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Lookup NU author(s): Professor Paul Acarnley,
Dr Chris French,
Dr Christopher Johnson
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The traditional method of thermal design for a power electronics system is to work out the worse case operating conditions, then select the power device that is capable of the job. To ensure that the heatsink can transfer the heat loss from the device whatever the ambient conditions might be, the thermal diffusion of the heatsink will be much greater than that of the device case and even more so for the device's active junction. This implies that the transient performance can not be evaluated purely with the traditional heatsink mounted temperature sensor, i.e. it is only valid as a mechanism for ensuring that the devices stay within the designed safe operating region, this will inevitably lead to a thermal derating of the switching device. This paper introduces an observer-based method of estimating the active junction temperature of a power MOSFET. With this approach the instantaneous performance of the device can be constantly monitored and controlled. The algorithm uses the devices electrical terminal quantities of load current and on-state voltage for its estimation. The observer model performance is constantly monitored by a load estimation scheme, where the error generated between this and the measured current can be used to update the model. The estimation scheme is shown operating in real time within a DSP based drive system and consequently thermal time performance of the estimation scheme is illustrated with the aid of experimental results.
Author(s): Acarnley PP, French CD, Johnson CM
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: 8th European Conference on Power Electronics and Applications
Year of Conference: 1999
Number of Volumes: 1
Publisher: EPE Association
Library holdings: Search Newcastle University Library for this item