A Smart IGBT Gate Driver IC with Temperature Compensated Collector Current Sensing
IEEE transactions on power electronics
Precision current measurement is a critical function that must be incorporated into modern high voltage and high current power systems. Conventional IGBT current sensing methods usually employ discrete sensors such as lossy shunt resistors and involve accessing the high voltage collector load of the IGBT. This would normally present difficulties for integration. In this thesis, an IGBT collector current sensing technique which only utilizes the low voltage signal at the gate terminal is
... d. This technique is based on the unique Miller plateau relationship between the gate current and collector current (I G and I C ) for a particular gate resistance (R G ), and allows for a cycle by cycle measurement of I C during both turn-on and turn-off transients. This technique is theoretically verified, experimentally demonstrated and integrated into an IGBT gate driver IC. The presented gate driver IC has a highly configurable gate driver, an on-chip CPU for local data processing and an integrated current sensor. This IC is prototyped using TSMC 0.18µm BCD Gen-2 process. A polynomial curve fitting is implemented by the on-chip CPU to predict I C based on the digitized I G value. Measurements using a double pulse test setup at room temperature show that an accuracy of ±1 A could be iii ensured with a 2 nd order polynomial curve fitting, within the current range between 1 to 30 A for turn-on and 1 to 50 A for turn-off. After the temperature effect is analyzed and factored in, a 3rd order polynomial curve fitting is implemented, an estimated accuracy of ±0.5 A could be achieved within the current range of 1 to 30 A for turn-on and 1 to 50 A for turn-off from 25 to 75 o C. iv Acknowledgments First and foremost, I would like to express my deepest appreciation to my supervisor, Professor Wai Tung Ng, for his insightful guidance and great support throughout my entire graduate studies. My research background was focused on power device modeling and fabrication for my M.A.SC degree. However, I decided to endeavor to the power circuit and power IC design area for my PhD research. Without his tremendous support and confidence in me, this challenging transition would not be possible. I am truly thankful to have the opportunity to work under his guidance in the past six and half years. The things that I have learnt from him not only include technical and problem solving skills, but also attitudes towards life and family, which will inspire me and motivate me for my future life journey.