Online Ringing Characterization as a Diagnostic Technique for IGBTs in Power Drives

Embeddable features that are easily incorporated in traditional power drive systems are identified for prognostics and health management (PHM) systems. The proposed novel feature takes advantage of the original pulsewidth modulation (PWM) waveform produced by the inverter that is already available in the system as a succession of step functions to study the system's response at high frequencies. The high-order oscillatory responses (ringing) present in the voltages and currents of the system are a reflection of the interaction among the internal parametric components of the power devices, allowing device characterization. Evaluating the change over time of these parameters characterized from ringing becomes a key novel feature to assess the aging status of the power electronic circuit and electric machine with respect to transistor degradation. We propose the use of a low-cost bandpass analog filter centered at a high frequency, which is relevant as a feature input capable of aging tracking. The simplified model supporting ringing as a feature to evaluate component aging and its experimental evaluation are presented with experimental data, corroborating its viability as a practical real-time power device health-state indicator.