Floating-Reference On-State Voltage Measurement Strategy for Condition Monitoring Application

Due to its acceptable sensitivity to aging, on-state voltage is one of the best degradation indicators ever devised to monitor the condition of power semiconductors. The steep changes in the voltage of the semiconductors during switching have prompted the development of various circuits to extract the on-state voltage. This article proposes a simple converter-level structure for measuring the on-state voltage of every power semiconductor in a three-phase conventional inverter. As a result of its features, the proposed circuit enables the development of a hand-held portable monitoring device that can be used independently of the converter. Detailed information is given on how to design and select the components of the proposed monitoring system, along with its optimal operating conditions. In addition to the simulation results, a proof-of-concept prototype has been developed to evaluate the measurement accuracy and dynamic performance of the proposed circuit for the application of a three-phase inverter. The results confirm the overall effectiveness of the proposed topology and its comparable performance.