Rotating Speed Detection Method for Auto-Start Application of Automotive Alternator

In this paper, an alternator rotating speed detection method for auto-start application is presented, which proposes to detect the alternator rotating speed from the frequency of field signal at rotor side. The conventional methods detects the alternator rotating speed from the frequency of phase signal at stator side, which is easily interfered by the leakage current of rectifier diodes. The proposed method solves the above issue and stably gets the alternator rotating speed from the rotor signal even though the phase signal is distorted by the leakage current of rectifier diodes. Experimental results verified the analysis.