Purpose/Aim
During aircraft operation, the normal operation of the motor system plays a vital role in the safety and reliability of aircraft flight. According to the insulation structure of motors, motors can be divided into insulation type Ⅰ structure with rated voltage lower than 700V and insulation type Ⅱ structure with a rated voltage higher than 700V. Most of the insulation structures used in EMAs belong to type Ⅰ. However, some of the current studies have been conducted to evaluate the insulation status of type Ⅱ motor windings and life assessment. These theories are insufficient to support the evaluation of the insulation status of type Ⅰ. Therefore, this paper studies the influence of aging factors on the working life of insulation type Ⅰ structures.
Experimental/Modeling methods
Due to the low rated voltage of insulation type Ⅰ construction windings, only the influence of thermal stress on insulation aging needs to be considered during the test. In this test, an accelerated thermal aging test platform was built to study the changes of various insulation parameters under different thermal stresses, and a suitable parameter was selected as the characterization factor p to evaluate the performance state and realize life prediction of winding insulation. At the same time, a two-parameter Weibull distribution model is used to analyze the statistical law of the characterization factor.
Results/discussion
As shown in Figure 1, the surface of the sample became rough, and the mechanical hardness decreased after aging. When measuring the insulation capacitance (IC) of a sample at a high frequency, there was a strong correlation between its value and the aging time, and the measured value was relatively stable, and the measurement repeatability was high. Therefore, the ratio of the IC value measured in real-time to the IC₀ without aging was used as the characterization factor p of the insulation state to evaluate the performance state and life prediction of the insulation; the numerical degradation model is shown in Figure 2. Finally, the corresponding winding life prediction model was obtained on this basis, and the accuracy of the model was verified by samples with different temperature levels and different aging temperatures. The lifetime error is less than 10% at the test temperature below 300°C.
Conclusions
This paper proposes a test method for rapid thermal aging and multi-insulation parameter characterization of low-voltage aviation motor windings and builds a relevant test platform. The aging law that IC value decreases with the increase of insulation thermal aging time in a logarithmic function relationship is obtained, thus establishing a winding insulation life prediction model with IC/IC₀ as the insulation state characterization factor. Based on this model, the prediction of insulation life can be achieved by conducting only a few cycles of thermal aging tests on the windings. The error of the model is less than 10%, which provides a theoretical basis for the safe operation of insulation type Ⅰ windings and improves the reliability of the operation of low-voltage aero-motor systems.

Aging,,Aviation Motor Winding,，Life Model