Experimental Research On Current Sharing Characteristics Of Parallel Press Pack IGBT Chips

Press pack IGBT devices have the advantages of double-sided heat dissipation,failure short circuit and high-power density,which have been widely used in the field of high-voltage and high-power power conversion.Whereas,in light of the different chip parameters and the asymmetrical packaging parameters,there are unbalanced current distributions among the parallel chips,which seriously harm IGBT’s safe operation during the commutation.For the current sharing problem inside press pack IGBT devices,the theoretical basis and the simulation technology still need to be further developed.Up to now,the experimental investigation is the most direct and effective method.This paper mainly focuses on the experimental investigation,supplemented by theoretical analysis and simulation calculation,and carries out in-depth research on the current sharing experimental platform,current measurement technology,and current sharing characteristics among multiphysics factors.Firstly,three experimental platforms for the static characteristics,dynamic characteristics and current sharing characteristics of press pack IGBT chips are designed and established.The pressure fixture with a pressure equalizer and the heating system with PID control are proposed for the first time.The balance of chip surface pressure and the accuracy of chip temperature are realized.The symmetrically stacked bus is proposed to reduce the stray inductance of the circuit.Moreover,the decoupling method of multi-physics is put forward for the current sharing platform.The experimental platforms designed in this paper have the strengths of balanced pressure,accurate heating temperature and independent adjustment,which lay the foundation for the research of dynamic,static and current sharing characteristics in press pack IGBT chips.Secondly,the error cause,error model and correciton method of press pack IGBT chip current measurement by commercial Rogowski coil are studied.According to the influence of magnetic field and electric field on the current measurement error of commercial Rogowski coil,the error analysis models are established,and the error analytical formulas are given.On this basis,the correciton methods to reduce the measurement error are proposed,which can reduce the measurement error of commercial Rogowski coil from 13%to 0.5%.The correciton method proposed in this paper ensures the current measurement precision of Rogowski coil in the press pack IGBT chip.Thirdly,the influence factors on static and dynamic characteristics of the press pack IGBT chip are systematically studied.As for static characteristics,the dispersion and statistical laws in static characteristics parameters are obtained.Then,the effects of temperature and mechanical pressure on the static characteristics are investigated.As for dynamic characteristics,the influence of different voltage,current,gate resistance,temperature and mechanical pressure on the dynamic characteristics of the press pack IGBT chip was obtained.The experimental results provide data support for the study of current sharing characteristics of press pack IGBT chips.Finally,the influence of different factors on the current sharing characteristics of press pack IGBT chips was studied.Through the current sharing experiment platform,the influence law of chip parameters,stray inductance,temperature and mechanical pressure on the current sharing characteristics are obtained.Through theoretical analysis and simulation calculation,the influence mechanisms of different factors on current sharing characteristics are revealed.These conclusions provide theoretical support for the multi-chip parallel technology inside press pack IGBT devices.