Transient Current Ratio Dendrite Net for High-Resistance Connection Diagnosis in BLDCM

High-resistance connection (HRC) in brushless dc motors (BLDCMs) would cause motor performance reduction, equipment breakdown, and even fires. Therefore, it is important to diagnose HRC. Until now, there have been few studies focusing on HRC diagnosis, and most of them cannot adapt well to various application scenarios. To address this problem, the transient current ratio dendrite net (TCR-DD) is proposed for HRC diagnosis. TCR-DD consists of two parts: transient current ratio (TCR) and dendrite net (DD). TCR is a novel index that is constructed with the ratio of transient currents in three-phase and averaged in the mechanical cycle. TCR can be utilized for HRC detection and HRC phase localization. DD is applied to estimate the HRC resistances, whose inputs are TCR, mean voltage, mean current, and rotating speed. These inputs are easily measured or available in some motor driver systems. To validate the effectiveness of the proposed method, the HRC experiments of wye-connected and delta-connected BLDCM are, respectively, conducted under various operating conditions. Based on these experimental data, the comparison results reveal that TCR has better sensitivity to HRC resistance and better noise immunity, and TCR-DD shows better performance and greater adaptability than other methods.