Sensitivity and robustness aspects of sensorless rotor temperature estimation technique for Permanent Magnet Synchronous Motor

The work focuses on tuning issues of a recently presented sensorless rotor temperature estimation technique for Permanent Magnet Synchronous Motors (PMSMs). The method implies an intermittent injection of a voltage pulse in the d-axis of the motor while keeping the load current zero. Thus, the resulting d-current response depends on both the initial value of the d-current itself and the actual magnetization level of the permanent magnets. Since the magnetization of the magnets depends on the temperature, different d-current slopes are associated with given temperature levels of the magnets. The sensitivity of the method depends strongly on the initial d-current and the injected voltage pulse width. Several method operating conditions will be discussed and compared in terms of sensitivity and influence on the motor performance.