Effect of bidirectional excitation on seismic performance of regular RC frame buildings designed for modern codes

The existing practice to estimate seismic performance of a regular building is to carry out nonlinear time history analysis using two-dimensional models subjected to unidirectional excitations, even though the multiple components of ground motion can affect the seismic response, significantly. During seismic shaking, columns are invariably subjected to bending in two orthogonal vertical planes, which leads to a complex interaction of axial force with the biaxial bending moments. This article compares the seismic performance of regular and symmetric RC moment frame buildings for unidirectional and bidirectional ground motions. The buildings are designed and detailed according to the Indian codes, which are at par with the other modern seismic codes. A fiber-hinge model, duly calibrated with the biaxial experimental results, is utilized to simulate the inelastic behavior of columns under bidirectional bending. A comparison of the estimated seismic collapse capacity is presented, illustrating the importance of considering the bidirectional effects. The results from fragility analysis indicate that the failure probabilities of buildings under the bidirectional excitation are significantly higher as compared to those obtained under the unidirectional excitation.

Predictive Model for Conducting Electromagnetic Interference by Bidirectional Excitation Controller

Bidirectional excitation controller is used in the excitation system of brushed DC motor. There are many monitoring sensors and weak current switches nearby. Therefore, it is necessary to study the conduction interference of the excitation controller. Firstly, based on the working principle of bidirectional excitation controller, the propagation path model and corresponding equivalent circuit of bidirectional excitation controller are established. Then, the parasitic capacitance parameters between the switch tube and the heat sink were extracted by ANSYS Q3D software, and the dynamic model of IGBT was established by using ANSYS Simplorer software. Based on ANSYS software, the prediction model of the equipment conducted electromagnetic interference was obtained. Finally an excitation controller conducting interference test platform was built, and the predicted results were compared with the measured interference results of the experimental platform to verify the accuracy of the prediction model.

Dynamical Modeling, Simulation and Analysis for Voltage Regulation System of Hybrid Excitation Doubly Salient Generator

Hybrid Excitation Doubly Salient Generator (HEDSG) with parallel magnetic circuits is performed in this paper, and the main flux in the machine is determined by the permanent magnet and the field coils. The structure and working principle of the generator are described in detail. In order to build the voltage regulation system of HEDSG, a bidirectional excitation voltage regulator is proposed, which could keep the output voltage of the generator stable by adjusting the field current. The two control loops including excitation current feed-forward and output voltage feedback loops are applied in the voltage regulator. Subsequently, the mathematical model of the voltage regulation system is constructed after the transfer function of the generator is obtained by using system identification method. Moreover, in order to realize the field current bidirectional flow, bipolar pulse width modulation is also applied in the regulator, and the control parameters influencing on the output voltage are analyzed. Lastly, the prototype of bidirectional excitation voltage regulator is designed and theoretical analysis and simulation results are verified by the stable and dynamic experiments.