Study On Nonlinear Behavior And Switching Loss Of SiC Diode

The continuous improvement of the switching frequency and power density put forward higher requirements to the reliability of power converters. Power semiconductor devices is an important component of the power converter and its switching characteristics will directly affect the performance and service life of the power converter. Compared with the traditional silicon power semiconductor devices,silicon carbide(SiC) power semiconductor devices have many advantages, such as high temperature resistance, low leakage current,high power, low loss, etc. Because of this advantages, SiC power semiconductor devices can better meet the requirements of the future development of the power converter. Therefore, the research on the switching characteristics of SiC power semiconductor devices has attracted widely attention.SiC diode is studied in this paper. Through the experiment, we find that the device will produce period doubling bifurcation, chaos and other nonlinear behavior under a certain switching frequency and voltage, which will greatly reduce the stability and reliability of power electronic circuits. So we use semiconductor physics theory to establish analysis model of SiC diode. The period doubling bifurcation,chaos and other nonlinear phenomena under different conditions is studied, in order to explore the mechanism of nonlinear behaviors. At the same time, the operation characteristics of SiC diode in the Buck circuit is studied by experiment in this paper.Through the comparison of the switching loss of SiC diode and the traditional diode,the superior performance of SiC diode is presented. It mainly discuses the following subjects:(1) The structure and working principle are brief introduced and analyzed. Based on the theory of semiconductor physics and using Fourier analysis method to simplify the drift region of diode analysis model, we can establish the nonlinear dynamic model of the diode.(2) The nonlinear dynamic model of 5KV/5A SiC diode is used in simulink to establish the relation between the external electrical characteristics and internal carrier changes. Then, this model is used in chaos circuit to analyze the period doubling bifurcation and chaos phenomenon, and thus to explore the mechanism of nonlinear behaviors.(3) The comparison in switching characteristics of the SiC diodes and the traditional diode is analyzed by double pulse test experiment. On this basis, the switching loss of SiC diode is studied in Buck circuit, and the results show SiC diode is ascendance in reducing loss and improving efficiency of superiority.