Research On Measurement Of Multiple Chip Currents In A Press-pack IGBT

In recent years,with the rapid development of the technology of fully-controlled power semiconductors represented by IGBT,the technology about Voltage Source Converter High Voltage Direct Current(VSC-HVDC)incrementally becomes well-rounded.DC transmission system is continuously developing towards multi-terminal system,High-voltage DC circuit breakers are considered as a core component of the entire HVDC system.Due to its low control power,large current capacity and high switching speed,press-pack IGBTs are widely used in High-voltage DC circuit breaker.Through the parallel connection of multiple IGBT chips and multiple diodes in reverse,the capacity of press-pack IGBT can be improved.However,during the turn-on and turn-off period,the maximum current overshoot of the parallel chip inside the module has a great impact on the reliability of the module.Therefore,in order to realize the reliability research of press-pack IGBT,it is necessary to measure the current distribution among chips inside the module during the turn-on and turn-off period.Firstly,this thesis introduces current measurement technologies for power electronics,analyzes the advantages and disadvantages of each measurement technology and its application areas.And for the press-pack IGBT module(4.5kV/1.2kA)from Westcode,the research object in this thesis,the Rogowski transducer is mainly discussed in detail.Then,the principle of the traditional Rogowski transducer is elaborated.Base on the Rogowski principle,we developed a micro print circuit board(PCB)"Rogowski transducer" for the research object in this thesis.And according to the impedance characteristics of the PCB Rogowski coil,the traditional compound integrator is optimized.Besides it,an integrated PCB Rogowski coil is also proposed,which enables to measure current among chips without changing inside structure of the module.Finally,the PCB Rogowski transducer is calibrated and tested to verify the performance by experiments.By applying this technique to the high voltage mixed DC circuit breaker test platform,the imbalance current among chips during the turn-on period in different drive mode is measured for the further reliability design.