IGBT Module Current Prediction Model And Current Equalization Control Research

Insulated Gate Bipolar Transistor(IGBT)modules have the advantage of high power density.The IGBT module can withstand voltages up to 6.5 KV and nominal currents up to750 A,meeting the requirements of most high voltage and high power applications.IGBT modules are widely used in fields such as high-speed rail,renewable energy,and industrial drives.However,in some high-power applications,the current capacity of a single IGBT module is insufficient to meet design requirements,and IGBT modules are usually connected in parallel.The problem of uneven current distribution in parallel IGBT module applications has always affected the stability of the entire system,and it is necessary to study the influence parameters and current equalization methods of parallel IGBT module current equalization.The research work of this article is mainly divided into the following parts:(1)Firstly,the development process of IGBT was discussed in detail.The development status and existing problems of IGBT module parallel connection were analyzed,followed by a study of the basic structure and working principle of IGBT.Finally,the requirement for building a dual-pulse testing platform was investigated,providing a foundation for subsequent research.(2)A dynamic current prediction model for IGBT modules based on gate charge has been proposed,which establishes the relationship between the gate charge of the IGBT module and its dynamic current.The experimental verification of the dynamic current prediction model shows that,at a junction temperature of 25℃,the maximum errors of the turn-on transient current prediction model are 4.52% and 5.12% for testing voltages of400 V and 600 V,respectively;and the maximum errors of the turn-off transient current prediction model are 3.78% and 4.34% for testing voltages of 400 V and 600 V,respectively,which are within the allowable range.The reliability of the IGBT module dynamic current model has been verified as it can accurately predict at a junction temperature of 125℃.(3)A static current prediction model based on gate charge was proposed for IGBT modules,and the relationship between gate charge and static current of IGBT modules was established.A transconductance model that is not affected by temperature changes was established to reduce the influence of temperature on static current prediction,and the IGBT module static current prediction model was experimentally verified.At a junction temperature of 25 ℃,the maximum errors of the static current prediction model were4.52% and 5.12% at testing voltages of 400 V and 600 V,respectively,which were within the allowable range of error.Accurate prediction was also achieved at a junction temperature of 125 ℃,verifying the accuracy of the IGBT module static current prediction model.(4)An IGBT module parallel current sharing analysis and testing platform was constructed.Firstly,detailed analysis of the parameters affecting the static and dynamic current sharing of IGBT module parallel connection was conducted through experiments.Secondly,the current sharing control strategy for IGBT module parallel connection was studied,and methods such as gate voltage compensation and asynchronous drive signal compensation were proposed and experimentally verified.These methods significantly improved the current sharing degree of IGBT parallel connection and increased the reliability of IGBT module parallel connection.