Optimization 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. 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 dcurrent and the injected voltage pulse width. Several method operating points will be discussed and compared in terms of sensitivity and influence on the motor performance.