Like any other electric motor, a permanent magnet electric motor works on electromagnetic principles and has some mechanical function to perform at every instance of its operation. With increasing demand for more compact power density in miniature motors, the establishment of useful life and the methodology to establish that life becomes important for motor manufacturers or engineers.

Let’s first review the way to predict the life of such permanent magnet motors, using a Weibull diagram and reliability fundamentals.  Based on a complex mathematical model, the Weibull diagram allows estimating the expected life of a motor by measuring a few samples.  This can better help understand the process used to estimate motor life in an application.