller, the path following control model of the vibratory roller was built and the influence of drum vibration is considered since the roller a...

Coupling analysis method for a large-scale structure exposed to synchronous hoisting loads

Large-scale synchronous hoisting equipment is widely used in the construction field. A coupling analysis method for global and local structures exposed to synchronous hoisting loads under working conditions is presented. An integrated analysis flow based on virtual prototyping is provided for the coupling analysis process with different design and simulation software tools, which includes project design, CAD and CAE model-building and interchange, data coupling and analysis. The theoretical basis of finite element analysis for synchronous hoisting loads is deduced. A practical case of the coupling analysis for a large-scale structure exposed to synchronous hoisting loads is studied and validated. The coupling analysis method can well improve the analysis level and efficiency to predict the mechanical effects in an operating situation.