Electro thermal analysis of AC commutator motor driving A food mixer with load integrated model

Abstract

Fractional and higher kilo watt Universal Motors are widely used in food mixers at homes to large industrial blenders respectively. To ensure safety, and longevity in operation, it becomes significant to concentrate on the thermal performance of the machine. For a successful performance of the electrical machines, it is necessary to predict an accurate temperature distribution in most sensitive parts of the machine to prevent the damages that can occur either by breakdown or failure in winding insulation. The insulation failure is due to heating of the windings used in the motor. As the insulation failure reduces the life of the electrical machine, the hotspot temperature in the winding must be predicted earlier and mitigated to increase the life of the machine. newlineThe objective of this work is to propose a novel load integrated dynamic electro thermal model for a Universal Motor used in food mixer to predetermine the thermal behaviour and estimate the unmeasured temperature in the rotating parts. The texture and size of the mixing/grinding load has a great impact on the thermal behaviour of the driving motor and needs to be represented appropriately in the model. This thesis proposes an appropriate load model integrated with the electrothermal model which has direct influence on heat generation sources. The proposed model is suitable of predetermining the temperature at various parts of the system for load cycles experienced in the food mixer. A better thermal performance is predicted through intermittent control technique. Temperature of inaccessible rotor parts are estimated with the design of asymptotic estimator with measurements from accessible stator parts. Experimental verification of the proposed model and estimated technique on a 550W food mixer validates the effectiveness of proposed scheme. Results are useful in predetermining and preventing thermal runaway problems in food mixer. A reduced order model derived using balanced truncation method is proposed and validated. newline