Research On Dynamic And Static Characteristics And Modeling Method Of IGBT In Hybrid High Voltage DC Circuit Breaker

The high voltage DC circuit breaker based on IGBTs is the critical technology for multi-terminal flexible HVDC transmission.The dynamic and static characteristics optimations for IGBT are vital parts of engineering.This paper focuses on the dynamic and static features and modeling method of IGBT in hybrid high voltage DC circuit breakers and carries out the following research:1.To meet the needs of dynamic and static characteristic analysis and modeling method of high-power IGBT,this paper first studies the extraction method of chip typical parameters of high-power IGBT devices.Aiming at the defect that the existing high-power IGBT technical parameter manual provides insufficient parameters for the atypical working condition of the hybrid HVDC circuit breaker,a simple test method for desaturation current under laboratory conditions is proposed,which provides a typical basis for the extraction of static characteristic parameters of IGBT and the prediction of desaturation current under large driving voltages.An experimental extraction method of IGBT terminal nonlinear capacitance Cgd is proposed,which effectively improves the accuracy of dynamic characteristic modeling;The characteristic parameter extraction test platform for high-power press-pack IGBT is developed,meeting the test requirements of typical IGBTs in DC circuit breakers.The development of the IGBT parameter extraction test platform lays a foundation for device characteristic parameter extraction and further study of dynamic and static characteristics(DSC)of devices.2.Considering that the distribution characteristics of carriers in an IGBT are the core content affecting the DSC,this paper studies the distribution characteristics of carriers in high-power IGBT under 1-D/2-D distribution,different injection conditions based on the finite element method.The results show that the analysis and modeling for DSC of high-power IGBT need to consider the carrier 2-D distribution effect and different injection levels,which will significantly increase the complexity of DSC modeling.To solve this problem,this paper studies the carrier distribution under quasi-static(QS)and non-quasi-static(NQS)conditions for the first time.The differences and influencing factors of carrier distribution under the two conditions are revealed.The research shows that when the IGBT gate channel is in the on state,the DSC of IGBT obtained based on the two conditions are basically the same.The research conclusion can provide a new idea for the analysis and modeling of DSC for high-power IGBT.3.Taking the difference in carrier distribution between QS and NQS conditions as a breakthrough,this paper uses the high-efficiency advantage of modeling DSC based on QS conditions and proposes a fast,accurate,and general modeling method for DSC of high power IGBTs.In this method,when the boundary of the IGBT depletion layer is around the gate,a U-I characteristic external behavior model of IGBT under QS conditions is proposed.The model can avoid calculating carrier 2-D distribution and dependence on complex structural parameters of the gate on the premise of ensuring accuracy.It has the advantages of simplicity,few extraction parameters and,high precision,good engineering applicability.When the boundary of the IGBT depletion layer crosses the gate region,based on the finite-difference numerical method,an accurate calculation method considering the excess carriers in the base region under different injection conditions is proposed for QS and NQS conditions,respectively.By experiments and comparison with existing models,the advantages of this modeling method in calculation speed,calculation accuracy,and applicability to different operating conditions are verified.4.Based on the MAST hardware design language,taking a typical 4.5kV/3kA high power press-pack IGBT as an example,the proposed model is successfully implemented in the general power electronics simulation software SABER.First,according to the typical 15kA/3ms conduction condition,the conduction loss characteristics under different driving voltages are calculated and analyzed.The analysis results guide the selection of driving voltage.Then,taking the typical module with diode full-bridge topology as an example,the distribution and calculation method of the stray inductance of busbar in semiconductor components are studied.Based on the principle of partial element equivalent circuit(PEEC),a general method of partial inductance for cylindrical busbar used with cylindrical press-pack devices is proposed,which can effectively improve the calculation efficiency while ensuring the calculation accuracy.Then,the influence mechanism of different busbar stray inductance in semiconductor components on the dynamic characteristics of IGBT is studied.Based on the conclusion,the corresponding suggestions on the assembly scheme of large-scale series semiconductor components are proposed.On this basis,the influence of stray inductance in semiconductor modules on the dynamic equilibrium characteristics of parallel IGBTs is further studied,and the busbar structure optimization design method is proposed.The conclusions can reference the selection or customization of IGBTs,the design of driving units,and the optimal design of connection busbar in semiconductor modules.