A Coil Temperature Estimation for Disk Rotor Type Brushless DC Motors

Electrical motors are used in a wide range of industrial fields, including drones and automobiles. With the development of these fields, motors are required to have higher torque, which can be achieved by applying a current higher than the rated value. However, conventional motors are limited by the current to prevent damage to the motor. In addition, the motor may get damaged if the current exceeds this rating. Therefore, it is essential to measure the coil temperature. Unfortunately, the complicated structure of the motors makes it difficult to install a thermometer inside them. A conventional study developed a coil temperature estimation formula to achieve high torque. The temperature estimation equation can only be estimated when a specific current is applied. Therefore, this study proposes a novel temperature estimation formula that uses heat conduction and heat transfer. The proposed estimation formula can always be used to estimate temperature, even if the current value changes. Finally, the proposed estimation formula was evaluated by comparing the measured values using an actual motor.