This document introduces the use of a magnetic field analysis to obtain the speed versus time graph, the current waveform, and the torque versus time graph for a universal motor.
The speed versus time graph from when the motor starts to 0.4 seconds is indicated in Fig. 1, the current waveform of the stator coil is indicated in Fig. 2, and the torque versus time graph is indicated in Fig. 3.
The universal motor reaches a rotation speed of 6,000 rpm at approximately 0.35 seconds as indicated in Fig. 1. Furthermore, the larger the current flowing through the stator coil is, the larger the torque becomes when the motor is started. As the rotation speed increases, the current and torque decrease.