Sensitivity analysis of a permanent magnet temperature observer for PM synchronous machines using the Monte Carlo method

Monitoring rotor temperatures In permanent magnet machines is vital to avoid irreversible demagnetization. Different strategies have been developed among which the permanent magnet temperature observer (PMTO) stands out given its independence from signal injection and thermal models. In spite of its uncomplicated implementation, PMTO accuracy and sensitivity had been not deeply studied. This contribution presents a sensitivity analysis of the PMTO considering manufacture tolerances in the sensors that influence its performance: position, current, and DC-link voltage sensors. Results from Monte Carlo simulations showed a complex interaction between the sensor tolerances and achievable observer accuracy. While current sensor deviations play a minimum role in PMTO accuracy, voltage and position sensor deviations are critical. A statistical analysis reveled that a production quality control based on a sample of the population is not enough to guarantee an appropriate PMTO accuracy. Thus, specific sensor deviation ranges are required and were determined in this contribution.