Research On SiC-Based Drive System Of Switched Reluctance Generator

Wide band gap(WBG)semiconductors have attracted the attention of industry and academia for their excellent performance.Due to the performance of traditional Si semiconductor devices have approached its physical limit,it is difficult to make another disruptive breakthrough.Hence,the WBG semiconductors will greatly broaden the application range of power semiconductor devices.Among WBG semiconductor devices,silicon carbide(SiC)power devices have been able to achieve large-scale commercial production.This paper mainly studies the driving system of switched reluctance generator(SRG)Based on SiC devices.The power converter of SRG is mainly asymmetric H-bridge(AHB)topology.However,it has many disadvantages such as large number of devices,high power loss and high heat dissipation requirements.Therefore,the commercialization of SRG is limited to a certain extent for this reson.In this paper,AHB power converter is studied by using SiC devices instead of traditional Si power devices.Firstly,the simulation and comparative analysis of the SiC MOSFET and Si IGBT show that the switching characteristics of SiC MOSFET is better than that of Si IGBT.After the preliminary power loss analysis,it is confirmed that the use of SiC power converter to drive SRG has practical significance.The analysis results show that the power loss of SiC power converter is still lower even under the condition of medium and low power level.Finally,the driving circuit of SiC MOSFET is introduced and its function is demonstrated in detail.Secondly,considering the strong nonlinearity of SRG phase inductance,the traditional switching transient model cannot meet the established requirements.Therefore,a switching transient model that take the nonlinear phase inductance into consideration is proposed.PSpice & Simulink co-simulation results show that the nonlinear phase inductance of the SRG reduced the switching time of the SiC MOSFET.Then,for the purpose of a precise estimation of power loss,a power loss model is established by the proposed transient model through PSpice & Simulink co-simulations.A comparison of the results of simulations and experiments indicates that the established power loss model shows satisfactory precision.Finally,experimental results indicate the SiC AHB power converter has better overall performance.Finally,according to the complex network theory,the improved evaluation method is applied to evaluate the component importance of SiC AHB power conversion circuit.The results illustrate that SiC diode features the highest importance.This coincides with the reliability evaluation result that diode failure will directly lead to system failure,which verifies the correctness of the evaluation results of importance from the side.In addition,the evaluation results show that the accuracy of the applied method is higher than that of using network degree,the closeness or betweenness index.There are 38 figures,9 tables and 100 references in this thesis.