This paper proposes a health indicator estimation method based on the digital-twin concept aiming for condition monitoring of power electronic converters. The method is noninvasive, without additional hardware circuits, and calibration requirements. An application for a Buck DC-DC converter is demonstrated with theoretical analyses, practical considerations, and experimental verifications. The digital replica of an experimental prototype is established, which includes the power stage, sampling circuit, and close-loop controller. Particle Swarm Optimization (PSO) algorithm is applied to estimate the unknown circuit parameters of interest based on the incoming data from both the digital twin and the physical prototype. Cluster-data of the estimated health indicators under different testing conditions of the Buck converter is analyzed and used for observing the degradation trends of key components, such as capacitor and MOSFET. The outcomes of this study serve as a key step for achieving non-invasive, cost-effective, and robust condition monitoring for power electronic converters.

This letter proposes a converter-level method for measuring the on-state voltages of all power semiconductors in a single-phase inverter by using a single circuit only. The proposed circuit distinguishes itself by connecting to the middle-point of each phase-leg, instead of the two powerterminals of individual devices as conventional methods do. It has the advantages of reduced circuit complexity, size, cost, and ease of connection. The principle and theoretical analysis of the proposed converter-level method are discussed. A case study on a single-phase full-bridge inverter is demonstrated to prove the concept.

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This paper discloses part of an invention on plugand-play converter-level on-state voltage measurement methods for power semiconductor devices. To exclude the external power supply required in on-state voltage measurement circuits, a selfpower solution is proposed to provide the required bidirectional low-voltage power sources. The application of the measurement circuit with the proposed self-power solution is demonstrated for a single-switch, a single-phase inverter, and a three-phase inverter.

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In this paper, a universal H-bridge circuit is used as a loading emulator to investigate the loss and thermal models of the power semiconductor. Based on its operation principle and modulation method, the dominating factors’ (e.g., power factor, loading current, fundamental frequency, and switching frequency) impact on the thermal stress of power semiconductors is considerably evaluated. The junction temperature in terms of the mean value and its swing is verified by using Piecewise Linear Electrical Circuit Simulation (PLECS) simulation and experimental setup. It helps to allocate the loading condition in order to obtain the desired thermal stress.

IEEE Transactions on Instrumentation and Measurement(d)a j−1 Sigma points of dth particle at time t j−1 . K jKalman gain at time t j . wWeights of particles (or smoothers).