Akio Uenishi

An experimental and numerical study on the forward biased SOA of IGBTs

Thermal and electrical destructions of n-ch 600 V punchthrough type IGBTs in F.B.SOA are investigated by experiments and simulations, The cause of the thermal destruction is the thermal disappearance of built-in potential of p-n junction between the n/sup +/ emitter and the p base of the IGBT integral DMOSFET occurring at the critical temperature of /spl sim/650 K. Experiment and simulation results for the critical temperature show a good agreement. The cause of the electrical destruction is impact ionization at the n/sup -/ drift/n/sup +/ buffer junction in addition to the n/sup -/ drift/p base junctions. That triggers a positive feedback mechanism of increasing IGBT integral pnp transistor current which causes the device to lose gate controllability. The experimentally obtained critical power dissipation is /spl sim/2000 kW/cm/sup 2/. This value is ten times greater than BJTs. It was also found that emitter ballast resistance (EBR) plays an important role in describing the F.B.SOA of IGBTs.

A simple and effective carrier lifetime evaluation method with diode test structures in IGBT

A simple and effective method of evaluating the carrier lifetime of a power device chip is proposed. In this method, Test Element Groups (TEGs) of diodes fabricated in the periphery of an Insulated Gate Bipolar Transistor (IGBT) chip were used as carrier lifetime monitors of the IGBTs n/sup -/ layer. The measured forward voltage drops (V/sub f/) of the diode-TEGs were compared with simulated V/sub f/ and the lifetime was determined from the lifetime parameter of simulations. The estimated lifetime value was verified by the reverse recovery current characteristic.

New intelligent power module for electric vehicles

A new intelligent power module (IPM) of 450 A, 600 V has been developed. There are three major aspects in IPM development: IGBT (insulated gate bipolar transistor) device technology, packaging technology, and intelligent driver and protection circuits technology. The IGBT device has low power loss and high switching speed. The packaging has a smart housing with special easy-to-use connectors and high density mounting. The developed circuits constitute a three phase inverter bridge, driver and three protection functions (short-circuit, over-temperature, and control supply under-voltage lock) in addition to a serially-coded fault output function. Furthermore, reliability and cost are important factors for electric vehicles. This paper describes the structure and the superior electric characteristics of the new IPM.