Study on the position control of the e-actuator for e-VGT
The e-VGT (electrical Variable Geometry Turbocharger), a kind of turbocharger is a electronic device that controls the flow rate and amount of exhaust gas. Therefore, the position of the actuator must be controlled quickly and accurately. To control the position of the e-actuator, the authors use PI control on a position controller including a current controller. However, since the e-actuator has big friction and spring force, a general PI controller isn't suitable for the e-actuator. To solve the problem, they find mechanical modeling of the e-actuator. And using the mechanical modeling, the controller that is suitable for the e-actuator is made.
Microprocessor-Based High-Efficiency Drive of a DC Motor
This paper presents a method to improve the efficiency of dc motors, dc shunt motors, and dc series motors. The method is based upon the field control. It is derived that the ratio of the armature current to the field current should be maintained constant to maximize the efficiency at a specific speed. The power circuits and the control loops are suggested to realize the principle, and the real-time control is implemented with a microprocessor. Also, in order to assess the stability of the overall systems, the proposed systems are analyzed with the small signal linearization. Experimental results show that the remarkable improvement in efficiency has been accomplished by the proposed method and the suggested systems are stable.
Tests of composite beams with web holes
Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount of shear connection between slab and steel section in the region of a web hole, and on the effect of construction loads acting on the steel section prior to composite action being effective.It is shown that limited shear connection at the hole will significantly affect the strength when loading produces a high shear-to-moment ratio, and a theory is presented which conservatively takes this into account. The effect of construction loads on unshored construction is shown to be small when these do not exceed 60% of the non-composite beam resistance at the hole.