Educational and Experimental Study for Evaluation of an Universal Motor

The present paper refers to a special electrical motor, the universal one, which is used in home appliances and electrical tools. It is very important for this motor to be tested and evaluated under different conditions of load and power supply, in order to find the optimum functioning parameters. The load that was used is an electrical one consisting of an automotive type alternator with all the necessary electrical circuits. For this set-up (universal motor connected to an electrical alternator), an important number of parameters can be measured and computed. The objectives of this work are to determine the influence of the supply voltage type (D.C., A.C. and PWM) and the characteristics of the motor for different loads. This evaluation procedure can be defined as a low-cost one, mainly because it doesn't use a transducer for mechanical torque such that the investigation's result is the same. The procedure is applicable for all kind of motors. It is also useful for didactic purposes and for evaluating the motor performance in different situations.