Title:

A Smart IGBT Gate Driver IC with Temperature Compensated Collector Current Sensing

Advisor: Ng, Wai Tung
Issue Date: Jun-2018
Abstract (summary): 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 presented. This technique is based on the unique Miller plateau relationship between the gate current and collector current (IG and IC) for a particular gate resistance (RG), and allows for a cycle by cycle measurement of IC 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 IC based on the digitized IG value. Measurements using a double pulse test setup at room temperature show that an accuracy of ±1 A could be ensured with a 2nd 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 oC.
Content Type: Thesis

Permanent link

https://hdl.handle.net/1807/89895

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