Condition monitoring of inverter power devices based on electromagnetic acoustic emissions

Unlike conventional voltage and current sensing, this paper studies the use of acoustic emission signals to detect the condition of the power device for a DC–AC inverter. As a relatively new method for monitoring power devices, there are some unknown phenomena in acoustic emissions (also called mechanical stress wave). Therefore, the authors present an experimental setup that is used to analyze acoustic emission signals. Based on experimental results, some interesting points have been found: (1) The generation of a mechanical stress wave is verified for the first time. (2) The time-domain peak value, energy, and rise time of the mechanical stress wave at the turn-on time of a power device are barely affected by the load. Meanwhile, these values decrease with an increase of the load at the turn-off time. (3) The frequency-domain peak value of the mechanical stress wave tends to decrease with an increase of the load, and the peak frequency is barely affected by the load. These mechanical stress analysis results can be utilized for condition monitoring in many applications.