Drive Voltage Dynamic Characteristic Modeling Analysis Of Parallel IGBT Modules In DC Circuit Breaker

Hybrid HVDC circuit breaker is the core equipment to ensure the safe operation of DC power grid,and it has become one of the key points in the research of HVDC and flexible HVDC.As a key component of circuit breaker,the gate driving voltage of parallel IGBT(insulated gate bipolar transistor)is close to the safety limit under the condition of Hybrid DC circuit breaker.Voltage over-limit is a key problem in the electrical design of the circuit breaker.However,due to the dispersion of IGBT parameters and the difference of parasitic parameters of power circuit,the driving voltage stress of parallel devices will be imbalance.Therefore,this paper focuses on the dynamic analysis of driving voltage of IGBT in parallel of hybrid DC circuit breaker.In this paper,a parallel IGBT turn-off the drive voltage test platform with continuously adjustable driving voltage is built.According to different connection structures of parallel devices,connection busbars of different structures was designed to provide a hardware basis for studying dynamic characteristics of driving voltage of parallel devices under special conditions of circuit breakers.The dynamic characteristics of IGBT driving voltage in parallel submodules during high current switching were analyzed.Based on the Parallel IGBT hard parallel structure of the driving circuit and the asymmetry of the circuit parameters,the driving voltage fluctuation problem was described.Then,a parallel device module simulation model including SPT+-IGBT mechanism model and continued-current diode was built,with the extraction of stray inductors connected to the bus by the flux chain method and the boundary element method,and the high current experiment of the parallel module was carried out to verify the high accuracy of the model in the field of switching off the driving voltage fluctuation of the reaction device.Furthermore,this paper analyzed the dynamic driving voltage imbalance of parallel devices from the aspects of device parameters,power circuit and drive circuit parameters mismatch.The influence of device parameter dispersion on driving voltage fluctuation was studied,and the phenomenon of switching off driving voltage fluctuation of IGBT module with the stray inductance of the circuit as the control quantity was analyzed theoretically,and the influence law of spurious parameter was analyzed by simulation.Based on the voltage safety margin coefficient which can be used to quantitatively analyze the influence of stray parameters,the basic scheme of stray inductance design for parallel components was proposed and verified by experiment.