Efficient Sensorless Speed Control Techniques for BLDC Motors Using Back-EMF Zero-Crossing

Sensorless control of Brushless DC (BLDC) motors is a cost-effective and reliable alternative to traditional Hall sensor-based methods, eliminating the need for additional hardware while enhancing system robustness. This study integrates a proportional-integral (PI) controller with a robust closed-loop sensorless speed control strategy for a BLDC motor. Back-EMF Zero-Crossing Detection (ZCD). By introducing a 30° phase delay for exact commutation and collecting rotor position information from the back-EMF of the unexcited phase, the suggested method eliminates the need for position sensors. By dynamically modifying the PulseWidthModulation (PWM) duty cycle of the VoltageSource Inverter (VSI) based on real-time speed error, an API controller is built to control motor speed. MATLAB/Simulink is used to model and simulate the system, which consists of a BLDC motor, VSI, DClink capacitor, and AC rectifier. Real-time implementation using dSPACE further validates the suggested control strategy by demonstrating stable speed control, fast dynamic response, and decreased steady-state error. The sensorless control method provides a cost-effective, efficient, and reliable solution, making it highly suitable for industrial automation, electric vehicles, and renewable energy applications.