Interpolated FFT for real-time detection of belt slip in automotive electric power generation and storage system

Belt slip is an important type of mechanical fault in the automotive electric power generation and storage (EPGS) system. This paper proposes a robust and sensorless solution for detecting serpentine belt slip. The speed of the claw-pole alternator is directly extracted from the rectifier ripple frequency from the alternator output voltage. The estimated alternator speed is then continuously compared with the engine speed to detect possible belt slip. The proposed method is implemented in a real-time fashion on an EPGS test bench. The experimental results show that the method is able to estimate the alternator speed accurately even during fast mechanical transients. The belt-slip fault can thus be reliably detected within a wide speed range. Although originally developed for automotive alternators, the sensorless speed estimation method can be also applied to other AC generators with a DC-link rectifier.