High Frequency Capacitive behavior of field stop trench gate IGBTs operating in Short Circuit
A wide experimental characterization about the input capacitance of Field Stop Trench Gate IGBTs is presented. It was achieved thanks to a novel experimental set-up which allows us to measure the input capacitance in the active region where the device operate during the Short Circuit (SC). The experimental results have been interpreted with the help of FEM simulations which confirm that negative capacitance is correlated with the accumulation of holes at the interface between N- IGBT base and gate oxide.
Real-time system for monitoring the electro-thermal behaviour of power electronic devices used in boost converters
Abstract Reliability of power electronic devices (PEDs) is a key issue to secure power supplies in modern word, especially, those generated from renewable energy sources. Thermal stress due to switching frequency and environmental conditions are commonest cause of currently unsatisfactory PEDs reliability scores. In this paper, the electro thermal performance of PEDs and related parameters are critically investigated using three types of differently manufactured insulated gate bipolar transistors (IGBTs). Namely, punch through (PT), non-punch through (NPT) and field stop (FS) silicon trench gate technologies. First, currents and voltages of the examined IGBTs were measured under different operating temperatures, switching frequencies and electrical loading conditions. Second, power losses of the examined devices were calculated, in real time, based on their measured currents and voltages using realistic mathematical model embedded in a dSPACE system. Subsequently, the power losses for each device were used as an input to a finite element model to graphically predict heat distributions for each of the monitored devices. Compared to expensive measurements taken by high-resolution thermal imaging cameras, the accuracy of the developed system achieved 97%. The obtained results demonstrate the developed model would serve as an inexpensive and powerful tool for monitoring PEDs thermal conditions.
The origins and characteristics of negative capacitance in metal–insulator–metal devices
Abstract Impedance analysis of ZnS metal–insulator–metal structures has revealed strong negative capacitance behaviour. Under low-field conditions, the devices are highly insulating with capacitance consistent with their geometry and dielectric constant. However, at high fields they become conducting and the capacitance falls to zero and then becomes negative. It may exceed the geometrie value by over five orders of magnitude. This frequency-domain behaviour is explained in terms of the unusual time-domain behaviour of the devices. The origins of negative capacitance are shown to He in the modulation of the differential conductance by the a.c. measurement voltage, combined with the interpretation of the response in terms of an electrical equivalent circuit. The application of equivalent-circuit analysis to such systems is discussed. Negative capacitance has been observed in a wide range of other systems which can now also be understood within the theoretical framework presented.