Study on inspection of the initial rotor position of BLDC based on high-frequency signal injection

In order to detect the initial rotor position of sensorless brushless DC motor in stationary condition, this paper applied the high-frequency signal injection. Utilizing the motor saliency effects, this method worked out the initial rotor position via detecting the different current response of the three phase caused by high-frequency signal injection. This method made up the defect of conventional detection method which behaved unsatisfactorily when motor is in stationary condition. Simulation results showed that in the case of stationary, method proposed by this paper not only detected the initial rotor position accurately, but also reduced the torque ripple of the motor. So by applying this method, the dynamic and static performance of the system can be improved.