A Low-cost, Minimally-invasive Embedded Monitoring Method for Early Detection of Transistor On-state Resistance Degradation in Power Electronics Systems

A novel embedded sensing and diagnosis method is proposed for early detection of on-state resistance (RON) variations in power transistors. It is intended for the reliability improvement of power electronics systems, such as DC-DC converters, as is the case in this paper. The method relies on minimally-invasive interfacing circuits, which minimizes the overall reliability degradation, while allowing the operation of the DC-DC converter combined with signal processing algorithms. It is therefore a low-cost solution suitable for embedded applications during the operation of highly-integrated power electronics systems. It allows detecting small on-state resistance (RON) variations in increments of 70 mΩ in switching power transistors, based on the sensing of drain-source voltage (VDS), which is used as a monitoring of component aging or early warning of component failure. The VDS is measured through the combination of a voltage sensing circuit that includes a voltage clamper function to accommodate high VDS voltage, and a read-back function interfacing with a signal processing unit. The read-back signal is processed by a filtering behavioral model which eliminates high-level noise perturbations coming from the supply rail and provides a reliable early awareness of RON variations.