Low Power Brushed Direct Current Motor Commutation Noise Analysis

Brushed DC (BDC) motors are widely used in cost-sensitive applications due to their simplicity and affordability, typically relying on Hall sensors or optical gate-based sensors for position and speed control. This paper explores the potential for sensorless control in BDC motors with power consumption below 5W, with the aim of further reducing costs by eliminating the need for physical sensors. The study begins with an overview of the low-cost encoder mechanisms, followed by an in-depth analysis of the commutation process and the mathematical modeling of the motor. Empirical measurements validate the-oretical findings, demonstrating the derivation of an index signal from the commutation ripple, which enables precise rotation feedback. In addition, the paper discusses the implementation of signal conditioning circuitry on development boards to facili-tate advanced digital signal processing in educational settings. This approach opens new opportunities for higher education students to experiment with and verify various sensorless control algorithms, using voltage and current noise as key inputs for embedded motor control applications.