Aside from the direct temperature measurement, there are two major techniques for the stator winding temperature esti mation: thermal-model-based approaches and parameter-based approaches. The thermal-model based approaches estimate the temperature from an equivalent thermal circuit 16H101. The most well-known method is the lumped-parameter thermal net work proposed by Mellor et al. [6]. This detailed system is an eighth-order dynamic model, with a large number of thermal resistances and capacitances, either derived analytically from the machine's dimensions and material thermal properties, or directly obtained from various offline tests. With some accept able sacrifices of accuracy, a few simplified thermal models have been proposed [7] 19]; the computation is less complicated, but there are still a significant amount of model parameters to be identified from the motor specification and offline experiments To summarize, this method is complex; it cannot be univer sally implemented for different types of electric machines 16l; and the accuracy cannot be guaranteed under various cooling conditions [21-15], [11]