IGBT集电极电压高精度测量方法研究

High-precision measurement method of IGBT collector voltage

IGBT导通和截止电压相差较大,传统的检测电路无法实现其宽范围、高精确度的测量。首先,本文提出了一种IGBT导通和截止电压集成的测量电路,实现了IGBT导通和截止电压的准确测量。进而给出了具有高动态性能的IGBT截止和导通电压分立测量电路,前者通过电阻分压、电容补偿实现了IGBT开关暂态集电极电压的高带宽测量;后者利用电流源给二极管注入微小电流实现IGBT导通饱和压降的精确测量,并实验验证了IGBT导通和截止集电极电压测量电路的高带宽和高精确度性能,测量精确度分别为5m V和10V。最后,对IGBT导通饱和压降-结温-集电极电流三者间存在的线性关系进行实验验证,并结合IGBT输出特性形成的分段线性函数,形成了更简单、实用的IGBT结温在线估计方法。

Because of great difference between the on-state and off-state of voltages of IGBT,it is impossible for the traditional measuring circuits to implement its wide-range and high-precision detection.First of all,this paper presented an integrated measuring circuit for the IGBT on-state and off-state voltages,so that an accurate measurement can be carried out.On this basis,the discrete measurement circuits for the IGBT on-state and off-state voltages were given to meet the high dynamic performance of the switching-transient collector voltage.The high bandwidth measurement of the collector voltage in the IGBT which was in a switching transient state was carried out through the resistor divider and capacitor compensation circuit.The accurate measurement of IGBT saturation voltage drop depended on the current sources to inject small current into the diodes,respectively.Then,various tests were carried out and verified that the measurement circuit for IGBT collector voltage detection is of high-bandwidth and high-precision performance,with the accuracy of measurement up to 5mV and 10V,respectively.Finally,the experimental verification of the linear relationship existing among the saturation voltage drop,junction temperature and collector current of IGBT were conducted.Besides,combing with output curve of IGBT,the junction temperature was estimated by using the measured saturation voltage drop and collector current.