Thermal modelling of AC commutator motors for domestic appliances

The author evaluates the temperature rise of small AC commutator motors used in domestic appliances. The AC commutator motor construction is similar to a series wound DC machine with laminated stator and rotor. These machines differ from normal industrial electric motors in many cases as they are often designed to be an integral part of the appliance rather than a bolt-on source of mechanical power. This requires the thermal model to be adapted to each application. The basis of the study in this case was a hover mower. The three principle parts of the thermal analysis discussed by the author are: a method for determining the electric, magnetic and friction losses; a method for determining the flow of cooling air through the machine; and a method for evaluating the temperature rise within the machine based upon the losses and the flow of cooling air