From May 2001 to October 2004
Project Leader(s): Dr Volker Pickert
Sponsors: EPSRC (GR/R02634)
Reliable operation of a power electronic switching device is limited by the instantaneous temperature of the device junction. However direct measurement of device temperature is possible only in the laboratory using specialised and expensive equipment. This project will develop methods of estimating device temperature using readily-available measurements, such as device voltage, current and ambient temperature, in conjunction with an electro-thermal model of the device, which can be evaluated in real-time. As well as developing and implementing the model as part of a closed-loop observer, the project will define convenient methods for establishing model parameter values. With a real-time estimate of device junction temperatures available to the current controller, it will be possible to operate the converter consistently closer to the limits imposed by the heatsink capacity and to adopt innovative loss-reduction strategies as these limits are approached. In pulsed power applications device life expectancy can be much reduced by thermal cycling: during a power pulse the device is heated very rapidly and then left to cool until the next power pulse is delivered. The availability of a fast reliable estimate to device temperature opens up the intriguing possibility of reducing temperature variation by artificially generating losses within the device during inactive periods.
Professor Volker Pickert