Online optimised stator flux reference approximation for maximum torque-per-ampere operation of interior permanent-magnet machine drive under direct torque control

The reliability of press-fit connectors of IGBT modules was investigated. No change in contact resistance between press-fit pins and PCB vias was found after active thermal cycling, vibration and corrosion. However, the press-out forces after active thermal cycling have been reduced by ~30%. In addition to chemical tin, also the cheaper hot air levelling (HAL) was used as PCB finish and similar results have been shown. Furthermore, the current-carrying capability (also termed ampacity) of the press-fit pins was tested applying nominal current and two times nominal current. Again, no difference in electrical contact resistance before and after the test was found. Cases where one of the two pin legs was without contact to the via were also investigated by this method. It was shown that these partially open contacts are not influencing the current carrier capability significantly. Additional to the measurements, 3D finite element modelling (FEM) was employed to investigate the current distribution within the pin-via-trace geometry. Good agreement to the experimental resistance measurements was found, supporting the findings stated above.