Research On PCB Rogowski Coil Current Transformer For Press-pack IGBT Module

The imbalance between energy distribution and the demand for electricity determines that DC transmission technology has become one of the most effective means of improving energy efficiency.High-voltage direct current(HVDC)puts higher demands on power semiconductor devices such as Press-Pack IGBTs.In order to obtain greater current-passing capability,multiple IGBT modules are usually connected in parallel.The inevitable error in the manufacturing process will cause the parameters of the IGBT devices to be inconsistent.In addition,the propagation delay time of the gate unit and the stray inductance of the parallel branch will cause the IGBT parallel current distribution to be unbalanced and reduce the stability of the whole system.Therefore,measuring the balance of current in the Press-Pack IGBT module is of great significance for realizing its reliability research.Firstly,this thesis introduces the research status of IGBT parallel current sharing technology and the technology of measuring current in the integrated power electronic modules.Considering the bump layout of Westcodes's 4.5kV/1.2kA Press-Pack IGBT device,which is the research object of this thesis,and features of switching current in device,the thesis focuses on the development of Rogowski coils.Secondly,the measurement principle of the traditional Rogowski coil is introduced.By comparing the Rogowski coils with different structures,the PCB Rogowski coil is designed as the sampling component of the current.Based on the lumped parameter model of Rogowski coils,the frequency characteristics of Rogowski coils under two different operating states:self-integration and differential,are analyzed.Combined with the application of PCB Rogowski coils,the factors affecting the measurement accuracy are simulated and analyzed.In order to achieve the integration of the differential signal of Rogowski coils,this thesis compares digital integrators based on different integration algorithms with different types of analog integrators,and the integration circuit scheme combining the passive integration circuit and the active integration circuit is finally designed and optimized.Finally,the electromagnetic parameters of PCB Rogowski coils are measured by impedance analyzer.The frequency characteristics of Rogowski coils are analyzed by constructing the lumped parameter equivalent circuit model in PSpice software.A simple transformation experiment is designed to verify the differential working mode of PCB Rogowski coils.The overall model of PCB Rogowski current transformer is built in PSpice software for AC analysis and transient analysis.The performance of the designed current transformer is proved by measuring the standard lightning current,which lays a foundation for the reliability research of the Press-Pack IGBT.